A biomechanical evaluation of three prosthetic feet

  • Elena Jane Harris

Student thesis: Master's Thesis

Abstract

Countless new prosthetic products are released for sale in the UK every year. Manufacturers attend prosthetic centres and inform the clinicians of the benefits of each product but provide little or no evidence to support their claims. Budget constraints on the NHS mean that use of any product should be supported with good clinical evidence to justify the prescription cost. A primary aim of this study was to show the importance of evidence based practice within prosthetics. This goal was achieved by using 3D gait analysis to compare gait patterns with 3 moderate activity Prosthetic Feet ( Ossur Assure, Blatchfords Epirus and College Park Tribute) walking down an incline. The gait patterns were compared to a normal subject walking down a slope. It was hypothesised that; 1. All of the feet would perform in a similar manner in relation to joint angle, moments and GRF. 2. The joint angle, moments and GRF will significantly differ from the control subject. 3. Subjectively due to the similarities in the design the amputees will feel equally confident wearing the Blatchford’s Epirus foot and College Park’s Tribute foot but differently wearing the Ossur Assure foot.Six individuals with unilateral trans tibial amputations participated in walking down a seven-degree slope using 3DGA; each trying all three prosthetic feet. Each participant was also asked to complete a short questionnaire relating to the confidence they felt while walking down the slope with each prosthetic foot. All feet performed equally well throughout all tests.Compared to the control subject the closest matching joint movement was the knee joint, which in the normal subject remained flexed throughout the gait cycle but in some amputee subjects is extended at IC. The most dissimilar joint behaviour for the amputees was the ankle; this remained predominantly in plantar flexion throughout the gait cycle except for a brief spell which showed a reduced amount of dorsiflexion at 50% of the gait cycle compared to the control subject. The moment at the hip, knee and ankle joint followed a similar pattern as the control data with the ankle joint being the closest. The GRF data indicated which foot the subjects may have preferred.The questionnaire showed no foot was significantly preferred by the subjects. No one foot walked significantly better down the slope than another. Each subject demonstrated a gait that was stable. However, their gait didn’t match the control subject exactly. Objective testing did not give a definitive answer of what foot should be prescribed and neither did the subjective data. The small sample size means definitive answers were difficult to achieve. However, the research does highlight the need for the use of evidence based practice in clinic’s as the results could potentially be worth £500 per amputee patient to the NHS. As a result of the findings of this study it could be suggested that further research is recommended in the locating the prosthetic ankle joint position, further investigating the link between the GRF and the subject’s opinion and defining the optimal gait for an amputee.
Date of Award1 Mar 2012
LanguageEnglish
Awarding Institution
  • University Of Strathclyde
SupervisorStephanos Solomonidis (Supervisor) & Philip Riches (Supervisor)

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