Lower limb kinematic and kinetic differences between transtibial amputee fallers and non-fallers.

Stair walking relies on concentric contraction of the ankle plantarflexor and knee extensor muscles, which are either absent or weakened in transtibial amputees. As a result the risk of falling is increased in this population. The aim of this study was to compare the gait patterns of transtibial amputee fallers and non-fallers during stair ascent. Eleven participants (fallers = 6; non-fallers = 5) walked along a 3-m walkway and ascended a three-step staircase with handrails, at their self-selected pace, while three-dimensional kinematic data were collected from the lower limbs. A force plate was embedded into the first step and kinetic data were measured for the intact lead limb only. The fallers walked significantly faster (p = 0.00) and exhibited less hip flexion (p = 0.05) and less anterior pelvic tilt (p = 0.04) compared to the non-fallers. The fallers had significantly greater first and second peak vertical ground reaction force (GRF) on the intact limb than the non-fallers (p = 0.05 and p = 0.01, respectively) contributing to the significantly larger ankle (p = 0.02) and hip moments (p = 0.04). These findings suggested the amputee non-fallers performed mechanically demanding tasks more cautiously. Two of the participants self-selected a 'step to' gait pattern, ascending one step at a time. This may be considered a compensatory mechanism for the lack of ankle mobility and functional muscle performance in these two transtibial amputees.