Systematic Review of Studies Examining Transtibial Prosthetic Socket Pressures with Changes in Device Alignment

Abstract

Suitable lower-limb prosthetic sockets must provide an adequate distribution of the pressures created from standing and ambulation. A systematic search for articles reporting socket pressure changes in response to device alignment perturbation was carried out, identifying 11 studies. These were then evaluated using the American Academy of Orthotists and Prosthetists guidelines for a state-of-the-science review. Each study used a design where participants acted as their own controls. Results were available for 52 individuals and five forms of alignment perturbation. Four studies were rated as having moderate internal and external validity, the remainder were considered to have low validity. Significant limitations in study design, reporting quality and in representation of results and the suitability of calculations of statistical significance were evident across articles. Despite the high inhomogeneity of study designs, moderate evidence supports repeatable changes in pressure distribution for specific induced changes in component alignment. However, there also appears to be a significant individual component to alignment responses. Future studies should aim to include greater detail in the presentation of results to better support later meta-analyses.

Keywords: Below-knee; Misalignment; Normal stress; Pressure distribution; Prostheses.

Fig. 1

Potential alignment modifications to transtibial prostheses. The eighth possible adjustment—changes to pylon height—is not shown (and was not investigated by any included articles)

Fig. 2

Flowchart of the literature search and study selection process

Fig. 3

a Distribution of date of publication of selected studies. b Publication venue of included studies. c Nationality of study participants in included reports. d Reasons for amputation in study participants in included reports. Kang 2006 is reported as vascular although the article reports that cause was “vascular disease such as trauma or diabetes mellitus”. e The tested socket design of study participants in included reports. PTB patella tendon bearing, TSB total socket bearing. Sanders 1999 used participants who habitually used PTB sockets, but test prostheses were manufactured using computer aided design and manufacturing. Courtney 2016 is reported as one PTB and one hydrocast socket as both designs were tested on a single participant