Beck Owen N, Taboga Paolo, Grabowski Alena M
Department of Integrative Physiology, University of Colorado, Boulder, Colorado, United States of America.
Department of Veterans Affairs, Eastern Colorado Healthcare System, Denver, Colorado, United States of America.
PLoS One. 2016 Dec 14;11(12):e0168298. doi: 10.1371/journal.pone.0168298. eCollection 2016.
The mechanical stiffness of running-specific prostheses likely affects the functional abilities of athletes with leg amputations. However, each prosthetic manufacturer recommends prostheses based on subjective stiffness categories rather than performance based metrics. The actual mechanical stiffness values of running-specific prostheses (i.e. kN/m) are unknown. Consequently, we sought to characterize and disseminate the stiffness values of running-specific prostheses so that researchers, clinicians, and athletes can objectively evaluate prosthetic function. We characterized the stiffness values of 55 running-specific prostheses across various models, stiffness categories, and heights using forces and angles representative of those measured from athletes with transtibial amputations during running. Characterizing prosthetic force-displacement profiles with a 2nd degree polynomial explained 4.4% more of the variance than a linear function (p<0.001). The prosthetic stiffness values of manufacturer recommended stiffness categories varied between prosthetic models (p<0.001). Also, prosthetic stiffness was 10% to 39% less at angles typical of running 3 m/s and 6 m/s (10°-25°) compared to neutral (0°) (p<0.001). Furthermore, prosthetic stiffness was inversely related to height in J-shaped (p<0.001), but not C-shaped, prostheses. Running-specific prostheses should be tested under the demands of the respective activity in order to derive relevant characterizations of stiffness and function. In all, our results indicate that when athletes with leg amputations alter prosthetic model, height, and/or sagittal plane alignment, their prosthetic stiffness profiles also change; therefore variations in comfort, performance, etc. may be indirectly due to altered stiffness.
跑步专用假肢的机械刚度可能会影响腿部截肢运动员的功能能力。然而，每个假肢制造商都是根据主观刚度类别而非基于性能的指标来推荐假肢。跑步专用假肢的实际机械刚度值（即kN/m）尚不清楚。因此，我们试图对跑步专用假肢的刚度值进行表征并加以传播，以便研究人员、临床医生和运动员能够客观地评估假肢功能。我们使用与经胫骨截肢运动员跑步时测量的力和角度具有代表性的力和角度，对55种不同型号、刚度类别和高度的跑步专用假肢的刚度值进行了表征。用二次多项式表征假肢力-位移曲线比线性函数能多解释4.4%的方差（p<0.001）。制造商推荐的刚度类别的假肢刚度值在不同假肢型号之间存在差异（p<0.001）。此外，与中立位（0°）相比，在3 m/s和6 m/s跑步速度下典型角度（10°-25°）时，假肢刚度低10%至39%（p<0.001）。此外，在J形假肢中，假肢刚度与身高呈负相关（p<0.001），但在C形假肢中并非如此。跑步专用假肢应在各自活动的要求下进行测试，以得出刚度和功能的相关表征。总之，我们的结果表明，当腿部截肢运动员改变假肢型号、高度和/或矢状面排列时，他们的假肢刚度曲线也会发生变化；因此，舒适度、性能等方面的差异可能间接归因于刚度的改变。
