Residual limb shear strain during gait is correlated with patient reported outcomes for persons with transfemoral amputation

Abstract

The purpose of this study was to measure residual limb skin strain and strain rate within the socket during gait in individuals with a transfemoral amputation and to determine if skin strain during gait is related to patient-reported comfort and function. It was hypothesized that greater skin strain and skin strain rate would correlate to worse patient-reported outcomes. It was also hypothesized that skin strain would progressively increase from the distal to the proximal end of the residuum and maximum strain would occur shortly after heel strike. Dynamic biplane radiography (DBR), combined with conventional motion capture, was used to measure skin deformation within the socket during treadmill walking for 10 persons with unilateral transfemoral amputation. The questionnaire for persons with a transfemoral amputation (Q-TFA) was administered to assess prosthetic use, mobility, health problems, and global health. Q-TFA Prosthetic Use score and Problem score were negatively correlated with the peak shear strains in the proximal and distal regions of the residuum, respectively. Maximum shear strain increased progressively from proximal to distal regions of the residual limb. Within-subject variability in shear strain waveforms during gait was 0.7% or less, but between-subject variability was 3.3% to 5.0% shear. This study demonstrates that skin shear within the socket of persons with transfemoral amputation can be measured during gait using DBR and the results suggest that greater skin shear in the proximal region of the socket is related to decreased prosthetic use.