To describe the results of Total Hip Artroplasty (THA) treatment, and to analyze the risk factors related to the early failure of acetabular components in irradiated hips.

Between January 1990 and January 2000, eighteen primary total hip arthroplasties in twelve patients were treated at our hospital. The mean follow-up period was fifty-eight months. The acetabular components were of hemispherical design with an ingrowth surface in fourteen cases and roof rings in four cases. The risk factors analyzed: age, total radiation dose, onset of symptoms after irradiation (< or ≤ or =4 years, >4 years), and the risk of failure of acetabular components after THA.

The latent period was significantly related to the survival rate with a cutoff point of four years (p=0.03). Adjusting for age, total radiation dose, and component type, the risk of failure was fifteen times higher (95% confidence interval: 1.03-227.44) in patients with a disease onset latency of > or ≥ or =4 years than in those with a latent period of <4 years.

It is suggested that any arthroplasty might be unwise if the portal of irradiation includes the acetabulum and the latent period of disease onset after irradiation exceeds four years.