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Miyake K, Fujishiro T, Yamamoto Y, Usami Y, Hayama S, Nakaya Y, Neo M. Influence of cranium orientation on cervical sagittal alignment during radiographic examination: a radiographic analysis. Spine J 2024:S1529-9430(24)00928-8. [PMID: 39147140 DOI: 10.1016/j.spinee.2024.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 06/24/2024] [Accepted: 08/09/2024] [Indexed: 08/17/2024]
Abstract
BACKGROUND CONTEXT During the radiographic examination, the cranium orientation varies not only individually but also within the same subject, in different imaging sessions. Knowing how changes in the orientation of the cranium influences cervical sagittal alignment during the radiographic examination of the cervical spine can aid clinicians in the accurate evaluation for cervical sagittal alignment in clinical practice. PURPOSE To radiographically examine the influence of cranium orientation on cervical sagittal alignment during radiographic examination in an asymptomatic cohort. STUDY DESIGN A prospective radiographic study. PATIENT SAMPLE Eighty asymptomatic volunteers (mean age, 40.4 years; 50.0% male) were enrolled. OUTCOME MEASURES Cervical sagittal parameters including the regional slope (C1 slope, C2 slope, C5 slope, C7 slope, and T1 slope), Cobb angle (O-C1 angle, C1-C2 angle, C2-C5 angle, C5-C7 angle, and C7-T1 angle), and cranial/cervical offset (sella turcica tilt [ST tilt] and C2 tilt). METHODS In all participants, standing lateral radiographs of the cervical spine were taken in 3 forward-gazing positions: anteverted-cranium (AC) position; neutral-cranium (NC) position; and retroverted-cranium (RC) position. Cervical sagittal parameters, including the regional slope, Cobb angle, and cranial/cervical offset, in these 3 positions were statistically compared. RESULTS The C1 and C2 slopes were anteverted and retroverted in the AC and RC positions, respectively, compared to those in the NC position. The C5 slope, C7 slope, and T1 slope were constant among the 3 positions. In O-C2 and C2-C5, statistically significant differences in the regional Cobb angles were identified among the 3 positions; however, there were no significant differences in the C5-C7 or C7-T1 segments. Cranial and cervical offsets of ST tilt and C2 tilt increased and decreased when the cranium was anteverted and retroverted, respectively. CONCLUSIONS The current study suggests that the adjustment of the cranium orientation when taking cervical spine radiographs is mainly controlled at the upper cervical spine of the O-C2 segment in an asymptomatic cohort. On radiograph, alignment in the upper cervical segment of O-C2 changes; accordingly, the middle cervical segment of C2-C5 can change during the adjustment of cranium orientation. However, alignment in the lower cervical segment of C5-C7 and the cervicothoracic junction of C7-T1 remains constant. Further, cranial/cervical offset increases and decreases when the cranium is anteverted and retroverted, respectively. Our results can help the accurate evaluation of cervical sagittal alignment on plain radiographs in clinical practice.
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Affiliation(s)
- Katsuhiro Miyake
- Department of Orthopedic Surgery, Osaka Medical and Pharmaceutical University
| | - Takashi Fujishiro
- Department of Orthopedic Surgery, Osaka Medical and Pharmaceutical University.
