RESUMO
The primary objective was to test the hypothesis that walking with a shock-absorbing pylon (SAP) decreases the peak magnitude and frequency content of the heel-strike-initiated shock wave transmitted to the stump. The secondary hypotheses were that walking with a SAP decreases the heel-strike transient force between the ground and the foot and increases function as measured by walking velocity and subjective assessments. Seven people with unilateral trans-tibial amputations walked at self-selected speeds without and with a SAP. As the primary outcome measure, accelerometers were used mounted proximally and distally along the prosthetic pylon to measure the transmitted shock wave. Secondary measures included ground reaction forces from a force plate, a ten-minute walking test to determine walking speed and a questionnaire to evaluate gait function and subjective preference. The SAP provided no significant shock absorption as indicated by either the mean peak proximal accelerations of 3.19 g and 2.82 g (p = 0.28) without and with the SAP respectively or the mean difference between the peak proximal and distal accelerometers, 0.16 g and 0.19 g (p = 0.58). No significant change in the frequency content was found. Variances were high. There were no significant differences noted in the secondary measures. Although this study failed to identify any statistically significant effects due to the SAP, the magnitude and variance of the data will permit an accurate estimation of the appropriate sample size for future studies required to determine the efficacy of SAPs.
