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

Background: Altered 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. Methods: Gait 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 alpha = 0.004 was used to adjust for multiple comparisons. Findings: In 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 degrees greater, knee flexion velocity was reduced by 17.6 degrees/sec, and peak knee extension moment was increased by 0.011 Nm/kg . m compared to non-trip steps. Interpretation: It 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. (C) 2015 Elsevier Ltd. All rights reserved.