Metal-on-metal total hip arthroplasty: Causes and high incidence of early failure

Early failures of metal-on-metal total hip arthroplasty (THA) occur due to aseptic loosening, metal hypersensitivity reactions, pseudotumor formation, and component seizing. The purpose of this study was to investigate the timing, common modes of failure, clinical outcomes, and incidence of metal-on-metal THA revisions. A review was performed of 80 patients who underwent revision of a failed metal-on-metal THA for any reason. The most common reason for metal-on-metal failure was aseptic acetabular loosening, with a rate of 56.25% (45/80 patients). Early failure of metal-on-metal THAs was noted, with 78% of these revisions being performed within 2 years of the index operation and 92.5% within 3 years. Furthermore, 13% of patients experienced significant localized soft tissue reactions. Mean preoperative Harris Hip Score was 42.35±14.24 and mean postoperative Harris Hip Score was 66.5±23.2 (range, 9.55-95.4), with an average follow-up of 438±492 days (range, 40-2141), or 1.2 years. It is imperative that clinicians be cognizant of the fact that the proposed advantages of metal-on-metal THA are not without potential detrimental sequelae. This article proposes an algorithm to aid in diagnosing the etiology of a painful metal-on-metal THA, as well as 2 classification schemes regarding metal-on-metal THA complications to help direct treatment.