Outcome of Acetabular Components of Primary Total Hip Arthroplasty in Patients with Osteonecrosis of the Acetabulum after Previous Pelvic Irradiation
MR Cho
Department of Orthopaedic Surgery, Gospel Hospital, College of Medicine, Kosin University, Busan, Korea

Purpose: This paper describes the results of treatment of THA in irradiated hips, and analyzes the risk factors related to the early failure of the acetabular components.

Materials and Methods: Eighteen primary total hip arthroplasties from twelve patients were analyzed. The mean follow-up period was fifty-eight months (range, twenty to 139 months). The acetabular components were of hemispherical design with an ingrowth surface of titanium fiber-metal in fourteen cases and roof rings in four cases. Risk factors were analyzed between age, total radiation dose, onset of symptoms after irradiation (£ 4 years, > 4 years), and the risk of failure in the acetabular components after THA.

Results: When only nine cases of failure were considered, the interval from operation to failure had a positive association with total radiation dose and a negative association with the ages of the affected patients or the latent period before onset of symptoms. When all the cases were included in the survival analyses, the survival rates did not depend on either patient age or total radiation dose. The latent period was significantly related to the survival rate with a cutoff point of four years (p = 0.03). After age, total radiation dose, and component type were adjusted, the risk of failure was fifteen times higher (95% confidence interval: 1.03-227.44) in patients ³ 4 years of the latent period, compared to those < 4 years of the latent period.

Conclusions: It is suggested that any arthroplasty other than a resection arthroplasty is unwise if the portal of irradiation includes the acetabulum and the latent period of the disease onset after irradiation is more than four years.