Damage of Oxinium Femoral Heads Subsequent to Hip Arthroplasty Dislocation: Three Retrieval Case Studies

Oxinium exhibits 4900 times less volumetric wear and 640 times less deep scratches in laboratory wear testing compared with traditional cobalt-chromium alloys. Despite the superior wear resistance because of the thin ceramic surface, the zirconium alloy substrate is relatively soft (Hv = 285) when compared with cobalt-chrome alloy femoral heads (ISO 5832-12; Hv = ~420,) and may deform in contact with acetabular shell materials (ISO5832-3; Hv = 350) in the case of dislocation. Three retrieval cases highlight the damage that may occur during dislocation and/or when performing closed reduction maneuvers. It is recommended that closed reduction be attempted with caution because significant head damage can occur. This may lead to accelerated polyethylene wear. In the case of successful reduction, close patient follow-up is recommended. Open reduction with femoral head inspection and exchange may be preferable if difficulty is encountered in closed reduction maneuvers.