Early results of total hip replacement with the metasul metal-on-metal cementless prosthesis

Background: The need for better durability and longevity in total hip arthroplasty in high demand patients is a constant challenge. For this purpose, a metal-on-metal prosthesis with improved tribology was developed. Our early results using this implant are presented. Materials and Methods: A prospective analysis was performed for 56 Metasul hip arthroplasties between 1997 and 2001. There were 39 patients (43 hips) available for both clinical and radiographic evaluation at an average follow-up period of 42 months. Outcomes were measured using the Harris hip score. Discussion: The average Harris hip score increased from 40.7 to 81.1. Subjectively, 87% of the primary cases were satisfied. The majority of patients had pain-free range of motion and had returned to improved daily functions. One technical intraoperative complication (false route) was resolved with immediate revision. Two patients required cerclage wiring, due to a femoral crack. There were two cases of persistent distal peroneal nerve palsy. Three cases of anterior dislocations were reduced and did not recur. A case of positive intraoperative culture was successfully treated with intravenous antibiotics. Two patients required revision to a cemented acetabular prosthesis, one due to cup loosening and the other due to a painful hip with a suspected infection. Radiolucent lines were seen in the acetabulum in one case, which underwent revision. No femoral or pelvic radiolucent lines were found. Conclusions: We have had relatively satisfactory results in the early follow-up period. It remains premature to draw conclusions as to the superiority of this system over a conventional metal-on-polyethylene bearing prosthesis. Long-term follow-up studies are needed.