Standing sway and weight-bearing distribution in people with below-knee amputations

Upright stability in humans has been found to decrease with age, certain diseases, or trauma. We investigated stability of standing in people with below-knee amputations (BKA) and in able-bodied controls. Body sway was evaluated during standing on a set of two Kistler force plates, first with eyes open and then with eyes closed. People with BKA were tested twice--first, one to two days after receiving their prostheses, and second, on completing their prosthetic rehabilitation. The results indicate that both able-bodied people and those with BKA sway more with their eyes closed. However, people with BKA are significantly less stable when they stand with either closed eyes or open eyes. We demonstrated that the differences between the groups studied are due to a proprioceptive deficit as a result of partial limb loss. We also found that there was a gradual process of compensation and adaptation, as some people with BKA sway less at the end of the rehabilitation period.