Screw sockets: survivorship analysis after eight years

A comparative analysis of the radiographic results of 111 screw sockets (65 tapered and 46 hemispherical cup sectors) was made to evaluate both their behaviour over a period of time and the validity of their use today. The follow-up was performed on average 42 months after the implant. Overall survivorship shows a high risk of failure during the fourth year and a greatly increased rate of failure after the sixth year. Comparison of the survival curves of the two types of acetabular component revealed no significant differences. The two types considered were, however, of different sizes: the implanted taper sockets were on average 6.6 mm larger than the comparable hemispherical cup sector acetabular components, thus involving a greater loss of acetabular bone.