Maxian T A, Brown T D, Weinstein S L
Department of Orthopaedic Surgery, University of Iowa, Iowa City 52242.
J Biomech. 1995 Feb;28(2):159-66. doi: 10.1016/0021-9290(94)00054-8.
Two computer models of nonuniform contact stress on the articular surface of the human hip were used to study the relationship between chronically excessive articular cartilage contact stress and long-term clinical outcome in a series of patients with congenital dislocation of the hip (CDH). The analyzed database consisted of 409 stylus digitized radiographs from 83 patients with unilateral CDH, who had been treated by closed reduction, and whose average follow-up time was 29.2 y. The first model (nonuniform Legal) involved a three-dimensional contact stress distribution function whose pole was coincident with the resultant force acting through the hip, and which acted over a contact area whose borders were determined soley by bony landmarks. In the second model (Brinckmann), the direction of the pole of the contact stress distribution function was initially unknown; one border of the contact region was determined by radiographic landmarks, while the other border depended upon the pole of the iteratively determined contact stress distribution function. In both models, the contact stress distributions were converted to area engagement histograms, corresponding to the fractional areas of cartilage experiencing specific ranges of stress (0.5 MPa increments). These histograms were integrated over time to calculate a cumulative contact stress overdose, which was then compared to clinical outcome. Reasonable correlations (Spearman rho = 0.63-0.66) with patient outcomes were obtained for optimally chosen damage thresholds, although these thresholds were appreciably different (2.0 versus 4.5 MPa) due to the respective modelling assumptions.
使用两种人体髋关节关节面非均匀接触应力的计算机模型，来研究一系列先天性髋关节脱位（CDH）患者中，慢性过度的关节软骨接触应力与长期临床结果之间的关系。分析的数据库包含来自83例单侧CDH患者的409张触针数字化射线照片，这些患者均接受了闭合复位治疗，平均随访时间为29.2年。第一个模型（非均匀Legal模型）涉及一个三维接触应力分布函数，其极点与通过髋关节作用的合力重合，且作用于一个仅由骨性标志确定边界的接触区域。在第二个模型（Brinckmann模型）中，接触应力分布函数的极点方向最初未知；接触区域的一个边界由射线照相标志确定，而另一个边界则取决于迭代确定的接触应力分布函数的极点。在这两个模型中，接触应力分布都被转换为面积接触直方图，对应于经历特定应力范围（以0.5 MPa递增）的软骨部分面积。这些直方图随时间积分以计算累积接触应力过量，然后将其与临床结果进行比较。对于最佳选择的损伤阈值，与患者结果获得了合理的相关性（Spearman相关系数rho = 0.63 - 0.66），尽管由于各自的建模假设，这些阈值明显不同（分别为2.0和4.5 MPa）。
