CEMENTLESS ACETABULAR COMPONENTS

Four hundred and fifteen patients with cementless acetabular components of either a smooth threaded (130) or porous surfaced (285) variety were compared for clinical symptoms and radiographic signs of component loosening. At a mean 4.8 year follow-up none of the patients with porous acetabular components had signs of component instability. At a mean 3.9 year follow-up 27 (21%) of the patients with a smooth threaded acetabular component showed radiographic signs of instability and 33 (25%) had clinical symptoms. The disappointing short-term results with these threaded cups in our hands have prompted us to abandon their use in favour of the porous surfaced hemispherical cups. Aseptic loosening remains the leading cause of failure of cemented total hip arthnoplasties (Charnley 1982; Suth-er!and et a! 1 982; Callaghan et a! 1985; Pellicci et a! 1985). For femoral components, the loosening rate decreases with time, but acetabular loosening tends to increase. This has prompted changes in cup design, improvements in cementing techniques and the use o