| | - Yuki Yamamoto
- Department of Orthopedic Surgery, Osaka Medical and Pharmaceutical University
| | - Yoshitada Usami
- Department of Orthopedic Surgery, Osaka Medical and Pharmaceutical University
| | - Sachio Hayama
- Department of Orthopedic Surgery, Osaka Medical and Pharmaceutical University
| | - Yoshiharu Nakaya
- Department of Orthopedic Surgery, Osaka Medical and Pharmaceutical University
| | - Masashi Neo
- Department of Orthopedic Surgery, Osaka Medical and Pharmaceutical University
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Henao Romero S, Sierra Peña JA, Diaz Orduz RC, Berbeo-Calderon ME. Horizontal Gaze Assessment: An Extensive Narrative Review. World Neurosurg 2024; 187:e1011-e1016. [PMID: 38750886 DOI: 10.1016/j.wneu.2024.05.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 05/07/2024] [Indexed: 06/09/2024]
Abstract
OBJECTIVE Bipedalism was a significant milestone in the evolutionary development of Homo sapiens sapiens, influencing neocortical evolution and subsequent behavioral changes. Coordinated visual and sensory inputs are crucial for posture, environmental interaction, and surgical planning, with horizontal gaze being a pivotal parameter. This narrative review aims to explore various geometric measures used to assess horizontal gaze in patients, highlighting their applications in surgical planning. METHODS A literature review was conducted in indexed databases using Mesh terms like "Cervical Vertebrae" and "Visual Fields" along with keywords such as "horizontal gaze" and "sagittal spine parameters." Among 477 initially identified articles, 41 were selected for inclusion after rigorous filtering. RESULTS The most recognized method for assessing horizontal gaze is the Chin Brow Vertical Angle (CBVA), initially described in patients with ankylosing spondylitis. Clinical photography is employed as a tool for CBVA calculation, while other measures like McGregor slope and Slope of the Line of Sight have been considered as alternatives to CBVA. Each method presents its unique advantages and limitations. CONCLUSIONS This review highlights the need for further research into horizontal gaze measurement methods. Developing novel approaches to determine horizontal gaze can significantly enhance surgical planning and, consequently, improve patient outcomes. The ongoing exploration of these geometric measures offers promising prospects for advancing the field and optimizing patient care.
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Affiliation(s)
- Sara Henao Romero
- Department of Neurosurgery, Hospital Universitario San Ignacio, Pontificia Universidad Javeriana, Bogotá, Colombia; Neurosurgery research seedbed, Pontificia Universidad Javeriana, Bogotá, Colombia.
| | | | - Roberto Carlos Diaz Orduz
- Department of Neurosurgery, Hospital Universitario San Ignacio, Pontificia Universidad Javeriana, Bogotá, Colombia
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Hey HWD, Lin S, Tay HW, Tay YJ, Liu GKP, Wong HK. Understanding "Kyphosis" and "Lordosis" for Sagittal Balancing in Two Common Standing Postures. Spine (Phila Pa 1976) 2021; 46:1603-1611. [PMID: 34747908 DOI: 10.1097/brs.0000000000004106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Cross-sectional radiographic comparison study. OBJECTIVE The aim of this study was to understand whole-body balancing in directed and natural standing postures, through comparison of kypholordotic ratios on whole-body radiographs of young, healthy subjects. SUMMARY OF BACKGROUND DATA Recent studies highlighted the importance of understanding whole-body balancing, proposing the use of the more physiological natural standing posture, together with the conventional directed standing posture, for imaging. METHODS Sixty healthy, 21-year-old subjects (36 males, 24 females) were recruited. EOS whole-body radiographs of subjects in directed and natural standing postures were obtained. Radiographic parameters compared include C2-sagittal vertical axis (C2-SVA), C7-SVA, C2-7-SVA, global cervical angles (C0-T1 and C2-C7), regional cervical angles (C0-C2, C2-C4, C4-C7), T1-slope, global thoracic angles (T1-T12 and T1-inflection vertebra [Inf]), thoracolumbar angle (T11-L2), global lumbar angles (T12-S1 and Inf-S1), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), spinocoxa angle (SCA), and femoral alignment angle (FAA). Kypholordotic ratios of T1-12/T12-S1, T1-Inf/Inf-S1, Tl-Inf/SCA, and (T1-Inf + FAA)/(T1-slope + SCA) were calculated and compared. RESULTS Compared to directed standing, natural standing has greater C2-SVA and C7-SVA, more lordotic global and regional cervical angles (except C0-2 angle), higher T1-slope, larger T1- T12 and T1-Inf kyphotic angles, smaller T12-S1 and Inf-S1 lordotic angles, larger PT, more lordotic SCA, and smaller SS and FAA angles. T1-12/T12-S1 and T1-Inf/Inf-S1 ratios in natural standing, and (Tl-Inf + FAA)/(T1-slope + SCA) ratio in both postures approximate 1. There were significant differences between postures for Tl-l2/Tl2-Sl, Tl-Inf/Inf-Sl and Tl-Inf/SCA ratios. CONCLUSION Whole-body balancing requires understanding of the balance between kyphosis and lordosis, which varies with the posture of patients. Analysis of kypholordotic ratios obtained in this study allude to the importance of performing whole-body imaging in the directed standing posture, and whole-spine or whole-body imaging in the natural standing posture, so as to fully understand spinal and whole body balancing for spinal realignment surgeries.Level of Evidence: Level 3.
