Shock absorption during transtibial amputee gait: Does longitudinal prosthetic stiffness play a role?

Background: Reduced-stiffness components are often prescribed in lower-limb prostheses, but their efficacy in augmenting shock absorption has been inconclusive.Objectives: To perform a systematic variation of longitudinal prosthetic stiffness over a wide range of values and to evaluate its effect on shock absorption during gait.Study design: Repeated-measures crossover experiment.Methods: Twelve subjects with a unilateral transtibial amputation walked at normal and fast self-selected speeds. Longitudinal prosthetic stiffness was modified by springs within a shock-absorbing pylon: normal (manufacturer recommended), 75% of normal (medium), 50% of normal (soft), and rigid (displacement blocked). The variables of interest were kinematic (stance-phase knee flexion and pelvic obliquity) and kinetic (prosthetic-side ground reaction force loading peak magnitude and timing).Results: No changes were observed in kinematic measures during gait. A significant difference in peak ground reaction force magnitudes between medium and normal (p = 0.001) during freely selected walking was attributed to modified walking speed (p = 0.008). Ground reaction force peaks were found to be statistically different during fast walking, but only between isolated stiffness conditions. Thus, altering longitudinal prosthesis stiffness produced no appreciable change in gait biomechanics.Conclusion: Prosthesis stiffness does not appear to substantially influence shock absorption in transtibial prosthesis users.

背景：下肢假肢中经常使用刚度降低的部件，但其在增强减震方面的功效尚无定论。 目的：在较大范围内对假肢纵向刚度进行系统改变，并评估其对步态期间减震的影响。 研究设计：重复测量交叉实验。 方法：12名单侧胫骨截肢受试者以正常和自选快速速度行走。通过减震支柱内的弹簧改变假肢纵向刚度：正常（制造商推荐值）、正常的75%（中等）、正常的50%（软）以及刚性（位移受阻）。关注的变量包括运动学（站立相膝关节屈曲和骨盆倾斜）和动力学（假肢侧地面反作用力加载峰值大小和时间）。 结果：步态期间运动学测量未观察到变化。在自由选择行走期间，中等刚度和正常刚度之间地面反作用力峰值大小存在显著差异（p = 0.001），这归因于行走速度的改变（p = 0.008）。在快速行走期间发现地面反作用力峰值在统计学上存在差异，但仅在个别刚度条件之间。因此，改变假肢纵向刚度对步态生物力学没有产生明显变化。 结论：假肢刚度似乎不会对胫骨截肢假肢使用者的减震产生重大影响。