Justin Z. Laferrier, Johnson and Wales University Physical Therapy Department, USA
Major advances in research and development as it pertains prosthetic feet have increased the quality of life for many individuals with amputations in the last decade. However, a negative aspect of these advancements is that the majority of end users are not able to benefit from these advances in technology. While these prosthetics are technologically impressive and work well for the small number of individuals, they fail to meet the needs of the majority of amputees worldwide. More than 80% of the world’s amputee population reside in low resource countries. Approximately 95% of these individuals do not have access to prosthetics. Research is needed in this area to promote the design and development of a cost-effective prosthetic foot that meets economic, environmental, cultural, and physical standards including durability, local availability, simple repair, local production, lightweight, biomechanically appropriate, and structural integrity in adverse climates and working conditions.
We have developed and preliminarily tested four prosthetic foot designs and have determined an optimal design of a prosthetic foot that fits our design criteria. The design criteria include low-cost (about $9 USD), load variable (able to support and function at +/- 100 pounds from the designed weight), durable (able to withstand environmental stresses found in developing countries) and the ability to store and
return energy throughout variable loads (200% energy return). The prosthetic is made from Delrin, which is a low-cost thermoplastic that can be used in injection molding, which is an inexpensive manufacturing method. The prosthetic also includes a natural rubber insert, which will allow the foot to be load variable and able to store and return energy. This foot will imitate the natural gait cycle and provide enough energy storage and return to make walking more biomechanically acceptable. The optimal design of
this prosthetic foot will allow amputees from low resource countries to continue to work, which will include walking considerable distances over rough terrains and carrying varying degrees of heavy loads. The materials (Delrin and natural rubber) and manufacturing method (injection molding) are both available in developing countries, so the prosthetic can be made on site, which will also reduce cost by
eliminating shipping fees.