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Affiliation(s)
- Hwee Weng Dennis Hey
- University Orthopedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore
| | - Shuxun Lin
- University Orthopedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore
| | - Hui Wen Tay
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Yuan Jie Tay
- University Orthopedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore
| | - Gabriel Ka-Po Liu
- University Orthopedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore
| | - Hee-Kit Wong
- University Orthopedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore
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Hey HWD, Lim JXY, Tan CS, Liu GKP, Wong HK. Audit and Comparison Between Radiographic Markers of Gaze Direction Using EOS Imaging - An Essential Step to Streamline Existing Methods. Spine (Phila Pa 1976) 2021; 46:E1202-E1210. [PMID: 34474453 DOI: 10.1097/brs.0000000000004213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Retrospective cohort study on prospectively implemented EOS protocol. OBJECTIVE This study aims to audit and compare existing radiological definitions of gaze direction-chin brow vertical angle (CBVA), McGregor slope (McGS), slope of line of sight (SLS), orbital-internal occipital protuberance (OIOP) slope angle, and Tangent to the hard palate (THP) in a neutral, healthy, and asymptomatic cohort. SUMMARY OF BACKGROUND DATA The ability to accurately define direction of gaze is the first step when striving for horizontal gaze restoration in any affected individual with rigid sagittal deformity. Yet, the radiological definition of gaze direction remains poorly standardized. METHODS Hundred healthy subjects who could achieve horizontal gaze underwent whole-body standing EOS radiographs taken under a strictly standardized protocol. Radiographic measurements of global spinal sagittal parameters and surrogate measures of horizontal gaze were analyzed and compared. RESULTS The mean age was 45 ± 15.9 years, with a balanced male-to-female-ratio. Their C7 SVA was -7.7 mm ± 24.8 mm, PI was 51.0o ± 11.4o, PI-LL was -0.9o ± 13.0o and T1-slope was 21.2o ± 9.2o. Measured horizontal gaze parameters were as follows: CBVA (1.07o ± 5.48o), McGS (-3.23o ± 5.63o), SLS (0.45o ± 5.34o), OIOP (5.03o ± 4.66o), THP (-0.17o ± 6.27o). CBVA correlated strongly with McGS (r = 0.679, P < 0.001), SLS (r = 0.592, P < 0.001), OIOP (r = 0.697, P < 0.001), and THP (r = -0.504, P < 0.001). OIOP had the lowest variance amongst all parameters and showed less variability compared to CBVA (SD 4.66 Var 21.69 vs. SD 5.48 Var 30.08, P = .012). Multivariate analysis showed that C2-7 angle was the only parameter found to be associated with OIOP values (P = 0.006). CONCLUSION OIOP is the least variable, and most robust radiological method in determining gaze direction. It uses easily recognizable anatomical landmarks and an angular criterion, which makes it advantageous both with x-rays or slot scanners.Level of Evidence: 3.
