Subjective evaluations and objective measurements of the ischial-ramal containment prosthesis

We examined 12 transfemoral amputees, 6 using the IRC socket and 6 the QL socket, to confirm whether the ischial-ramal containment (IRC) socket is truly superior to the quadrilateral (QL) socket. In subjective evaluation, the IRC group was significantly better in the total score and in items of comfort, that is, to sit on a chair and lumbar lordosis at heel off (Mann-Whitney test, P < 0.05), better but not significant in the items of comfortable to wear, comfortable to go up and down stairs, and truncal sway during stance phase. By computed tomography, the femur of the IRC group was kept in a position significantly more medial than that of the QL group (Mann-Whitney test, P < 0.05); but no significant difference in gluteal medial muscle atrophy ratios between the two groups was found (Mann-Whitney test, P > 0.05). By X-ray, the stump of the IRC group was maintained significantly more adducted during one foot standing on the prosthesis (Mann-Whitney test, P < 0.05), but the lateral force ratio during mid-stance of the IRC group was smaller, but not significantly, than that of the QL group. Physiological cost index (PCI), an indirect simple method for evaluating oxygen consumption of gait, had no significant difference between the two groups (Mann-Whitney test, P > 0.05), and a multiple regression analysis revealed that the stump length ratio and lateral force ratio during mid-stance were significant explanatory variables for predicting PCI (adjusted R square: 0.87, F-value: 11.85, P < 0.05). The results of this study have revealed that the advantage of the IRC socket is a tender feeling of the stump, but that the metabolic efficiency is not superior to the QL socket at the most comfortable speed.