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Marcotte-Chénard A, Tremblay R, Deslauriers L, Geraldes P, Gayda M, Christou D, Mampuya W, Little JP, Riesco E. Comparison of 10 × 1-minute high-intensity interval training (HIIT) versus 4 × 4-minute HIIT on glucose control and variability in females with type 2 diabetes. Appl Physiol Nutr Metab 2024; 49:487-500. [PMID: 38052023 DOI: 10.1139/apnm-2023-0326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Two high-intensity interval training (HIIT) regimens are often used in research and clinical settings. Yet, there has been no direct comparison to determine if one can improve glucose control and variability to a greater extent in individuals living with type 2 diabetes (T2D). Fourteen older females with T2D participated in a semi-randomized control trial where HIIT10 (10 × 1-min intervals at 90% heart rate max; HRmax) and HIIT4 (4 × 4-min intervals at 90% of HRmax) were compared to a control condition (CON; no exercise). Continuous glucose monitoring was used to assess glucose control and variability over 24 h after each condition. Both HIIT10 (-2.1 ± 1.1 mmol/L) and HIIT4 (-2.1 ± 1.3 mmol/L) acutely lowered glucose compared to CON (-0.7 ± 0.8 mmol/L; p = 0.001), with no difference between exercise conditions. This glucose-lowering effect did not persist over the 24-h post-exercise period, as both mean glucose (p = 0.751) and glucose variability (p = 0.168) were not significantly different among conditions. However, exploratory analyses focusing on individuals with less optimal glucose control (above median 24-h mean glucose in the CON condition; n = 7) revealed that 24-h mean glucose (7.4 [7.14-8.92] vs. 8.4 [7.5-9.9] mmol/L; p = 0.048), glucose variability (p = 0.010), and peak glucose (p = 0.048) were lower following HIIT10 compared to CON, while HIIT4 reduced time spent in moderate hyperglycemia compared to CON (p = 0.023). Both HIIT10 and HIIT4 acutely lower glycemia, but the effect does not persist over 24 h. However, in individuals with worse glucose control, HIIT10 may improve mean 24-h glucose and glycemic variability, while HIIT4 may reduce time spent in moderate hyperglycemia.
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Affiliation(s)
- A Marcotte-Chénard
- Research Centre on Aging, CIUSSS de l'Estrie - CHUS, Sherbrooke, QC J1H 4C4, Canada
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke QC, J1K 2R1, Canada
| | - R Tremblay
- Research Centre on Aging, CIUSSS de l'Estrie - CHUS, Sherbrooke, QC J1H 4C4, Canada
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke QC, J1K 2R1, Canada
| | - L Deslauriers
- Research Centre on Aging, CIUSSS de l'Estrie - CHUS, Sherbrooke, QC J1H 4C4, Canada
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke QC, J1K 2R1, Canada
| | - P Geraldes
- CHUS Research Centre, University of Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
| | - M Gayda
- ÉPIC Center of the Montreal Heart Institute, University of Montreal, Montreal, QC H1T 1N6, Canada
| | - D Christou
- Department of Applied Physiology & Kinesiology, University of Florida, Gainesville, FL 32611-8205, USA
| | - W Mampuya
- Research Centre on Aging, CIUSSS de l'Estrie - CHUS, Sherbrooke, QC J1H 4C4, Canada
- CHUS Research Centre, University of Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
| | - J P Little
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC V1V 1V7, Canada
| | - E Riesco
- Research Centre on Aging, CIUSSS de l'Estrie - CHUS, Sherbrooke, QC J1H 4C4, Canada
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke QC, J1K 2R1, Canada
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Sowula PT, Izatt MT, Labrom RD, Askin GN, Little JP. Assessing progressive changes in axial plane vertebral deformity in adolescent idiopathic scoliosis using sequential magnetic resonance imaging. Eur Spine J 2024; 33:663-672. [PMID: 37962687 DOI: 10.1007/s00586-023-08004-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 09/24/2023] [Accepted: 10/14/2023] [Indexed: 11/15/2023]
Abstract
PURPOSE To understand how the axial plane deformity contributes to progression of the three-dimensional spinal deformity of Adolescent Idiopathic Scoliosis (AIS), with a main thoracic curve type, using a series of sequential magnetic resonance images (MRI). METHODS Twenty-seven AIS patients (at scan 1: mean 12.4 years (± 1.5), mean Cobb angle 29.1°(± 8.8°)) had 3 MRI scans (T4-L1) performed at intervals of mean 0.7 years (± 0.4). The outer profile of the superior and inferior endplates were traced on a reformatted axial image using ImageJ (NIH). Endplate AVR, and intravertebral rotation (IVR), defined as the difference between superior and inferior endplate AVR, was calculated for each vertebral level. RESULTS For all patients and scans, the mean AVR was greatest at the curve apex, with AVR diminishing in a caudal and cephalic direction from the apex. At scan 3 the mean apical AVR was 15.1°(± 4.6°) with a mean change in apical AVR between MRI 1 and 3 of 2.7°(± 2.9°). The increase in standing height between MRI 1 and 3 was mean 7.4 cm (± 4.6). Linear regression showed a positive correlation between apical AVR and Cobb angle (R2 = 0.57, P < 0.001), and a positive correlation between apical AVR and rib hump (R2 = 0.54, p < 0.001). The mean change in IVR was greater 3 vertebral levels cephalic and caudal to the apex (1.4°(± 4.1°) and 1.2°(± 2.0°), respectively), compared to the apex (0.4°(± 3.1°)). CONCLUSIONS AVR increased, during curve progression, most markedly at the curve apex. The greatest IVR was observed at the periapical levels, with the apex by contrast having only a modest degree of rotation, suggesting the periapical vertebral levels of the scoliosis deformity may be a significant driver in the progression of AIS.
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Affiliation(s)
- Pawel T Sowula
- Biomechanics and Spine Research Group, Centre for Biomedical Technologies at the Centre for Children's Health Research, School of Mechanical, Medical and Process Engineering, Queensland University of Technology, 62 Graham St, South Brisbane, 4104, Australia.
- Queensland Children's Hospital, Brisbane, Australia.
| | - Maree T Izatt
- Biomechanics and Spine Research Group, Centre for Biomedical Technologies at the Centre for Children's Health Research, School of Mechanical, Medical and Process Engineering, Queensland University of Technology, 62 Graham St, South Brisbane, 4104, Australia
- Queensland Children's Hospital, Brisbane, Australia
| | - Robert D Labrom
- Biomechanics and Spine Research Group, Centre for Biomedical Technologies at the Centre for Children's Health Research, School of Mechanical, Medical and Process Engineering, Queensland University of Technology, 62 Graham St, South Brisbane, 4104, Australia
- Queensland Children's Hospital, Brisbane, Australia
- Mater Hospital, Brisbane, Australia
| | - Geoffrey N Askin
- Biomechanics and Spine Research Group, Centre for Biomedical Technologies at the Centre for Children's Health Research, School of Mechanical, Medical and Process Engineering, Queensland University of Technology, 62 Graham St, South Brisbane, 4104, Australia
- Queensland Children's Hospital, Brisbane, Australia
- Mater Hospital, Brisbane, Australia
| | - J Paige Little
- Biomechanics and Spine Research Group, Centre for Biomedical Technologies at the Centre for Children's Health Research, School of Mechanical, Medical and Process Engineering, Queensland University of Technology, 62 Graham St, South Brisbane, 4104, Australia
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Duncombe P, Izatt MT, Pivonka P, Claus A, Little JP, Tucker K. Quantifying Muscle Size Asymmetry in Adolescent Idiopathic Scoliosis Using Three-dimensional Magnetic Resonance Imaging. Spine (Phila Pa 1976) 2023; 48:1717-1725. [PMID: 37432908 DOI: 10.1097/brs.0000000000004715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Accepted: 04/29/2023] [Indexed: 07/13/2023]
Abstract
STUDY DESIGN This is a case-control study of prospectively collected data. OBJECTIVE To quantify paraspinal muscle size asymmetry in adolescent idiopathic scoliosis (AIS) and determine if this asymmetry is (i) greater than observed in adolescent controls with symmetrical spines; and (ii) positively associated with skeletal maturity using Risser grade, scoliosis severity using the Cobb angle, and chronological age in years. SUMMARY OF BACKGROUND DATA AIS is a three-dimensional deformity of the spine which occurs in 2.5% to 3.7% of the Australian population. There is some evidence of asymmetry in paraspinal muscle activation and morphology in AIS. Asymmetric paraspinal muscle forces may facilitate asymmetric vertebral growth during adolescence. METHODS An asymmetry index [Ln(concave/convex volume)] of deep and superficial paraspinal muscle volumes, at the level of the major curve apex (Thoracic 8-9 th vertebral level) and lower-end vertebrae ( LEV , Thoracic 10-12 th vertebral level), was determined from three-dimensional Magnetic Resonance Imaging of 25 adolescents with AIS (all right thoracic curves), and 22 healthy controls (convex=left); all female, 10 to 16 years. RESULTS Asymmetry index of deep paraspinal muscle volumes was greater in AIS (0.16±0.20) than healthy spine controls (-0.06±0.13) at the level of the apex ( P <0.01, linear mixed-effects analysis) but not LEV ( P >0.05). Asymmetry index was positively correlated with Risser grade ( r =0.50, P <0.05) and scoliosis Cobb angle ( r =0.45, P <0.05), but not age ( r =0.34, P >0.05). There was no difference in the asymmetry index of superficial paraspinal muscle volumes between AIS and controls ( P >0.05). CONCLUSIONS The asymmetry of deep apical paraspinal muscle volume in AIS at the scoliosis apex is greater than that observed at equivalent vertebral levels in controls and may play a role in the pathogenesis of AIS.
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Affiliation(s)
- Phoebe Duncombe
- School of Biomedical Sciences, The University of Queensland, Australia
| | - Maree T Izatt
- Biomechanics and Spine Research Group, Centre for Children's Health Research, Queensland University of Technology, Australia
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Australia
| | - Peter Pivonka
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Australia
| | - Andrew Claus
- School of Health & Rehabilitation Sciences, The University of Queensland, Australia
- Royal Brisbane and Women's Hospital, Tess Cramond Pain and Research Centre, Australia
| | - J Paige Little
- Biomechanics and Spine Research Group, Centre for Children's Health Research, Queensland University of Technology, Australia
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Australia
| | - Kylie Tucker
- School of Biomedical Sciences, The University of Queensland, Australia
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Labrom FR, Izatt MT, Askin GN, Labrom RD, Claus AP, Little JP. Quantifying Typical Progression of Adolescent Idiopathic Scoliosis: Longitudinal Three-Dimensional MRI Measures of Disk and Vertebral Deformities. Spine (Phila Pa 1976) 2023; 48:1642-1651. [PMID: 37702242 DOI: 10.1097/brs.0000000000004829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 09/06/2023] [Indexed: 09/14/2023]
Abstract
STUDY DESIGN A prospective cohort study. OBJECTIVE Detail typical three-dimensional segmental deformities and their rates of change that occur within developing adolescent idiopathic scoliosis (AIS) spines over multiple timepoints. SUMMARY OF BACKGROUND DATA AIS is a potentially progressive deforming condition that occurs in three dimensions of the scoliotic spine during periods of growth. However, there remains a gap for multiple timepoint segmental deformity analysis in AIS cohorts during development. MATERIALS AND METHODS Thirty-six female patients with Lenke 1 AIS curves underwent two to six sequential magnetic resonance images. Scans were reformatted to produce images in orthogonal dimensions. Wedging angles and rotatory values were measured for segmental elements within the major curve. Two-tailed, paired t tests compared morphologic differences between sequential scans. Rates of change were calculated for variables given the actual time between successive scans. Pearson correlation coefficients were determined for multidimensional deformity measurements. RESULTS Vertebral bodies were typically coronally convexly wedged, locally lordotic, convexly axially rotated, and demonstrated evidence of local mechanical torsion. Between the first and final scans, apical measures of coronal wedging and axial rotation were all greater in both vertebral and intervertebral disk morphology than nonapical regions (all reaching differences where P <0.05). No measures of sagittal deformity demonstrated a statistically significant change between scans. Cross-planar correlations were predominantly apparent between coronal and axial planes, with sagittal plane parameters rarely correlating across dimensions. Rates of segmental deformity changes between earlier scans were characterized by coronal plane convex wedging and convexly directed axial rotation. The major locally lordotic deformity changes that did occur in the sagittal plane were static between scans. CONCLUSIONS This novel investigation documented a three-dimensional characterization of segmental elements of the growing AIS spine and reported these changes across multiple timepoints. Segmental elements are typically deformed from initial presentation, and subsequent changes occur in separate orthogonal planes at unique times.
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Affiliation(s)
- Fraser R Labrom
- Biomechanics & Spine Research Group, Centre for Children's Health Research, Queensland University of Technology, Brisbane, Australia
- Queensland Children's Hospital and Mater Health Services, Brisbane, Australia
| | - Maree T Izatt
- Biomechanics & Spine Research Group, Centre for Children's Health Research, Queensland University of Technology, Brisbane, Australia
- Queensland Children's Hospital and Mater Health Services, Brisbane, Australia
| | - Geoffrey N Askin
- Biomechanics & Spine Research Group, Centre for Children's Health Research, Queensland University of Technology, Brisbane, Australia
- Queensland Children's Hospital and Mater Health Services, Brisbane, Australia
| | - Robert D Labrom
- Biomechanics & Spine Research Group, Centre for Children's Health Research, Queensland University of Technology, Brisbane, Australia
- Queensland Children's Hospital and Mater Health Services, Brisbane, Australia
| | - Andrew P Claus
- Tess Cramond Pain and Research Centre, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia
- University of Queensland, School of Health & Rehabilitation Sciences, St Lucia, Queensland, Australia
| | - J Paige Little
- Biomechanics & Spine Research Group, Centre for Children's Health Research, Queensland University of Technology, Brisbane, Australia
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Rayward L, Pearcy M, Kerr G, Pivonka P, Little JP. Engineering the perfect mattress: The influence of substrate mechanics on deep tissue stresses in supine. Clin Biomech (Bristol, Avon) 2023; 110:106130. [PMID: 37897845 DOI: 10.1016/j.clinbiomech.2023.106130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 10/17/2023] [Accepted: 10/18/2023] [Indexed: 10/30/2023]
Abstract
BACKGROUND With increasing global interest in sleep hygiene, sleep ergonomics is an area that has been largely understudied. During sleep individuals turn over during the night to restore blood flow in occluded blood vessels, indicating that control of local tissue pressure may play a role in improving sleep comfort. This study investigates the influence of mattress stiffness on tissue compressive stresses during supine lying. METHODS A subject-specific 3D finite element (FE) model of the pelvis area has been developed to simulate supine lying on substrates of varying firmness. Constitutive parameters for the adipose-skin tissue and muscle-organ tissue were calibrated using a novel application of the inverse finite element method. FINDINGS The compressive stress was consistently greatest in the muscle interfacing the sacrum at 18.5 kPa on the soft foam, and 30.9 kPa on the firm foam. From soft to firm, the compressive stress increased by 67% at the sacrum, 20% at the ischium, 42% at the lesser trochanter, and 50% at the skin. INTERPRETATION The non-linearity of the foam substrate had a pressure distributing effect, relieving the peak compressive stresses at the sacrum, indicating that it may be possible to design arrays of foam substrates that can provide most efficient pressure relief.
