Abstract

As of 2005, there were 1.6 million people living with limb loss in the US. Studies have shown an effect of amputation on balance. Balance has mainly been studied during quiet standing in double-legged stance and results are conflicting regarding the amount of sway in amputees compared to controls. Few studies have assessed single-legged stance, but they all agree that sway is not different when standing on the non-amputated leg only or on a control leg, although standing time is decreased in amputees. Other variables, including cutaneous sensation, proprioception and strength have also been found to be decreased in both the amputated and non-amputated legs. Not much is known about single-legged stance, perturbed standing or the relationship between balance and cutaneous sensation, proprioception and strength in amputees. The goal of this study was to assess balance in traumatic transtibial amputees during perturbations when standing on the non-amputated leg. Whole body kinematics, 3D ground reaction forces and activity in eight trunk and lower limb muscles were recorded during the balance testing. Three other measurements were taken on the same leg as the balance test: cutaneous sensation, proprioception and strength.

There is no difference in sway between amputees and able-bodied controls although there is a trend suggesting an increase in sway in controls after the perturbation. Amputees exhibited less variability than controls in sway variables. Decreased variability in the balance task may be due to decreased balance confidence in amputees. No differences were found between groups in cutaneous sensation, proprioception and strength although a trend was revealed for controls to be stronger than amputees. Although some aspects of balance were significantly correlated to cutaneous sensation and proprioception, strength was the measure that was most often significantly correlated with balance in amputated individuals. Electromyographic activity increased after the perturbation in five muscles, although no differences were found between groups. The amputees and controls also did not differ in terms of muscle latencies, but a different activation pattern was found in the peroneus longus.