Biomechanical evaluation of prosthetic feet
An evaluation method was developed which can be used generally for the assessment of any prosthetic feet. The two most common prosthetic feet prescribed to below-knee and above-knee amputees are the Uniaxial and SACH feet. A review of prescription practices shows that in the United Kingdom about 80% of the below-knee and above-knee amputees are fitted with a Uniaxial foot, whereas in the United States about 80% are fitted with the SACH foot. These contradictory prescription practices between the two countries, prompted the project to be concentrated on the evaluation of the SACH and Uniaxial feet. The method developed includes a subjective assessment procedure and a biomechanical evaluation on the function of the two prosthetic feet and their effects on whole body gait kinematics and lower limb kinetics. A review of the methods used in gait analysis is presented in the thesis. This forms a basis for the selection of a suitable gait recording system for the project. A background study of lower limb prosthetics in general and a review of prosthetic ankle/foot assemblies in particular are also presented. The methodology and instrumentation used in the project are given. Altogether, six below-knee and five above-knee amputees were tested. Due to insufficient supply of heel bumper stiffness by the manufacturer for the Uniaxial foot, heel bumpers of varying stiffnesses had to be made in the Bioengineering Unit. The development of the analytical procedure for the three-dimensional analysis is presented. A suite of computer programs was written to facilitate the handling of the large amount of data, details of which are included in the Appendix. Results from the analysis of the tests performed are discussed. Although some apparent differences were observed between the SACH and Uniaxial feet, no conclusion can be drawn as to which is better for the function of the amputee.