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Affiliation(s)
- Lionel Rayward
- Biomechanics and Spine Research Group, Centre for Biomedical Technologies, Queensland University of Technology, Australia.
| | - Mark Pearcy
- Biomechanics and Spine Research Group, Centre for Biomedical Technologies, Queensland University of Technology, Australia
| | - Graham Kerr
- School of Exercise & Nutrition Sciences, Faculty of Healthy, Queensland University of Technology, Australia
| | - Peter Pivonka
- Faculty of Engineering, School of Mech., Medical & Process Engineering, Queensland University of Technology, Australia
| | - J Paige Little
- Biomechanics and Spine Research Group, Centre for Biomedical Technologies, Queensland University of Technology, Australia
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Roser MJ, Askin GN, Labrom RD, Zahir SF, Izatt M, Little JP. Vertebral body tethering for idiopathic scoliosis: a systematic review and meta-analysis. Spine Deform 2023; 11:1297-1307. [PMID: 37432604 PMCID: PMC10587225 DOI: 10.1007/s43390-023-00723-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 06/17/2023] [Indexed: 07/12/2023]
Abstract
PURPOSE Vertebral body tethering (VBT) is a recent procedure to correct and reduce spinal curves in skeletally immature patients with adolescent idiopathic scoliosis (AIS). The purpose of this systematic review and meta-analysis is to determine the expected curve reduction and potential complications for adolescent patients after VBT. METHODS PubMed, Embase, Google Scholar and Cochrane databases were searched until February 2022. Records were screened against pre-defined inclusion and exclusion criteria. Data sources were prospective and retrospective studies. Demographics, mean differences in Cobb angle, surgical details and complication rates were recorded. Meta-analysis was conducted using a random-effects model. RESULTS This systematic review includes 19 studies, and the meta-analysis includes 16 of these. VBT displayed a statistically significant reduction in Cobb angle from pre-operative to final (minimum 2 years) measurements. The initial mean Cobb angle was 47.8° (CI 95% 42.9-52.7°) and decreased to 22.2° (CI 95% 19.9-24.5°). The mean difference is - 25.8° (CI 95% - 28.9-22.7) (p < 0.01). The overall complication rate was 23% (CI 95% 14.4-31.6%), the most common complication was tether breakage 21.9% (CI 95% 10.6-33.1%). The spinal fusion rate was 7.2% (CI 95% 2.3-12.1%). CONCLUSION VBT results in a significant reduction of AIS at 2 years of follow-up. Overall complication rate was relatively high although the consequences of the complications are unknown. Further research is required to explore the reasons behind the complication rate and determine the optimal timing for the procedure. VBT remains a promising new procedure that is effective at reducing scoliotic curves and preventing spinal fusion in the majority of patients. LEVEL OF EVIDENCE Systematic review of Therapeutic Studies with evidence level II-IV.
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Affiliation(s)
- Megan J. Roser
- Orthopaedics Department, Queensland Children’s Hospital, South Brisbane, Australia
- Biomechanics and Spine Research Group (BSRG), Centre for Children’s Health Research, Queensland University of Technology (QUT), Brisbane, Australia
| | - Geoffrey N. Askin
- Orthopaedics Department, Queensland Children’s Hospital, South Brisbane, Australia
- Biomechanics and Spine Research Group (BSRG), Centre for Children’s Health Research, Queensland University of Technology (QUT), Brisbane, Australia
| | - Robert D. Labrom
- Orthopaedics Department, Queensland Children’s Hospital, South Brisbane, Australia
- Biomechanics and Spine Research Group (BSRG), Centre for Children’s Health Research, Queensland University of Technology (QUT), Brisbane, Australia
| | - Syeda Farah Zahir
- Queensland Cyber Infrastructure Foundation (QCIF), Facility for Advanced Bioinformatics, The University of Queensland (UQ), Brisbane, Australia
| | - Maree Izatt
- Orthopaedics Department, Queensland Children’s Hospital, South Brisbane, Australia
- Biomechanics and Spine Research Group (BSRG), Centre for Children’s Health Research, Queensland University of Technology (QUT), Brisbane, Australia
| | - J. Paige Little
- Biomechanics and Spine Research Group (BSRG), Centre for Children’s Health Research, Queensland University of Technology (QUT), Brisbane, Australia
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Suresh S, Perera P, Izatt MT, Labrom RD, Askin GN, Little JP. Development and validation of a semi-automated measurement tool for calculating consistent and reliable surface metrics describing cosmesis in Adolescent Idiopathic Scoliosis. Sci Rep 2023; 13:5574. [PMID: 37019938 PMCID: PMC10076386 DOI: 10.1038/s41598-023-32614-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 03/30/2023] [Indexed: 04/07/2023] Open
Abstract
Adolescent Idiopathic Scoliosis (AIS) is a 3D spine deformity that also causes ribcage and torso distortion. While clinical metrics are important for monitoring disorder progression, patients are often most concerned about their cosmesis. The aim of this study was to automate the quantification of AIS cosmesis metrics, which can be measured reliably from patient-specific 3D surface scans (3DSS). An existing database of 3DSS for pre-operative AIS patients treated at the Queensland Children's Hospital was used to create 30 calibrated 3D virtual models. A modular generative design algorithm was developed on the Rhino-Grasshopper software to measure five key AIS cosmesis metrics from these models-shoulder, scapula and hip asymmetry, torso rotation and head-pelvis shift. Repeat cosmetic measurements were calculated from user-selected input on the Grasshopper graphical interface. InterClass-correlation (ICC) was used to determine intra- and inter-user reliability. Torso rotation and head-pelvis shift measurements showed excellent reliability (> 0.9), shoulder asymmetry measurements showed good to excellent reliability (> 0.7) and scapula and hip asymmetry measurements showed good to moderate reliability (> 0.5). The ICC results indicated that experience with AIS was not required to reliably measure shoulder asymmetry, torso rotation and head-pelvis shift, but was necessary for the other metrics. This new semi-automated workflow reliably characterises external torso deformity, reduces the dependence on manual anatomical landmarking, and does not require bulky/expensive equipment.
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Affiliation(s)
- Sinduja Suresh
- Biomechanics and Spine Research Group (BSRG), Centre for Biomedical Technologies (CBT) at the Centre for Children's Health Research (CCHR), School of Mechanical Medical and Process Engineering, Queensland University of Technology, Brisbane, Australia.
| | - Pasan Perera
- Biomechanics and Spine Research Group (BSRG), Centre for Biomedical Technologies (CBT) at the Centre for Children's Health Research (CCHR), School of Mechanical Medical and Process Engineering, Queensland University of Technology, Brisbane, Australia
| | - Maree T Izatt
- Biomechanics and Spine Research Group (BSRG), Centre for Biomedical Technologies (CBT) at the Centre for Children's Health Research (CCHR), School of Mechanical Medical and Process Engineering, Queensland University of Technology, Brisbane, Australia
- Orthopaedics Department, Queensland Children's Hospital (QCH), Brisbane, Australia
| | - Robert D Labrom
- Biomechanics and Spine Research Group (BSRG), Centre for Biomedical Technologies (CBT) at the Centre for Children's Health Research (CCHR), School of Mechanical Medical and Process Engineering, Queensland University of Technology, Brisbane, Australia
- Orthopaedics Department, Queensland Children's Hospital (QCH), Brisbane, Australia
| | - Geoffrey N Askin
- Biomechanics and Spine Research Group (BSRG), Centre for Biomedical Technologies (CBT) at the Centre for Children's Health Research (CCHR), School of Mechanical Medical and Process Engineering, Queensland University of Technology, Brisbane, Australia
- Orthopaedics Department, Queensland Children's Hospital (QCH), Brisbane, Australia
| | - J Paige Little
- Biomechanics and Spine Research Group (BSRG), Centre for Biomedical Technologies (CBT) at the Centre for Children's Health Research (CCHR), School of Mechanical Medical and Process Engineering, Queensland University of Technology, Brisbane, Australia
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Meszaros-Beller L, Hammer M, Riede JM, Pivonka P, Little JP, Schmitt S. Effects of geometric individualisation of a human spine model on load sharing: neuro-musculoskeletal simulation reveals significant differences in ligament and muscle contribution. Biomech Model Mechanobiol 2023; 22:669-694. [PMID: 36602716 PMCID: PMC10097810 DOI: 10.1007/s10237-022-01673-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 12/08/2022] [Indexed: 01/06/2023]
Abstract
In spine research, two possibilities to generate models exist: generic (population-based) models representing the average human and subject-specific representations of individuals. Despite the increasing interest in subject specificity, individualisation of spine models remains challenging. Neuro-musculoskeletal (NMS) models enable the analysis and prediction of dynamic motions by incorporating active muscles attaching to bones that are connected using articulating joints under the assumption of rigid body dynamics. In this study, we used forward-dynamic simulations to compare a generic NMS multibody model of the thoracolumbar spine including fully articulated vertebrae, detailed musculature, passive ligaments and linear intervertebral disc (IVD) models with an individualised model to assess the contribution of individual biological structures. Individualisation was achieved by integrating skeletal geometry from computed tomography and custom-selected muscle and ligament paths. Both models underwent a gravitational settling process and a forward flexion-to-extension movement. The model-specific load distribution in an equilibrated upright position and local stiffness in the L4/5 functional spinal unit (FSU) is compared. Load sharing between occurring internal forces generated by individual biological structures and their contribution to the FSU stiffness was computed. The main finding of our simulations is an apparent shift in load sharing with individualisation from an equally distributed element contribution of IVD, ligaments and muscles in the generic spine model to a predominant muscle contribution in the individualised model depending on the analysed spine level.
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Affiliation(s)
- Laura Meszaros-Beller
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane, Australia.,Institute for Modelling and Simulation of Biomechanical Systems, University of Stuttgart, Stuttgart, Germany
| | - Maria Hammer
- Institute for Modelling and Simulation of Biomechanical Systems, University of Stuttgart, Stuttgart, Germany.,Stuttgart Center for Simulation Science (SC SimTech), University of Stuttgart, Stuttgart, Germany
| | - Julia M Riede
- Institute for Modelling and Simulation of Biomechanical Systems, University of Stuttgart, Stuttgart, Germany
| | - Peter Pivonka
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane, Australia
| | - J Paige Little
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane, Australia
| | - Syn Schmitt
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane, Australia. .,Institute for Modelling and Simulation of Biomechanical Systems, University of Stuttgart, Stuttgart, Germany. .,Stuttgart Center for Simulation Science (SC SimTech), University of Stuttgart, Stuttgart, Germany.
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Rayward L, Pearcy M, Izatt M, Green D, Labrom R, Askin G, Little JP. Predicting spinal column profile from surface topography via 3D non-contact surface scanning. PLoS One 2023; 18:e0282634. [PMID: 36952526 PMCID: PMC10035928 DOI: 10.1371/journal.pone.0282634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 02/17/2023] [Indexed: 03/25/2023] Open
Abstract
INTRODUCTION 3D Non-Contact surface scanning (3DSS) is used in both biomechanical and clinical studies to capture accurate 3D images of the human torso, and to better understand the shape and posture of the spine-both healthy and pathological. This study sought to determine the efficacy and accuracy of using 3DSS of the posterior torso, to determine the curvature of the spinal column in the lateral lying position. METHODS A cohort of 50 healthy adults underwent 3DSS and Magnetic Resonance Imaging (MRI) to correlate the contours of the external spine surface with the internal spinal column. The correlation analysis was composed of two phases: (1) MRI vertebral points vs MRI external spine surface markers; and (2) MRI external spine surface markers vs 3DSS external spine surface markers. The first phase compared the profiles of fiducial markers (vitamin capsules) adhered to the skin surface over the spinous processes against the coordinates of the spinous processes-assessing the linear distance between the profiles, and similarity of curvature, in the sagittal and coronal planes. The second phase compared 3DSS external spine surface markers with the MRI external spine surface markers in both planes, with further qualitative assessment for postural changes. RESULTS The distance between the MRI vertebral points and MRI external spine surface markers showed strong statistically significant correlation with BMI in both sagittal and coronal planes. Kolmogorov-Smirnov (KS) tests showed similar no significant difference in curvature, k, in almost all participants on both planes. In the second phase, the coronal 3DSS external spine surface profiles were statistically different to the MRI external spine surface markers in 44% of participants. Qualitative assessment showed postural changes between MRI and 3DSS measurements in these participants. CONCLUSION These study findings demonstrate the utility and accuracy of using anatomical landmarks overlaid on the spinous processes, to identify the position of the spinal bones using 3DSS. Using this method, it will be possible to predict the internal spinal curvature from surface topography, provided that the thickness of the overlaying subcutaneous adipose layer is considered, thus enabling postural analysis of spinal shape and curvature to be carried out in biomechanical and clinical studies without the need for radiographic imaging.
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Affiliation(s)
- Lionel Rayward
- Biomechanics and Spine Research Group, School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane City, Australia
| | - Mark Pearcy
- Biomechanics and Spine Research Group, School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane City, Australia
| | - Maree Izatt
- Biomechanics and Spine Research Group, School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane City, Australia
| | | | - Robert Labrom
- Biomechanics and Spine Research Group, School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane City, Australia
- Wesley Hospital, Auchenflower, Australia
| | - Geoffrey Askin
- Biomechanics and Spine Research Group, School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane City, Australia
- Mater Health Services, South Brisbane, Australia
| | - J Paige Little
- Biomechanics and Spine Research Group, School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane City, Australia
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Rayward L, Little JP. A subject-specific FEM to predict deep tissue mechanical stresses when supine: Development of efficient contact interfaces using Shared Topology. J Biomech 2022; 137:111085. [DOI: 10.1016/j.jbiomech.2022.111085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 03/17/2022] [Accepted: 04/05/2022] [Indexed: 10/18/2022]
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Little JP, Green D, Izatt MT, Moloney G, Askin GN. Patient-Customised Theatre Mattress Supports for Spinal Surgery: A Pilot Study Presenting a Novel Engineering Virtual Design and Manufacturing Technique. J Med Device 2022. [DOI: 10.1115/1.4053604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Abstract
Optimal patient positioning for spine surgery is vital for surgical success and the minimisation of complications intra-/post-operatively. In patients with complex co-morbidities, commercially available surgical positioning equipment is inadequate. To overcome this, a novel method was developed to create custom-fit patient-specific theatre mattresses for patients undergoing spine surgery. An innovative digital workflow involving 3D surface scanning, 3D simulation and computer aided design was developed to manufacture customised theatre supports with patient-specific requirements. These supports offered the surgeon an enhanced ability to relieve load bearing on prominent anatomical features or where desired, to tailor the support surface to the patient's anatomy for lengthy surgery. The bespoke theatre mattress was evaluated by whether the support resulted in a complication-free surgery. Using this new workflow, case examples for two patients with complex co-morbidities were described. The spine surgeon and anaesthetist reported the patient-specific custom mattresses were fit as per the required design, provided sufficient clearance around anatomical prominences and areas that required to be unloaded, had sufficient clearance for the anaesthetic method and cannulation, provided excellent surgical access and stability during surgery, and postoperatively no soft tissue overload over bony prominence and implanted devices. Positive patient outcomes after successful lengthy surgical interventions were associated with these patient-specific, contoured mattress supports. Future projects will seek to utilise this technology for other types of surgeries and intra-operative positioning requirements, and for a broader demographic of patients in both the paediatric and adult setting.
