Cohen B, Chorney G S, Phillips D P, Dick H M, Mow V C
Department of Orthopaedic Surgery, Columbia University, New York, NY 10032.
J Orthop Res. 1994 Nov;12(6):804-13. doi: 10.1002/jor.1100120608.
The compressive behavior of the bovine distal femoral growth plate was studied in vitro. Strain-rate controlled, compression stress-relaxation experiments were performed on cylindrical bone-growth plate-bone specimens from the interior and periphery of the growth plate. The questions addressed in this study were (a) Can the nonlinear biphasic theory, one with strain-dependent permeability, be used to represent the compressive stress-relaxation behavior of bovine growth plate? (b) How do different assumptions concerning the permeabilities of the chondro-osseous interfaces influence the inferred material properties of the growth plate? and (c) Are there any differences in these properties between the periphery and the interior of the growth plate? Intrinsic biphasic material properties--aggregate modulus (HA), Poisson's ratio (v), and nonlinear strain-dependent permeability coefficients (ko and M)--were calculated from the compression stress-relaxation data with use of a finite element model and a least squares curve-fitting procedure. To verify this constitutive model for the growth plate, an independent set of finite element analyses was performed with use of the determined intrinsic biphasic properties, and comparisons were made between these finite element predictions and two additional sets of experimental data subsequently obtained for the same specimens with use of two slower rates of compression. Excellent agreement was achieved between these finite element predictions and the latter two sets of data. The aggregate modulus was found to be insensitive to the permeability of the chondro-osseous interface. The permeability coefficients were very sensitive to, and the Poisson's ratio was only slightly sensitive to the interface permeability condition. Therefore, the periphery of the growth plate is more compliant and permeable than the interior.
对牛股骨远端生长板的压缩行为进行了体外研究。对取自生长板内部和周边的圆柱形骨-生长板-骨标本进行了应变率控制的压缩应力松弛实验。本研究探讨的问题是：(a) 具有应变依赖性渗透率的非线性双相理论能否用于描述牛生长板的压缩应力松弛行为？(b) 关于软骨-骨界面渗透率的不同假设如何影响生长板推断的材料特性？以及 (c) 生长板周边和内部的这些特性是否存在差异？利用有限元模型和最小二乘曲线拟合程序，从压缩应力松弛数据中计算出本征双相材料特性——聚集模量(HA)、泊松比(v)以及非线性应变依赖性渗透系数(ko和M)。为了验证该生长板本构模型，利用确定的本征双相特性进行了一组独立的有限元分析，并将这些有限元预测结果与随后对相同标本以两种较慢压缩速率获得的另外两组实验数据进行了比较。这些有限元预测结果与后两组数据之间取得了极好的一致性。发现聚集模量对软骨-骨界面的渗透率不敏感。渗透系数对界面渗透率条件非常敏感，而泊松比对其仅略有敏感。因此，生长板的周边比内部更具顺应性和渗透性。
