OBJECTIVETo study the clinical results of metal on metal hip resurfacing arthroplasty for developmental dysplasia patients.

METHODSFrom March 2005 to December 2006, 34 cases of developmental dysplasia patients (Crowe I, Crowe II) were attempted to have metal on metal hip resurfacing arthroplasty. There were 29 females (32 hips), 5 males (5 hips). The average age was 45 (26 - 57) years old. Radiographic and clinical evaluations were taken at 6 weeks, 3 months, 1 year and then once a year postoperatively. The average Harris score was 35 (25 - 44). Hip flexion was 101 degrees , abduction 24 degrees , adduction 15 degrees .

RESULTSThree patients were turned to total hip arthroplasty during operations. Thirty-one patients (34 hips) received hip resurfacing surgery. These 31 patients were followed for average 21.4 months (12 - 33 months). The average Harris score was 94 (82 - 100) at the latest follow-up, and there was statistical difference compared with the preoperative score (P < 0.01). Hip flexion increased to 133 degrees , abduction to 48 degrees , adduction to 26 degrees . No radiolucency line was found at both acetabular and femoral sides in all the patients. The average abduction angle of acetabular cup was 43 degrees (40 degrees - 53 degrees ), and the average stem shaft angle was 139 degrees (130 degrees - 145 degrees ).

CONCLUSIONSThe short term result is excellent. While the mid to long term results for hip resurfacing arthroplasty in developmental dysplasia patients are still looking forward, and the meticulous surgical technique and strict patient selection are the key of the good results.