A study published in Gait & Posture that examined how prosthetic alignment affects the biomechanical loading in individuals with unilateral transfemoral amputations found that significantly larger hip joint moment on the intact side may be associated with the higher incidence of hip osteoarthritis on the intact side. The researchers concluded that alignment significantly affects the hip and knee joint moments, but each person’s biomechanical response to alignment changes are different.

The biomechanical changes caused by different alignments should be considered in prosthetic fitting; however, the quantitative effect of alignment on the kinetic features of individuals with transfemoral amputation remains unclear, the study concludes.

Gait tests of ten people with transfemoral amputations and 15 without amputations (control group) were performed. Several prosthetic alignment conditions were used, including an initial alignment and eight malalignments. The hip and knee joint moments of the people with amputation under various alignments were analyzed and compared with those of the control group. Statistical analyses were performed by one-way analysis of variances (ANOVA), repeated measure multivariate ANOVA, and paired t-tests.

The peaks and impulses of the hip abductor and external rotator moments on the residual side were significantly smaller than those of the control group. The peaks of the hip extensor, adductor, and external rotator moments on the intact side were significantly larger than those on the residual side. Alignment significantly affected the intact hip and knee joint moments for each individual with an amputation, but there was no consistent effect among them.

The researchers concluded that the results may imply that the method for optimizing alignment should be personalized.