Peg legs andbionic limbs: the development of lower extremity prosthetics

Abstract

At the 2000 Paralympic Games in Sydney, a new world record for the hundred metre sprint for below knee amputees was set at 11·09 seconds (the current recordfor able bodied athletes is 9·78 seconds). Such an astonishing result is a tribute not only to the talent and determination of the athlete concerned, but also to the part played by high performance lower extremity prostheses. Whilst advances in materials technology have led to improvements in almost all sports, they have altogether revolutionised performance levels in disabled sports. Following a potted history of the evolution of prosthetic devices, this paper reviews relevant aspects of the anatomy of the lower extremity and the biomechanics of human ambulation, and introduces the various components of prosthetic devices. The latest developments in ‘intelligent’ prosthetic devices make use of a magnetorheological fluid which acts as a damper in the knee joint and provides a more natural gait. In addition, a microprocessor embedded inside the prosthesis can enable automatic real time gait control, thus allowing the leg to adapt to different walking speeds and to more demanding environments such as stairs. Some observations are also made on how the self-image of the amputee and the perception of the amputee in society are affected by the functional and aesthetic characteristics of prosthetic equipment.