Prostheses and the forward reach of sitting lower-limb amputees

The hypothesis that prostheses improve the forward reach of sitting lower-limb amputees was tested. While sitting with only ischial support, ten unilateral below-knee (BK) amputees could reach farther when they wore their prostheses than when they did not, when reaching at 45 degrees toward or away from the side of the amputation, with mean differences (+/- 1 SD) of 10.7cm (+/- 6.9, p less than 0.0001) and 4.4cm (+/- 4.1, p less than 0.01), respectively. With ten unilateral above-knee (AK) amputees, the differences were not statistically significant. Seven bilateral amputees (mixed levels) were able to reach farther with their prostheses on than off, with mean differences of 41.2cm (+/- 9.5) and 31.5cm (+/- 7.9) for reaches at 0 degrees and 45 degrees, respectively (p less than 0.0001). With the prostheses off, their reach was significantly greater when their thighs were supported than when they were sitting with only ischial support. These findings suggest that (1) prostheses improve the anterolateral reach of unilateral BK amputees, and the straight forward and anterolateral reach of bilateral amputees; (2) when prostheses are not being worn, a sitting surface which provides support through the residual limbs improves forward reach; and (3) the design of AK prostheses should reflect the patient's needs, both standing and sitting.