A Patient Specific Musculoskeletal Model Simulation of Limb Salvage Surgery to Investigate How Altered Hip Biomechanics Impacts Functional Outcomes

Abstract

Sarcoma cancer of the proximal femur is a bone tumor that develops near the hip joint. The most common method of treatment is limb salvage surgery (LLS), a highly invasive surgery that often leads to impaired movement including walking due to soft tissue resection. The current thesis focuses on 1) systematically reviewing current literature of functional outcomes after proximal femur LSS to determine if specific methods of muscle reattachment lead to better limb function, and 2) objectively analysing how reducing hip muscle strength impacts one’s ability to achieve healthy gait. Findings from the systematic review suggest using artificial mesh or ligaments for LLS may be a good alternative to allograft prosthesis composites and trochanter osteotomy, producing good functional outcomes with low rates of complications. It was also determined current literature is lacking objective quantitative analysis of patients’ limb function after surgery. Objective 2 was executed using instrumented gait analysis to record the gait kinematics, kinetics and EMG patterns of a patient who received LSS for proximal femur sarcoma. Data from the gait analysis was used to create a patient-specific musculoskeletal model. Healthy gait kinematics were applied to the model and specific hip muscle strengths were systematically reduced to simulate different surgical interventions. After an 85% reduction in gluteus medius and minimus muscle strength, healthy gait kinematics were not achieved. Reducing muscle strength of the gluteus medius and minimus together had a greater impact on the model’s ability to achieve healthy gait kinematics then when reduced individually. An understanding of how patient’s limb function is impacted after surgery can inform surgical technique, implant design and physiotherapy programs leading to better quality of life for patients after surgery.