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Affiliation(s)
- J. Paige Little
- Biomechanics and Spine Research Group, Centre for Children's Health Research, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Daniel Green
- Sealy of Australia, Wacol, Queensland, Australia
| | - Maree T. Izatt
- Biomechanics and Spine Research Group, Centre for Children's Health Research, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Gregory Moloney
- Queensland Children's Hospital, Brisbane, Queensland, Australia
| | - Geoffrey N. Askin
- Biomechanics and Spine Research Group, Centre for Children's Health Research, Queensland University of Technology, Brisbane, Queensland, Australia; Queensland Children's Hospital, Brisbane, Queensland, Australia
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Little JP, Chapman E, Parr A, Moloney G, Bowler S, Labrom RD, Askin GN. Morphological changes in the respiratory system: an MRI investigation of differences between the supine and left lateral decubitus positions. Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization 2021. [DOI: 10.1080/21681163.2021.1906323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- J. Paige Little
- IHBI at Centre for Children’s Health Research, Queensland University of Technology, Brisbane, Australia
| | - Erin Chapman
- IHBI at Centre for Children’s Health Research, Queensland University of Technology, Brisbane, Australia
| | - Adam Parr
- IHBI at Centre for Children’s Health Research, Queensland University of Technology, Brisbane, Australia
- Department of Orthopaedics, Queensland Children’s Hospital, Brisbane, Australia
| | - Gregory Moloney
- Department of Orthopaedics, Queensland Children’s Hospital, Brisbane, Australia
| | - Simon Bowler
- Mater Health, Mater Private Hospital, Brisbane, Australia
| | - Robert D. Labrom
- IHBI at Centre for Children’s Health Research, Queensland University of Technology, Brisbane, Australia
- Department of Orthopaedics, Queensland Children’s Hospital, Brisbane, Australia
| | - Geoffrey N. Askin
- IHBI at Centre for Children’s Health Research, Queensland University of Technology, Brisbane, Australia
- Department of Orthopaedics, Queensland Children’s Hospital, Brisbane, Australia
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Labrom FR, Izatt MT, Claus AP, Little JP. Adolescent idiopathic scoliosis 3D vertebral morphology, progression and nomenclature: a current concepts review. Eur Spine J 2021; 30:1823-1834. [PMID: 33866395 DOI: 10.1007/s00586-021-06842-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 03/11/2021] [Accepted: 04/08/2021] [Indexed: 11/24/2022]
Abstract
PURPOSE There has been a recent shift toward the analysis of the pathoanatomical variation of the adolescent idiopathic scoliosis (AIS) spine with the three dimensions, and research of level-wise vertebral body morphology in single anatomical planes is now replete within the field. In addition to providing a precise description of the osseous structures that are the focus of instrumented surgical interventions, understanding the anatomical variation between vertebral bodies will elucidate possible pathoaetiological mechanisms of the onset of scoliotic deformity. METHODS This review aimed to discuss the current landscape of AIS segmental vertebral morphology research and provide a comprehensive report of the typical patterns observed at the individual vertebral level. RESULTS We have detailed how these vertebrae are typically characterised by lateral wedging to the convexity, have a marked degree of anterior overgrowth, are rotated towards the convexity, have inherent gyratory mechanical torsion created within them and are associated with pedicles on the concave side being narrower, longer and more laterally angled. For the most part, these findings are most pronounced at and around the apex of a scoliotic curve, with these deformations reducing towards junctional vertebrae. We have also summarised a nomenclature defined by the Scoliosis Research Society, highlighting the need for more consistent reporting of these level-wise dimensional anatomical changes. CONCLUSION Finally, we emphasised how a marked degree of heterogeneity exists between the included investigations, namely in scoliotic curve-type inclusion, imaging modality and timepoint of analysis within scoliosis' longitudinal development, and how improvement in these study design characteristics will enhance ongoing research.
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Affiliation(s)
- Fraser R Labrom
- Biomechanics and Spine Research Group, Level 5, Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, 62 Graham St, South Brisbane, QLD, 4101, Australia. .,Faculty of Medicine, University of Queensland, St Lucia, QLD, Australia.
| | - Maree T Izatt
- Biomechanics and Spine Research Group, Level 5, Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, 62 Graham St, South Brisbane, QLD, 4101, Australia
| | - Andrew P Claus
- Tess Cramond Pain and Research Centre, Royal Brisbane and Women's Hospital, Brisbane, QLD, Australia.,School of Health & Rehabilitation Sciences, University of Queensland, St Lucia, QLD, Australia
| | - J Paige Little
- Biomechanics and Spine Research Group, Level 5, Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, 62 Graham St, South Brisbane, QLD, 4101, Australia
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Pickering E, Pivonka P, Little JP. Toward Patient Specific Models of Pediatric IVDs: A Parametric Study of IVD Mechanical Properties. Front Bioeng Biotechnol 2021; 9:632408. [PMID: 33659242 PMCID: PMC7917075 DOI: 10.3389/fbioe.2021.632408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 01/18/2021] [Indexed: 12/31/2022] Open
Abstract
Patient specific finite element (FE) modeling of the pediatric spine is an important challenge which offers to revolutionize the treatment of pediatric spinal pathologies, for example adolescent idiopathic scoliosis (AIS). In particular, modeling of the intervertebral disc (IVD) is a unique challenge due to its structural and mechanical complexity. This is compounded by limited ability to non-invasively interrogate key mechanical parameters of a patient's IVD. In this work, we seek to better understand the link between mechanical properties and mechanical behavior of patient specific FE models of the pediatric lumbar spine. A parametric study of IVD parameter was conducted, coupled with insights from current knowledge of the pediatric IVD. In particular, the combined effects of parameters was investigated. Recommendations are made toward areas of importance in patient specific FE modeling of the pediatric IVD. In particular, collagen fiber bundles of the IVD are found to dominate IVD mechanical behavior and are thus recommended as an area of primary focus for patient specific FE models. In addition, areas requiring further experimental research are identified. This work provides a valuable building block toward the development of patient specific models of the pediatric spine.
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Affiliation(s)
- Edmund Pickering
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane, QLD, Australia.,Biomechanics and Spine Research Group, Centre for Children's Health Research, Queensland University of Technology, Brisbane, QLD, Australia
| | - Peter Pivonka
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane, QLD, Australia.,Biomechanics and Spine Research Group, Centre for Children's Health Research, Queensland University of Technology, Brisbane, QLD, Australia
| | - J Paige Little
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane, QLD, Australia.,Biomechanics and Spine Research Group, Centre for Children's Health Research, Queensland University of Technology, Brisbane, QLD, Australia
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Davis CM, Grant CA, Izatt MT, Askin GN, Labrom RD, Adam CJ, Pearcy MJ, Little JP. Characterization of progressive changes in pedicle morphometry and neurovascular anatomy during growth in adolescent idiopathic scoliosis versus adolescents without scoliosis. Spine Deform 2020; 8:1193-1204. [PMID: 32557264 DOI: 10.1007/s43390-020-00160-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 06/08/2020] [Indexed: 11/30/2022]
Abstract
STUDY DESIGN Prospective cohort study. OBJECTIVES Investigate the progressive changes in pedicle morphometry and the spatial relationship between the pedicles and neurovascular structures in patients with AIS during growth. Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional spine deformity. AIS pedicles are known to be asymmetrical when compared to adolescents without scoliosis. Defining the anatomical changes occurring progressively in scoliosis as it increases with time and growth is essential for understanding the pathophysiology of scoliosis and for treatment planning. MRI is the ideal method to study the growing spine without ionising radiation. METHODS 24 females with AIS (mean 12.6 years, right sided main thoracic curves) and 20 non-scoliotic females (mean 11.5 years) were selected from an ongoing database. Participants underwent two 3D MRI scans (3 T scanner, T1, 0.5 mm isotropic voxels) approximately 1 year apart (AIS: mean 1.3 ± 0.05 years, control: mean 1.0 ± 0.1 years). The pedicle width, chord length, pedicle height, transverse pedicle angle, sagittal pedicle angle, distance from vertebrae to aorta and distance from pedicle to dural sac were measured from T5 to T12. Inter- and intra-observer variability was assessed. RESULTS From scans 1-2 in the AIS group, the dural sac became closer to the left pedicle (p < 0.05, T6, T8-T10 and T12) while the distance from the vertebrae to the aorta increased (p < 0.05, T6-T10). No significant changes in these measurements were observed in the non-scoliotic group. Between scans, the AIS chord length and transverse pedicle angle increased on the left side around the apex (p < 0.05) creating asymmetries not seen in the non-scoliotic cohort. The mean pedicle height increased symmetrically in the non-scoliosis cohort (p < 0.05) and asymmetrically in the AIS group with the right side growing faster than the left at T6-T7 (p < 0.05). CONCLUSION Asymmetrical growth patterns occur in the vertebral posterior elements of AIS patients compared to the symmetrical growth patterns found in the non-scoliotic participants. LEVEL OF EVIDENCE Level II prospective comparative study.
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Affiliation(s)
- Colin M Davis
- Biomechanics and Spine Research Group, Institute of Health and Biomedical Innovation at Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, Level 5, 62 Graham Street, South Brisbane, QLD, 4101, Australia.,Queensland Children's Hospital, Brisbane, Australia
| | - Caroline A Grant
- Biomechanics and Spine Research Group, Institute of Health and Biomedical Innovation at Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, Level 5, 62 Graham Street, South Brisbane, QLD, 4101, Australia
| | - Maree T Izatt
- Biomechanics and Spine Research Group, Institute of Health and Biomedical Innovation at Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, Level 5, 62 Graham Street, South Brisbane, QLD, 4101, Australia
| | - Geoffrey N Askin
- Biomechanics and Spine Research Group, Institute of Health and Biomedical Innovation at Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, Level 5, 62 Graham Street, South Brisbane, QLD, 4101, Australia.,Queensland Children's Hospital, Brisbane, Australia
| | - Robert D Labrom
- Biomechanics and Spine Research Group, Institute of Health and Biomedical Innovation at Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, Level 5, 62 Graham Street, South Brisbane, QLD, 4101, Australia.,Queensland Children's Hospital, Brisbane, Australia
| | - Clayton J Adam
- Biomechanics and Spine Research Group, Institute of Health and Biomedical Innovation at Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, Level 5, 62 Graham Street, South Brisbane, QLD, 4101, Australia
| | - Mark J Pearcy
- Biomechanics and Spine Research Group, Institute of Health and Biomedical Innovation at Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, Level 5, 62 Graham Street, South Brisbane, QLD, 4101, Australia
| | - J Paige Little
- Biomechanics and Spine Research Group, Institute of Health and Biomedical Innovation at Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, Level 5, 62 Graham Street, South Brisbane, QLD, 4101, Australia.
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Labrom FR, Izatt MT, Contractor P, Grant CA, Pivonka P, Askin GN, Labrom RD, Little JP. Sequential MRI reveals vertebral body wedging significantly contributes to coronal plane deformity progression in adolescent idiopathic scoliosis during growth. Spine Deform 2020; 8:901-910. [PMID: 32451976 DOI: 10.1007/s43390-020-00138-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 05/11/2020] [Indexed: 01/06/2023]
Abstract
STUDY DESIGN Cross-sectional study. OBJECTIVES To provide a comprehensive, multi-stage investigation of vertebral body (VB) and intervertebral disc (IVD) coronal plane deformities for adolescent idiopathic scoliosis (AIS) patients with a main thoracic curve type, using a series of sequential magnetic resonance images (MRIs). Despite numerous investigations of AIS deformity at the spinal segmental level, there is little consensus as to the major contributor to the lateral curvature of a scoliotic spine. Moreover, scoliotic deformity is often described along a continuum of progression, with few studies having characterised the change in segmental deformity for AIS patients whose deformity progresses clinically over time. METHODS 30 female AIS patients with primary thoracic curves were included between 2012 and 2016. Three sequential MRIs were captured for each patient. Datasets were reformatted to produce true coronal plane images of the thoracic spine (T4-L1). Overall curve morphology, coronal plane IVD and VB segmental deformity and rates of growth were analysed. RESULTS Right-side asymmetry was greater in IVDs (18.5 ± 23.9%) when compared to VBs (8.3 ± 9.2%) (P < 0.05) by third scans. Despite this, 77% of patients demonstrated the majority (> 50%) of their coronal curvature was attributed to VB wedging when measured across all three scans. Regardless of progression status, scan number, or region, the sum of the VB wedging angle was greater than the sum of the IVD wedging angle (all P ≤ 0.05). There was no correlation between the rates of major curve angle progression and standing height increase, VB height growth, or IVD height growth (P > 0.05). CONCLUSIONS VB wedging contributed more to the lateral deformity observed in primary thoracic subtypes of AIS patients than IVD wedging. While IVDs demonstrated the greatest asymmetric deformity, their relatively smaller height resulted in a smaller proportional change in lateral curve angle compared to the VBs. LEVEL OF EVIDENCE IV.
