New socket design could improve outcomes for transfemoral amputees

SAN ANTONIO – A new socket design could improve prosthetic comfort and control for transfemoral amputees, according to a speaker at the American Orthotic and Prosthetic Association National Assembly, here.

Randall Alley, BSc, CP, owner of Biodesigns Inc., said among the critical defects in the traditional approach to current prosthetic sockets are peripheral connectivity and rigid linkage between a static ischium and a dynamic femur. Also, some sockets lack biomechanical focus, have loose connections and resemble “buckets and tubes,” he said.

“The fundamental principles of traditional approaches cannot do what we are trying to get them to do because they lack any influence on the bone. We have been focusing in the wrong place – taking what is obvious and ignoring the elephant in the room. Very little research has been done on controlling the bone shaft, and so the question is, ‘how do we do it?'”

Alley said radiographs conducted for the study demonstrate that the High-Fidelity Interface system could minimize bone motion within the socket. The design uses targeted centripetal compression that squeezes tissue inward at four biomechanically optimized zones along the shaft. It also uses centrifugal release, which leaves open areas which displaced tissue can move outwardly.

Randall Alley


“We need to prevent the socket from shifting and if we can do something like compression and release, it will not happen” Alley said. “When we have external forces acting on the interface, they will be transmitted to the patient in the proper manner and not stored by the socket itself.”

Alley said his team will continue to collect more data and comparisons. They recently received a DARPA contract for further exploration of the High-Fidelity Interface. Alley also told O&P News the system can be used for both lower and upper extremities. by Shawn M. Carter


Alley R. Paper C4. Presented at: American Orthotic and Prosthetic Association National Assembly; Oct. 7-10, 2015; San Antonio.

Disclosure: Alley reports he is owner of Biodesigns Inc. and creator of the High-Fidelity Interface.

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