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Affiliation(s)
| | - Joel Xue Yi Lim
- Department of Orthopedic Surgery, National University Health System, Singapore
| | - Chuen Seng Tan
- Saw Swee Hock School of Public Health, National University of Singapore, Singapore
| | - Gabriel Ka Po Liu
- Department of Orthopedic Surgery, National University Health System, Singapore
| | - Hee Kit Wong
- Department of Orthopedic Surgery, National University of Singapore, Singapore
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Hey HWD, Tay HW, Wong GC, Tan KA, Lau ETC, Wong SJ, Liu KPG, Wong HK. Fulcrum to Generate Maximum Extension of the Spine and Hip-Proposing A New Strategy using EOS Imaging for Patient-specific Assessment of Degenerated Lumbar Spines. Spine (Phila Pa 1976) 2021; 46:E832-E839. [PMID: 33660680 DOI: 10.1097/brs.0000000000004025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN A retrospective, radiographic comparative study conducted in a single academic institution. OBJECTIVE This study aims to compare fulcrum extension with conventional extension imaging to determine maximum "hip lordosis" (HL), an important novel patient-specific parameter in spinal realignment surgery, as well as understand the extension capabilities of the lower lumbar spine, which together, are key contributors to whole-body balancing. SUMMARY OF BACKGROUND DATA Recent literature recognizes the hip as an important contributor to whole-body lordosis beyond a compensator for spinal imbalance. METHODS Patients >45 years' old with mechanical low back pain due to degenerative spinal conditions were included and grouped based on the imaging performed-fulcrum or conventional extension. All imaging was performed using EOS under standardized instructions and visual aids. Radiographic parameters include global lumbar angle (GLA), inflexion-S1 (Inf-S1) angle, segmental lumbar angles, pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), femoral alignment angle (FAA), HL and spinocoxa angle (SCA). Unpaired t test was used to compare between radiographic parameters. RESULTS One hundred patients (40 males and 60 females, mean age 63.0 years) underwent either fulcrum or conventional extension EOS® imaging. Both groups had comparable baseline radiographic parameters. Fulcrum extension gave a larger mean GLA (-60.7° vs. -48.5°, P = 0.001), Inf-S1 angle (-58.8° vs. -48.8°, P = 0.003), SCA (-36.5° vs. -24.8°, P < 0.001), L4/5 and L5/S1 lordosis (-20.7° vs. -17.7°, P = 0.041, and -22.3° vs. -17.1°, P = 0.018, respectively), compared to conventional extension. PI, SS, PT, FAA, and HL were similar between both extension postures. CONCLUSION Fulcrum extension, compared to conventional extension, is better at generating lordosis in the lower lumbar spine, thus improving preoperative assessment of stiffness or instability of the lumbar spine. Both extension methods were equally effective at determining the patient-specific maximum HL to assess the flexibility and compensation occurring at the hip, potentially guiding surgical management of patients with degenerative spines.Level of Evidence: 3.
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Affiliation(s)
- Hwee Weng Dennis Hey
- University Orthopedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore.,Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Hui Wen Tay
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Gordon Chengyuan Wong
- University Orthopedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore
| | - Kimberly-Anne Tan
- University Orthopedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore
| | - Eugene Tze-Chun Lau
- University Orthopedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore
| | - Seng Juong Wong
- University Orthopedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore
| | - Ka-Po Gabriel Liu
- University Orthopedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore
| | - Hee-Kit Wong
- University Orthopedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore.,Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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Azimi P, Yazdanian T, Benzel EC, Montazeri A. Global Sagittal Balance of Spine in Asymptomatic Controls: A Systematic Review and Meta-Analysis. World Neurosurg 2021; 154:93-108. [PMID: 34314909 DOI: 10.1016/j.wneu.2021.07.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 07/04/2021] [Accepted: 07/08/2021] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To assess the global sagittal balance of spine (GSBS) in asymptomatic controls. METHODS PubMed, Scopus, Cochrane library, and Web of Science searched up to July 2020. Studies were screened for the GSB parameters including T1 pelvic angle (TPA), spinosacral angle (SSA), sagittal vertical axis (SVA), C7/sacrofemoral distance ratio (Barrey index), odontoid hip axis (OD-HA), and Full Balance Index (FBI) as measured in asymptomatic participants. A meta-analysis was performed to synthesize pooled estimates. Heterogeneity and publication bias were assessed. RESULTS Overall, 76 studies were identified including 12,169 participants (54.7% female) with mean age ranges from 12.0 to 72.9 years old. We used the Newcastle-Ottawa Scale (NOS) to evaluate the quality of studies included in this review. Begg's test did not indicate obvious publication bias. The pooled analysis reveals that the mean (standard deviation) normative values were: 1) age ˃18 years, SSA (°), 127.6 (0.89); SVA absolute value (millimeters), 13.1 (1.13); TPA (°), 9.8 (1.13); T1SPI (°), -4.3 (0.57); and Barrey index absolute value, 0.51 (0.3). The mean value of the OD-HA (°) was reported 2.9 (1.6), and the FBI average value was less than 5°. 2) Age ≤18 years, SSA (°), 132.1 (8.3); SVA absolute value (millimeters), 11.9 (2.0); and Barrey index, -0.7 (8.3). A significant difference was observed between the 2 age groups based on SVA and SSA. CONCLUSIONS This paper presents normative data on TPA, SSA, SVA, Barrey index, OD-HA, and FBI as a reference for evaluating/measuring a GSB of spine in asymptomatic controls.
