Pinnacle® modular metal-on-metal articulation in primary total hip arthroplasty: mid-term results of 195 cases.

Studies concerning Pinnacle® modular metal-on- metal (MoM) total hip arthroplasty (THA) show better results than for most other MoM THAs. The goal of this study was to report on the revision rate, clinical outcome and metal ion levels regarding this specific prosthesis. Retrospectively selected patients were evaluated clinically, and Visual Analogue Score for pain (VAS), Harris Hip Score (HHS) and Hip disability and Osteoarthritis Outcome Score (HOOS) were determined. Blood metal ion levels were measured. 195 patients were included (mean follow-up 6.4 years). MoM related revision was performed in 5.1%. Clinical outcome was good, with a mean VAS of 6.7 out of 100, HHS of 88.9 and HOOS of 80.7. Five year survival was 96.6%, eight year survival decreased to 90.0%. No correlation could be found between metal ion levels and outcome. Although clinical outcome was good, overall survival of the Pinnacle® MoM is unacceptably low compared to MoP survival.