Effects of alignment on interface pressure for transtibial amputee during walking.

PURPOSE: To assess the mechanical behaviour at interface for unilateral transtibial amputees during walking when the prosthesis is misaligned, since studies examining interface pressure between residual limb and prosthetic socket have been restricted to unsupported stance and natural gait.

METHOD: One male subject with transtibial amputation volunteers for the study. Interface pressures over five sites are measured under three sagittal alignment settings. MP (mean peak interface pressure), TP(90+) (time in which pressure exceeded 90% of peak pressure) and TPI(90+) (time-pressure integral at the period of sustained sub-maximal load) are discussed for each alignment setting.

RESULTS: Compared with optimal alignment, the trend of interface pressure, the mean peak pressure do not change much,but the duration of sub-maximal pressure changes remarkably, except that at the patellar tendon, and finally the TPI(90+) changes considerably with different alignment settings.

CONCLUSIONS: The results offer the clinician and paramedical staff further insight in residual limb/socket interface mechanics in the transtibial amputation patients and provide potentially useful information for socket design and prosthesis fitting.