Primary total hip arthroplasty with hydroxyapatite coated titanium femoral stems. Does design philosophy influence long term outcome?: Results of a prospective randomised controlled trial with follow-up of 10-15 years.

We present results of a prospective randomised controlled trial examining two cohorts of patients treated with proximally (Group A) and fully coated (Group B) femoral components with long term follow up. Patients were reviewed preoperatively and 6, 12, 26 and 52 weeks post operatively then annually. The Merle d'Aubigne Postel (MDP) hip score was used to assess clinical outcome. A Visual Analog Score (VAS) was also recorded. Statistical calculation was performed using the student's t- test and Kaplan Meier survival analysis. One hundred and four patients were included in group A and 103 patients in group B. Mean age was 60.4 years and 60.8 years respectively. Mean follow- up was 12.9 years. Mean pre-operative MDP scores were 8.8 and 9.5 in Groups A and B respectively. Mean pre-operative VAS score 7.8 and 7.4 respectively. At final follow up mean MDP and VAS were 16.9, 16.6 and 2.1, 2.4 respectively. Three femoral revisions occurred in Group A. Seven revisions occurred in Group B. Survival of the femoral component with revision for any reason as the end point was 96% in Group A and 94.8% in Group B. Both components produced symptomatic relief and similar revision rates. Thigh pain occurred only in Group A.