Kang Y H, Park J B
Department of Biomedical Engineering, College of Engineering, The University of Iowa, Iowa City, USA.
J Biomed Mater Res. 1998 Fall;43(3):261-9. doi: 10.1002/(sici)1097-4636(199823)43:3<261::aid-jbm6>3.0.co;2-l.
Fixation of polymeric implants, especially an ultrahigh molecular weight polyethylene (UHMWPE) acetabular cup, to a host bone site has been a challenge since its first conception from the Charnley low friction total hip arthroplasty. Destabilization of the acetabular cup, similar to the well-documented cases of femoral stems, is caused mainly by aseptic loosening; the mobile loosened particles further contribute to the progression of aseptic loosening. Although the obvious fixation problems lie in the bone-bone cement interface, little work has been done to reduce the loosening by improving the acetabular components as a whole in cemented procedures. Most of the grooved outer surface, external fixation devices, and metal backings have been introduced to avoid problematic fixation of the cup to bone cement; nevertheless, the designs themselves to some degree became the source of the loosening problems. One possible way to improve the adhesion of acrylic bone cement to the UHMWPE acetabular cup is precoating the surface with polymethylmethacrylate (PMMA). This study successfully precoated the UHMWPE surface with PMMA, showing good chemical and mechanical stability, and suggests the optimal conditions of variables involved in the newly developed precoating process. The highest interfacial tensile strength was 11.51 +/- 0.65 MPa, which is stronger than those of UHMWPE and metal in metal-backed cups (6.3 MPa) and bone-bone cement (8.5 MPa). Further chemical analysis and mechanical testing are in progress, yet the present result of the mechanical tensile strength test showed that the precoating process for the UHMWPE surface could be a viable means toward stable fixation of the polymeric implants by using PMMA bone cement.
自Charnley低摩擦全髋关节置换术首次构思以来，将聚合物植入物，尤其是超高分子量聚乙烯（UHMWPE）髋臼杯固定到宿主骨部位一直是一项挑战。髋臼杯的不稳定，类似于股骨柄有充分记录的情况，主要是由无菌性松动引起的；活动的松动颗粒进一步促使无菌性松动的进展。尽管明显的固定问题存在于骨-骨水泥界面，但在骨水泥固定手术中，通过整体改进髋臼部件来减少松动的工作做得很少。大多数带槽的外表面、外固定装置和金属背衬已被引入，以避免髋臼杯与骨水泥的固定出现问题；然而，这些设计本身在某种程度上成为了松动问题的根源。一种提高丙烯酸骨水泥与UHMWPE髋臼杯附着力的可能方法是用聚甲基丙烯酸甲酯（PMMA）预涂表面。本研究成功地用PMMA预涂了UHMWPE表面，显示出良好的化学和机械稳定性，并提出了新开发的预涂过程中涉及的变量的最佳条件。最高界面拉伸强度为11.51±0.65MPa，比金属背衬杯中的UHMWPE和金属（6.3MPa）以及骨-骨水泥（8.5MPa）的强度更强。进一步的化学分析和力学测试正在进行中，但目前的力学拉伸强度测试结果表明，UHMWPE表面的预涂过程可能是一种通过使用PMMA骨水泥实现聚合物植入物稳定固定的可行方法。
