Falls outcome measure.

Many people with chronic stroke (PwCS) exhibit deficits in step width modulation, an important strategy for walking balance. A single exposure to swing leg perturbations can temporarily strengthen this modulation. The objective of this parallel, double-blinded, randomized controlled trial was to investigate whether repeated perturbations cause sustained increases in step modulation (NCT02964039; funded by the VA). 54 PwCS at the Medical University of South Carolina were randomly assigned to one of three intervention groups: Control (n = 18), with minimal forces; Assistive (n = 18), pushing the swing leg toward a mechanically appropriate location; Perturbing (n = 18), pushing the swing leg away from a mechanically appropriate location. All intervention groups included 24 training sessions over 12-weeks with up to 30-minutes of treadmill walking while interfaced with a novel force-field and a 12-week follow-up period, with five interspersed assessment sessions. Our primary outcome measure was paretic step width modulation, the partial correlation between step width and pelvis displacement (ρSW). Secondarily, we quantified swing and stance leg contributions to step modulation, clinical assessments of walking balance and confidence, and real-world falls. Outcomes were analyzed for participants who completed all assessment sessions (n = 44). Only the Perturbing group exhibited significant increases in paretic ρSW, which were present after 4-weeks of training and sustained through follow-up (t = 2.42–3.17). These changes were due to improved control of paretic swing leg positioning. However, perturbation-induced changes in step modulation were not always significantly greater than those in the Control group, and clinical assessments were similar across intervention groups. Participants in the Perturbing group experienced a lower fall rate than those in the Control group (incidence rate ratio = 0.53), although our small sample size warrants caution. The present results indicate that perturbations can cause sustained modifications of targeted biomechanical characteristics of post-stroke gait, although such changes alone may be insufficient to change more complex clinical assessments.慢性脑卒中患者（People with Chronic Stroke, PwCS）常存在步宽调节功能缺陷，而步宽调节是维持步行平衡的关键策略。单次摆动腿扰动干预可暂时增强此类调节能力。本项平行双盲随机对照试验（临床试验注册号：NCT02964039，由美国退伍军人事务部VA资助）旨在探究重复扰动是否可使步宽调节能力获得持续性提升。南卡罗来纳医科大学的54例慢性脑卒中患者被随机分配至3个干预组：对照组（n=18），仅施加极小作用力；辅助组（n=18），将摆动腿推至力学适配位置；扰动组（n=18），将摆动腿推离力学适配位置。所有干预组均包含为期12周的24次训练课程，每次训练受试者需在新型力场辅助下于跑步机上步行至多30分钟；同时设置12周随访期，期间穿插5次评估环节。本研究的主要结局指标为患侧步宽调节能力，即步宽与骨盆位移之间的偏相关系数（ρ_SW）。次要结局指标包括：摆动腿与支撑腿对步宽调节的贡献度、步行平衡与信心的临床评估，以及真实世界跌倒事件统计。本研究仅对完成全部评估环节的44例受试者的数据进行分析。仅扰动组的患侧ρ_SW出现显著提升，该提升在训练4周后即可观测到，并持续至随访结束（t=2.42~3.17）。此类变化源于患侧摆动腿位置控制能力的改善。但扰动干预带来的步宽调节改善并非始终显著优于对照组，且各组间的临床评估结果无显著差异。扰动组受试者的跌倒率低于对照组（发生率比=0.53），但本研究样本量较小，相关结论需谨慎解读。本研究结果表明，扰动干预可使脑卒中后步态的目标生物力学特性获得持续性改变，但仅靠此类变化或许不足以改善更为复杂的临床评估指标。