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Comparison of nonmicroprocessor knee mechanism versus C-Leg on Prosthesis Evaluation Questionnaire, stumbles, falls, walking tests, stair descent, and knee preference

Jason T. Kahle, CPO, LPO, et al.

Figure.Average responses of 19 subjects on first 15 questions of Prosthesis Evaluation Questionnaire (PEQ) for microprocessor knee mechanisms (i.e., C-Leg) vs nonmicroprocessor knee mechanisms (NMKMs).

Manufacturers of microprocessor-controlled prosthetic knee mechanisms, specifically the C-Leg® (Otto Bock; Minneapolis, Minnesota), claim the knee allows subjects to seamlessly change speed, descend stairs step-over-step, and recover from stumbles. To test these and other potential functions, we gave 19 transfemoral amputees the opportunity to accommodate to a C-Leg and tested them in a series of nine evaluative measures. First, we tested subjects in their previously accommodated nonmicroprocessor-controlled prosthetic knee mechanism and then, following an accommodation period, tested the subjects again on a C-Leg. Testing included subjective measures of prosthesis function and prosthesis-related quality of life, number of stumbles and falls, walking tests (of various speeds and distances), and a question on preference. The C-Leg yielded improvements in all categories tested and was preferred by most subjects. A secondary analysis revealed that many subjects who were initially considered limited community ambulators were able to increase their status to unlimited community ambulators when they used the C-Leg. We will look more closely at microprocessor candidacy in a more functionally diverse sample of subjects in future studies.


Volume 45 Number 1, 2008
   Pages 1 — 14

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