The Journal of Bone and Joint Surgery (American). 2010;92:1720-1731.
doi:10.2106/JBJS.I.00695
© 2010 The Journal of Bone and Joint Surgery, Inc.
Postmortem Study of Femoral Osteolysis Associated with Metal-on-Metal Articulation in Total Hip ReplacementAn Analysis of Nine Cases
Monika Huber, MD1,
Georg Reinisch, PhD2,
Peter Zenz, MD1,
Karl Zweymüller, MD3 and
Felix Lintner, MD1
1 Institute of Pathology and Bacteriology (M.H. and F.L.) and Department of Orthopaedic Surgery (P.Z.), SMZ Otto Wagner Spital, Baumgartner Hoehe 1, 1145 Vienna, Austria. E-mail address for M. Huber: Monika.Huber{at}wienkav.at
2 Biomechanische Forschungsgesellschaft mbH, Rechte Wienzeile, 1040 Vienna, Austria
3 Department of Orthopaedic Surgery, Gersthof, Wielemansgasse 28, 1180 Vienna, Austria
Investigation performed at the Institute of Pathology and Bacteriology, SMZ Otto Wagner Spital, Vienna, Austria
Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity.
Background Improved metal-on-metal articulations were reintroduced in total hip replacement to avoid the osteolysis sometimes seen with conventional ultra-high molecular weight polyethylene bearings. Osteolysis and local lymphocytic infiltration have been reported at revision of some metal-on-metal devices. We report similar and additional results in a study of second-generation metal-on-metal hip implants retrieved post mortem.
Methods Components and surrounding tissues were collected post mortem from seven patients with nine total hip replacements (Zweymüller SL stem with an Alloclassic cup) with Metasul metal-on-metal articulations. All available patient information was recorded. Radiographs of the hips were evaluated for osteolysis. Sections of joint capsule as well as of the femoral implant with surrounding bone were reviewed, and energy-dispersive x-ray analysis was used to evaluate the composition of wear products. The amount of wear was measured for each component (nine femoral heads and eight cup inserts), when possible, by a coordinate measurement machine with use of the dimensional method.
Results The patients died between three and ten years after arthroplasty, and six of the seven were asymptomatic at the time of death. One patient, with the highest rate of total wear (i.e., wear of femoral head and acetabular cup; 7.6 µm/yr), had increasing hip pain for one year, and histological analysis confirmed the radiographic findings of osteolysis. For two other patients, histological analysis confirmed the radiographic findings of asymptomatic osteolysis. For three patients, histological analysis revealed osteolysis that had escaped conventional radiographic analysis. Joint capsule tissue showed evidence of metallosis in all hips and local lymphocytic infiltration in eight hips. Energy-dispersive x-ray analysis revealed elements attributable to CoCrMo alloy in all hips and traces of corrosion products in three hips.
Conclusions The postmortem findings of osteolysis and/or lymphocytic infiltration associated with eight clinically well-functioning, low wear devices (a total wear rate of <4 µm/yr) suggest there may be frequent, unappreciated femoral bone loss and local immunological response in patients with second-generation metal-on-metal hip implants. Compared with previous postmortem studies, our findings showed the extent of osteolysis was similar to that with metal-on-polyethylene articulations.

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