Functional Muscle Transfers in Lower Limb Sarcoma: 3D Gait Analysis and Environmental Simulation

Introduction

Rationale

The purpose of this study is to assess patient's function after functional limb restoring surgery, performed after ablative tumour surgery or trauma. However, there are no studies as yet providing objective proof of the recovery of function after this type of surgery.

Background information including literature review

Sarcoma surgery has progressed from limb amputation to limb preserving surgery since the early 1980s. Although this has been a major advance, a preserved limb does not equate to a functional limb. Patients may be left with significant disability and reliant on walking aids or braces, and unable to return to normal activities

The West of Scotland Sarcoma service has developed and refined surgical procedures to restore function in the lower limb after major resection surgery. This is one of the few centres in the world that have done significant numbers of function restoring surgeries, and are recognised as experts in this field, having published the protocol for functional reconstruction in the Journal of Bone and Joint Surgery and in the book Reconstructive Surgery of the Lower Extremity.

Procedures for functional restoration include Quadriceps reconstruction (to restore knee extension) - this is the most common type of functional lower limb reconstruction. Hamstring transfers were originally described for use in polio over a century ago, sartorius transfers, and free functional muscles transfers such as the latissimus dorsi or contralateral rectus femoris/ vastus lateralis.

Other techniques for functional reconstruction include anterior leg compartment reconstruction (to restore foot dorsiflexion/ prevent foot-drop) and posterior leg compartment reconstruction (to restore plantar-flexion). Techniques such as the free functional anterolateral thigh - rectus femoris muscle combined flap are also used.

Previous studies have not provided objective proof of restoration of gait, and have been limited to scores such as the Musculoskeletal Tumor Society Score (MSTS), range of motion, and Medical Research Council (MRC) grade power. These scores are of limited value in establishing whether a patient's gait is normal, and may be subject to investigator bias.

Two objective techniques will be used to assess normality of gait after functional reconstruction:

1. Three-dimensional clinical gait analysis (3DCGA) provides a robust and objective technique for measurement of how an individual walks both for clinical use and for research purposes.
2. Environmental Simulator (the Motek system at Strathclyde University): this is the only environmental simulator of its type out-with the Ministry of Defence in the United Kingdom. It provides simulated environments on a large projected screen with the patient attached to a safety harness, whilst walking on an adjustable treadmill. This allows simulation of urban environments, negotiation of trip hazards, walking up hills and shopping tasks. This will permit more tangible answers regarding the objective return to function of patients in an environmental context that they can understand eg "Will I be able to go hillwalking?" "Will I be safe to go shopping without crutches or a brace?".

Aim/Primary and Secondary Objectives

The aim of this study is to objectively assess the normality of gait after functional reconstructive surgery, and to assess whether patients can return to activities of daily living using the Environmental simulator

Methodology

Patients who have undergone functional reconstructive surgery will be identified from a prospectively held database. The patients will be invited to participate by letter and given an information sheet. Should the patient wish to participate in the study they will be invited to clinic to discuss the study with the senior researcher (SL) and sign a consent form related to gait analysis and the environmental simulator.

There are 3 components to the study:

1. Patient Reported Outcome Measurements - using validated questionnaires including the Toronto Extremity Salvage Score (TESS). Clinical assessment will include MRC grade power and range of motion.
2. 3D Gait analysis - this employs 3D cameras and pressure sensors to objectively assess the patient's ability to walk, and can identify subtle differences in gait that cannot be identified on questionnaires or on simple video analysis. Electromyography may be used to assess active muscle contraction as part of the gait analysis.
3. Environmental simulator - this will employ a state-of-the-art simulator that can assess a patient's ability to navigate simulated environments eg walking up a hill, navigating an urban environment, and shopping tasks.