Typing and particle analysis of squeaking hip endoprostheses : First histopathological analysis to examine the squeaking pathogenesis of ceramic-on-ceramic bearings

Abstract

Since the use of ceramic-on-ceramic (CoC) hip endoprostheses complications in the form of squeaking noises have occasionally occurred. This is the first histopathological analysis of the synovia-like interface membrane (SLIM) of ceramic squeaking hip endoprostheses with the aim to gain new insights into the squeaking pathogenesis. Seven CoC hip endoprostheses with squeaking pathogenesis are analyzed by SLIM consensus classification, particle algorithm, CD3 quantification, semiquantitative CD68 macrophages, Oil-Red positive macrophages, hemosiderin evaluation and in twocases by energy dispersive X‑ray spectroscopy (EDX). In 1733 hip joint prosthesis pathology cases, asqueaking revision incidence of 0.40% was determined. In addition to SLIM type I(1/7), only SLIM type IV(6/7) was detected. 4/7CoC cases showed combinations of micro, macro and, for the first time, supramacro (166.5 µm) ceramic wear particles. The EDX analysis confirmed the ceramic and an additional metallic abrasion. Increased focal concentrated low inflammatory markers (CD3/CD68) with hemosiderin(5/7) and lipid depositions (Oil-Red positive macrophages)(6/7) occurred. Apathogenetic connection between SLIM typeI/IV and squeaking can be assumed. SLIM types showed apartly light microscopic ceramic particle-dependent, partly independent predominantly low-grade inflammation. Hemosiderin and Oil-Red positive macrophages are signs of synovial tissue damage and indicate biomechanical misload (impingement) and dysfunction as cause of the squeaking pathogenesis.