Szivek J A, Anderson P L, Benjamin J B
Department of Surgery, University of Arizona, Tucson 85724, USA.
J Arthroplasty. 1996 Dec;11(8):952-63. doi: 10.1016/s0883-5403(96)80137-9.
Seven total knee arthroplasty systems were tested to determine contact stress patterns and contact areas using a calibrated Fuji film stress analysis technique. Knees were loaded to 2,000 N (204 kg) at 15 degrees, 60 degrees, 90 degrees, and 135 degrees flexion at 24 and 37 degrees C. Evaluation of stresses at 37 degrees C at 15 degrees and 60 degrees using an average contact stress assessment technique indicated that the LCS meniscal bearing knee system, (DePuy, Warsaw, IN), the AMK knee with a constrained insert (DePuy), and the PFC knee with a posterior-lipped insert (Johnson and Johnson, Raynham, MA) had the lowest average contact stresses (near or below 10 MPa). The PFC with a regular insert (Johnson and Johnson) the Ortholoc II (Dow Corning Wright, Arlington, TN), and the AMK with a regular insert (DePuy) had intermediate contact stresses. The AMK with a Hylamer-M insert (DePuy) and the MG II (Zimmer, Warsaw, IN) had the highest average contact stresses (near or above 20 MPa). A stress-calibrated Fuji film measurement technique has shown that an assessment of ranges of contact stress provides much more information about regions of expected wear than an assessment of average contact stresses. Testing of the tibiofemoral articulation of artificial knees revealed that all knees had some areas of contact with maximum stresses in excess of 15 MPa. As the yield strength of ultrahigh-molecular-weight polyethylene is approximately 15 MPa, all tibial inserts could wear to some extent. Peak contact stresses at four test angles of the AMK, Series 7000 (Osteonics, Allendale, NJ:) Genesis (Smith & Nephew Orthopaedics, Memphis, TN), and MG II patellofemoral articulations were high (above 30 MPa). Contact areas varied from line-shaped to bilateral circular or elliptical shapes. The LCS knee system experienced substantially lower patellofemoral contact stresses and larger contact areas. Changes in conformity of knee designs are warranted to overcome wear problems. Peak contact stresses measured from the LCS meniscal bearing tibiofemoral and patellofemoral joint were in excess of 30 MPa in some areas at low flexion angles. This design does create large areas of contact at very low contact pressures, however, and for this reason is expected to wear less than other designs.
使用校准后的富士胶片应力分析技术对七种全膝关节置换系统进行了测试，以确定接触应力模式和接触面积。在24摄氏度和37摄氏度下，膝关节在15度、60度、90度和135度屈曲时加载至2000牛（204千克）。使用平均接触应力评估技术对37摄氏度下15度和60度时的应力进行评估，结果表明，LCS半月板支撑膝关节系统（德普伊公司，印第安纳州华沙）、带约束性衬垫的AMK膝关节（德普伊公司）以及带后唇衬垫的PFC膝关节（强生公司，马萨诸塞州雷纳姆）的平均接触应力最低（接近或低于10兆帕）。带常规衬垫的PFC膝关节（强生公司）、Ortholoc II（道康宁赖特公司，田纳西州阿灵顿）以及带常规衬垫的AMK膝关节（德普伊公司）的接触应力处于中等水平。带Hylamer - M衬垫的AMK膝关节（德普伊公司）和MG II膝关节（齐默公司，印第安纳州华沙）的平均接触应力最高（接近或高于20兆帕）。一种经过应力校准的富士胶片测量技术表明，与平均接触应力评估相比，接触应力范围评估能提供更多有关预期磨损区域的信息。对人工膝关节胫股关节的测试表明，所有膝关节都有一些接触区域，其最大应力超过15兆帕。由于超高分子量聚乙烯的屈服强度约为15兆帕，所有胫骨衬垫都会有一定程度的磨损。AMK系列7000（奥斯特尼克斯公司，新泽西州阿伦代尔）、创世纪膝关节（史赛克骨科公司，田纳西州孟菲斯）以及MG II髌股关节在四个测试角度的峰值接触应力都很高（超过30兆帕）。接触面积从线状到双侧圆形或椭圆形不等。LCS膝关节系统的髌股接触应力明显较低，接触面积较大。有必要改变膝关节设计的贴合度以克服磨损问题。在低屈曲角度下，LCS半月板支撑胫股关节和髌股关节某些区域测得的峰值接触应力超过30兆帕。不过，这种设计确实在非常低的接触压力下产生了大面积的接触，因此预计其磨损程度低于其他设计。