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Affiliation(s)
- Fraser R Labrom
- Biomechanics and Spine Research Group, Level 5, Centre for Children's Health Research, Institute of Health and Biomedical Innovation, Queensland University of Technology and Mater Health Services, 62 Graham St, South Brisbane, 4104, Australia.
| | - Maree T Izatt
- Biomechanics and Spine Research Group, Level 5, Centre for Children's Health Research, Institute of Health and Biomedical Innovation, Queensland University of Technology and Mater Health Services, 62 Graham St, South Brisbane, 4104, Australia
| | - Prathmesh Contractor
- Biomechanics and Spine Research Group, Level 5, Centre for Children's Health Research, Institute of Health and Biomedical Innovation, Queensland University of Technology and Mater Health Services, 62 Graham St, South Brisbane, 4104, Australia.,Queensland Children's Hospital and Mater Health Services, Brisbane, Australia
| | - Caroline A Grant
- Biomechanics and Spine Research Group, Level 5, Centre for Children's Health Research, Institute of Health and Biomedical Innovation, Queensland University of Technology and Mater Health Services, 62 Graham St, South Brisbane, 4104, Australia
| | - Peter Pivonka
- Biomechanics and Spine Research Group, Level 5, Centre for Children's Health Research, Institute of Health and Biomedical Innovation, Queensland University of Technology and Mater Health Services, 62 Graham St, South Brisbane, 4104, Australia
| | - Geoffrey N Askin
- Biomechanics and Spine Research Group, Level 5, Centre for Children's Health Research, Institute of Health and Biomedical Innovation, Queensland University of Technology and Mater Health Services, 62 Graham St, South Brisbane, 4104, Australia.,Queensland Children's Hospital and Mater Health Services, Brisbane, Australia
| | - Robert D Labrom
- Biomechanics and Spine Research Group, Level 5, Centre for Children's Health Research, Institute of Health and Biomedical Innovation, Queensland University of Technology and Mater Health Services, 62 Graham St, South Brisbane, 4104, Australia.,Queensland Children's Hospital and Mater Health Services, Brisbane, Australia
| | - J Paige Little
- Biomechanics and Spine Research Group, Level 5, Centre for Children's Health Research, Institute of Health and Biomedical Innovation, Queensland University of Technology and Mater Health Services, 62 Graham St, South Brisbane, 4104, Australia
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Jung ME, Locke SR, Bourne JE, Beauchamp MR, Lee T, Singer J, MacPherson M, Barry J, Jones C, Little JP. Cardiorespiratory fitness and accelerometer-determined physical activity following one year of free-living high-intensity interval training and moderate-intensity continuous training: a randomized trial. Int J Behav Nutr Phys Act 2020; 17:25. [PMID: 32102667 PMCID: PMC7045584 DOI: 10.1186/s12966-020-00933-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 02/14/2020] [Indexed: 02/01/2023] Open
Abstract
Background Free-living adherence to high-intensity interval training (HIIT) has not been adequately tested. This randomized trial examined changes in cardiorespiratory fitness (CRF) and accelerometer-measured purposeful physical activity over 12 months of free-living HIIT versus moderate-intensity continuous training (MICT). Methods Ninety-nine previously low-active participants with overweight/obesity were randomly assigned to HIIT (n = 47) or MICT (n = 52). Both interventions were combined with evidence-based behaviour change counselling consisting of 7 sessions over 2 weeks. Individuals in HIIT were prescribed 10 X 1-min interval-based exercise 3 times per week (totalling 75 min) whereas individuals in MICT were prescribed 150 min of steady-state exercise per week (50 mins 3 times per week). Using a maximal cycling test to exhaustion with expired gas analyses, CRF was assessed at baseline and after 6 and 12 months of free-living exercise. Moderate-to-vigorous physical activity of 10+ minutes (MVPA10+) was assessed by 7-day accelerometry at baseline, 3, 6, 9, and 12 months. Intention to treat analyses were conducted using linear mixed models. Results CRF was improved over the 12 months relative to baseline in both HIIT (+ 0.15 l/min, 95% CI 0.08 to 0.23) and MICT (+ 0.11 l/min, 95% CI 0.05 to 0.18). Both groups improved 12-month MVPA10+ above baseline (HIIT: + 36 min/week, 95% CI 17 to 54; MICT: + 69 min/week, 95% CI 49 to 89) with the increase being greater (by 33 min, 95% CI 6 to 60) in MICT (between group difference, P = 0.018). Conclusion Despite being prescribed twice as many minutes of exercise and accumulating significantly more purposeful exercise, CRF improvements were similar across 12 months of free-living HIIT and MICT in previously low-active individuals with overweight/obesity.
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Affiliation(s)
- M E Jung
- School of Health and Exercise Sciences Faculty of Health and Social Development, The University of British Columbia Okanagan, FHSD 3333 University Way ART360, Kelowna, BC, V1V 1V7, Canada.
| | - S R Locke
- School of Health and Exercise Sciences Faculty of Health and Social Development, The University of British Columbia Okanagan, FHSD 3333 University Way ART360, Kelowna, BC, V1V 1V7, Canada
| | | | - M R Beauchamp
- The University of British Columbia, Vancouver Campus, Vancouver, Canada
| | - T Lee
- The University of British Columbia, Vancouver Campus, Vancouver, Canada
| | - J Singer
- The University of British Columbia, Vancouver Campus, Vancouver, Canada
| | - M MacPherson
- School of Health and Exercise Sciences Faculty of Health and Social Development, The University of British Columbia Okanagan, FHSD 3333 University Way ART360, Kelowna, BC, V1V 1V7, Canada
| | - J Barry
- School of Health and Exercise Sciences Faculty of Health and Social Development, The University of British Columbia Okanagan, FHSD 3333 University Way ART360, Kelowna, BC, V1V 1V7, Canada
| | - C Jones
- School of Health and Exercise Sciences Faculty of Health and Social Development, The University of British Columbia Okanagan, FHSD 3333 University Way ART360, Kelowna, BC, V1V 1V7, Canada
| | - J P Little
- School of Health and Exercise Sciences Faculty of Health and Social Development, The University of British Columbia Okanagan, FHSD 3333 University Way ART360, Kelowna, BC, V1V 1V7, Canada
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Little JP, Rayward L, Pearcy MJ, Izatt MT, Green D, Labrom RD, Askin GN. Predicting spinal profile using 3D non-contact surface scanning: Changes in surface topography as a predictor of internal spinal alignment. PLoS One 2019; 14:e0222453. [PMID: 31557174 PMCID: PMC6762190 DOI: 10.1371/journal.pone.0222453] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 08/29/2019] [Indexed: 01/20/2023] Open
Abstract
Introduction 3D non-contact surface scanners capture highly accurate, calibrated images of surface topography for 3D structures. This study sought to establish the efficacy and accuracy of using 3D surface scanning to characterise spinal curvature and sagittal plane contour. Methods 10 healthy female adults with a mean age of 25 years, (standard deviation: 3.6 years) underwent both MRI and 3D surface scanning (3DSS) (Artec Eva, Artec Group Inc., Luxembourg) while lying in the lateral decubitus position on a rigid substrate. Prior to 3DSS, anatomical landmarks on the spinous processes of each participant were demarcated using stickers attached to the skin surface. Following 3DSS, oil capsules (fiducial markers) were overlaid on the stickers and the subject underwent MRI. MRI stacks were processed to measure the thoracolumbar spinous process locations, providing an anatomical reference. 3D coordinates for the markers (surface stickers and MRI oil capsules) and for the spinous processes mapped the spinal column profiles and were compared to assess the quality of fit between the 3DSS and MRI marker positions. Results The RMSE for the polynomials fit to the spinous process, fiducial and surface marker profiles ranged from 0.17–1.15mm for all subjects. The MRI fiducial marker location was well aligned with the spinous process profile in the thoracic and upper lumbar spine for nine of the subjects. Over the 10 subjects, the mean RMSE between the MRI and 3D scan sagittal profiles for all surface markers was 9.8mm (SD 4.2mm). Curvature was well matched for seven of the subjects, with two showing differing curvatures across the lumbar spine due to inconsistent subject positioning. Conclusion Comparison of the observed trends for vertebral position measured from MRI and 3DSS, suggested the surface markers may provide a useful method for measuring internal changes in sagittal curvature or skeletal changes.
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Affiliation(s)
- J. Paige Little
- Biomechanics and Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
- * E-mail:
| | - Lionel Rayward
- Biomechanics and Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | - Mark J. Pearcy
- Biomechanics and Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | - Maree T. Izatt
- Biomechanics and Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | | | - Robert D. Labrom
- Biomechanics and Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
- Wesley Hospital, Brisbane, Australia
| | - Geoffrey N. Askin
- Biomechanics and Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
- Mater Health Services, Brisbane, Australia
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Izatt MT, Lees D, Mills S, Grant CA, Little JP. Determining a reliably visible and inexpensive surface fiducial marker for use in MRI: a research study in a busy Australian Radiology Department. BMJ Open 2019; 9:e027020. [PMID: 31375607 PMCID: PMC6688688 DOI: 10.1136/bmjopen-2018-027020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
OBJECTIVES Single-use commercial surface fiducial markers are used in clinical imaging for a variety of applications. The current study sought to find a new, reliably visible, easily sourced and inexpensive fiducial marker alternative for use with MRI. DESIGN Five commonly requested MRI sequences were determined (three-dimensional (3D) T1-weighted, T1 coronal, 3D T2-weighted, T2 fat suppressed, proton density), to examine the visibility of 18 items (including a commercial fiducial marker). SETTING Clinical 3T MRI scanner in an Australian Tertiary Hospital and an Australian University Biomedical Engineering research group. INTERVENTIONS 18 marker alternatives were scanned using five common MRI sequences. Images were reformatted to obtain both an image through the mid-height of each marker and a maximum intensity z-projection image over the volume of the marker. Variations in marker intensity were profiled across each visible marker and a visibility rating defined. MAIN OUTCOME MEASURES Outcome measures were based on quantitative assessment of a clear intensity contrast ratio between the marker and the adjacent tissue and a qualitative assessment of visibility via a 3-point scale. RESULTS The fish oil capsule, vitamin D capsule, paint ball pellet, soy sauce sushi tube and commercial markers were typically visible to a high quality on all the imaging sequences and demonstrated a clear differential in intensity contrast against the adjacent tissue. Other common items, such as plasticine 'play doh' and a soft 'Jelly baby' sweet, were surprise candidates, demonstrating high-quality visibility and intensity contrast for the 3D T1-weighted sequence. CONCLUSIONS Depending on the basis for referral and MRI sequence chosen, four alternative fiducial markers were determined to be inexpensive, easily sourced and consistently visible. Of these, the vitamin D capsule provided an excellent balance between availability, size, cost, usability and quality of the visualised marker for all the commonly used MRI sequences analysed.
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Affiliation(s)
- Maree T Izatt
- Biomechanics and Spine Research Group, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Deborah Lees
- Biomechanics and Spine Research Group, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Susan Mills
- Mater Medical Imaging, Mater Misericordiae Brisbane Ltd, South Brisbane, Queensland, Australia
| | - Caroline A Grant
- Biomechanics and Spine Research Group, Queensland University of Technology, Brisbane, Queensland, Australia
| | - J Paige Little
- Biomechanics and Spine Research Group, Queensland University of Technology, Brisbane, Queensland, Australia
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Little JP, Loch-Wilkinson TJ, Sundberg A, Izatt MT, Adam CJ, Labrom RD, Askin GN. Quantifying Anterior Chest Wall Deformity in Adolescent Idiopathic Scoliosis: Correlation With Other Deformity Measures and Effects of Anterior Thoracoscopic Scoliosis Surgery. Spine Deform 2019; 7:436-444. [PMID: 31053314 DOI: 10.1016/j.jspd.2018.09.069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 08/22/2018] [Accepted: 09/23/2018] [Indexed: 10/26/2022]
Abstract
STUDY DESIGN Retrospective cohort study. OBJECTIVES This study investigated how anterior chest wall deformity is affected by thoracoscopic anterior scoliosis fusion (TASF) surgery in adolescent idiopathic scoliosis patients. We aimed to determine correlations pre- and postoperatively with other clinical and radiological scoliosis measures. BACKGROUND DATA Scoliosis surgery aims to halt progression of the deformity, and to reduce its severity. Currently, deformity correction is clinically measured in terms of Cobb angle and rib hump (RH); however, a significant cosmetic concern for patients is anterior chest wall deformity. METHODS Pre- and postoperative CT scans of 28 female, Lenke type 1 patients with a mean preoperative Cobb angle of 50.2° ± 7.1° were retrieved from the Research Group's surgical database. Using ImageJ, 3D reconstructions of the thorax were created. Two observers measured the anterior chest wall deformity as a chest wall angle (CWA) and posterior deformity as a posterior apical deformity angle (PDA). We investigated pre- to postoperative changes in CWA, PDA, RH, and Cobb angle as well as their interrelationship. RESULTS All deformity parameters (Cobb angle, RH, CWA, and PDA) showed statistically significant improvement post TASF. Correlation was found between RH and Cobb angle pre- and postoperatively, Cobb angle and CWA preoperatively and between postoperative change in Cobb angle and CWA. No relationship was found between CWA and RH or PDA. CONCLUSIONS Anterior chest wall deformity is independent from the posterior chest wall measures RH and PDA, indicating that the anterior chest wall deformity is not reflected in the posterior rib cage. The correlation between Cobb angle and CWA indicates that the deformity in the spine and the deformity in the ribs are related, and shows that the anterior chest wall deformity is improved post thoracoscopic anterior scoliosis fusion surgery as the lateral deviation of the spine is corrected. LEVEL OF EVIDENCE Level III.
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Affiliation(s)
- J P Little
- Biomechanics and Spine Research Group, Centre for Children's Health Research, Institute of Health & Biomedical Innovation, Queensland University of Technology and Mater Health Services, Level 5, 62 Graham Street, South Brisbane 4101, Queensland, Australia.
| | - T J Loch-Wilkinson
- Biomechanics and Spine Research Group, Centre for Children's Health Research, Institute of Health & Biomedical Innovation, Queensland University of Technology and Mater Health Services, Level 5, 62 Graham Street, South Brisbane 4101, Queensland, Australia
| | - A Sundberg
- Biomechanics and Spine Research Group, Centre for Children's Health Research, Institute of Health & Biomedical Innovation, Queensland University of Technology and Mater Health Services, Level 5, 62 Graham Street, South Brisbane 4101, Queensland, Australia
| | - M T Izatt
- Biomechanics and Spine Research Group, Centre for Children's Health Research, Institute of Health & Biomedical Innovation, Queensland University of Technology and Mater Health Services, Level 5, 62 Graham Street, South Brisbane 4101, Queensland, Australia
| | - C J Adam
- Biomechanics and Spine Research Group, Centre for Children's Health Research, Institute of Health & Biomedical Innovation, Queensland University of Technology and Mater Health Services, Level 5, 62 Graham Street, South Brisbane 4101, Queensland, Australia
| | - R D Labrom
- Biomechanics and Spine Research Group, Centre for Children's Health Research, Institute of Health & Biomedical Innovation, Queensland University of Technology and Mater Health Services, Level 5, 62 Graham Street, South Brisbane 4101, Queensland, Australia
| | - G N Askin
- Biomechanics and Spine Research Group, Centre for Children's Health Research, Institute of Health & Biomedical Innovation, Queensland University of Technology and Mater Health Services, Level 5, 62 Graham Street, South Brisbane 4101, Queensland, Australia
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Little JP, Pettet GJ, Hutmacher DW, Loessner D. SpheroidSim-Preliminary evaluation of a new computational tool to predict the influence of cell cycle time and phase fraction on spheroid growth. Biotechnol Prog 2018; 34:1335-1343. [PMID: 30009492 DOI: 10.1002/btpr.2692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 04/04/2018] [Accepted: 06/28/2018] [Indexed: 11/11/2022]
Abstract
BACKGROUND There is a relative paucity of research that integrates materials science and bioengineering with computational simulations to decipher the intricate processes promoting cancer progression. Therefore, a first-generation computational model, SpheroidSim, was developed that includes a biological data set derived from a bioengineered spheroid model to obtain a quantitative description of cell kinetics. RESULTS SpheroidSim is a 3D agent-based model simulating the growth of multicellular cancer spheroids. Cell cycle time and phases mathematically motivated the population growth. SpheroidSim simulated the growth dynamics of multiple spheroids by individually defining a collection of specific phenotypic traits and characteristics for each cell. Experimental data derived from a hydrogel-based spheroid model were fit to the predictions providing insight into the influence of cell cycle time (CCT) and cell phase fraction (CPF) on the cell population. A comparison of the number of active cells predicted for each analysis showed that the value and method used to define CCT had a greater effect on the predicted cell population than CPF. The model predictions were similar to the experimental results for the number of cells, with the predicted total number of cells varying by 8% and 12%, respectively, compared to the experimental data. CONCLUSIONS SpheroidSim is a first step in developing a biologically based predictive tool capable of revealing fundamental elements in cancer cell physiology. This computational model may be applied to study the effect of the microenvironment on spheroid growth and other cancer cell types that demonstrate a similar multicellular clustering behavior as the population develops. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1335-1343, 2018.