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Affiliation(s)
- Parisa Azimi
- Department of Neurosurgery, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | | | - Edward C Benzel
- Cleveland Clinic Foundation, Department of Neurosurgery, Cleveland, Ohio, USA
| | - Ali Montazeri
- Mental Health Research Group, Health Metrics Research Centre, Iranian Institute for Health Sciences Research, ACECR, Tehran, Iran
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Hey HWD, Zhuo WH, Tan YHJ, Tan JH. Accuracy of freehand pedicle screws versus lateral mass screws in the subaxial cervical spine. Spine Deform 2020; 8:1049-1058. [PMID: 32314180 DOI: 10.1007/s43390-020-00119-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 04/06/2020] [Indexed: 10/24/2022]
Abstract
STUDY DESIGN Radiographic comparative study with prospectively collected data. OBJECTIVES To assess the accuracy of subaxial cervical pedicle screw (CPS) placement with freehand technique compared to lateral mass screws (LMS). The freehand cervical pedicle screw insertion technique guided by intraoperative lateral C-arm imaging has been shown to be both safe and effective. However, no study has performed a 100% audit of this technique using pre- and postoperative computed tomography (CT) to determine its true accuracy, as well as its reduction capability of CPS and LMS instrumentation. METHODS 36 consecutive patients treated surgically by a single surgeon with the exclusive practice of LMS and subsequently CPS over 2 years were included. CT and EOS slot scanner were performed pre- and post-operatively to determine the extent of pedicle screw breach and to assess sagittal alignment reduction between CPS and LMS groups. Predictors of pedicle screw breaches were also identified using multivariate analysis. RESULTS CPS fixation was more effective in restoring global cervical angle and had superior reduction capability of cervical lordosis at the levels of C3/4 (5.00 ± 3.92, p = 0.008), C4/5 (6.63 ± 5.5, p = 0.010) and C5/6 (7.22 ± 6.19, p = 0.004) compared to LMS fixation. Pedicle screw breaches occurred most commonly at C4 (p = 0.003), and most commonly involved the lateral pedicle wall (p < 0.001). Placement of freehand pedicles screws on the concavity of rotated vertebrae was predictive of pedicle screw breach (OR 2.567, 95% CI 1.058-6.228, p = 0.037). There was no significant difference in the complication rate. CONCLUSIONS Although freehand cervical pedicle screw fixation is technically more demanding, it is generally safe and effective. However, the increased risk of screw breaches in the context of a rotated spine should be taken into consideration. Lateral mass screw fixation is advised if spinal realignment is not necessary.
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Affiliation(s)
- Hwee Weng Dennis Hey
- Department of Orthopaedic Surgery, National University Health System (NUHS), Singapore, Singapore. .,Yong Loo Lin School of Medicine, National University of Singapore (NUS), Singapore, Singapore.
