INTERFACE PRESSURES AND SHEAR STRESSES AT 13 SOCKET SITES ON 2 PERSONS WITH TRANSTIBIAL AMPUTATION

Residual limb/prosthetic socket interface pressures and shear stresses were measured at 13 sites on two subjects with unilateral transtibial amputation(TTA) using total-contact patellar-tendon-bearing prosthese s. Maximal interface stresses during stance phase for each of 13 trans ducer sites were determined, then means for all steps calculated. Maxi mal pressure and resultant shear stress during stance phase were shown at anterior distal or mid-limb sites and the maxima occured during th e first 50% of stance phase. Anterior medial and lateral proximal site s showed their greatest pressure during the second 50%. At lateral mid -limb and popliteal fossa sites, resultant shear stress directions sug gest that soft tissue was displaced toward the socket brim during weig ht-bearing. Results also suggest that skin across the distal tibial cr est was in tension at the times of the first and second peaks in the s hank axial force-time curve in all sessions. Significant differences ( p<0.05) in maximal stresses between sessions conducted >3 weeks apart were apparent for both subjects.