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Affiliation(s)
- J P Little
- Queensland University of Technology (QUT), Brisbane, QLD, Australia
| | - G J Pettet
- Queensland University of Technology (QUT), Brisbane, QLD, Australia
| | - D W Hutmacher
- Queensland University of Technology (QUT), Brisbane, QLD, Australia.,Australian Research Centre for Additive Biomanufacturing, QUT, Brisbane, QLD, Australia.,George W Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA.,Institute for Advanced Study, Technical University of Munich, Garching, Germany
| | - D Loessner
- Queensland University of Technology (QUT), Brisbane, QLD, Australia.,Barts Cancer Institute, Queen Mary University of London, London, U.K
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Estaki M, Pither J, Baumeister P, Little JP, Gill SK, Ghosh S, Marsden K, Ahmadi-Vand Z, Gibson DL. A287 PHYSICAL ACTIVITY AS A MODULATOR OF INTESTINAL MICROBIOTA, IMMUNE RESPONSES, AND SHORT-CHAIN FATTY ACIDS PRODUCTION. J Can Assoc Gastroenterol 2018. [DOI: 10.1093/jcag/gwy008.288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- M Estaki
- Biology, UBC - Okanagan, KELOWNA, BC, Canada
| | - J Pither
- Biology, UBC - Okanagan, KELOWNA, BC, Canada
| | | | - J P Little
- Biology, UBC - Okanagan, KELOWNA, BC, Canada
| | - S K Gill
- Biology, UBC - Okanagan, KELOWNA, BC, Canada
| | - S Ghosh
- Biology, UBC - Okanagan, KELOWNA, BC, Canada
| | - K Marsden
- Biology, UBC - Okanagan, KELOWNA, BC, Canada
| | | | - D L Gibson
- Biology, UBC - Okanagan, KELOWNA, BC, Canada
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Yu CG, Grant CA, Izatt MT, Labrom RD, Askin GN, Adam CJ, Little JP. Change in Lung Volume Following Thoracoscopic Anterior Spinal Fusion Surgery: A 3-Dimensional Computed Tomography Investigation. Spine (Phila Pa 1976) 2017; 42:909-916. [PMID: 28609321 DOI: 10.1097/brs.0000000000001949] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Lung volumes and thoracic anatomy were measured from low-dose computed tomography (CT) scans preoperatively and 2 years following thoracoscopic anterior spinal fusion (TASF) for adolescent idiopathic scoliosis (AIS). OBJECTIVE The aim of this study was to assess changes in lung volume after TASF surgical correction. SUMMARY OF BACKGROUND DATA AIS patients are known to have decreased pulmonary function as a consequence of their spinal and ribcage deformity. Several studies have evaluated changes in pulmonary function clinically after scoliosis correction surgery showing varied results. To date, there have been no published studies using CT to evaluate lung volume changes following TASF. METHODS Twenty-three female AIS patients with both pre- and 2 years postoperative low-dose CT scans were selected from an ethically approved, historical databank. Three-dimensional lung volumes were reconstructed to determine anatomical lung volumes. Right and left lung volumes, total lung volume, and right-to-left lung volume ratio were obtained as well as hemithoracic symmetry, to indicate the extent of thorax deformity. Cobb angle, rib hump, levels fused in surgery, and patient height were used for correlation analysis with the lung volume results. RESULTS Left lung volume, total lung volume, and hemithoracic ratio all increased significantly 2 years after surgery. There was no significant change in right-to-left lung volume ratio (P = 0.36). Statistical regression found significant positive correlation between lung volume changes, reduction in Cobb angle, increase in height, and improvement in hemithoracic symmetry ratio. CONCLUSION TASF resulted in a statistically significant increase in lung volume following surgery, as well as improvement in the symmetry of the thoracic architecture; however, the postoperative lung volumes remained in the lower 50th percentile relative to females without thoracic deformity. Furthermore, change in lung volume was significantly correlated with changes in Cobb angle, hemithoracic asymmetry, and increased patient height, which are important consequences of thoracic deformity correction surgery. LEVEL OF EVIDENCE 3.
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Affiliation(s)
- Caroline G Yu
- Paediatric Spine Research Group, Institute of Health and Biomedical Innovation - Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, Brisbane, Queensland, Australia
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Tourell MC, Kirkwood M, Pearcy MJ, Momot KI, Little JP. Load-induced changes in the diffusion tensor of ovine anulus fibrosus: A pilot MRI study. J Magn Reson Imaging 2017. [DOI: 10.1002/jmri.25759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Monique C. Tourell
- School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology; Brisbane Australia
| | - Margaret Kirkwood
- School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology; Brisbane Australia
| | - Mark J. Pearcy
- Paediatric Spine Research Group, Centre for Children's Health Research @ IHBI, School of Chemistry, Physics and Mechanical Engineering; Queensland University of Technology; Brisbane Australia
| | - Konstantin I. Momot
- School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology; Brisbane Australia
| | - J. Paige Little
- Paediatric Spine Research Group, Centre for Children's Health Research @ IHBI, School of Chemistry, Physics and Mechanical Engineering; Queensland University of Technology; Brisbane Australia
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Little JP, Izatt MT, Adam CJ, Lofgren O, Sundberg A, Labrom RD, Askin GN. Evaluating the Change in Axial Vertebral Rotation Following Thoracoscopic Anterior Scoliosis Surgery Using Low-Dose Computed Tomography. Spine Deform 2017; 5:172-180. [PMID: 28449960 DOI: 10.1016/j.jspd.2016.12.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 11/03/2016] [Accepted: 12/15/2016] [Indexed: 11/15/2022]
Abstract
BACKGROUND CONTEXT In recent years, there has been increasing appreciation of the need to treat scoliosis as a three-dimensional deformity. PURPOSE Assessment of surgical strategies and outcomes should consider not only the coronal plane correction but also derotation of the transverse plane deformity that can affect trunk appearance. STUDY DESIGN This study included a cohort of 29 female adolescent idiopathic scoliosis patients who received thoracoscopic single rod anterior fusion (TASF) surgery. This study used pre- and postoperative low-dose computed tomographic (CT) scans to accurately measure apical axial vertebral rotation (AVR). METHODS The pre- and postoperative values for clinically measured coronal Cobb correction and rib hump correction as well as AVR were compared to determine whether these values improved postoperatively. There are no conflicts of interest to report for authors of this investigation. RESULTS As expected, statistically significant reductions in coronal Cobb angle (mean preoperative Cobb 51°, reducing to 24° at the two-year follow-up) and rib hump (mean preoperative rib hump 15°, reducing to 7° at two-year follow-up) were achieved. The mean reduction in apical AVR measured using CT was only 3° (mean preoperative AVR 16°, reducing to 13° at two-year follow-up), which was statistically but not clinically significant. Significant correlations were found between Cobb angle and rib hump, between Cobb angle and AVR, and between AVR and rib hump, suggesting that patients with greater coronal Cobb correction also achieve better derotation with this surgical procedure. CONCLUSIONS The historical low-dose CT data set permitted detailed three-dimensional assessment of the deformity correction that is achieved using thoracoscopic anterior spinal fusion for progressive adolescent idiopathic scoliosis.
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Affiliation(s)
- J Paige Little
- Paediatric Spine Research Group, Institute of Health and Biomedical Innovation-Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, 62 Graham Street, South Brisbane, Queensland 4101, Australia.
| | - Maree T Izatt
- Paediatric Spine Research Group, Institute of Health and Biomedical Innovation-Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, 62 Graham Street, South Brisbane, Queensland 4101, Australia
| | - Clayton J Adam
- Paediatric Spine Research Group, Institute of Health and Biomedical Innovation-Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, 62 Graham Street, South Brisbane, Queensland 4101, Australia
| | - Olivia Lofgren
- Paediatric Spine Research Group, Institute of Health and Biomedical Innovation-Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, 62 Graham Street, South Brisbane, Queensland 4101, Australia
| | - Anna Sundberg
- Paediatric Spine Research Group, Institute of Health and Biomedical Innovation-Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, 62 Graham Street, South Brisbane, Queensland 4101, Australia
| | - Robert D Labrom
- Paediatric Spine Research Group, Institute of Health and Biomedical Innovation-Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, 62 Graham Street, South Brisbane, Queensland 4101, Australia
| | - Geoffrey N Askin
- Paediatric Spine Research Group, Institute of Health and Biomedical Innovation-Centre for Children's Health Research, Queensland University of Technology and Mater Health Services, 62 Graham Street, South Brisbane, Queensland 4101, Australia
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Davis CM, Grant CA, Pearcy MJ, Askin GN, Labrom RD, Izatt MT, Adam CJ, Little JP. Is There Asymmetry Between the Concave and Convex Pedicles in Adolescent Idiopathic Scoliosis? A CT Investigation. Clin Orthop Relat Res 2017; 475:884-893. [PMID: 27900714 PMCID: PMC5289204 DOI: 10.1007/s11999-016-5188-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 11/21/2016] [Indexed: 01/31/2023]
Abstract
BACKGROUND Adolescent idiopathic scoliosis is a complex three-dimensional deformity of the spine characterized by deformities in the sagittal, coronal, and axial planes. Spinal fusion using pedicle screw instrumentation is a widely used method for surgical correction in severe (coronal deformity, Cobb angle > 45°) adolescent idiopathic scoliosis curves. Understanding the anatomic difference in the pedicles of patients with adolescent idiopathic scoliosis is essential to reduce the risk of neurovascular or visceral injury through pedicle screw misplacement. QUESTIONS/PURPOSES To use CT scans (1) to analyze pedicle anatomy in the adolescent thoracic scoliotic spine comparing concave and convex pedicles and (2) to assess the intra- and interobserver reliability of these measurements to provide critical information to spine surgeons regarding size, length, and angle of projection. METHODS Between 2007 and 2009, 27 patients with adolescent idiopathic scoliosis underwent thoracoscopic anterior correction surgery by two experienced spinal surgeons. Preoperatively, each patient underwent a CT scan as was their standard of care at that time. Twenty-two patients (mean age, 15.7 years; SD, 2.4 years; range, 11.6-22 years) (mean Cobb angle, 53°; SD, 5.3°; range, 42°-63°) were selected. Inclusion criteria were a clinical diagnosis of adolescent idiopathic scoliosis, female, and Lenke type 1 adolescent idiopathic scoliosis with the major curve confined to the thoracic spine. Using three-dimensional image analysis software, the pedicle width, inner cortical pedicle width, pedicle height, inner cortical pedicle height, pedicle length, chord length, transverse pedicle angle, and sagittal pedicle angles were measured. Randomly selected scans were remeasured by two of the authors and the reproducibility of the measurement definitions was validated through limit of agreement analysis. RESULTS The concave pedicle widths were smaller compared with the convex pedicle widths at T7, T8, and T9 by 37% (3.44 mm ± 1.16 mm vs 4.72 mm ± 1.02 mm; p < 0.001; mean difference, 1.27 mm; 95% CI, 0.92 mm-1.62 mm), 32% (3.66 mm ± 1.00 mm vs 4.82 mm ± 1.10 mm; p < 0.001; mean difference, 1.16 mm; 95% CI, 0.84 mm-1.49 mm), and 25% (4.10 mm ± 1.57 mm vs 5.12 mm ± 1.17 mm; p < 0.001; mean difference, 1.02 mm; 95% CI, 0.66 mm-1.39 mm), respectively. The concave pedicle heights were smaller than the convex at T5 (9.43 mm ± 0.98 vs 10.63 mm ± 1.10 mm; p = 0.002; mean difference, 1.02 mm; 95% CI, 0.59 mm-1.45 mm), T6 (8.87 mm ± 1.37 mm vs 10.88 mm ± 0.81 mm; p < 0.001; mean difference, 2.02 mm; 95% CI, 1.40 mm-2.63 mm), T7 (9.09 mm ± 1.24 mm vs 11.35 mm ± 0.84 mm; p < 0.001; mean difference, 2.26 mm; 95% CI, 1.81 mm-2.72 mm), and T8 (10.11 mm ± 1.05 mm vs 11.86 mm ± 0.88 mm; p < 0.001; mean difference, 1.75 mm; 95% CI, 1.30 mm-2.19 mm). Conversely, the concave transverse pedicle angle was larger than the convex at levels T6 (11.37° ± 4.48° vs 8.82° ± 4.31°; p = 0.004; mean difference, 2.54°; 95% CI, 1.10°-3.99°), T7 (12.69° ± 5.93° vs 8.65° ± 3.79°; p = 0.002; mean difference, 4.04°; 95% CI, 1.90°-6.17°), T8 (13.24° ± 5.28° vs 7.66° ± 4.87°; p < 0.001; mean difference, 5.58°; 95% CI, 2.99°-8.17°), and T9 (19.95° ± 5.69° vs 8.21° ± 4.02°; p < 0.001; mean difference, 4.74°; 95% CI, 2.68°-6.80°), indicating a more posterolateral to anteromedial pedicle orientation. CONCLUSIONS There is clinically important asymmetry in the morphologic features of pedicles in individuals with adolescent idiopathic scoliosis. The concave side of the curve compared with the convex side is smaller in height and width periapically. Furthermore, the trajectory of the pedicle is more acute on the convex side of the curve compared with the concave side around the apex of the curve. Knowledge of these anatomic variations is essential when performing scoliosis correction surgery to assist with selecting the correct pedicle screw size and trajectory of insertion to reduce the risk of pedicle wall perforation and neurovascular injury.
