Willert H G, Bertram H, Buchhorn G H
Orthopaedic Department, University of Göttingen, Federal Republic of Germany.
Clin Orthop Relat Res. 1990 Sep(258):108-21.
Movement at the interface between bone and cement and fractures of the cement can cause fragmentation of the polymethylmethacrylate (PMMA) bone cement implant. In order to obtain further information about the effect of PMMA fragments on the surrounding tissue and the role of such particles in the development of bone resorption, the authors investigated 17 patients with cemented total hip endoprostheses showing osteolysis and implant loosening in the femoral shaft with (Group B) and without (Group A) involvement of the acetabulum. The roentgenographic follow-up examinations revealed an initially slow and later more rapid extension of the endosteal bone erosions, with a predilection for the tip of the stem, the lesser trochanter, and laterally for the middle of the stem. At revision surgery, tissue samples were taken from the joint capsule and the bone-cement interface, in particular from the osteolysis in the femoral shaft and the acetabulum. The tissue samples were processed for histology, microscopically examined, and semiquantitatively evaluated. The retrieved devices were also carefully inspected. Large foreign-body granulomas were found at the bone-cement interface and in the joint capsule. Histiocytes and foreign-body giant cells stored particles of PMMA and polyethylene, of which fragmented bone cement predominated. Granulomatous tissue invaded bone canals and marrow spaces and induced resorption of the surrounding bone. In four cases in Group A, tissue from the osteolysis contained only fragmented bone cement, demonstrating that PMMA particles alone may be responsible for triggering focal bone resorption. Osteolysis seems to begin at the site where disintegration of bone cement begins. In cases in which polyethylene particles were found in the tissue in addition to fragmented bone cement, wear from the ultrahigh molecular weight polyethylene socket has been increased by entrapment of PMMA particles between the joint surfaces. Thus, fragmentation of bone cement and abrasion of polyethylene enhance each other. Bone cement particles promote polyethylene wear, which in turn promotes granuloma formation, bone resorption, and subsequent bone cement disintegration.
骨与骨水泥界面处的活动以及骨水泥骨折可导致聚甲基丙烯酸甲酯（PMMA）骨水泥植入物破碎。为了进一步了解PMMA碎片对周围组织的影响以及此类颗粒在骨吸收发展中的作用，作者对17例全髋关节置换术患者进行了研究，这些患者的股骨干出现骨溶解和植入物松动，其中髋臼受累的为B组，未受累的为A组。X线随访检查显示，骨内膜骨侵蚀最初进展缓慢，随后加快，主要发生在柄尖、小转子以及柄中部外侧。翻修手术时，从关节囊和骨水泥界面取材，特别是从股骨干和髋臼的骨溶解部位取材。对组织样本进行组织学处理、显微镜检查和半定量评估。对取出的假体也进行了仔细检查。在骨水泥界面和关节囊中发现了大型异物肉芽肿。组织细胞和异物巨细胞内含有PMMA和聚乙烯颗粒，其中破碎的骨水泥颗粒占主导。肉芽肿组织侵入骨管和骨髓腔，导致周围骨质吸收。A组4例患者，骨溶解部位的组织中仅含有破碎的骨水泥，表明仅PMMA颗粒可能是引发局部骨吸收的原因。骨溶解似乎始于骨水泥开始崩解的部位。在组织中除了破碎的骨水泥还发现聚乙烯颗粒的病例中，由于PMMA颗粒夹在关节面之间，超高分子量聚乙烯髋臼杯的磨损增加。因此，骨水泥破碎和聚乙烯磨损相互促进。骨水泥颗粒促进聚乙烯磨损，进而促进肉芽肿形成、骨吸收以及随后的骨水泥崩解。
