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Amirouche F, Solitro GF, Gligor BZ, Hutchinson M, Koh J. Investigating the effect of autograft diameter for quadriceps and patellar tendons use in anterior cruciate ligament reconstruction: a biomechanical analysis using a simulated Lachman test. Front Surg 2023; 10:1122379. [PMID: 37886636 PMCID: PMC10598649 DOI: 10.3389/fsurg.2023.1122379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 09/12/2023] [Indexed: 10/28/2023] [Imported: 11/01/2023] Open
Abstract
Introduction Current clinical practice suggests using patellar and quadriceps tendon autografts with a 10 mm diameter for ACL reconstruction. This can be problematic for patients with smaller body frames. Our study objective was to determine the minimum diameter required for these grafts. We hypothesize that given the strength and stiffness of these respective tissues, they can withstand a significant decrease in diameter before demonstrating mechanical strength unviable for recreating the knee's stability. Methods We created a finite element model of the human knee with boundary conditions characteristic of the Lachman test, a passive accessory movement test of the knee performed to identify the integrity of the anterior cruciate ligament (ACL). The Mechanical properties of the model's grafts were directly obtained from cadaveric testing and the literature. Our model estimated the forces required to displace the tibia from the femur with varying graft diameters. Results The 7 mm diameter patellar and quadriceps tendon grafts could withstand 55-60 N of force before induced tibial displacement. However, grafts of 5.34- and 3.76-mm diameters could only withstand upwards of 47 N and 40 N, respectively. Additionally, at a graft diameter of 3.76 mm, the patellar tendon experienced 234% greater stiffness than the quadriceps tendon, with similar excesses of stiffness demonstrated for the 5.34- and 7-mm diameter grafts. Conclusions The patellar tendon provided a stronger graft for knee reconstruction at all diameter sizes. Additionally, it experienced higher maximum stress, meaning it dissociates force better across the graft than the quadriceps tendon. Significantly lower amounts of force were required to displace the tibia for the patellar and quadriceps tendon grafts at 3.76- and 5.34-mm graft diameters. Based on this point, we conclude that grafts below the 7 mm diameter have a higher chance of failure regardless of graft selection.
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Amirouche F, Dolan M, Pradhan S, Mikhael M, Monsef JB. Assessment of Cervical and Lumbar Kinematics in Simulated Open and Closed Kinetic Chain. Int J Spine Surg 2023; 17:51-59. [PMID: 36302601 PMCID: PMC10025859 DOI: 10.14444/8382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] [Imported: 08/29/2023] Open
Abstract
BACKGROUND The pelvic girdle and spine vertebral column work as a long chain influenced by pelvic tilt. This study aims to assess the effect of open and closed chain anterior pelvic tilt (APT) or posterior pelvic tilt (PPT) on cervical and lumbar spine kinematics using an in vitro cadaveric spine model. METHODS Three human cadaveric spines with intact pelvis were suspended with the skull fixed in a metal frame. Optotrak 3-dimensional motion system captured coordinates of pin markers at 24 different points for real-time tracking of cervical and lumbar regions. Additional geometric parameters were measured to calculate pelvic incidence and pelvic tilt. A force-torque digital gauge applied consistent force to standardize the acetabular or sacral axis' APT and PPT during simulated open- and closed-chain movements, respectively. RESULTS In closed-chain PPT, significant differences in relative intervertebral decompression were noted between spinal levels C2/C3 (4.85 mm) and C5/C6 (1.26 mm), while compression was noted between L1/L2 (-2.54 mm) and L5/S1 (-11.84 mm) and between L3/L4 (-2.78 mm) and L5/S1 (-11.84 mm) (P < 0.05). Displacement during closed-chain PPT was significantly greater than during open-chain PPT for cervical and lumbar spines. In closed-chain APT, significant differences in relative intervertebral decompression were noted between spinal levels L1/L2 (2.87 mm) and L5/S1 (24.48 mm) and between L3/L4 (2.94 mm) and L5/S1 (24.48 mm) (P < 0.05). Pelvic incidence remained the same as the pelvis tilted anterior and posterior. CONCLUSIONS In PPT, open-chain pelvic tilts did not produce as much cervical and lumbar intervertebral displacement compared with closed-chain pelvic tilts. In contrast, APT saw fewer differences between open- and closed-chain tilting. There was a reciprocal relationship between pelvic tilt and sacral slope, producing a constant pelvic incidence throughout all pelvic tilt angles. CLINICAL RELEVANCE The results of this study may help determine how a patient's pelvic tilt is causing pain and using that knowledge to guide rehabilitation of stabilizing muscles. The data produced here may also be helpful in determining which rehabilitation exercises may be more difficult or prone to injury for patients with either excessive anterior or posterior pelvic tilt. LEVEL OF EVIDENCE: 5
