Cohen B, Chorney G S, Phillips D P, Dick H M, Buckwalter J A, Ratcliffe A, Mow V C
Department of Orthopaedic Surgery, Columbia University, New York, New York 10032.
J Orthop Res. 1992 Mar;10(2):263-75. doi: 10.1002/jor.1100100214.
The tensile properties of distal femoral growth plates from 12-month-old cows were determined on uniformly prepared straight bone-growth plate-bone specimens (7 x 7 mm2 in cross-section) from predetermined anatomical sites on the physis. Each specimen was distracted to failure using a computer-controlled servo-hydraulic testing machine at a strain rate of 0.004 s-1. It was found that the exponential constitutive law, using finite deformation formulation for strain, provides an excellent description of the stress-strain behavior of all the specimens up to the point of failure. The ultimate stress and both tangent moduli (i.e., the toe region tangent modulus and the tangent modulus calculated at 75% of ultimate strain) varied with anatomical site. The anterior region was the strongest, followed by the posterior/lateral. The anterior and posterior/lateral regions were also the stiffest, whereas the posterior/medial and center regions were the weakest and most compliant. The bone-growth plate-bone specimen exhibited a low ultimate strain (13.8% +/- 6%) that did not vary significantly throughout the growth plate. This result suggests that disruption of the physis may occur in vivo even at the lower distractions currently recommended for the clinical chondrodiatasis procedure for leg lengthening. The biochemical composition of the growth plate in the anatomical regions correlated well with the tensile properties. There was a greater collagen content in the regions that were the stiffest and strongest. The gross morphology of the growth plate of the bovine distal femur is also described in this study. There is a regular pattern to the undulations of the physis at several dimensional levels. Histologic findings showed that orientation of the hypertrophic cell columns and transphyseal septa are aligned nearly parallel to the longitudinal axis of the diaphyseal shaft. This column orientation is not affected by the undulation of the primary contour of the physis, which at certain locations may be inclined as much as 60 degrees relative to the diaphyseal axis. The orientation of the hypertrophic cell columns appears to be one of the dominant microstructural features influencing the tensile behavior of the bone-growth plate-bone specimens.
对12月龄奶牛股骨远端生长板的拉伸特性进行了测定，所用标本为从骨骺预定解剖部位制备的均匀一致的直骨-生长板-骨标本（横截面为7×7平方毫米）。使用计算机控制的伺服液压试验机以0.004 s-1的应变率对每个标本进行拉伸直至破坏。结果发现，采用有限变形应变公式的指数本构定律能够很好地描述所有标本直至破坏点的应力-应变行为。极限应力和两个切线模量（即趾部区域切线模量和在极限应变的75%处计算的切线模量）随解剖部位而变化。前部区域最强，其次是后部/外侧区域。前部和后部/外侧区域也是最硬的，而后部/内侧和中心区域最薄弱且最具柔韧性。骨-生长板-骨标本的极限应变较低（13.8%±6%），在整个生长板中变化不显著。这一结果表明，即使在目前腿部延长临床软骨扩张术推荐的较低牵张水平下，骨骺在体内也可能发生破坏。生长板各解剖区域的生化组成与拉伸特性密切相关。最硬和最强的区域胶原蛋白含量更高。本研究还描述了牛股骨远端生长板的大体形态。在几个维度水平上，骨骺的起伏有规律可循。组织学结果显示，肥大细胞柱和跨骨骺隔的方向几乎与骨干纵轴平行。这种柱方向不受骨骺主要轮廓起伏的影响，在某些位置，骨骺主要轮廓相对于骨干轴可能倾斜多达60度。肥大细胞柱的方向似乎是影响骨-生长板-骨标本拉伸行为的主要微观结构特征之一。
