The Flek-shin: a composite material for use in flexible shank below-knee prostheses.

Introduction Conventional below-knee prostheses are manufactured of rigid materials for durability and stability. The use of glass fibre and resin composite materials to form the rigid shank of the below-knee prosthesis is well established in many countries and forms part of the modern practice of cosmetic prosthesis manufacture. While these materials are strong, durable , easily worked and cosmetically acceptable, there are a number of disadvantages. Mechanically they are essentially inert. The finished limb resists compressive and bending forces and as a consequence running, jumping and even vigorous walking are performed only with difficulty and certainly at high energy cost to the wearer . A new material has been developed at the Wellington Artificial Limb Centre and the Wellington School of Medicine which is semirigid but sufficiently flexible to allow its energy storing propert ies to be utilized in amputee gait. No data on the suitability of this new composite material for use in artificial limbs exist. As part of the development of this material it was essential to determine its fatigue strength and durability before further development of this exciting new concept could proceed.