Biomedical Engineering - Research Publications
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ItemEffects of Prophylactic Knee Bracing on Lower Limb Kinematics, Kinetics, and Energetics During Double-Leg Drop Landing at 2 Heights(SAGE PUBLICATIONS INC, 2016-07)BACKGROUND: Anterior cruciate ligament (ACL) injuries commonly occur during landing maneuvers. Prophylactic knee braces were introduced to reduce the risk of ACL injuries, but their effectiveness is debated. HYPOTHESES: We hypothesized that bracing would improve biomechanical factors previously related to the risk of ACL injuries, such as increased hip and knee flexion angles at initial contact and at peak vertical ground-reaction force (GRF), increased ankle plantar flexion angles at initial contact, decreased peak GRFs, and decreased peak knee extension moment. We also hypothesized that bracing would increase the negative power and work of the hip joint and would decrease the negative power and work of the knee and ankle joints. STUDY DESIGN: Controlled laboratory study. METHODS: Three-dimensional motion and force plate data were collected from 8 female and 7 male recreational athletes performing double-leg drop landings from 0.30 m and 0.60 m with and without a prophylactic knee brace. GRFs, joint angles, moments, power, and work were calculated for each athlete with and without a knee brace. RESULTS: Prophylactic knee bracing increased the hip flexion angle at peak GRF by 5.56° (P < .001), knee flexion angle at peak GRF by 4.75° (P = .001), and peak hip extension moment by 0.44 N·m/kg (P < .001). Bracing also increased the peak hip negative power by 4.89 W/kg (P = .002) and hip negative work by 0.14 J/kg (P = .001) but did not result in significant differences in the energetics of the knee and ankle. No differences in peak GRFs and peak knee extension moment were observed with bracing. CONCLUSION: The application of a prophylactic knee brace resulted in improvements in important biomechanical factors associated with the risk of ACL injuries. CLINICAL RELEVANCE: Prophylactic knee braces may help reduce the risk of noncontact knee injuries in recreational and professional athletes while playing sports. Further studies should investigate different types of prophylactic knee braces in conjunction with existing training interventions so that the sports medicine community can better assess the effectiveness of prophylactic knee bracing.
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ItemProphylactic knee bracing alters lower-limb muscle forces during a double-leg drop landing(ELSEVIER SCI LTD, 2016-10-03)Anterior cruciate ligament (ACL) injury can be a painful, debilitating and costly consequence of participating in sporting activities. Prophylactic knee bracing aims to reduce the number and severity of ACL injury, which commonly occurs during landing maneuvers and is more prevalent in female athletes, but a consensus on the effectiveness of prophylactic knee braces has not been established. The lower-limb muscles are believed to play an important role in stabilizing the knee joint. The purpose of this study was to investigate the changes in lower-limb muscle function with prophylactic knee bracing in male and female athletes during landing. Fifteen recreational athletes performed double-leg drop landing tasks from 0.30m and 0.60m with and without a prophylactic knee brace. Motion analysis data were used to create subject-specific musculoskeletal models in OpenSim. Static optimization was performed to calculate the lower-limb muscle forces. A linear mixed model determined that the hamstrings and vasti muscles produced significantly greater flexion and extension torques, respectively, and greater peak muscle forces with bracing. No differences in the timings of peak muscle forces were observed. These findings suggest that prophylactic knee bracing may help to provide stability to the knee joint by increasing the active stiffness of the hamstrings and vasti muscles later in the landing phase rather than by altering the timing of muscle forces. Further studies are necessary to quantify whether prophylactic knee bracing can reduce the load placed on the ACL during intense dynamic movements.
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ItemSubject-specific musculoskeletal modeling in the evaluation of shoulder muscle and joint function(ELSEVIER SCI LTD, 2016-11-07)Upper limb muscle force estimation using Hill-type muscle models depends on musculotendon parameter values, which cannot be readily measured non-invasively. Generic and scaled-generic parameters may be quickly and easily employed, but these approaches do not account for an individual subject's joint torque capacity. The objective of the present study was to develop a subject-specific experimental testing and modeling framework to evaluate shoulder muscle and joint function during activities of daily living, and to assess the capacity of generic and scaled-generic musculotendon parameters to predict muscle and joint function. Three-dimensional musculoskeletal models of the shoulders of 6 healthy subjects were developed to calculate muscle and glenohumeral joint loading during abduction, flexion, horizontal flexion, nose touching and reaching using subject-specific, scaled-generic and generic musculotendon parameters. Muscle and glenohumeral joint forces calculated using generic and scaled-generic models were significantly different to those of subject-specific models (p<0.05), and task dependent; however, scaled-generic model calculations of shoulder glenohumeral joint force demonstrated better agreement with those of subject-specific models during abduction and flexion. Muscles in generic musculoskeletal models operated further from the plateau of their force-length curves than those of scaled-generic and subject-specific models, while muscles in subject-specific models operated over a wider region of their force length curves than those of the generic or scaled-generic models, reflecting diversity of subject shoulder strength. The findings of this study suggest that generic and scaled-generic musculotendon parameters may not provide sufficient accuracy in prediction of shoulder muscle and joint loading when compared to models that employ subject-specific parameter-estimation approaches.
