OBJECTIVETo study the short-term results of metal on metal hip resurfacing arthroplasty (HRA) for the treatment of patients with ankylosing spondylitis (AS), to explore the indications and technology of this surgery.

METHODSFrom February 2006 to April 2008, 11 patients (15 hips) with ankylosing spondylitis were treated with metal on metal total hip resurfacing arthroplasty. Among them, 9 patients were male, and 2 patients were female, with an average age of 32.5 years (ranged from 16 to 53 years). The comparative study on preoperative and postoperative pain, range of motion, correction of deformity and function evaluation were performed. The preoperative and postoperative Harris scores were compared and the feasibility and technical difficulty were analyzed.

RESULTSTen patients were followed up for an average period of 16.2 months (ranged from 8 to 34 months) and 1 patient was lost. Pain disappeared in 10 patients. There were no heterotopic ossification, no femoral neck fracture, no dislocation, no infection and no revision in all patients. From preoperation to present, the mean flexion angle of hip was improved from preoperative 0 degrees to 75 degrees to postoperative 35 degrees to 105 degrees; the mean abducting angle of hip was improved from preoperative 0 degrees to 30 degrees to postoperative 15 degrees to 55 degrees; and the average Harris hip score improved significantly from (30.9 +/- 3.4) (2-47) to (85.1 +/- 3.1) (46-94). According to evaluation criteria, 10 hips got an excellent result, 3 good and 1 poor.

CONCLUSIONThe total hip resurfacing arthroplasty is an effective solution for the treatment of the younger and active patients with AS and it shows satisfactory short-term results. It is very significant to analysis the different conditions of patients so as to choose proper strategy.