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Koh J, Diaz RL, Tafur JC, Lin Y, Echenique DB, Amirouche F. Small Chondral Defects Affect Tibiofemoral Contact Area and Stress: Should a Lower Threshold Be Used for Intervention? Orthop J Sports Med 2022; 10:23259671221129308. [PMID: 36419474 PMCID: PMC9677309 DOI: 10.1177/23259671221129308] [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: 06/29/2022] [Accepted: 07/27/2022] [Indexed: 08/29/2023] [Imported: 08/29/2023] Open
Abstract
BACKGROUND Chondral defects in the knee have biomechanical differences because of defect size and location. Prior literature only compares the maximum stress experienced with large defects. HYPOTHESIS It was hypothesized that pressure surrounding the chondral defect would increase with size and vary in location, such that a size cutoff exists that suggests surgical intervention. STUDY DESIGN Controlled laboratory study. METHODS Isolated chondral defects from 0.09 to 1.0 cm2 were created on the medial and lateral femoral condyles of 6 human cadaveric knees. The knees were fixed to a uniaxial load frame and loaded from 0 to 600 N at full extension. Another defect was created at the point of tibiofemoral contact at 30° of flexion. Tibiofemoral contact pressures were measured. Peak contact pressure was the highest value in the area delimited within a 3-mm rim around the defect. The location of the peak contact pressure was determined. RESULTS At full extension, the mean maximum pressures on the medial femoral condyle ranged from 4.30 to 6.91 MPa at 0.09 and 1.0 cm2, respectively (P < .01). The location of the peak pressure was found posteromedial in defects between 0.09 and 0.25 cm2, shifting anterolaterally at sizes 0.49 and 1.0 cm2 (P < .01). The maximum pressures on the lateral femoral condyle ranged from 3.63 to 5.81 MPa at 0.09 and 1.0 cm2, respectively (P = .02). The location of the peak contact pressure point was anterolateral in defects between 0.09 and 0.25 cm2, shifting posterolaterally at 0.49 and 1.0 cm2 (P < .01). No differences in contact pressure between full extension and 30° of flexion were found for either the lateral or medial condyles. CONCLUSION Full-thickness chondral defects bilaterally had a significant increase in contact pressure between defect sizes of 0.49 and 1.0 cm2. The location of the maximum contact pressures surrounding the lesion also varied with larger defects. Contact area redistribution and cartilage stress change may affect adjacent cartilage integrity. CLINICAL RELEVANCE Size cutoffs may exist earlier in the natural history of chondral defects than previously realized, suggesting a lower threshold for intervention.
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Boroda N, Pradhan S, Forsthoefel CW, Mardjetko SM, Bou Monsef J, Amirouche F. Motion capture evaluation of sagittal spino-pelvic biomechanics after lumbar spinal fusion. Spine Deform 2022; 10:473-478. [PMID: 34981456 DOI: 10.1007/s43390-021-00448-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 11/20/2021] [Indexed: 11/27/2022] [Imported: 08/29/2023]
Abstract
PURPOSE The spine and pelvis coexist as a dynamic linked system in which spinal and pelvic parameters are correlated. Investigation of this system can inform the understanding and treatment of spinal deformity. Here, we demonstrate the use of motion capture technology to measure spine biomechanical parameters using a novel testing apparatus. METHODS Three complete cadaveric spines with skull and pelvis were mounted into a biomechanical testing apparatus. Each lumbar vertebra was monitored by motion capture cameras as the spines underwent maximal anterior and posterior pelvic tilts about two sagittal axes at a controlled speed and applied force. These axes were defined as the sacral axis which passes transversely through the ilium and S1, and the acetabular axis which passes transversely through both acetabula. The experiments were repeated after L4-L5 fusion, and then, after both L4-L5 and T12-S1 fusion with pedicle screw instrumentation. Data were collected for total range of motion and for coupled translation at each functional spinal unit (FSU). RESULTS Total range of motion and coupled translation within functional spinal units (FSUs) was decreased after spinal fusion. The displacement of each individual FSU was captured and summarized along with the observed patterns under each experimental condition. CONCLUSION Lumbar fusion decreases spinal motion in the sagittal plane in both overall ROM and individual coupled translations of lumbar vertebrae. This was demonstrated using motion capture technology which is useful for quantifying the translations of individual FSUs in a multisegmental spinal model.