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Affiliation(s)
- Colin M. Davis
- grid.1024.70000000089150953Paediatric Spine Research Group, Institute of Health and Biomedical Innovation at Centre for Children’s Health Research, Queensland University of Technology, Brisbane, Australia ,grid.1491.d0000000406421746Mater Health Services, South Brisbane, Australia
| | - Caroline A. Grant
- grid.1024.70000000089150953Paediatric Spine Research Group, Institute of Health and Biomedical Innovation at Centre for Children’s Health Research, Queensland University of Technology, Brisbane, Australia ,grid.1491.d0000000406421746Mater Health Services, South Brisbane, Australia
| | - Mark J. Pearcy
- grid.1024.70000000089150953Paediatric Spine Research Group, Institute of Health and Biomedical Innovation at Centre for Children’s Health Research, Queensland University of Technology, Brisbane, Australia ,grid.1491.d0000000406421746Mater Health Services, South Brisbane, Australia
| | - Geoffrey N. Askin
- grid.1024.70000000089150953Paediatric Spine Research Group, Institute of Health and Biomedical Innovation at Centre for Children’s Health Research, Queensland University of Technology, Brisbane, Australia ,grid.1491.d0000000406421746Mater Health Services, South Brisbane, Australia
| | - Robert D. Labrom
- grid.1024.70000000089150953Paediatric Spine Research Group, Institute of Health and Biomedical Innovation at Centre for Children’s Health Research, Queensland University of Technology, Brisbane, Australia ,grid.1491.d0000000406421746Mater Health Services, South Brisbane, Australia
| | - Maree T. Izatt
- grid.1024.70000000089150953Paediatric Spine Research Group, Institute of Health and Biomedical Innovation at Centre for Children’s Health Research, Queensland University of Technology, Brisbane, Australia ,grid.1491.d0000000406421746Mater Health Services, South Brisbane, Australia
| | - Clayton J. Adam
- grid.1024.70000000089150953Paediatric Spine Research Group, Institute of Health and Biomedical Innovation at Centre for Children’s Health Research, Queensland University of Technology, Brisbane, Australia ,grid.1491.d0000000406421746Mater Health Services, South Brisbane, Australia
| | - J. Paige Little
- grid.1024.70000000089150953Paediatric Spine Research Group, Institute of Health and Biomedical Innovation at Centre for Children’s Health Research, Queensland University of Technology, Brisbane, Australia ,grid.1491.d0000000406421746Mater Health Services, South Brisbane, Australia
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Newell N, Little JP, Christou A, Adams MA, Adam CJ, Masouros SD. Biomechanics of the human intervertebral disc: A review of testing techniques and results. J Mech Behav Biomed Mater 2017; 69:420-434. [PMID: 28262607 DOI: 10.1016/j.jmbbm.2017.01.037] [Citation(s) in RCA: 184] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 01/06/2017] [Accepted: 01/23/2017] [Indexed: 01/08/2023]
Abstract
Many experimental testing techniques have been adopted in order to provide an understanding of the biomechanics of the human intervertebral disc (IVD). The aim of this review article is to amalgamate results from these studies to provide readers with an overview of the studies conducted and their contribution to our current understanding of the biomechanics and function of the IVD. The overview is presented in a way that should prove useful to experimentalists and computational modellers. Mechanical properties of whole IVDs can be assessed conveniently by testing 'motion segments' comprising two vertebrae and the intervening IVD and ligaments. Neural arches should be removed if load-sharing between them and the disc is of no interest, and specimens containing more than two vertebrae are required to study 'adjacent level' effects. Mechanisms of injury (including endplate fracture and disc herniation) have been studied by applying complex loading at physiologically-relevant loading rates, whereas mechanical evaluations of surgical prostheses require slower application of standardised loading protocols. Results can be strongly influenced by the testing environment, preconditioning, loading rate, specimen age and degeneration, and spinal level. Component tissues of the disc (anulus fibrosus, nucleus pulposus, and cartilage endplates) have been studied to determine their material properties, but only the anulus has been thoroughly evaluated. Animal discs can be used as a model of human discs where uniform non-degenerate specimens are required, although differences in scale, age, and anatomy can lead to problems in interpretation.
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Affiliation(s)
- N Newell
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom.
| | - J P Little
- Paediatric Spine Research Group, IHBI at Centre for Children's Health Research, Queensland University of Technology, Brisbane, Australia
| | - A Christou
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - M A Adams
- Centre for Applied Anatomy, University of Bristol, Southwell Street, Bristol BS2 8EJ, United Kingdom
| | - C J Adam
- Paediatric Spine Research Group, IHBI at Centre for Children's Health Research, Queensland University of Technology, Brisbane, Australia
| | - S D Masouros
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
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Tourell MC, Kirkwood M, Pearcy MJ, Momot KI, Little JP. Load-induced changes in the diffusion tensor of ovine anulus fibrosus: A pilot MRI study. J Magn Reson Imaging 2016; 45:1723-1735. [PMID: 28500665 DOI: 10.1002/jmri.25531] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 10/07/2016] [Indexed: 12/22/2022] Open
Abstract
PURPOSE To assess the feasibility of diffusion tensor imaging (DTI) for evaluating changes in anulus fibrosus (AF) microstructure following uniaxial compression. MATERIALS AND METHODS Six axially aligned samples of AF were obtained from a merino sheep disc; two each from the anterior, lateral, and posterior regions. The samples were mechanically loaded in axial compression during five cycles at a rate and maximum compressive strain that reflected physiological conditions. DTI was conducted at 7T for each sample before and after mechanical testing. RESULTS The mechanical response of all samples in unconfined compression was nonlinear. A stiffer response during the first loading cycle, compared to the remaining cycles, was observed. Change in diffusion parameters appeared to be region-dependent. The mean fractional anisotropy increased following mechanical testing. This was smallest in the lateral (2% and 9%) and largest in the anterior and posterior samples (17-25%). The mean average diffusivity remained relatively constant (<2%) after mechanical testing in the lateral and posterior samples, but increased (by 5%) in the anterior samples. The mean angle made by the principal eigenvector with the spine axis in the lateral samples was 73° and remained relatively constant (<2%) following mechanical testing. This angle was smaller in the anterior (55°) and posterior (47°) regions and increased by 6-16° following mechanical testing. CONCLUSION These preliminary results suggest that axial compression reorients the collagen fibers, such that they become more consistently aligned parallel to the plane of the endplates. LEVEL OF EVIDENCE 1 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;45:1723-1735.
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Affiliation(s)
- Monique C Tourell
- School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Australia
| | - Margaret Kirkwood
- School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Australia
| | - Mark J Pearcy
- Paediatric Spine Research Group, Centre for Children's Health Research @ IHBI, School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Australia
| | - Konstantin I Momot
- School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Australia
| | - J Paige Little
- Paediatric Spine Research Group, Centre for Children's Health Research @ IHBI, School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Australia
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Little JP, Pearcy MJ, Izatt MT, Boom K, Labrom RD, Askin GN, Adam CJ. Understanding how axial loads on the spine influence segmental biomechanics for idiopathic scoliosis patients: A magnetic resonance imaging study. Clin Biomech (Bristol, Avon) 2016; 32:220-8. [PMID: 26658078 DOI: 10.1016/j.clinbiomech.2015.11.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Revised: 11/17/2015] [Accepted: 11/17/2015] [Indexed: 02/07/2023]
Abstract
BACKGROUND Segmental biomechanics of the scoliotic spine are important since the overall spinal deformity is comprised of the cumulative coronal and axial rotations of individual joints. This study investigates the coronal plane segmental biomechanics for adolescent idiopathic scoliosis patients in response to physiologically relevant axial compression. METHODS Individual spinal joint compliance in the coronal plane was measured for a series of 15 idiopathic scoliosis patients using axially loaded magnetic resonance imaging. Each patient was first imaged in the supine position with no axial load, and then again following application of an axial compressive load. Coronal plane disc wedge angles in the unloaded and loaded configurations were measured. Joint moments exerted by the axial compressive load were used to derive estimates of individual joint compliance. FINDINGS The mean standing major Cobb angle for this patient series was 46°. Mean intra-observer measurement error for endplate inclination was 1.6°. Following loading, initially highly wedged discs demonstrated a smaller change in wedge angle, than less wedged discs for certain spinal levels (+2,+1,-2 relative to the apex, (p<0.05)). Highly wedged discs were observed near the apex of the curve, which corresponded to lower joint compliance in the apical region. INTERPRETATION While individual patients exhibit substantial variability in disc wedge angles and joint compliance, overall there is a pattern of increased disc wedging near the curve apex, and reduced joint compliance in this region. Approaches such as this can provide valuable biomechanical data on in vivo spinal biomechanics of the scoliotic spine, for analysis of deformity progression and surgical planning.
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Affiliation(s)
- J P Little
- Paediatric Spine Research Group, Institute for Health and Biomedical Innovation - Centre for Children's Health Research, Queensland University of Technology and Mater Health Services Ltd., Brisbane, Australia.
| | - M J Pearcy
- Paediatric Spine Research Group, Institute for Health and Biomedical Innovation - Centre for Children's Health Research, Queensland University of Technology and Mater Health Services Ltd., Brisbane, Australia
| | - M T Izatt
- Paediatric Spine Research Group, Institute for Health and Biomedical Innovation - Centre for Children's Health Research, Queensland University of Technology and Mater Health Services Ltd., Brisbane, Australia
| | - K Boom
- Paediatric Spine Research Group, Institute for Health and Biomedical Innovation - Centre for Children's Health Research, Queensland University of Technology and Mater Health Services Ltd., Brisbane, Australia
| | - R D Labrom
- Paediatric Spine Research Group, Institute for Health and Biomedical Innovation - Centre for Children's Health Research, Queensland University of Technology and Mater Health Services Ltd., Brisbane, Australia
| | - G N Askin
- Paediatric Spine Research Group, Institute for Health and Biomedical Innovation - Centre for Children's Health Research, Queensland University of Technology and Mater Health Services Ltd., Brisbane, Australia
| | - C J Adam
- Paediatric Spine Research Group, Institute for Health and Biomedical Innovation - Centre for Children's Health Research, Queensland University of Technology and Mater Health Services Ltd., Brisbane, Australia
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MacPherson REK, Baumeister P, Peppler WT, Wright DC, Little JP. Reduced cortical BACE1 content with one bout of exercise is accompanied by declines in AMPK, Akt, and MAPK signaling in obese, glucose-intolerant mice. J Appl Physiol (1985) 2015; 119:1097-104. [PMID: 26404616 DOI: 10.1152/japplphysiol.00299.2015] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 09/17/2015] [Indexed: 12/15/2022] Open
Abstract
Obesity and type 2 diabetes are significant risk factors in the development of neurodegenerative diseases, such as Alzheimer's disease. A variety of cellular mechanisms, such as altered Akt and AMPK and increased inflammatory signaling, contribute to neurodegeneration. Exercise training can improve markers of neurodegeneration, but the underlying mechanisms remain unknown. The purpose of this study was to determine the effects of a single bout of exercise on markers of neurodegeneration and inflammation in brains from mice fed a high-fat diet. Male C57BL/6 mice were fed a low (LFD; 10% kcal from lard)- or a high-fat diet (HFD; 60% kcal from lard) for 7 wk. HFD mice underwent an acute bout of exercise (treadmill running: 15 m/min, 5% incline, 120 min) followed by a recovery period of 2 h. The HFD increased body mass and glucose intolerance (both P < 0.05). This was accompanied by an approximately twofold increase in the phosphorylation of Akt, ERK, and GSK in the cortex (P < 0.05). Following exercise, there was a decrease in beta-site amyloid precursor protein cleaving enzyme 1 (BACE1; P < 0.05) and activity (P < 0.001). This was accompanied by a reduction in AMPK phosphorylation, indicative of a decline in cellular stress (P < 0.05). Akt and ERK phosphorylation were decreased following exercise in HFD mice to a level similar to that of the LFD mice (P < 0.05). This study demonstrates that a single bout of exercise can reduce BACE1 content and activity independent of changes in adiposity. This effect is associated with reductions in Akt, ERK, and AMPK signaling in the cortex.
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Affiliation(s)
- R E K MacPherson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - P Baumeister
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | | | - D C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - J P Little
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
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Newell N, Grant CA, Izatt MT, Little JP, Pearcy MJ, Adam CJ. A semiautomatic method to identify vertebral end plate lesions (Schmorl's nodes). Spine J 2015; 15:1665-73. [PMID: 25912497 DOI: 10.1016/j.spinee.2015.04.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 03/10/2015] [Accepted: 04/15/2015] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT There are differences in the definitions of end plate lesions (EPLs), often referred to as Schmorl's nodes, that may, to some extent, account for the large range of reported prevalence (3.8%-76%). PURPOSE The purpose of this study was to develop a technique to measure the size, prevalence, and location of EPLs in a consistent manner. STUDY DESIGN/SETTING This study proposed a method using a detection algorithm that was applied to five adolescent females (average age, 15.1 [range, 13.0-19.2] years) with idiopathic scoliosis (average major Cobb angle, 60° [range, 55°-67°]). METHODS Existing low-dose, computed tomography scans were segmented semiautomatically to extract three-dimensional morphology of each vertebral end plate. Any remaining attachments to the posterior elements of adjacent vertebrae or end plates were then manually sectioned. An automatic algorithm was used to determine the presence and position of EPLs. RESULTS End plate lesions were identified in 15 of the 170 (8.8%) end plates analyzed with an average depth of 3.1 mm. Eleven of the 15 EPLs were seen in the lumbar spine. The algorithm was found to be most sensitive to changes in the minimum EPL gradient at the edges of the EPL. CONCLUSIONS This study describes an imaging analysis technique for consistent measurement of the prevalence, location, and size of EPLs. The technique can be used to analyze large populations without observer errors in EPL definitions.
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Affiliation(s)
- Nicolas Newell
- Paediatric Spine Research Group, Queensland University of Technology and Mater Health Services Brisbane Ltd, 2 George Street, Brisbane, Queensland, 4000, Australia.
| | - Caroline A Grant
- Paediatric Spine Research Group, Queensland University of Technology and Mater Health Services Brisbane Ltd, 2 George Street, Brisbane, Queensland, 4000, Australia
| | - Maree T Izatt
- Paediatric Spine Research Group, Queensland University of Technology and Mater Health Services Brisbane Ltd, 2 George Street, Brisbane, Queensland, 4000, Australia
| | - J Paige Little
- Paediatric Spine Research Group, Queensland University of Technology and Mater Health Services Brisbane Ltd, 2 George Street, Brisbane, Queensland, 4000, Australia
| | - Mark J Pearcy
- Paediatric Spine Research Group, Queensland University of Technology and Mater Health Services Brisbane Ltd, 2 George Street, Brisbane, Queensland, 4000, Australia
| | - Clayton J Adam
- Paediatric Spine Research Group, Queensland University of Technology and Mater Health Services Brisbane Ltd, 2 George Street, Brisbane, Queensland, 4000, Australia
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Hutmacher DW, Little JP, Pettet GJ, Loessner D. Biomaterial science meets computational biology. J Mater Sci Mater Med 2015; 26:185. [PMID: 25893394 DOI: 10.1007/s10856-015-5518-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 02/27/2015] [Indexed: 06/04/2023]
Abstract
There is a pressing need for a predictive tool capable of revealing a holistic understanding of fundamental elements in the normal and pathological cell physiology of organoids in order to decipher the mechanoresponse of cells. Therefore, the integration of a systems bioengineering approach into a validated mathematical model is necessary to develop a new simulation tool. This tool can only be innovative by combining biomaterials science with computational biology. Systems-level and multi-scale experimental data are incorporated into a single framework, thus representing both single cells and collective cell behaviour. Such a computational platform needs to be validated in order to discover key mechano-biological factors associated with cell-cell and cell-niche interactions.
