Postural and movement adaptations by individuals with a unilateral below-knee amputation during gait initiation

The present study examined the compensatory strategies adopted by individuals with a unilateral below-knee amputation (BKA) during gait initiation. Eleven individuals with a unilateral BKA and 11 able-bodied subjects initiated gait at three step length conditions (+0, +25 and +50% of preferred step length). A lead-limb condition was also introduced, such that all participants were required to initiate gait with both their left and right limbs. For all step length and lead-limb conditions, it was found that individuals with a unilateral BKA required more time to initiate gait, as compared with the able-bodied. This increase in movement duration was attributed to the stability and movement limitations of the prosthetic limb. On the other hand, by prolonging the task duration, these individuals were also able to employ a 'horizontal impulse' strategy, whereby they could create a similar magnitude of horizontal impulse as the able-bodied without the need to apply a large magnitude of peak antero-posterior (A-P) force.