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Labib M, Amirouche F, Pradhan S, Bobko A, Koh J. A Biomechanical Analysis of Shoulder Muscle Excursions During Abduction, After the Treatment of Massive Irreparable Rotator Cuff Tears Using Superior Capsular Reconstruction (SCR), Bursal Acromial Reconstruction (BAR), and SCR with BAR. J Shoulder Elb Arthroplast 2022; 6:24715492221109001. [PMID: 35782774 PMCID: PMC9240589 DOI: 10.1177/24715492221109001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 05/19/2022] [Accepted: 06/02/2022] [Indexed: 01/17/2023] [Imported: 08/29/2023] Open
Abstract
Introduction Current understanding of the biomechanical effects of treatment options for irreparable rotator cuff (RC) tears is lacking. This study examines how shoulder muscle lengths and excursions are affected by superior capsular reconstruction (SCR), bursal acromial reconstruction (BAR), and SCR with BAR, following a complete supraspinatus tear. Method Six fresh-frozen cadaveric shoulders were examined. Deltoid and RC muscle lengths were measured at 0, 30, 45, 60, and 90° of shoulder abduction under six conditions: (1) intact, (2) partially torn supraspinatus, (3) completely torn supraspinatus, (4) SCR, (5) SCR with BAR, and (6) BAR. Muscle excursions from 0–90° of abduction were then calculated. Results Subscapularis muscle lengths after SCR, BAR, and SCR with BAR were significantly greater (post-hoc Tukey HSD test; p < .01) compared to the other conditions. Supraspinatus, infraspinatus, teres minor, and deltoid lengths were not significantly different (ANOVA test; p > .01) between the conditions. All muscle excursions remained statistically similar between the conditions (ANOVA test; p > .01). Conclusion These findings demonstrate that the use of SCR, BAR, or SCR with BAR for a complete supraspinatus tear, may increase subscapularis muscle length while maintaining other shoulder muscle lengths. An increase in subscapularis length can allow for more effective subscapularis muscle strengthening and increased compensatory function in the long term. Additionally, all shoulder muscle excursions are preserved after partial or complete supraspinatus tears and after SCR, BAR, or SCR with BAR. Therefore, these surgical treatments can initially normalize shoulder muscle function during 0–90° of abduction, after an irreparable supraspinatus tear.
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Soulii L, Amirouche F, Solitro G, Boroda N, Echenique DB, Mejia A, Gonzalez MH. Evaluation of A2 and A4 Hand Pulley Repair Using Tendon Graft Rings. J Hand Surg Am 2021; 46:626.e1-626.e6. [PMID: 33579590 DOI: 10.1016/j.jhsa.2020.11.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 09/23/2020] [Accepted: 11/27/2020] [Indexed: 02/02/2023] [Imported: 08/29/2023]
Abstract
PURPOSE To compare the mechanical characteristics of A2 and combined A2-A4 pulley repair in the intact and damaged flexor pulley system. METHODS After control testing, we recorded tendon excursion and flexion of 11 cadaveric fingers after several interventions: (1) complete excision of A2 and A4, (2) repair of the A2 with one ring of tendon graft, (3) repair of the A2 with 2 rings of tendon graft, and (4) repair of the A2 with 2 rings combined with repair the A4 with one ring. RESULTS At the proximal interphalangeal (PIP) joint, the maximum rotational angle decreased by an average of 30% after complete excision of the A2 and A4 pulleys. This angle was still decreased compared with the control by an average of 25% after one-ring repair at A2, 23% after 2-ring repair at A2, and 17% after 2-ring repair at A2 combined with one-ring repair at A4. At the metacarpophalangeal joint, the average maximum rotational angle decreased by an average of 17% after complete excision of the A2 and A4 pulleys. This angle was still decreased compared with the control by an average of 11% after one-ring repair at A2, 7% after 2-ring repair at A2, and 4% after 2-ring repair at A2 combined with one-ring repair at A4. Kinematic behavior at the PIP joint with an intact pulley system was most closely approximated by the 3-loop repair. The least similar behavior was with a 2-ring construct at A2. CONCLUSIONS All repairs increased average flexion at the PIP and metacarpophalangeal joints compared with the unrepaired samples. The 3-ring configuration exhibited a higher recovery of PIP flexion compared with the other repairs. CLINICAL RELEVANCE Although each repair restored flexion, clinical studies are necessary to evaluate the clinical relevance of the mechanical results of this study.
