Abstract
Second-generation metal-on-metal bearings have been used since the late 1980s as alternative bearings to eliminate aseptic loosening due to polyethylene wear.
This study is the first with a long term follow-up for Meteasul, (Zimmer GmbH, Winterthur, Switzerland) metal on metal (MoM) hip replacement; in literature most of the studies have a mean follow-up of 7 years. Metasul showed better performances than other MoM couplings, with a low failure rate at long term follow-up and low revision rate for aspetic loosening.
The aim of the present study was to evaluate the long-term results of a series of Metasul implanted between January 1993 and July 1997. 145 cementless THAs with a 28 mm Metasul articulation were performed in 114 consecutive patients. Implant survivorship was calculated and clinical and radiographic evaluations were performed on 93 hips still available for follow-up at a mean of 19 years postoperatively (43 hips are dead or lost to FU, 29, 6%).
Nine hips (6.2%) were revised. The cumulative probability of survival of the overall implant at 19 years postoperatively with revision for any reason as the end point, was 0.937 (95% confidence interval, 0.888 to 0.985). The cumulative probability of survival of Metasul with revision for any reason as the end point, was 0.956 (95% confidence interval, 0.916 to 0.997).
Clinical outcome has been evaluated with modified Harris Hip Score for 93 hips with an average of 88.8 points.
Various degrees of radiolucencies and osteolysis were found proximally around the femoral components of 25 hips (20%).
Most of the patients has normal serum levels of metal ions (Co and Cr), and no cases of systemic toxicity has been reported.
Cementless Metasul THAs showed high probability of survival at 19 years postoperatively.
