Abstract
Question: Is the histopathological response of the peri-prosthetic tissue to metal-on-metal bearings comparable to the well studied reactions to polyethylene debris or do specific reactions exist and are theses reactions depending on the implant design?
Methods: Periprosthetic tissue samples from 19 THR and Hip Resurfacings (11 Birmingham Hip Resurfacings, 2 (historical)McMinn Hybrid Hip Resurfacings, 5 MetaSUL THR) with a variety of failure mechanisms were examined histopathologically and immunohistochemically.
Results: Only the samples of the (historical) McMinn Hybrid resurfacings showed a stronger histiocytic foreign body reaction and a higher grade metallosis. In all other cases only a mild if any histiocytic foreign body reaction was found. Additionally a chronic lymphoplasmacellular tissue reaction was present in all cases. 3 cases showed a higher grade chronic lymphoplasmacellular inflammatory tissue response comparable to a specific immune reaction.
Discussion: We found two different response mechanisms of the periprosthetic tissues to metal-on-metal bearings. In addition to the classic histiocytic foreign body reaction which was usual mild and only stronger in cases with a greater amount of metallic debris a lymphoplasmacellular inflammatory reaction usually was present but did not reach the level of inflammatory alterations associated with potential osteolysis and was not related to the implant or amount of wear. In 3 of our 19 cases the lymphoplasmacellular infiltration was stronger and comparable to a specific immune reaction. The significance of the specific immune reaction could not be further explained because a correlation to the failure mechanisms was not detectable
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
