Carter D R, Wong M
Veterans Administration Medical Center, Rehabilitation Research and Development Center, Palo Alto, California.
J Orthop Res. 1988;6(1):148-54. doi: 10.1002/jor.1100060120.
In 1911, Gebhardt used a photoelastic model to relate mechanical stresses to the ossification pattern of the chondroepiphysis. Pauwels later conducted a photoelastic study using the same model geometry to develop a theory that the secondary ossific nucleus originates at a position of high-magnitude hydrostatic pressure where the shear stresses are zero. We conducted two-dimensional finite element analyses of the model used by Gebhardt and Pauwels. We demonstrate that Pauwels's photoelastic results are correct but are based on the imposition of incorrect boundary conditions. When more realistic boundary conditions were used, the finite element results changed dramatically. These results suggest that (a) the ossific nucleus appears in an area of high shear (deviatoric) stresses; (b) the edge of the advancing ossification front (zone of Ranvier or ossification grove) also experiences high shear stresses; and (c) the joint surface, where articular cartilage forms, is exposed to high-magnitude hydrostatic compression. These findings support the theory proposed by Carter and associates that intermittently applied shear stresses (or strain energy) promote endochondral ossification and that intermittently applied hydrostatic compression inhibits or prevents cartilage degeneration and ossification.
1911年，格布哈特使用光弹性模型将机械应力与软骨骨骺的骨化模式联系起来。保罗斯后来使用相同的模型几何结构进行了一项光弹性研究，以发展一种理论，即次级骨化核起源于静水压力高且剪应力为零的位置。我们对格布哈特和保罗斯使用的模型进行了二维有限元分析。我们证明保罗斯的光弹性结果是正确的，但基于施加了不正确的边界条件。当使用更现实的边界条件时，有限元结果发生了巨大变化。这些结果表明：(a)骨化核出现在高剪应力（偏应力）区域；(b)前进的骨化前沿（朗维埃区或骨化沟）边缘也承受高剪应力；(c)形成关节软骨的关节表面承受高静水压力。这些发现支持了卡特及其同事提出的理论，即间歇性施加的剪应力（或应变能）促进软骨内骨化，间歇性施加的静水压力抑制或防止软骨退变和骨化。
