Szivek J A, Cutignola L, Volz R G
Department of Surgery, University of Arizona, Tucson 85724, USA.
J Arthroplasty. 1995 Aug;10(4):480-91. doi: 10.1016/s0883-5403(05)80150-0.
The Fuji film (Itochu, Los Angeles, CA) area analysis technique demonstrates that a more accurate assessment of tibiofemoral contact stresses is possible when the film is used at 37 degrees C and at the upper end of its sensitivity range (in this case, a 2,000-N load). An AMK with a regular and Hylamer-M insert (DePuy, Warsaw, IN), an MG II (Zimmer, Warsaw, IN), an Omnifit (Osteonics, Allendale, NJ), an Ortholoc III (Dow Corning Wright, Midland, MI), a PCA II (Howmedica, Rutherford, NJ), and a PFC (Johnson & Johnson Orthopaedics, Raynham, MA) had average contact stresses that varied only 12% at 60 degrees flexion. At 0 degrees, 15 degrees and 60 degrees flexion, stresses ranged from 13 to 25 MPa. Contact area distribution ratios, which were smaller at 37 degrees C than at 24 degrees C, provide a quantitative means of grouping implants according to the shape of the tibiofemoral contact area. The Omnifit, MG II, PCA II, and PFC had small ratios (symmetric areas). The AMK and Ortholoc III had large ratios (asymmetric contact areas). If the impression is reflective of wear, it would be expected to be focal in knees with small ratios and contact areas, and uniform in knees with large ratios and contact areas, whereas large ratios and small areas would imply a linear wear pattern. Calibrated electrical resistance contact stress measurements indicated that the Fuji film measurements underestimated the magnitude of contact stresses. They also provided a means of quantifying the rate of area increase during initial loading of the knees, with the highest area increase noted for the knee with the roughest insert (Ortholoc III) and the lowest area increase for the knee with the smoothest insert (PCA II).
富士胶片（伊藤忠商事株式会社，加利福尼亚州洛杉矶）区域分析技术表明，当胶片在37摄氏度且处于其灵敏度范围上限（在此情况下为2000牛负荷）使用时，对胫股接触应力进行更准确的评估是可行的。带有常规和Hylamer - M内衬的AMK（迪普伊公司，印第安纳州华沙）、MG II（齐默公司，印第安纳州华沙）、Omnifit（奥斯特尼克斯公司，新泽西州阿伦代尔）、Ortholoc III（道康宁赖特公司，密歇根州米德兰）、PCA II（豪美医疗器械公司，新泽西州卢瑟福）以及PFC（强生矫形公司，马萨诸塞州雷纳姆）在60度屈曲时的平均接触应力变化仅为12%。在0度、15度和60度屈曲时，应力范围为13至25兆帕。37摄氏度时的接触面积分布比率小于24摄氏度时的，这提供了一种根据胫股接触面积形状对植入物进行分组的定量方法。Omnifit、MG II、PCA II和PFC的比率较小（对称区域）。AMK和Ortholoc III的比率较大（不对称接触区域）。如果这种压痕反映磨损情况，那么预计在比率和接触面积小的膝关节中磨损是局部的，而在比率和接触面积大的膝关节中磨损是均匀的，而比率大且面积小则意味着线性磨损模式。校准电阻接触应力测量表明，富士胶片测量低估了接触应力的大小。它们还提供了一种量化膝关节初始加载过程中面积增加速率的方法，插入物最粗糙的膝关节（Ortholoc III）面积增加最高，而插入物最光滑的膝关节（PCA II）面积增加最低。
