Prescription of prosthetic ankle-foot mechanisms after lower limb amputation

Abstract

Background: A prosthesis can be divided into several components: the prosthetic socket; the prosthetic ankle-foot mechanism; and for higher levels of amputation, the prosthetic knee. This review focuses on the prosthetic ankle-foot mechanism, which forms an important part of the prosthesis in terms of mobility. A correct prosthetic prescription can be derived by matching the functional abilities of the individual with a lower limb amputation with the technical and functional aspects of the various prosthetic ankle-foot mechanisms. However, there seems to be no clear clinical consensus on the precise prescription criteria for the various prosthetic ankle-foot mechanisms in relation to the functional abilities of individuals with a lower limb amputation. Objectives: To obtain information about aspects of prosthetic ankle-foot mechanisms and daily functioning of individuals with a lower limb prosthesis, for appropriate prosthetic prescription criteria. Search methods: We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (April 2006), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2006, Issue 2), MEDLINE (1966 to April 2006), EMBASE (1983 to April 2006), CINAHL (1982 to April 2006), AMED (Allied and Complimentary Medicine) (1985 to April 2006), and reference lists of articles. No language restrictions were applied. Selection criteria: All randomised controlled trials and quasi-randomised controlled trials comparing different ankle foot mechanisms for lower limb amputation in adults. No language restrictions were applied. Data collection and analysis: Two review authors independently identified potential articles from the literature search. Methodological quality was assessed using a checklist comprising 13 criteria. The reviewers extracted data using pre-defined extraction forms. Main results: Twenty-six trials were included, with a total of 245 participants. The numbers of participants in the included trials ranged from three to sixteen. The methodological quality was moderate. Only one study was of high quality. All included studies used cross-over designs allowing sufficient control for confounding. In individuals with a transtibial amputation, there seems to be a small tendency towards a greater stride length when walking with the Flex-foot in comparison to the SACH (solid-ankle cushioned heel) foot. When walking speed was increased, the energy cost was lower. In high activity individuals with a transfemoral amputation, there is limited evidence for the superiority of the Flex foot during level walking compared with the SACH foot in respect of energy cost and gait efficiency. Authors' conclusions: There is insufficient evidence from high quality comparative studies for the overall superiority of any individual type of prosthetic ankle-foot mechanism, although there is a small trend towards the Flex-foot in comparison with the SACH foot for greater stride length and lower energy cost in individuals with a transtibial amputation, and improved gait efficiency and lower energy cost in high activity individuals with a transfemoral amputation. In prescribing prosthetic-ankle foot mechanisms for individuals with a lower limb amputation, practitioners should take into account availability, patient functional needs, the type of knee mechanism to be prescribed and the inter-relationship with ankle-foot mechanisms, and cost.