| | - Wen-Hai Zhuo
- Yong Loo Lin School of Medicine, National University of Singapore (NUS), Singapore, Singapore
| | - Yong Hao Joel Tan
- Department of Orthopaedic Surgery, National University Health System (NUHS), Singapore, Singapore
| | - Jiong Hao Tan
- Department of Orthopaedic Surgery, National University Health System (NUHS), Singapore, Singapore
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Characterization of Sagittal Spine Alignment With Reference to the Gravity Line and Vertebral Slopes: An Analysis of Different Roussouly Curves. Spine (Phila Pa 1976) 2020; 45:E481-E488. [PMID: 32282653 DOI: 10.1097/brs.0000000000003379] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
UNLABELLED MINI: Spinal sagittal realignment necessitates a reference posture, and thus far this has only been defined for an "averaged" curve via horizontal offsets from the gravity line (GL). This prospective study of 169 healthy subjects demonstrates normative sagittal spatial orientation of each vertebra, for all Roussouly curve types, using vertebral slopes and horizontal offsets from the GL. STUDY DESIGN Prospective study. OBJECTIVE To map the healthy standing alignment of the adult spine, grouped according to Roussouly curve types, using both horizontal offset distance from the gravity line (GL), as well as vertebral slope measurements. SUMMARY OF BACKGROUND DATA Spinal sagittal realignment requires a reference posture, and this has been defined in the literature via horizontal offsets from the GL. While useful, this does not provide information on the orientation of each vertebral segment, or distinguish between the various physiological curve types. METHODS A total of 169 consecutive young adult subjects with healthy spines were recruited over a year. (EOS Imaging, Paris, France) whole body radiographs were performed. Radiographic measurements collected included sagittal vertical axis (SVA), T1-slope, global cervical angle (GCA), global thoracic angle (GTA), global lumbar angle (GLA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), apical and inflection vertebrae. Outcome measures comprised slope measurements, and distance offsets relative to the GL for individual vertebrae from T3 to S1. RESULTS GLA, PI, PT, SS, apex of lordosis, and inflection vertebra were significantly different across groups, while SVA, T1-slope, GCA, GTA, and apex of kyphosis were not. Mean PI to LL discrepancy for Type I to IV groups were 8.0°, 2.3°, 4.8°, and 3.0°, respectively. Between groups, T3, T7 to T12, and L2 to S1 slopes and T9 to L3 offset distances from GL were significantly different, while the distance of the hip center from the GL was not. GLA was significantly different between curve types except between Type 1 and 2 curves, while the inflection vertebrae were not significantly different between Type 1 and 2 curves, as well as Type 3 and 4 curves. CONCLUSION This study demonstrates normative sagittal spatial orientation of each vertebra in healthy adults, for each Roussouly type. Comparison across groups suggests the possibility of further refining the sagittal curve patterns described by Roussouly. LEVEL OF EVIDENCE 3.
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Teo AQA, Thomas AC, Hey HWD. Sagittal alignment of the cervical spine: do we know enough for successful surgery? JOURNAL OF SPINE SURGERY 2020; 6:124-135. [PMID: 32309651 DOI: 10.21037/jss.2019.11.18] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Over the past decade, there has been growing interest in the sagittal alignment of the cervical spine and its correlation to clinical outcomes. It is now known that cervical lordosis is not universally physiological and should not be pursued in all patients undergoing surgery. Rather, it is increasingly understood that it is how these angular parameters (lordosis or kyphosis) interact with translational parameters that is reflective of overall cervical spine and whole spine balance, which in turn impacts patient outcomes. This review synthesises currently available evidence relating to the sagittal alignment of the cervical spine. Radiographic assessment of the cervical spine including horizontal gaze is discussed and alignment in physiological and pathological states analysed. The interdependence of spinal segments is reviewed, with cervical alignment correction influencing the adjacent thoracic spine, and similarly lumbar lordosis (LL) and global balance correction changing cervical spine alignment. Cervical kyphosis with associated cervical sagittal imbalance is known to lead to poorer post-operative outcomes, and this dichotomy in outcomes has not been shown to improve even with alignment correction. Further work is required to uncover the extent to which cervical spine alignment correction should be attempted toward improved patient outcomes, in order to plan and deliver patient-specific surgical realignment targets.
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Affiliation(s)
- Alex Quok An Teo
- University Orthopaedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore, Singapore
| | - Andrew Cherian Thomas
- University Orthopaedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore, Singapore
| | - Hwee Weng Dennis Hey
- University Orthopaedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore, Singapore
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