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Solitro GF, Mainnemare F, Amirouche F, Mehta A. A novel technique with reduced computed tomography exposure to predict vertebral compression fracture: a finite element study based on rat vertebrae. Med Biol Eng Comput 2018; 57:795-805. [PMID: 30402789 DOI: 10.1007/s11517-018-1918-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 10/21/2018] [Indexed: 10/27/2022] [Imported: 08/29/2023]
Abstract
Vertebral compression fractures are a significant clinical issue with an annual incidence of approximately 750,000 cases in the USA alone. Mechanical properties of vertebrae are successfully evaluated through finite element (FE) models based on vertebrae CT. However, clinical drawbacks associated to radiation transmission encouraged to explore the possibility to use selected or reduced portions of the vertebra. The objective of our study was to develop a new procedure to predict vertebral compression fracture from sub-volumes. We reconstructed rat vertebras from micro-CT of thoracic and lumbar groups. Each vertebra was partitioned into three sub-volumes of different axial thickness. FE simulating compression tests were performed on each model to evaluate their failure load and stiffness. Using a power function, a high correlation was found for stiffness and strength. The sub-volume with three fifths thickness had a failure load of 180.7 ± 19.2 N for thoracic and of 209.5 ± 27.4 N for the lumbar vertebra. These values were not significantly different from the values found for the entire vertebra (p > 0.05). Based on our findings, failure loads and stiffnesses obtained with reduced CT scans can be successfully used to predict full vertebral failure. This sub-region analysis and power relationship suggests that one can limit radiation exposure to patients when bone characterization is needed. Graphical abstract Estimated mechanical properties in relation to the extent of the computed tomography reconstruction.
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Segmental acetabular rim defects, bone loss, oversizing, and press fit cup in total hip arthroplasty evaluated with a probabilistic finite element analysis. INTERNATIONAL ORTHOPAEDICS 2016; 41:1527-1533. [PMID: 28012048 DOI: 10.1007/s00264-016-3369-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 12/02/2016] [Indexed: 01/21/2023] [Imported: 08/29/2023]
Abstract
PURPOSE Management of segmental rim defects and bone mineral density (BMD) loss in the elderly prior to total hip replacement is unclear within classification systems for acetabular bone loss. In this study, our objectives were (1) to understand how a reduction in BMD in the elderly affects the oversizing of a press-fit cup for primary fixation and (2) to evaluate whether the location of the segmental defect affected cup fixation. METHODS A finite element (FE) model was used to simulate and evaluate cup insertion and fixation in the context of segmental rim defects. We focused on the distribution of patients over age 70 and used BMD (estimated from CT) as a proxy for aging's implications on THR and used probabilistic FE analysis to understand how BMD loss affects oversizing of a press-fit cup. RESULTS A cup oversized by 1.10 ± 0.28 mm provides sufficient fixation and lower stresses at the cup-bone interface for elderly patients. Defects in the anterior column and posterior column both required the same mean insertion force for cup seating of 84% (taken as an average of 2 anterior column and 2 posterior column defects) compared to the control configuration, which was 5% greater than the insertion force for a superior rim defect and 12% greater than the insertion force for an inferior rim defect. CONCLUSIONS A defect along the superior or inferior rim had a minimal effect on cup fixation, while a defect in the columns created cup instability and increased stress at the defect location.
