Barker M K, Seedhom B B
Rheumatology and Rehabilitation Research Unit, University of Leeds, 36 Clarendon Road, Leeds LS2 9NZ, UK.
Rheumatology (Oxford). 2001 Mar;40(3):274-84. doi: 10.1093/rheumatology/40.3.274.
To investigate the relationship of the instantaneous compressive modulus with its deformation response to cyclic loading typical of that encountered at the knee joint during level walking.
The study was performed on 24 osteochondral plugs taken from three unembalmed cadaveric knees. As the compressive modulus of cartilage has been shown to vary topographically across the knee in an established manner, the specimens were taken from specific sites on the femur and tibia of each knee. All the cartilage specimens were immersed in Hanks' salt solution at 37 degrees C and were subjected to the same cyclic loading regimen that was representative of a typical walking cycle in a specialized indentation apparatus, for over 1 h.
The viscous and elastic components of matrix strain, the creep rate and the cartilage compressive modulus were measured. The latter was found to be significantly related to the strain response of cartilage to cyclic loading. Elastic strain varied exponentially with the compressive modulus; specimens with a modulus less than 4 MPa experienced elastic strains in the range 0.18-0.36, whereas stiffer specimens experienced strains between 0.05 and 0.13. Viscous strain varied linearly with cartilage stiffness and was as low as 0.02 at the lower values of the compressive modulus but increased to 0.22 for a compressive modulus of 18 MN/m(2). The rate of creep under cyclic load was inversely linearly related to cartilage stiffness. The strain response of soft specimens approached steady state by 200 cycles but that of stiff specimens did not approach it until 1300 cycles. It was hypothesized that the viscous strain response of cartilage can be explained in terms of differences in permeability between specimens of different compressive modulus, stiffer cartilage having a lower permeability than soft cartilage.
研究瞬时压缩模量与其在水平行走时膝关节典型循环载荷下变形响应之间的关系。
对取自三具未防腐处理尸体膝关节的24个骨软骨栓进行研究。由于已证实软骨的压缩模量在膝关节各部位存在地形学差异，因此从每个膝关节的股骨和胫骨特定部位获取标本。所有软骨标本均浸泡在37℃的汉克斯盐溶液中，并在专门的压痕装置中承受代表典型行走周期的相同循环加载方案，持续1小时以上。
测量了基质应变的粘性和弹性成分、蠕变率和软骨压缩模量。发现后者与软骨对循环载荷的应变响应显著相关。弹性应变随压缩模量呈指数变化；模量小于4MPa的标本弹性应变范围为0.18 - 0.36，而较硬的标本弹性应变在0.05至0.13之间。粘性应变随软骨刚度呈线性变化，在压缩模量较低值时低至0.02，但在压缩模量为18MN/m²时增加到0.22。循环载荷下的蠕变率与软骨刚度呈反线性关系。软标本的应变响应在200次循环时接近稳态，而硬标本直到1300次循环才接近稳态。据推测，软骨的粘性应变响应可以用不同压缩模量标本之间渗透率的差异来解释，较硬的软骨渗透率低于软软骨。
