Xu Hang, Greenland Kasey, Bloswick Donald, Zhao Jie, Merryweather Andrew
School of Medical Imaging, Xuzhou Medical University, Xuzhou, China; Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, USA.
Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, USA.
J Biomech. 2017 May 24;57:110-116. doi: 10.1016/j.jbiomech.2017.04.013. Epub 2017 Apr 20.
The elevated vacuum suspension system (EVSS) has demonstrated unique health benefits for amputees, but the effect of vacuum pressure values on knee contact force (KCF) is still unclear. The objective of this study was to investigate the effect of vacuum levels on KCF for unilateral transtibial amputees (UTA) using the EVSS. Three-dimensional gait was modeled for 9 UTA with five vacuum levels (0-20inHg [67.73kPa], 5inHg [16.93kPa] increments) and 9 non-amputees based on kinematic and ground reaction force data. The results showed that the vacuum level effects were significant for peak axial KCF, which had a relatively large value at 0 and 20inHg (67.73kPa). The intact limb exhibited a comparable peak axial KCF to the non-amputees at 15inHg (50.79kPa). At moderate vacuum levels (5inHg [16.93kPa] to 15inHg [50.79kPa]), co-contraction of quadriceps and hamstrings at peak axial KCF was similar for the intact limb, but was smaller for the residual limb comparing with the non-amputees. The intact limb showed a similar magnitude of quadriceps and hamstrings force at 15inHg (50.79kPa) to the non-amputees, but the muscle coordination patterns varied between the residual and intact limbs. These findings indicate that a proper vacuum level may partially compensate for the lack of ankle plantarflexor and reduce the knee loading. Of the tested vacuum levels, 15inHg (50.79kPa) appears most favorable, although additional analyses with more amputees are suggested to confirm these results prior to establishing clinical guidelines.
高真空悬吊系统（EVSS）已被证明对截肢者具有独特的健康益处，但真空压力值对膝关节接触力（KCF）的影响仍不清楚。本研究的目的是使用EVSS研究真空水平对单侧胫骨截肢者（UTA）KCF的影响。基于运动学和地面反作用力数据，对9名UTA和9名非截肢者在五个真空水平（0-20英寸汞柱[67.73千帕]，以5英寸汞柱[16.93千帕]递增）下的三维步态进行了建模。结果表明，真空水平对轴向峰值KCF有显著影响，在0和20英寸汞柱（67.73千帕）时该值相对较大。在15英寸汞柱（50.79千帕）时，健全肢体的轴向峰值KCF与非截肢者相当。在中等真空水平（5英寸汞柱[16.93千帕]至15英寸汞柱[50.79千帕]）下，健全肢体在轴向峰值KCF时股四头肌和腘绳肌的共同收缩与非截肢者相似，但残肢的共同收缩比非截肢者小。健全肢体在15英寸汞柱（50.79千帕）时股四头肌和腘绳肌的力量大小与非截肢者相似，但残肢和健全肢体之间的肌肉协调模式有所不同。这些发现表明，适当的真空水平可能部分补偿踝关节跖屈肌的不足并减轻膝关节负荷。在测试的真空水平中，15英寸汞柱（50.79千帕）似乎最为有利，不过在制定临床指南之前，建议对更多截肢者进行额外分析以证实这些结果。