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Amirouche F, Solitro GF, Magnan BP. Stability and Spine Pedicle Screws Fixation Strength-A Comparative Study of Bone Density and Insertion Angle. Spine Deform 2016; 4:261-267. [PMID: 27927514 DOI: 10.1016/j.jspd.2015.12.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 11/16/2015] [Accepted: 12/25/2015] [Indexed: 10/21/2022] [Imported: 08/29/2023]
Abstract
STUDY DESIGN Analysis of insertion angle and bone density on the pedicle screw fixation strength with a novel testing protocol that accounts for the articular processes. OBJECTIVE To analyze the relationship between pedicle screw fixation strength and bone mineral density for different transverse screw insertion angles. SUMMARY OF BACKGROUND DATA The stability of the screw can become compromised by demineralization of the vertebral bone due to diseases such as osteoporosis. A weakening of the bone-screw interface, and therefore, a decrease in the fixation strength of the screw, leads to an increased probability of instrument failure, most commonly by screw loosening or screw pullout. METHODS Using the ASTM F543 as reference, we performed pullout tests with an Instron mechanical testing machine of a posterior fixation construct mimicking two pedicle screws connected at a distance of 40 mm as suggested by the ASTM F1717 on four densities of polyurethane foam in accordance with the ASTM F1839-08 standard to simulate bone densities ranging from osteoporotic (5 pcf) to higher than normal (20 pcf) in four transverse insertion angles. RESULTS A linear regression with two independent variables was found to be Y = -354.8812 + 91.8102 × X1 - 6.8747 × X2 (X1 = density [pcf], X2 = angle [degrees]), with a correlation coefficient of 0.95 for all the experimental data. CONCLUSIONS Pedicle screw insertion angle and bone density are critical to pullout strength. However, in osteoporotic bone, the insertion angle has only a marginal influence on pullout strength. LEVEL OF EVIDENCE V.
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Amirouche F, Solitro G, Walia A. No effect of femoral offset on bone implant micromotion in an experimental model. Orthop Traumatol Surg Res 2016; 102:379-85. [PMID: 26970866 DOI: 10.1016/j.otsr.2016.01.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 01/15/2016] [Accepted: 01/19/2016] [Indexed: 02/02/2023] [Imported: 08/29/2023]
Abstract
BACKGROUND In total hip replacement (THR), the femoral offset (FO) is assessed preoperatively, and the surgeon must determine whether to restore, increase, or decrease the FO based on experience and the patient's clinical history. The FO is known to influence the abductor muscle strength, range of motion (ROM), gait, and hip pain after THR; however, the true effect of FO on bone implant micromotion is unclear. Therefore, we investigated to assess: (1) the muscle loading response during gait, (2) whether FO affects bone implant micromotion during gait. HYPOTHESIS A variation of ±10mm from the anatomical FO affects the muscle loading forces. MATERIALS AND METHODS We modified a personalized musculoskeletal model of the lower extremity to determine the 3-dimensional contact forces at the hip joint in the presence of a stem with varying offsets during a gait cycle. A detailed finite element (FE) model was then constructed for increased, restored, and decreased FOs. The maximum load obtained during normal walking gait from the musculoskeletal model was applied to the respective FE models, and the resultant stem-bone micromotion and stress distribution were computed. RESULTS Increasing the FO to +10mm decreased the peak force generated by the abductor muscles during the cycle by 15.0% and decreasing the FO to -10mm increased the von Mises stress distribution at the distal bone by 77.5% (P<0.05). A variation of the offset within 10mm of the anatomical offset showed no significant differences in micromotion (P>0.05) and peak stresses (P>0.05). DISCUSSION Coupling the musculoskeletal model of the gait cycle with FE analysis provides a realistic model to understand how FO affects bone implant micromotion. We found that there was no effect of FO on bone implant micromotion; thus, a surgeon does not need to evaluate the implications of FO on micromotion and can determine a FO that best decreases the work load of abductor muscles, increases ROM, and reduces hip pain. LEVEL OF EVIDENCE IV, biomechanical study.
