Eckstein F, Merz B, Müller-Gerbl M, Holzknecht N, Pleier M, Putz R
Anatomische Anstalt, Ludwig Maximilians Universität München, Germany.
Anat Rec. 1995 Nov;243(3):327-35. doi: 10.1002/ar.1092430307.
A deeper joint socket (concave incongruity) is found at most angles of flexion of the humero-ulnar joint and maintained over a wide range of physiological loading. It is, however, unclear how far this incongruity affects the distribution of load and subchondral mineralization of this joint as compared with a congruous configuration.
Two nonlinear, axisymmetrical finite element models with two cartilage layers were constructed, one congruous and one incongruous, with a joint space of realistic magnitude. The distribution of subchondral mineralization was determined by computed tomography osteoabsorptiometry in the same six specimens that were investigated in the first part of the study, and compared with the biomechanical data obtained there and the predictions of the models.
In the congruous case, the center of the socket is highly loaded, whereas the periphery does not experience mechanical stimulation. A central bone density maximum is predicted. With concave incongruity the position of the contact areas shifts from the joint margin towards the center as the load increases, and the peak stresses are considerably lower. A bicentric ventro-dorsal distribution pattern of subchondral mineralization is predicted, and this is actually found in the six specimens.
Concave incongruity is shown to determine load transmission and subchondral mineralization of the humero-ulnar joint. It is suggested that this shape leads to a more even distribution of stress, provides intermittent stimulation of the cartilaginous tissue, and has beneficial effects on the metabolism, nutrition, and lubrication of the articular cartilage during cyclic loading.
在大多数肱尺关节屈曲角度下可发现更深的关节窝（凹形不匹配），且在广泛的生理负荷范围内保持这种状态。然而，与匹配构型相比，这种不匹配对该关节的负荷分布和软骨下矿化的影响程度尚不清楚。
构建了两个具有两层软骨的非线性轴对称有限元模型，一个匹配模型和一个不匹配模型，关节间隙大小符合实际情况。通过计算机断层扫描骨吸收测定法确定了在本研究第一部分中所研究的相同六个标本中的软骨下矿化分布，并将其与在那里获得的生物力学数据以及模型预测结果进行比较。
在匹配情况下，关节窝中心承受高负荷，而周边未受到机械刺激。预计会出现中心骨密度最大值。在凹形不匹配情况下，随着负荷增加，接触区域的位置从关节边缘向中心移动，峰值应力显著降低。预计会出现软骨下矿化的双中心腹背分布模式，并且在这六个标本中实际观察到了这种情况。
凹形不匹配被证明决定了肱尺关节的负荷传递和软骨下矿化。有人认为这种形状会导致应力分布更加均匀，对软骨组织提供间歇性刺激，并且在循环负荷期间对关节软骨的代谢、营养和润滑具有有益影响。
