48. RANDOMISED DOUBLE-BLINDED STUDY COMPARING CLINICAL OUTCOME AND GAIT CHARACTERISTICS AFTER LARGE DIAMETER HEAD TOTAL HIP ARTHROPLASTY (LDH-THA) AND HIP RESURFACING (HR)

Abstract

Purpose: Better clinical outcome is generally reported after hip resurfacing when compared to conventional 28mmTHA. This may simply be the consequences of biased patient selection, patient perception or the advantageous use of larger diameter femoral heads in HR. The true clinical benefits of HR can only be assessed by comparison with LDH-THA in a blinded randomized study to eliminate/reduce those biases. This was the aim of the study.

Method: Charnley class A patients were randomized between HR or LDH-THA and kept blinded for one year. Clinical data, gait analysis, postural balance evaluations and functional tests were performed pre-operatively at 3, 6, 12 and 24 months postoperatively. Fourteen normal patients served as controls.

Results: Twenty-four patients were assigned to each group. There was no significant difference in WOMAC, SF-36, activity scores, and patient satisfaction. A slight advantage was observed for HR during the functional reach test (postural balance) and for LDH-THA during the step test (speed, strength and balance), all other tests showing no differences. Both groups quickly reached controls value for all tests by 3 months.

Conclusion: We have failed to demonstrate a clear difference in outcome between HR and LDH-THA. Both groups fully recovered quickly. The postulated clinical advantages of HR over 28mmTHA most likely result from using a larger head in highly motivated patients. The only clear advantage of HR over LDH-THA remains proximal femoral bone conservation, although with the excellent durability of currently used femoral stems, HR has to demonstrate comparable survivorship before bone conservation is considered a true benefit.