Review Question - QID 652

The non-dynamic response foot known as the solid ankle cushion heel (SACH) was introduced in the 1950’s and consists of a non-articulating wood keel surrounded by soft foam molded in the shape of a foot. The keel is entirely rigid and is unable to dorsiflex at late mid-stance resulting in an excessive rise in the center of mass as the patient progresses through stance on the prosthetic side. The elevation of the center of mass leads to increased loads on the sound side as weight is shifted from the prosthesis to the sound limb. The dynamic response foot consists of a keel which dynamically deforms under load but retains the memory of its pre-stressed configuration to return to its original shape on removing the load. The keel effectively becomes a spring allowing sufficient dorsiflexion and decreasing load on the sound side while still providing an adequate spring-like response for push off. This also means that the dynamic response foot has increased time in midstance of the gait. The dynamic response foot allows for much more active ambulation and has a faster gait velocity potential. Hafner et al and Romo authored review articles summarizing the technology of prosthetic feet. It is noted that patients are able to detect small changes in their prosthesis and this changes their perception for their preference of terminal devices and their performance while using them.