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Affiliation(s)
- Dietmar W Hutmacher
- Faculty of Science and Engineering, Queensland University of Technology, Brisbane, Australia,
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Dreischarf M, Zander T, Shirazi-Adl A, Puttlitz CM, Adam CJ, Chen CS, Goel VK, Kiapour A, Kim YH, Labus KM, Little JP, Park WM, Wang YH, Wilke HJ, Rohlmann A, Schmidt H. Comparison of eight published static finite element models of the intact lumbar spine: predictive power of models improves when combined together. J Biomech 2014; 47:1757-66. [PMID: 24767702 DOI: 10.1016/j.jbiomech.2014.04.002] [Citation(s) in RCA: 225] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 04/01/2014] [Accepted: 04/01/2014] [Indexed: 10/25/2022]
Abstract
Finite element (FE) model studies have made important contributions to our understanding of functional biomechanics of the lumbar spine. However, if a model is used to answer clinical and biomechanical questions over a certain population, their inherently large inter-subject variability has to be considered. Current FE model studies, however, generally account only for a single distinct spinal geometry with one set of material properties. This raises questions concerning their predictive power, their range of results and on their agreement with in vitro and in vivo values. Eight well-established FE models of the lumbar spine (L1-5) of different research centers around the globe were subjected to pure and combined loading modes and compared to in vitro and in vivo measurements for intervertebral rotations, disc pressures and facet joint forces. Under pure moment loading, the predicted L1-5 rotations of almost all models fell within the reported in vitro ranges, and their median values differed on average by only 2° for flexion-extension, 1° for lateral bending and 5° for axial rotation. Predicted median facet joint forces and disc pressures were also in good agreement with published median in vitro values. However, the ranges of predictions were larger and exceeded those reported in vitro, especially for the facet joint forces. For all combined loading modes, except for flexion, predicted median segmental intervertebral rotations and disc pressures were in good agreement with measured in vivo values. In light of high inter-subject variability, the generalization of results of a single model to a population remains a concern. This study demonstrated that the pooled median of individual model results, similar to a probabilistic approach, can be used as an improved predictive tool in order to estimate the response of the lumbar spine.
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Affiliation(s)
- M Dreischarf
- Julius Wolff Institute, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
| | - T Zander
- Julius Wolff Institute, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - A Shirazi-Adl
- Division of Applied Mechanics, Department of Mechanical Engineering, École Polytechnique, Montréal, Quebec, Canada
| | - C M Puttlitz
- Orthopaedic Bioengineering Research Laboratory, Colorado State University, USA
| | - C J Adam
- Paediatric Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | - C S Chen
- Department of Physical Therapy and Assistive Technology, National Yang-Ming University, Taipei, Taiwan
| | - V K Goel
- Departments of Bioengineering and Orthopaedic Surgery, Colleges of Engineering and Medicine, University of Toledo, USA
| | - A Kiapour
- Departments of Bioengineering and Orthopaedic Surgery, Colleges of Engineering and Medicine, University of Toledo, USA
| | - Y H Kim
- Department of Mechanical Engineering, Kyung Hee University, Yongin 446-701, Republic of Korea
| | - K M Labus
- Orthopaedic Bioengineering Research Laboratory, Colorado State University, USA
| | - J P Little
- Paediatric Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | - W M Park
- Department of Mechanical Engineering, Kyung Hee University, Yongin 446-701, Republic of Korea
| | - Y H Wang
- Department of Physical Therapy and Assistive Technology, National Yang-Ming University, Taipei, Taiwan
| | - H J Wilke
- Institute of Orthopaedic Research and Biomechanics, Ulm, Germany
| | - A Rohlmann
- Julius Wolff Institute, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - H Schmidt
- Julius Wolff Institute, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany; Institute of Orthopaedic Research and Biomechanics, Ulm, Germany
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Little JP, Izatt MT, Labrom RD, Askin GN, Adam CJ. An FE investigation simulating intra-operative corrective forces applied to correct scoliosis deformity. Scoliosis 2013; 8:9. [PMID: 23680391 PMCID: PMC3680303 DOI: 10.1186/1748-7161-8-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 05/06/2013] [Indexed: 11/22/2022]
Abstract
Background Adolescent idiopathic scoliosis (AIS) is a deformity of the spine, which may require surgical correction by attaching a rod to the patient’s spine using screws implanted in the vertebral bodies. Surgeons achieve an intra-operative reduction in the deformity by applying compressive forces across the intervertebral disc spaces while they secure the rod to the vertebra. We were interested to understand how the deformity correction is influenced by increasing magnitudes of surgical corrective forces and what tissue level stresses are predicted at the vertebral endplates due to the surgical correction. Methods Patient-specific finite element models of the osseoligamentous spine and ribcage of eight AIS patients who underwent single rod anterior scoliosis surgery were created using pre-operative computed tomography (CT) scans. The surgically altered spine, including titanium rod and vertebral screws, was simulated. The models were analysed using data for intra-operatively measured compressive forces – three load profiles representing the mean and upper and lower standard deviation of this data were analysed. Data for the clinically observed deformity correction (Cobb angle) were compared with the model-predicted correction and the model results investigated to better understand the influence of increased compressive forces on the biomechanics of the instrumented joints. Results The predicted corrected Cobb angle for seven of the eight FE models were within the 5° clinical Cobb measurement variability for at least one of the force profiles. The largest portion of overall correction was predicted at or near the apical intervertebral disc for all load profiles. Model predictions for four of the eight patients showed endplate-to-endplate contact was occurring on adjacent endplates of one or more intervertebral disc spaces in the instrumented curve following the surgical loading steps. Conclusion This study demonstrated there is a direct relationship between intra-operative joint compressive forces and the degree of deformity correction achieved. The majority of the deformity correction will occur at or in adjacent spinal levels to the apex of the deformity. This study highlighted the importance of the intervertebral disc space anatomy in governing the coronal plane deformity correction and the limit of this correction will be when bone-to-bone contact of the opposing vertebral endplates occurs.
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Affiliation(s)
- J Paige Little
- Paediatric Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology and Mater Health Services Brisbane, Room O718, Gardens Point Campus, 2 George Street, Brisbane, QLD, 4001, Australia.
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Loessner D, Little JP, Pettet GJ, Hutmacher DW. A multiscale road map of cancer spheroids – incorporating experimental and mathematical modelling to understand cancer progression. J Cell Sci 2013; 126:2761-71. [DOI: 10.1242/jcs.123836] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Computational models represent a highly suitable framework, not only for testing biological hypotheses and generating new ones but also for optimising experimental strategies. As one surveys the literature devoted to cancer modelling, it is obvious that immense progress has been made in applying simulation techniques to the study of cancer biology, although the full impact has yet to be realised. For example, there are excellent models to describe cancer incidence rates or factors for early disease detection, but these predictions are unable to explain the functional and molecular changes that are associated with tumour progression. In addition, it is crucial that interactions between mechanical effects, and intracellular and intercellular signalling are incorporated in order to understand cancer growth, its interaction with the extracellular microenvironment and invasion of secondary sites. There is a compelling need to tailor new, physiologically relevant in silico models that are specialised for particular types of cancer, such as ovarian cancer owing to its unique route of metastasis, which are capable of investigating anti-cancer therapies, and generating both qualitative and quantitative predictions. This Commentary will focus on how computational simulation approaches can advance our understanding of ovarian cancer progression and treatment, in particular, with the help of multicellular cancer spheroids, and thus, can inform biological hypothesis and experimental design.
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Gillen JB, Little JP, Punthakee Z, Tarnopolsky MA, Riddell MC, Gibala MJ. Acute high-intensity interval exercise reduces the postprandial glucose response and prevalence of hyperglycaemia in patients with type 2 diabetes. Diabetes Obes Metab 2012; 14:575-7. [PMID: 22268455 DOI: 10.1111/j.1463-1326.2012.01564.x] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
High-volume endurance exercise (END) improves glycaemic control in type 2 diabetes (T2D) but many individuals cite 'lack of time' as a barrier to regular participation. High-intensity interval training (HIT) is a time-efficient method to induce physiological adaptations similar to END, but little is known regarding the effect of HIT in T2D. Using continuous glucose monitoring (CGM), we examined the 24-h blood glucose response to one session of HIT consisting of 10 × 60 s cycling efforts at ~90% maximal heart rate, interspersed with 60 s rest. Seven adults with T2D underwent CGM for 24-h on two occasions under standard dietary conditions: following acute HIT and on a non-exercise control day (CTL). HIT reduced hyperglycaemia measured as proportion of time spent above 10 mmol/l (HIT: 4.5 ± 4.4 vs. CTL: 15.2 ± 12.3%, p = 0.04). Postprandial hyperglycaemia, measured as the sum of post-meal areas under the glucose curve, was also lower after HIT vs. CTL (728 ± 331 vs. 1142 ± 556 mmol/l·9 h, p = 0.01). These findings highlight the potential for HIT to improve glycaemic control in T2D.
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Little JP, Villanueva EB, Klegeris A. Therapeutic potential of cannabinoids in the treatment of neuroinflammation associated with Parkinson's disease. Mini Rev Med Chem 2011; 11:582-90. [PMID: 21699489 DOI: 10.2174/138955711795906905] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 03/31/2011] [Indexed: 11/22/2022]
Abstract
The cannabinoid system is represented by two principal receptor subtypes, termed CB1 and CB2, along with several endogenous ligands. In the central nervous system it is involved in several processes. CB1 receptors are mainly expressed by neurons and their activation is primarily implicated in psychotropic and motor effects of cannabinoids. CB2 receptors are expressed by glial cells and are thought to participate in regulation of neuroimmune reactions. This review aims to highlight several reported properties of cannabinoids that could be used to inhibit the adverse neuroinflammatory processes contributing to Parkinson's disease and possibly other neurodegenerative disorders. These include anti-oxidant properties of phytocannabinoids and synthetic cannabinoids as well as hypothermic and antipyretic effects. However, cannabinoids may also trigger signaling cascades leading to impaired mitochondrial enzyme activity, reduced mitochondrial biogenesis, and increased oxidative stress, all of which could contribute to neurotoxicity. Therefore, further pharmacological studies are needed to allow rational design of new cannabinoid-based drugs lacking detrimental in vivo effects.
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Affiliation(s)
- J P Little
- Department of Biology, University of British Columbia Okanagan, Kelowna, BC, Canada
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Little JP, Pearcy MJ, Tevelen G, Evans JH, Pettet G, Adam CJ. The mechanical response of the ovine lumbar anulus fibrosus to uniaxial, biaxial and shear loads. J Mech Behav Biomed Mater 2009; 3:146-57. [PMID: 20129414 DOI: 10.1016/j.jmbbm.2009.09.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 09/11/2009] [Accepted: 09/28/2009] [Indexed: 10/20/2022]
Abstract
Analytical and computational models of the intervertebral disc (IVD) are commonly employed to enhance understanding of the biomechanics of the human spine and spinal motion segments. The accuracy of these models in predicting physiological behaviour of the spine is intrinsically reliant on the accuracy of the material constitutive representations employed to represent the spinal tissues. There is a paucity of detailed mechanical data describing the material response of the reinforced-ground matrix in the anulus fibrosus of the IVD. In the present study, the 'reinforced-ground matrix' was defined as the matrix with the collagen fibres embedded but not actively bearing axial load, thus incorporating the contribution of the fibre-fibre and fibre-matrix interactions. To determine mechanical parameters for the anulus ground matrix, mechanical tests were carried out on specimens of ovine anulus, under unconfined uniaxial compression, simple shear and biaxial compression. Test specimens of ovine anulus fibrosus were obtained with an adjacent layer of vertebral bone/cartilage on the superior and inferior specimen surface. Specimen geometry was such that there were no continuous collagen fibres coupling the two endplates. Samples were subdivided according to disc region - anterior, lateral and posterior - to determine the regional inhomogeneity in the anulus mechanical response. Specimens were loaded at a strain rate sufficient to avoid fluid outflow from the tissue and typical stress-strain responses under the initial load application and under repeated loading were determined for each of the three loading types. The response of the anulus tissue to the initial and repeated load cycles was significantly different for all load types, except biaxial compression in the anterior anulus. Since the maximum applied strain exceeded the damage strain for the tissue, experimental results for repeated loading reflected the mechanical ability of the tissue to carry load, subsequent to the initiation of damage. To our knowledge, this is the first study to provide experimental data describing the response of the 'reinforced-ground matrix' to biaxial compression. Additionally, it is novel in defining a study objective to determine the regionally inhomogeneous response of the 'reinforced-ground matrix' under an extensive range of loading conditions suitable for mechanical characterisation of the tissue. The results presented facilitate the development of more detailed and comprehensive constitutive descriptions for the large strain nonlinear elastic or hyperelastic response of the anulus ground matrix.
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Affiliation(s)
- J P Little
- School of Engineering Systems, Queensland University of Technology, Brisbane, Australia.
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Little JP, Tevelen G, Adam CJ, Evans JH, Pearcy MJ. Development of a biaxial compression device for biological samples: preliminary experimental results for a closed cell foam. J Mech Behav Biomed Mater 2009; 2:305-9. [PMID: 19627835 DOI: 10.1016/j.jmbbm.2008.10.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Revised: 10/09/2008] [Accepted: 10/24/2008] [Indexed: 10/21/2022]
Abstract
Biological tissues are subjected to complex loading states in vivo and in order to define constitutive equations that effectively simulate their mechanical behaviour under these loads, it is necessary to obtain data on the tissue's response to multiaxial loading. Single axis and shear testing of biological tissues is often carried out, but biaxial testing is less common. We sought to design and commission a biaxial compression testing device, capable of obtaining repeatable data for biological samples. The apparatus comprised a sealed stainless steel pressure vessel specifically designed such that a state of hydrostatic compression could be created on the test specimen while simultaneously unloading the sample along one axis with an equilibrating tensile pressure. Thus a state of equibiaxial compression was created perpendicular to the long axis of a rectangular sample. For the purpose of calibration and commissioning of the vessel, rectangular samples of closed cell ethylene vinyl acetate (EVA) foam were tested. Each sample was subjected to repeated loading, and nine separate biaxial experiments were carried out to a maximum pressure of 204 kPa (30 psi), with a relaxation time of two hours between them. Calibration testing demonstrated the force applied to the samples had a maximum error of 0.026 N (0.423% of maximum applied force). Under repeated loading, the foam sample demonstrated lower stiffness during the first load cycle. Following this cycle, an increased stiffness, repeatable response was observed with successive loading. While the experimental protocol was developed for EVA foam, preliminary results on this material suggest that this device may be capable of providing test data for biological tissue samples. The load response of the foam was characteristic of closed cell foams, with consolidation during the early loading cycles, then a repeatable load-displacement response upon repeated loading. The repeatability of the test results demonstrated the ability of the test device to provide reproducible test data and the low experimental error in the force demonstrated the reliability of the test data.
