Joint kinetics in unilateral below-knee amputee patients during running

To explore the nature of the accommodations in running gait that persons with below-knee amputations make in response to the limb segment loss.

Two groups of volunteer subjects (n = 6 in each group). Individuals in one group had below-knee amputations; the second group had intact lower limbs.

Individuals ran at two nominal speeds, 2.7 m/sec and 3.5 m/sec, over a flush-mounted force platform. Ground reaction force data were combined with simultaneously recorded and subsequently digitized video data of coordinate motion to calculate joint and segment motion and net joint moment data.

The degree of left-to-right asymmetry for the amputee group was dependent on the variable of interest. There was symmetry in stride frequency and support moment and a marked asymmetry in ankle, knee, and hip moments. In response to increased running speed, both groups increased the amplitude of each joint moment. The nonamputee group appeared to increase the gain uniformly across the three joints, whereas the intact and prosthetic limbs were not uniformly increased. The temporal sequencing of the components for the intact and prosthetic limbs did not appear to differ from the nonamputee limb. This similarity in timing was unaffected by speed increases.

There was no need to develop completely new patterns of joint moments; rather, it was sufficient to retune the current moment patterns to account for new segmental properties and thus retain the internal timing characteristics.