Cemented metal-on-metal total hip replacement with 28-mm head: prospective, long-term, clinical, radiological and metal ions data.

PURPOSE

The aim of this study was to evaluate the long-term clinical, radiological and metal ion blood concentration results following 28-mm metal-on-metal cemented total hip replacement using Metasul(®) acetabular component and polished, cannulated Allopro CF-30 (Sulzer-Medica, subsequently Centerpulse-Zimmer, Winterthur, Switzerland) femoral component.

METHODS

Prospective follow-up of patients operated between 1997 and 2000 at a district general hospital.

RESULTS

Seventy-nine patients (89 implants) with female predominance and median age of 66 years (IQR 45-87 years) were prospectively followed up for mean 13 years (11-14 years). There was significant improvement in Harris hip score (paired Student's t test p = 0.0001). The mean plasma cobalt and chromium levels were 1.3 µg/L (IQR 0.5-23.9) and 3.6 µg/L (IQR 1.0-22), respectively. Elevated plasma metal ions >7 µg/L were noted in four asymptomatic patients with negative ultrasound examination. Radiolucent lines were present in various zones but majority were stable. One femoral component was revised due to aseptic femoral loosening. Three acetabular and one femoral component have radiologically failed but not revised yet. The Kaplan-Meier survival at 14 years was 92 % for failure as endpoint.

CONCLUSION

The long-term survival of Metasul(®) cemented total hip replacements using 28-mm metal-on-metal head is comparable with metal on polyethylene bearing devices.