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ItemThe use of laboratory gait analysis for understanding gait deterioration in people with multiple sclerosis(SAGE PUBLICATIONS LTD, 2016-12)Laboratory gait analysis or three-dimensional gait analysis (3DGA), which uses motion capture, force plates and electromyography (EMG), has allowed a better understanding of the underlying mechanisms of gait deterioration in patients with multiple sclerosis (PwMS). This review will summarize the current knowledge on multiple sclerosis (MS)-related changes in kinematics (angles), kinetics (forces) and electromyographic (muscle activation) patterns and how these measures can be used as markers of disease progression. We will also discuss the potential causes of slower walking in PwMS and the implications for 3DGA. Finally, we will describe new technologies and methods that will increase precision and clinical utilization of 3DGA in PwMS. Overall, 3DGA studies have shown that functionality of the ankle joint is the most affected during walking and that compensatory actions to maintain a functional speed may be insufficient in PwMS. However, altered gait patterns may be a strategy to increase stability as balance is also affected in PwMS.
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ItemGait compensatory mechanisms in unilateral transfemoral amputees(Elsevier, 2020-03)Individuals with unilateral transfemoral amputation depend on compensatory muscle and joint function to generate motion of the lower limbs, which can produce gait asymmetry; however, the functional role of the intact and residual limb muscles of transfemoral amputees in generating progression, support, and mediolateral balance of the body during walking is not well understood. The aim of this study was to quantify the contributions of the intact and the residual limb's contralateral muscles to body center of mass (COM) acceleration during walking in transfemoral amputees. Three-dimensional subject-specific musculoskeletal models of 6 transfemoral amputees fitted with a socket-type prosthesis were developed and used to quantify muscle forces and muscle contributions to the fore-aft, vertical, and mediolateral body COM acceleration using a pseudo-inverse ground reaction force decomposition method during over-ground walking. Anterior pelvic tilt and hip range of motion in the sagittal and frontal planes of the intact limb was significantly larger than those in the residual limb (p<0.05). The mean contributions of the intact limb hip muscles to body COM support, forward propulsion and mediolateral balance were significantly greater than those in the residual limb (p<0.05). Gluteus maximus contributed more to propulsion and support, while gluteus medius contributed more to balance than other muscles in the intact limb than the residual limb. The findings demonstrate the role of the intact limb hip musculature in compensating for reduced or absent muscles and joint function in the residual limb of transfemoral amputees during walking. The results may be useful in developing rehabilitation programs and design of prostheses to improve gait symmetry and mitigate post-operative musculoskeletal pathology.
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ItemIndividual muscle contributions to hip joint-contact forces during walking in unilateral transfemoral amputees with osseointegrated prostheses(Taylor & Francis, 2020-07-21)Direct skeletal attachment of prostheses in transfemoral amputees circumvents skin-interface complications associated with conventional sockets; however, joint pain and musculoskeletal disease is known to occur postoperatively. This study quantified hip contact forces and the roles of individual muscles in producing hip contact forces during walking in transfemoral amputees with osseointegrated prostheses. Musculoskeletal models were developed for four transfemoral amputees. Gluteus maximus and gluteus medius were the major contributors to the hip contact forces, and the intact limb hip muscles demonstrated greater contributions to hip contact forces than those of the residual limb. The findings may be useful for mitigating walking asymmetry.
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ItemLoad response of an osseointegrated implant used in the treatment of unilateral transfemoral amputation: An early implant loosening case study.(Elsevier, 2020-03)BACKGROUND: Osseointegrated implants for transfemoral amputees facilitate direct load transfer between the prosthetic limb and femur; however, implant loosening is a common complication, and the associated implant-bone loads remain poorly understood. This case study aimed to use patient-specific computational modeling to evaluate bone-implant interface loading during standing and walking in a transfemoral amputee with an osseointegrated implant prior to prosthesis loosening and revision surgery. METHODS: One male transfemoral amputee with an osseointegrated implant was recruited (age: 59-yrs, weight: 83 kg) and computed tomography (CT) performed on the residual limb approximately 3 months prior to implant failure. Gait analyses were performed, and the CT images used to develop a finite element model of the patient's implant and surrounding bone. Simulations of static weight bearing, and over-ground walking were then performed. FINDINGS: During standing, maximum and minimum principal strains in trabecular bone adjacent to the implant were 0.26% and -0.30%, respectively. Strains generated at the instant of contralateral toe-off and contralateral heel strike during walking were substantially higher and resulted in local trabecular bone yielding. Specifically, the maximum and minimum principal strains in the thin layer of trabecular bone surrounding the distal end of the implant were 1.15% and -0.98%, respectively. INTERPRETATION: Localised yielding of trabecular bone at the interface between the femur and implant in transfemoral amputee osseointegrated prosthesis recipients may present a risk of implant loosening due to periprosthetic bone fracture during walking. Rehabilitation exercises should aim to produce implant-bone loading that stimulates bone remodelling to provide effective bone conditioning prior to ambulation.