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Affiliation(s)
- J P Little
- School of Engineering Systems, Queensland University of Technology, Brisbane, Australia.
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Little JP, Gray HA, Murray DW, Beard DJ, Gill HS. Thermal effects of cement mantle thickness for hip resurfacing. J Arthroplasty 2008; 23:454-8. [PMID: 18358388 DOI: 10.1016/j.arth.2007.02.015] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Revised: 12/11/2006] [Accepted: 02/04/2007] [Indexed: 02/01/2023] Open
Abstract
Hybrid hip resurfacing arthroplasty with uncemented acetabular and cemented femoral fixation is increasingly becoming popular as an alternative to total hip arthroplasty. There is concern about femoral neck fractures, and long-term survival has not yet been demonstrated. Thermal necrosis may be an important factor for neck fracture and will affect the viability of the femoral bone. This cadaveric study investigated the thermal effect of thick (1.5 mm, n = 3) and thin (0.5 mm, n = 3) cement mantles; 5 thermocouples were used to record temperature at the femoral bone/cement interface during hip resurfacing arthroplasty. The highest recorded temperatures were significantly higher when a thick cement mantle is used (45.4 degrees C), compared to a thin cement mantle (32.7 degrees C). To reduce the potential for thermal necrosis, the thin cement mantle technique is recommended.
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Affiliation(s)
- J Paige Little
- Nuffield Department of Orthopaedic Surgery, University of Oxford, Nuffield Orthopaedic Centre, Oxford, UK
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Little JP, Pearcy MJ, Pettet GJ. Parametric equations to represent the profile of the human intervertebral disc in the transverse plane. Med Biol Eng Comput 2007; 45:939-45. [PMID: 17710459 DOI: 10.1007/s11517-007-0242-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Accepted: 07/27/2007] [Indexed: 11/28/2022]
Abstract
Computational and finite element models of the spine are used to investigate spine and disc mechanics. Subject specific data for the transverse profile of the disc could improve the geometric accuracy of these models. The current study aimed to develop a mathematical algorithm to describe the profile of the disc components, using subject-specific data points. Using data points measured from pictures of human intervertebral discs sectioned in the transverse plane, parametric formulae were derived that mapped the outer profile of the anulus and nucleus. The computed anulus and nucleus profile were a similar shape to the discs from which they were derived. The computed total disc area was similar to the experimental data. The nucleus:disc area ratios were sensitive to the data points defined for each disc. The developed formulae can be easily implemented to provide patient specific data for the disc profile in computational models of the spine.
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Affiliation(s)
- J Paige Little
- School of Engineering Systems, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.
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Little JP, Taddei F, Viceconti M, Murray DW, Gill HS. Changes in femur stress after hip resurfacing arthroplasty: response to physiological loads. Clin Biomech (Bristol, Avon) 2007; 22:440-8. [PMID: 17257719 DOI: 10.1016/j.clinbiomech.2006.12.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Revised: 12/05/2006] [Accepted: 12/08/2006] [Indexed: 02/07/2023]
Abstract
BACKGROUND Hip resurfacing arthroplasty is being increasingly considered as an alternative to total hip arthroplasty in young, active patients. Hip resurfacing arthroplasty is reported to preserve the normal joint mechanics. However, there is concern, in the short term, due to frequent occurrence of femoral neck fractures. METHODS We evaluated changes in femoral mechanics after hip resurfacing arthroplasty. We used an experimentally validated, distributed material finite element model of a cadaveric femur before and after hip resurfacing arthroplasty. Bone stiffness and strength values representing normal, elderly and osteoporotic bone were used. For a physiological load case, bone strains were compared with literature values for total hip arthroplasty and a risk of fracture scalar calculated. FINDINGS The changes in peak stresses after hip resurfacing arthroplasty were low in relation to the failure strength of bone and the fracture risk was low. The intact and implanted finite element models showed bone strains after hip resurfacing arthroplasty were closer to the intact condition than after total hip arthroplasty. INTERPRETATION The bone stresses predicted after resurfacing in both the normal and aged femoral neck were not sufficient to be a potential cause of fracture.
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Affiliation(s)
- J P Little
- OOEC/Nuffield Department of Orthopaedic Surgery, University of Oxford, Nuffield Orthopaedic Centre, Headington, Oxford OX3 7LD, UK
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Abstract
Degenerate intervertebral discs exhibit both material and structural changes. Structural defects (lesions) develop in the anulus fibrosus with age. While degeneration has been simulated in numerous previous studies, the effects of structural lesions on disc mechanics are not well known. In this study, a finite element model (FEM) of the L4/5 intervertebral disc was developed in order to study the effects of anular lesions and loss of hydrostatic pressure in the nucleus pulposus on the disc mechanics. Models were developed to simulate both healthy and degenerate discs. Degeneration was simulated with either rim, radial or circumferential anular lesions and by equating nucleus pressure to zero. The anulus fibrosus ground substance was represented as a nonlinear incompressible material using a second-order polynomial, hyperelastic strain energy equation. Hyperelastic material parameters were derived from experimentation on sheep discs. Endplates were assumed to be rigid, and annulus lamellae were assumed to be vertical in the unloaded state. Loading conditions corresponding to physiological ranges of rotational motion were applied to the models and peak rotation moments compared between models. Loss of nucleus pulposus pressure had a much greater effect on the disc mechanics than the presence of anular lesions. This indicated that the development of anular lesions alone (prior to degeneration of the nucleus) has minimal effect on disc mechanics, but that disc stiffness is significantly reduced by the loss of hydrostatic pressure in the nucleus. With the degeneration of the nucleus, the outer innervated anulus or surrounding osteo-ligamentous anatomy may therefore experience increased strains.
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Affiliation(s)
- J P Little
- School of Engineering Systems, Queensland University of Technology, BEE Research Portfolio, O Block-Level 7, Gardens Point, 2 George Street, Brisbane, Queensland 4001, Australia.
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Little JP, Adam CJ, Evans JH, Pettet GJ, Pearcy MJ. Nonlinear finite element analysis of anular lesions in the L4/5 intervertebral disc. J Biomech 2007; 40:2744-51. [PMID: 17383659 DOI: 10.1016/j.jbiomech.2007.01.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2006] [Accepted: 01/04/2007] [Indexed: 12/19/2022]
Abstract
Degenerate intervertebral discs exhibit both material and structural changes. Structural defects (lesions) develop in the anulus fibrosus with age. While degeneration has been simulated in numerous previous studies, the effects of structural lesions on disc mechanics are not well known. In this study, a finite element model (FEM) of the L4/5 intervertebral disc was developed in order to study the effects of anular lesions and loss of hydrostatic pressure in the nucleus pulposus on the disc mechanics. Models were developed to simulate both healthy and degenerate discs. Degeneration was simulated with either rim, radial or circumferential anular lesions and by equating nucleus pressure to zero. The anulus fibrosus ground substance was represented as a nonlinear incompressible material using a second-order polynomial, hyperelastic strain energy equation. Hyperelastic material parameters were derived from experimentation on sheep discs. Endplates were assumed to be rigid, and annulus lamellae were assumed to be vertical in the unloaded state. Loading conditions corresponding to physiological ranges of rotational motion were applied to the models and peak rotation moments compared between models. Loss of nucleus pulposus pressure had a much greater effect on the disc mechanics than the presence of anular lesions. This indicated that the development of anular lesions alone (prior to degeneration of the nucleus) has minimal effect on disc mechanics, but that disc stiffness is significantly reduced by the loss of hydrostatic pressure in the nucleus. With the degeneration of the nucleus, the outer innervated anulus or surrounding osteo-ligamentous anatomy may therefore experience increased strains.
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Affiliation(s)
- J P Little
- School of Engineering Systems, Queensland University of Technology, BEE Research Portfolio, O Block-Level 7, Gardens Point, 2 George Street, Brisbane, Queensland 4001, Australia.
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Pallett KE, Cramp SM, Little JP, Veerasekaran P, Crudace AJ, Slater AE. Isoxaflutole: the background to its discovery and the basis of its herbicidal properties. Pest Manag Sci 2001; 57:133-142. [PMID: 11455644 DOI: 10.1002/1526-4998(200102)57:2<133::aid-ps276>3.0.co;2-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This paper reviews the discovery of isoxaflutole (IFT), focusing on the chemical and physicochemical properties which contribute to the herbicidal behaviour of this new herbicide. IFT (5-cyclopropyl-1,2-isoxazol-4-yl alpha alpha alpha-trifluoro-2-mesyl-p-tolyl ketone) is a novel herbicide for pre-emergence control of a wide range of important broadleaf and grass weeds in corn and sugarcane. The first benzoyl isoxazole lead was synthesised in 1989 and IFT in 1990, and the herbicidal potential of the latter was identified in 1991. The decision to develop the molecule was taken after two years of field testing in North America. The biochemical target of IFT is 4-hydroxyphenylpyruvate dioxygenase (HPPD), inhibition of which leads to a characteristic bleaching of susceptible species. The inhibitor of HPPD is the diketonitrile derivative of IFT formed from opening of the isoxazole ring. The diketonitrile (DKN) is formed rapidly in plants following root and shoot uptake. The DKN is both xylem and phloem mobile leading to high systemicity. IFT also undergoes conversion to the DKN in the soil. The soil half-life of IFT ranges from 12 h to 3 days under laboratory conditions and is dependent on several factors such as soil type, pH and moisture. The log P of IFT is 2.19 and the water solubility is 6.2 mg litre-1, whereas the corresponding values for the DKN are 0.4 and 326 mg litre-1, respectively. These properties restrict the mobility of IFT, which is retained at the soil surface where it can be taken up by surface-germinating weed seeds. The DKN, which has a laboratory soil half-life of 20-30 days, is more mobile and is taken up by the roots. In addition to influencing the soil behaviour of IFT and DKN, the greater lipophilicity of IFT leads to greater uptake by seed, shoot and root tissues. In both plants and soil, the DKN is converted to the herbicidally inactive benzoic acid. This degradation is more rapid in maize than in susceptible weed species and this contributes to the mechanism of selectivity, together with the greater sowing depth of the crop.
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Affiliation(s)
- K E Pallett
- Aventis CropScience, Ongar Research Station, Fyfield Road, Ongar, Essex CM5 0HW, UK.
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Affiliation(s)
- D J Lee
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins Medical Institutions, Baltimore, MD 21287, USA
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Affiliation(s)
- J P Little
- Pediatric Ear, Nose, and Throat Associates, East Tennessee Children's Hospital, Knoxville, USA
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Abstract
Laryngomalacia is the most common cause of stridor in children. Previous studies using barium esophagrams or single-probe esophageal pH testing have indicated that 68% to 80% of infants with laryngomalacia have reflux. A recent study in a large series of pediatric patients has shown that these 2 testing modalities are relatively insensitive in detecting reflux when compared with 24-hour double-probe pH testing. This study was undertaken to determine the incidence and frequency of reflux in children with laryngomalacia by use of 24-hour double-probe pH monitoring. Twenty-four children with endoscopically diagnosed laryngomalacia underwent 24-hour double-probe pH testing. The distal probe was placed in the lower esophagus, and the proximal probe was placed just above the cricopharyngeus immediately posterior to the larynx. All 24 (100%) children had pharyngeal acid exposure as judged by the proximal pH probe. These children had a mean of 15.21 episodes of reflux to the level of the pharynx during the 24-hour study period. In contrast, only 16 (66%) children had abnormal acid exposure as measured by the distal esophageal probe. These results indicate that essentially all children with laryngomalacia have reflux of gastric acid to the pharyngeal level. Multiple authors have documented the detrimental effects of acid and the accompanying pepsin in the larynx and tracheobronchial tree. Persistent laryngeal edema is an almost universal finding in patients with reflux to the pharyngeal level and is a common finding in children with laryngomalacia. In some patients with laryngomalacia, reflux may be the primary cause of their airway compromise, whereas in others it may be a significant cofactor exacerbating a preexisting neurologic or anatomic abnormality.
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Affiliation(s)
- B L Matthews
- Department of Otolaryngology, Bowman Gray School of Medicine, Wake Forest University, North Carolina, USA
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Abstract
OBJECTIVE To examine the use of hyoid as a readily available autologous grafting material for the anterior cricoid split (ACS) procedure. DESIGN Prospective analysis of 20 patients undergoing ACS with hyoid interposition grafting for subglottic stenosis over a 3-year period. The patients received at least 1 year of follow-up after surgery. SETTING Tertiary care children's hospital. PATIENTS Twenty infants (age range, 2-9 months) with endoscopically confirmed acquired and congenital subglottic stenosis. Presenting symptoms included stridor, failure to extubate, and recurrent atypical croup. All 20 children underwent ACS with hyoid interposition grafting. RESULTS All 20 patients exhibited improvement in their symptoms of airway obstruction. All 12 patients in whom extubation had previously failed subsequently underwent successful extubation. The 8 patients with symptoms of stridor and atypical croup showed marked improvement in their symptoms. Serial bronchoscopy revealed mucosal healing and incorporation of the hyoid grafts. CONCLUSION Hyoid provides a readily available and reliable grafting material for interposition grafting in the ACS procedure for neonates and infants.
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Affiliation(s)
- W F McGuirt
- Department of Otolaryngology, Wake Forest University Medical Center, Brenner Children's Hospital, Winston-Salem, NC, USA
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Little JP, Matthews BL, Glock MS, Koufman JA, Reboussin DM, Loughlin CJ, McGuirt WF. Extraesophageal pediatric reflux: 24-hour double-probe pH monitoring of 222 children. Ann Otol Rhinol Laryngol Suppl 1997; 169:1-16. [PMID: 9228867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Although extraesophageal gastric reflux has been implicated as a cause of many pediatric airway and respiratory diseases, its prevalence in these conditions remains unknown due to the relative lack of sensitivity and/or specificity of traditional reflux testing methods. A prospective study of 222 children (ages 1 day to 16 years) was performed with 24-hour double-probe (simultaneous esophageal and pharyngeal) pH monitoring. Seventy-six percent (168/222) of the study population had abnormal findings in either one or both of the pH probes. Of those, 46% (78/168) had pharyngeal reflux (extraesophageal gastric acid documented by the pharyngeal probe), despite having normal esophageal acid exposure times according to the esophageal probe. Thus, had the pharyngeal probe not been used, 46% of the children with documented extraesophageal (pharyngeal) reflux would have been falsely presumed to have normal reflux parameters. Patients with laryngeal abnormalities, pulmonary abnormalities, and emesis had significantly more pharyngeal acid reflux (p < .001) than patients with nonrespiratory symptoms. These data suggest that extraesophageal reflux may be underestimated by single-probe intraesophageal monitoring alone, and that laryngopharyngeal reflux may play a role in the pathogenesis of the conditions studied.
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Affiliation(s)
- J P Little
- Department of Otolaryngology-Head and Neck Surgery, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina
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