30-years of experience with the cementless implanted Alloclassic total hip arthroplasty system-An ultra-long-term follow-up.

Objective: The aim of this study was to evaluate our long-term results with the Zweymüller hochgezogen and SL total hip arthroplasty system. This is the first study to provide a 30-year follow-up.

Methods: We reviewed 186 Alloclassic stem systems (Zweymüller hochgezogen (112) and SL (74), implanted in 179 patients from 1986 to 1987.Two different types of cementless acetabular components were used.143 patients had died over the last 30 years, so thirty out of 36 patients being still alive, with a mean follow-up of 29,48 years (SD 0,51), were contacted by telephone and evaluated radiologically and clinically. Our loss-to-follow up was 16,7%. The mean age at follow-up was 83,57 years (72,4-95,2; SD 6,77).

Results: If the endpoint is defined as the removal of the stem for aseptic loosening (3 cases), the overall survival rate is 98,38%. If the endpoint is revision for any reason (27 cases), the survival rate is 85,48%. Eleven patients needed an exchange of head and liner. The mean time from implantation until change of head and liner was 21,44 years (SD 5,92).Most of the radiolucent lines and osteolytic zones were found in the proximal Gruen-zones 1 and 7 (69,7 and 21,2%).

Conclusion: After 30 years of monitoring we can state that the evaluated system is very reliable in primary and secondary THA.