The Müller acetabular reinforcement ring--still an option in acetabular revision of Paprosky 2 defects? Longterm results after 10 years.

Aim of this study was to measure the clinical and radiological longterm outcome after acetabular revision arthroplasty using the Muller acetabular reinforcement ring. 96 patients with 103 revision arthroplasties and a mean age of 69 years (41 to 84) were included. The mean follow-up was 10 years (range 7 – 12). The radiologic analysis reports no signs of loosening in 76 %, 17 % showed possibly loosening and 7 % probable loosening. Definite radiologic loosening has not been detected. The mean center of rotation of the hip moved 0.15 cm (SD 0.74 cm) laterally and 0.1 cm (SD 0.97 cm) cranially based on the geometrically reconstructed center of rotation. A mean score of 58 points for the Harris Hip Score (range 14 – 93) indicated a poor functional outcome, while a mean value of 96 points (range 0 – 223) for the WOMAC Index indicated good results for functional outcome in daily living. The revision arthroplasty in cases with acetabular defects using the Muller acetabular reinforcement ring shows acceptable longterm results.