Postural Responses to Dynamic Perturbations in Amputee Fallers Versus Nonfallers: A Comparative Study With Able-Bodied Subjects

Objectives: To quantify postural responses in amputee fallers versus nonfallers by using computerized dynamic posturography. Design: All participants completed Standard protocols on the Sensory Organization Test (SOT) and Motor Control Test (MCT) of the NeuroCom Equitest. Setting: Human performance laboratory in a university in the United Kingdom. Participants: Transtibial amputees (n=9) and able-bodied subjects (n=9) (all categorized into fallers and nonfallers according to their falls history in the previous 9mo). Interventions: Not applicable. Main Outcome Measures: Equilibrium and strategy scores on the SOT. Postural response latency and weight distribution on the MCT. Results: Equilibrium scores were highest when somatosensory information was accurate, but there were no differences between the groups. Strategy scores were lower when visual cues and somatosensory information were inaccurate, and the fallers and nonfallers used a combination of ankle and hip strategies to prevent a loss of balance. The amputee nonfallers indicated they had a greater reliance on visual input even when it was inaccurate compared with the amputee fallers, whereas the control fallers used the hip strategy significantly more compared with the control nonfallers (SOT condition 6: 56 +/- 22 vs 72 +/- 10, P=.01). Weight distribution symmetry showed that the amputee nonfallers bore significantly more weight through their intact limb compared with the amputee fallers during backward and forward translations (P<.05). Conclusions: The SOT and MCT appeared to be population specific and therefore did not reliably identify fallers among transtibial amputees or distinguish between community-dwelling control fallers and nonfallers. Amputee and control fallers can prevent a fall during challenging static and dynamic conditions by adapting their neuromuscular responses. The results from this study have important implications for amputee gait rehabilitation, falls prevention, and treatment programs.