Correlations between residual limb length and joint moments during sitting and standing movements in transfemoral amputees

Background and aim: Longer residual limb lengths provide an increased lever arm. Longer residual limbs may produce increased joint moments; the two may be correlated. These correlations have not been evaluated in transfemoral amputees during transitional movements. Correlations between residual limb length and involved side joint moment could contribute to justification supporting maximal residual limb length preservation. This study investigated possible correlations between hip or knee moment and residual limb length. Technique: Hip and knee joint moments were determined while 21 transfemoral amputees performed sitting and standing movements and then evaluated for correlation with residual limb length. Discussion: Residual limb length was not correlated with either knee or involved side hip moments during sit to stand or stand to sit. Conversely, weak inverse correlations (p < 0.05) existed between sound hip moment magnitude and residual limb length. These correlations suggest that in community ambulating transfemoral amputees, longer residual limb length could decrease sound hip kinetic burden during transitional movement. Beyond correlations between residual limb length and sound hip transitional movement kinetics, there are other considerations in determining residual limb length during amputation. Clinical relevance This study examines relationships between lower limb joint moments and residual limb length related to sit-to-stand and stand-to-sit activities. The results have implications for amputation surgery and rehabilitation.