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Primary cup stability in THA with augmentation of acetabular defect. A comparison of healthy and osteoporotic bone. Orthop Traumatol Surg Res 2015; 101:667-73. [PMID: 26300456 DOI: 10.1016/j.otsr.2015.07.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 07/01/2015] [Accepted: 07/07/2015] [Indexed: 02/02/2023] [Imported: 08/29/2023]
Abstract
BACKGROUND CONTEXT Reconstruction of acetabular defect has been advocated as standard procedure in total hip arthroplasty. The presence of bony defects at the acetabulum is viewed as a cause of instability and acetabular wall augmentation is often used without proper consideration of surrounding bone density. The initial cup-bone stability is, however, a challenge and a number of studies supported by clinical follow-ups of patients suggested that if the structural graft needs supporting more than 50% of the acetabular component, a reconstruction cage device spanning ilium to ischium should be preferred to protect the graft and provide structural stability. This study aims to (1) investigate the relationship between cup motion and bone density and (2) quantify the re-distribution of stress at the defect site after augmentation. HYPHOTESIS Paprosky type I or II, acetabular defects, when reconstructed with bone screws supported by bioabsorbable calcified triglyceride bone cement are significantly less effective for osteoporotic bone than healthy bone. MATERIALS AND METHODS Acetabular wall defects were reconstructed on six cadaveric subjects with bioabsorbable calcified triglyceride bone cement using a re-bar technique. Data of the specimen with higher bone density was used to validate a Finite Element Model. Values of bone apparent density ranging from healthy to osteoporotic were simulated to evaluate (1) the cup motion, through both displacement and rotation, (2) and the von Mises stress distribution. RESULTS Defect reconstruction with bone screws and bioabsorbable calcified triglyceride bone cement results in a re-distribution of stress at the defect site. For a reduction of 65% in bone density, the cup displacement was similar to a healthy bone for loads not exceeding 300 N, as load progressed up to 1500 N, the reconstructed defect showed increase of 99 μm (128%) in displacement and of 0.08° in rotation angle. CONCLUSIONS Based on the results, we suggest that an alternative solution to wall defect augmentation with bone screws supported by bioabsorbable calcified triglyceride bone cement, be used for osteoporotic bone. LEVEL OF EVIDENCE Level IV, experimental and cadaveric study.
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Amirouche F, Solitro GF, Siemionow K, Drucker D, Upadhyay A, Patel P. Role of posterior elements in the disc bulging of a degenerated cervical spine. Int J Spine Surg 2015; 9:13. [PMID: 26056628 DOI: 10.14444/2013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] [Imported: 08/29/2023] Open
Abstract
BACKGROUND Many studies have been developed to characterize the mechanical behavior of the intervertebral disc specifically for the lumbar spine and there have been limited studies done on the cervical spine with the goal to evaluate the strength of the cervical spine under compression without any information on the bulging of the intervertebral discs. The goal of the current study is to examine the deformation response of the cervical intervertebral disc classified with grade III or greater degeneration and analyze the relationship between axial deformation and anterior and posterior bulge under compression up to 550 N. METHODS Each specimen was compressed for 3 cycles to a maximum load of 550N in steps of 50 N. The bulge was measured using Linear Variable Differential Transformers (LVDTs on an intact spinal segment, spinal segment with post laminectomy, and spinal segment post facetectomy. RESULTS The anterior budge for an intact spinal segment shows a change of slope at loads of 262N±66N. For a physiological load of 250N the vertical displacement or spine segment height was reduced by 10.1% for an intact segment and 8.78% for the laminectomy and facetectomy configurations with F = 0.159 (Fcrit = 3.89) with no statistical difference observed. For the post laminectomy there was a decrease of 35% in anterior bulge compared to the intact specimen. CONCLUSIONS Our results show that for grade III disc degeneration the cervical segments bulging for both the laminectomy and facetectomy procedures are not significantly different. In post laminectomy the average anterior and posterior bulges are similar to the average anterior and posterior bulge post facetectomy.
