Responses to gait perturbations in stroke survivors who prospectively experienced falls or no falls.

BACKGROUND: Steady-state gait characteristics appear promising as predictors of falls in stroke survivors. However, assessing how stroke survivors respond to actual gait perturbations may result in better fall predictions. We hypothesize that stroke survivors who fall have a diminished ability to adequately adjust gait characteristics after gait is perturbed. This study explored whether gait characteristics of perturbed gait differ between fallers and non fallers. METHOD: Chronic stroke survivors were recruited by clinical therapy practices. Prospective falls were monitored over a six months follow up period. We used the Gait Real-time Analysis Interactive Lab (GRAIL, Motekforce Link B.V., Amsterdam) to assess gait. First we assessed gait characteristics during steady-state gait and second we examined gait responses after six types of gait perturbations. We assessed base of support gait characteristics and margins of stability in the forward and medio-lateral direction. FINDINGS: Thirty eight stroke survivors complete our gait protocol. Fifteen stroke survivors experienced falls. All six gait perturbations resulted in a significant gait deviation. Forward stability was reduced in the fall group during the second step after a ipsilateral perturbation. INTERPRETATION: Although stability was different between groups during a ipsilateral perturbation, it was caused by a secondary strategy to keep up with the belt speed, therefore, contrary to our hypothesis fallers group of stroke survivors have a preserved ability to cope with external gait perturbations as compared to non fallers. Yet, our sample size was limited and thereby, perhaps minor group differences were not revealed in the present study.

Real-time visual feedback for gait retraining: toward application in knee osteoarthritis.

Real-time visual feedback might be effective for gait retraining in patients with knee osteoarthritis, to potentially relieve symptoms and postpone knee replacement. In this study, we investigated the effect of various types of real-time visual feedback on a kinetic and a kinematic gait parameter and the different kinematic strategies adopted to reduce knee load. Seventeen healthy subjects walked on an instrumented treadmill while receiving real-time visual kinetic feedback aimed at minimizing the external knee adduction moment (KAdM, reflecting the knee load) or kinematic feedback on the hip internal rotation angle (HIR, a gait modification to reduce the KAdM). Four types of visual feedback (bar, polar plot, color change, graph) were provided. The KAdM decreased by 50 % with kinetic feedback, while kinematic feedback resulted in an HIR increase of 8° but no decrease in KAdM. The degree of change was not influenced by the type of visual feedback. The kinematic changes that reduced KAdM were increased toe-in, increased step width, and decreased hip adduction. Real-time visual feedback can effectively modify gait parameters. Feedback of the KAdM may be more effective in reducing the KAdM than controlling a kinematic parameter that is assumed to unload the knee.

Evaluating asymmetry in prosthetic gait with step-length asymmetry alone is flawed.

Prosthetic gait is often asymmetric in step length, but the direction of this asymmetry varies inconsistently across amputees. This situation is akin to that seen in stroke patients, where step-length asymmetry has been shown to be the additive result of asymmetries in trunk progression and asymmetries in forward foot placement relative to the trunk. The present study examined the validity of this notion in three trans-tibial and seven trans-femoral amputees wearing a unilateral prosthesis while walking over a walkway at a comfortable and slower-than-comfortable speed. The latter manipulation was added to examine the expectation that the magnitude of the trunk-progression asymmetry - attributable to a weaker propulsion generating capacity on the prosthetic side - would be smaller when walking slower because of the diminished propulsion demands. Step length, forward foot placement relative to the trunk, and trunk progression of prosthetic and non-prosthetic steps, as well as asymmetries therein, were quantified. The direction of step-length and forward foot placement asymmetries varied inconsistently across (but consistently within) participants. As expected, step-length asymmetry depended on the combination of asymmetries in forward foot placement and trunk progression, with a smaller contribution of trunk-progression asymmetry at slow speed. These results extend our previous finding for hemiplegic patients that an analysis of gait asymmetry in terms of step length alone is flawed to prosthetic gait, implying that knowledge of asymmetries in trunk progression and forward foot placement relative to the trunk is required to help elucidate the contribution of underlying impairments (viz. propulsion generating capacity) and adopted compensations on prosthetic gait asymmetry.