Articular cartilage deformation under physiological cyclic loading-apparatus and measurement technique
Articular cartilage deformation under physiological cyclic loading-apparatus and measurement technique
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DOI：
10.1016/s0021-9290(96)00166-2
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发表时间：
1997-04-01
影响因子：
2.4
通讯作者：
Seedhom, BB
中科院分区：
文献类型：
--
作者：
Barker, MK;Seedhom, BB
在运动活动中，由于相对的关节表面之间失去接触，髋关节，尤其是膝关节的软骨区域在加载循环之间经历完全卸载的时期。在这些期间，这些软骨部位经历无负荷恢复。因此，为了研究关节软骨对生理循环载荷的变形反应，决定尽可能接近所描述的生理情况进行建模。为此，有必要设计一种装置，以克服伺服液压材料试验装置在指定零载荷下限时遇到的一些困难。在0-2.5 Hz频率范围内的循环负载由步进电机驱动的凸轮和从动件组件控制。可以使用双板凸轮设计来调节每个循环的加载与恢复持续时间的比率，使得软骨加载能够在1Hz循环内发生短至20 ms的持续时间。可使用可互换的不渗透、多孔、半球形或平面端压头。通过压缩弹簧来控制载荷幅度，从而提供宽范围的接触应力（0.04-7.0 MPa）。载荷上升时间由弹簧与阻尼器一起控制，使临界阻尼载荷在短至15 ms的间隔内达到其最大值。测量技术和随后的分析依赖于同时记录压头载荷和垂直位移，采样频率为5 kHz。(C)1997 Elsevier Science Ltd.
In locomotive activities, areas of cartilage in both the hip, and especially the knee, experience periods of complete unloading between loading cycles as contact is lost between opposing articulating surfaces. During these periods these cartilage sites experience load-free recovery. Therefore, it was decided to model as closely as possible the physiological situation described, in order to study the deformation response of articular cartilage to physiological cyclic loading. For this it was necessary to design an apparatus in order to overcome some of the difficulties experienced with servo-hydraulic materials testing apparatus when specifying a lower load limit of zero. Cyclic loading in the frequency range 0-2.5 Hz was controlled by a cam and follower assembly driven by a stepper motor. The ratio of loading to recovery duration per cycle could be adjusted using a two-plate cam design enabling cartilage loading to occur for a duration as short as 20 ms within a 1 Hz cycle. Interchangeable impervious, porous, hemispherical or plane-ended indenters could be used. Load amplitude was controlled by compression of a spring giving a wide range of contact stresses (0.04-7.0 MPa). Load rise times were controlled by the spring in conjunction with a dashpot, enabling critically damped loads to reach their maximum value within an interval as short as 15 ms. The measurement technique and subsequent analysis relied on simultaneous recording of indenter load and vertical displacement at a sampling frequency of 5 kHz. (C) 1997 Elsevier Science Ltd.