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Amirouche F, Solitro G, Broviak S, Gonzalez M, Goldstein W, Barmada R. Factors influencing initial cup stability in total hip arthroplasty. Clin Biomech (Bristol, Avon) 2014; 29:1177-85. [PMID: 25266242 DOI: 10.1016/j.clinbiomech.2014.09.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 09/11/2014] [Accepted: 09/11/2014] [Indexed: 02/07/2023] [Imported: 08/29/2023]
Abstract
BACKGROUND One of the main goals in total hip replacement is to preserve the integrity of the hip kinematics, by well positioning the cup and to make sure its initial stability is congruent and attained. Achieving the latter is not trivial. METHODS A finite element model of the cup-bone interface simulating a realistic insertion and analysis of different scenarios of cup penetration, insertion, under-reaming and loading is investigated to determine certain measurable factors sensitivity to stress-strain outcome. The insertion force during hammering and its relation to the cup penetration during implantation is also investigated with the goal of determining the initial stability of the acetabular cup during total hip arthroplasty. The mathematical model was run in various configurations to simulate 1 and 2mm of under-reaming at various imposed insertion distances to mimic hammering and insertion of cup insertion into the pelvis. Surface contact and micromotion at the cup-bone interface were evaluated after simulated cup insertion and post-operative loading conditions. FINDINGS The results suggest a direct correlation between under-reaming and insertion force used to insert the acetabular cup on the micromotion and fixation at the cup-bone interface. INTERPRETATION While increased under-reaming and insertion force result in an increase amount of stability at the interface, approximately the same percentage of surface contact and micromotion reduction can be achieved with less insertion force. We need to exercise caution to determine the optimal configuration which achieves a good conformity without approaching the yield strength for bone.
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Abraham E, League A, Amirouche F, Kulkarni N. A clove-hitch suture method for small-caliber tendon ends. J Bone Joint Surg Am 2012; 94:1303-7. [PMID: 22810401 DOI: 10.2106/jbjs.k.00414] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] [Imported: 08/29/2023]
Abstract
BACKGROUND The choices of suture methods used to secure the end of a small-caliber tendon with a combination of suture materials passing through and looping around the tendon are not well documented. A secure stitch-tendon unit may be an important factor in preserving muscle function, by facilitating healing without gapping or failure. METHODS Five types of suture methods utilizing four or fewer passes through the tendon end were mechanically tested on 178 canine flexor digitorum profundus tendons. An Instron apparatus was used to test the load to failure. RESULTS The single and double clove-hitch suture methods demonstrated improved repair strength when compared with the three other methods studied in this small-caliber canine tendon model. CONCLUSIONS The single and double clove-hitch suture method better secured the end of a small-caliber tendon compared with other methods. CLINICAL RELEVANCE The single (pull-out) and double (non-pull-out) clove-hitch suture methods are reliable alternatives for the repair of small-caliber tendons.
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Romero F, Amirouche F, Aram L, Gonzalez MH. Experimental and analytical validation of a modular acetabular prosthesis in total hip arthroplasty. J Orthop Surg Res 2007; 2:7. [PMID: 17506882 PMCID: PMC1891272 DOI: 10.1186/1749-799x-2-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2006] [Accepted: 05/16/2007] [Indexed: 11/10/2022] [Imported: 08/29/2023] Open
Abstract
A finite element model has been developed to predict in vivo micro motion between a modular acetabular cup and liner after cement less total hip arthroplasty. The purpose of this study is to experimentally validate the model. Six LVDT sensors were used to monitor the micromotion of the liner when subjected to loading conditions ranging from 250 N to 5000 N. Deformations at points of interest for both the experiment and FEM were compared. Results of the FEM with different coefficient of friction between the liner and the cup were investigated to correlate with the experimental results.
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Amirouche F, Gonzalez M, Koldoff J, Tioco J, Ham K. A biomechanical study of the finger pulley system during repair. Technol Health Care 2002; 10:23-31. [PMID: 11847445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] [Imported: 08/29/2023]
Abstract
This paper addresses the mechanics of the finger/pulley system when subjected to various excisions and repairs. Several cadaver hands were used to study the finger/pulley's function, finger joint dynamics, and the relationship between tendon excursion and finger joint angles of rotation. By using a method of continuous and simultaneous data acquisition of the entire finger joint's motion, a more detailed analysis was achieved. Our experimental investigation is based on the use of four micro-potentiometers inserted at the finger's joints and a pulley system to simulate tendon excursion. Using this procedure, a detailed kinematic analysis of the entire finger was performed. This included analysis of the intact hand, various pulley excisions, and reconstruction. In addition to introducing a new method of acquisition, a mathematical model was developed for the inverse dynamic analysis of the finger pulley system. From this model, the torques required at the joints for the motion were computed. The results provided new insight into possible ways of characterizing kinematic changes resulting from pulley damage and repair.
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