Long term results of the Bicontact D stem in dysplastic osteoarthritis: a 10-15 year follow-up study.

Purpose: The purpose of the present study was to investigate the results of total hip arthroplasty (THA) using the Bicontact D stem with a minimum 10 year follow-up that focused on patients with developmental dysplasia of the hip (DDH).

Methods: One hundred five patients with osteoarthritis due to DDH who underwent primary THA were included in this study. The mean final follow-up period was 12.7 ± 1.2 years (range 10-15 years). All cases were evaluated both clinically and radiographically, and Kaplan-Meier survivorship was determined as stem revision for any reason as the end point.

Results: Modified Harris hip score averaged 89.0 ± 1.1 (range 60-98) at the final follow-up. The survivorship was 99.0% (95% confidence interval 93.4-99.9%) at 15.0 years, and only one hip with a well-fixed stem required stem revision due to recurrent dislocations. Cortical hypertrophy (CH) was observed in 40 of 105 hips (38.1%), and stress shielding (SS) progressed to grade 3 or 4 in six hips (6 of 105 hips: 5.7%) during the study period. Among the six hips with progressed SS, Dorr type C proximal femoral geometry was seen in five hips.

Conclusion: This study of 105 THAs using the Bicontact D stem that focused on DDH patients with a minimum 10 year follow-up period achieved satisfactory clinical and radiological outcomes. Dorr type C proximal femoral geometry could be considered a risk factor for progressed SS.