[Implant fractures in ceramic hip endoprostheses].

Between 1974 and 1987, a total of 2356 ceramic hip endoprostheses, both primary and secondary, were implanted at the Orthopedic University Clinic in Homburg/Saar. Strem fractures occurred in three of these patients only, which corresponds to a relative frequency of 0.13%. In two instances, these were fatigue fractures of the AUTOPHOR I (WISIL) prosthesis stem, while in the third instance the fracture, of stem type 2 (ENDOCAST), was the result of a fault during casting. Fractures of ceramic components as a result of a direct trauma of sufficient force were observed in six cases (relative frequency of 0.25%). Persistent fractures only occurred where there was recurrent knocking of a long ceramic collar against the rim of the acetabulum (eight cases, relative frequency of 0.34%), mainly as a result of primary or secondary false positioning of the acetabulum (surgical error, aseptic loosening). Ceramic fractures when using the ceramics/polyethylene combination for joints have yet to be recorded. Given the authors' 12 years of experience, and considering the large number of patients treated fractures of high quality BIOLOX ceramics are a rarity. Both persistent fractures and exaggerated ceramic abrasion were almost always the result of false positioning of the acetabulum, with the recurrent knocking of the hip head ceramic collar playing a significant role. It is evident that the extent of tolerance of ceramics as regards undue strain with a subsequent danger of fracture is lower than that of the metal-polyethylene combination.