Cementless acetabular component without screw holes with immediate full weightbearing : a minimum 20-year follow-up study.

AIMS

This study aimed to evaluate the survival of a cementless component without screw holes in total hip arthroplasty (THA) at a minimum follow-up of 20 years. This design has the benefits of maximizing bone contact and reducing osteolysis by eliminating channels to backside wear. However, transacetabular screws cannot be used.

METHODS

A total of 71 hips in 58 patients receiving the same model of cementless component without screw holes (Depuy Duraloc 100 hydroxyapatite (HA) component) from June 1999 to March 2003 were prospectively followed up. All patients were allowed to have immediate full weightbearing. The mean age at THA was 53.7 years (28 to 74). Osteonecrosis was the leading cause of THA. Survival was assessed with any revision and component revision as the endpoint. Radiological parameters, including lateral opening angle, and the components' vertical and horizontal migration distances, were measured and compared between the early postoperative period and final follow-up.

RESULTS

Overall, 54 hips were assessed at a minimum 20-year follow-up. The mean follow-up was 22.9 years (20.9 to 24.5). Two component revisions occurred at 17.5 and 17.6 years later. Both components were well fixed but were revised, due to the need to upsize the articulation and component malpositioning, respectively. Conventional polyethylene (PE) was used in both hips, and 14 other hips were revised with the components well fixed and not revised. The estimated survival of the acetabular component and THA at 20 years was 96.4% and 74.5%, respectively. Mean changes in lateral opening angle and vertical and horizontal migration distances were 0.48° (SD 1.45°), -0.06 mm (SD 1.44), and -0.36 mm (SD 1.36), respectively, with no statistical significance.

CONCLUSION

This study provides evidence of excellent long-term survival of cementless components without screw holes. Immediate postoperative weightbearing did not lead to component migration in the long term.