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. / Thesis / Master of Applied Science (MASc) / Hip reconstructive surgery as treatment for bone cancer is a highly invasive surgery that negatively impacts patients walking patterns and ultimately quality of life. The current thesis investigates existing literature to determine if specific, innovative surgical techniques lead to better functional results for patients after surgery. A three-dimensional model of a patient who had hip reconstruction surgery for bone cancer was created using quantitative analysis of their walking patterns. The model was manipulated to simulate surgical intervention for hip cancer treatment. The model findings suggest when specific hip muscles are substantially affected by surgery, patients walking patterns are negatively impacted. Understanding how surgical intervention impacts walking patterns can inform surgical technique, implant design and physiotherapy programs leading to better quality of life for patients after surgery.

The purpose of this investigation was to assess the efficacy of a multifaceted gait analysis approach using a group of twenty osteosarcoma patients who underwent limb salvage surgery. Mean age at time of surgery was 16.1 years (range: 7-29), mean age at time of evaluation was 23.55 years (range: 11-43). Nine patients were treated with a Stryker Howmedica Modular Resection System (Stryker Kalamazoo, USA) and eleven patients were treated with a Stanmore custom made prosthesis (Stanmore implants worldwide Ltd, Stanmore, UK). Ten control participants with a mean age of 24.9 (range: 14-36) were recruited for the study. Ethical approval was gained through The University of Queensland Ethics Committee and The Royal Children’s Hospital and Health Service district Ethics Committee. Investigations included subjective, kinematic, kinetic, electromyographic and bioenergetic assessments. The subjective assessment incorporated results from the Musculoskeletal Tumour Society Rating Scale (MSTS) and the Toronto Extremity Salvage Score (TESS). Overall impairment was found to be 83.33% according to results of the MSTS and overall disability was found to be 86.00% according to results of the TESS. Kinematic findings showed that limb salvage participants walked with reduced velocity (p < 0.01) and increased step asymmetry (p < 0.01). Patients exhibited an increase in plantarflexion during the loading response (p < 0.001) and during terminal stance (p < 0.05), and an increase in dorsiflexion during mid-stance (p < 0.001). Knee kinematics revealed reduced extension during the loading response (p < 0.001) and increased frontal plane excursion throughout the gait cycle (p < 0.01). Patients exhibited increased lateral lean during loading response at the trunk (p < 0.05). Kinetic findings revealed a reduction in the magnitude of vertical ground reaction force during the loading response (p < 0.001) and a reduction in the magnitude of the anterior/posterior ground reaction shear force during terminal stance (p = 0.01). Furthermore, the internal ankle plantarflexor moment in terminal stance was reduced (p < 0.001), all sagittal plane knee moments were reduced (p < 0.05) and the internal hip adductor moment in terminal stance was reduced (p < 0.01). Electromyographic findings found that the limb salvage participants activated their rectus femoris for a significantly prolonged period (p < 0.5) and exhibited increased bilateral co-contraction of their rectus femoris and medial hamstring muscles (p < 0.05) compared with control participants. Bioenergetic findings revealed that the limb salvage participants exhibited an increased energetic cost (p < 0.01) and consumption rate (p < 0.01). Moderate correlations were observed between electromyographic and bioenergetic findings. Multivariate methods suggested that muscle removal, knee extension strength and knee flexion range of motion were all significant predictors of locomotor function. Length of bone resection and time from surgery were not predictive of post-operative function. The findings supported the efficacy of a multifaceted gait analysis approach for the assessment of pathological function under research conditions. The combined approach, using multiple measurements, allowed determination of functional status following musculoskeletal alteration. This enabled identification of primary and secondary compensations and allowed recommendations for improved treatment and rehabilitation.