A RANDOMISED PROSPECTIVE TRIAL TO COMPARE TWO DESIGNS OF HYDROXYAPATITE COATED FEMORAL STEMS FOR TOTAL HIP REPLACEMENT.

Abstract

The optimum design for the femoral component for cementless Total Hip Replacement is not known. We conducted an ethically approved, randomized and prospective trial to compare two radically different designs of fully hydroxyapatite(HA) coated femoral stems. We compared the original JRI Furlong stem with the Wright Anca fit stem which is more anatomical in design. The paper discusses the merits and disadvantages of these two stems. The same acetabular component was used in both samples. The only variable was the stem shape.

All patients placed on the senior authors’ waiting list for primary THR were asked if they would enter the trial. There were no restrictions for selection to the sample. Patients were then randomised for one of the two stems. The surgery was undertaken by one surgeon, in one centre, in matched patients and using the same well-tried CSF acetabular cup and bearings.

335 patients had been entered into the trial, 228 females and 126 males.

191 patients had the JRI furlong hip implanted (57%) and 146 are in the Anca sample (43%).

The number of perioperative fractures in the Furlong group was 13(6.8%)and in the Anca sample 22 (15.3%).

The periprosthetic and perioperative fracture rates for the two stems were found to be significantly different at three years into the study and the trial was stopped. The possible reasons for this difference are discussed.