Biomechanical gait characteristics of naturally occurring unsuccessful foot clearance during swing in individuals with chronic stroke

Abstract

BackgroundAltered gait mechanics are common following stroke and may increase the risk of falls. Paretic gait impairments have been previously compared to the non-paretic limb or control participants. Unfortunately, the biomechanical parameters underlying instances of naturally occurring unsuccessful foot clearance (trips) have yet to be examined in individuals with chronic stroke. MethodsGait data from 26 participants with chronic stroke were obtained on a dual-belt instrumented treadmill. Instances of successful and unsuccessful foot swing were identified. Temporal, kinematic, and kinetic measures of the paretic limb occurring during late stance, toe-off, and swing were compared between trip and non-trip steps using paired samples t-tests. An α=0.004 was used to adjust for multiple comparisons. FindingsIn the paretic limb, the ankle angle at toe off (P=0.003; d=0.64), knee flexion velocity at toe off (P<0.001; d=0.73), and peak knee extension moment during terminal stance (P<0.001; d=0.74) were significantly different between trips and non-trip steps. During trip steps, ankle plantarflexion at toe-off was 1.0° greater, knee flexion velocity was reduced by 17.6°/sec, and peak knee extension moment was increased by 0.011Nm/kg·m compared to non-trip steps. InterpretationIt appears to take only minor changes in the movement of the paretic limb to result in a trip in individuals with chronic stroke. Although small, the multi-joint biomechanical changes occurring in the paretic limb during unsuccessful foot clearance result in a functionally longer limb. Thus, interventions targeting multiple joints in the paretic limb may be needed to reduce the risk of trips following stroke.