OBJECTIVETo explore the correct localization of the acetabular component, surgical technique and the outcome in total hip arthroplasty (THA) for acetabular dysplasia with secondary osteoarthritis.

METHODSA retrospective review was undertaken of 44 hips (38 patients) that had had a total hip arthroplasty for acetabular dysplasia with secondary osteoarthritis from September.1989 to April. 2003. 14 were male (one bilateral) and 24 patients were female (5 bilateral). The mean duration of clinical and roentgenographic follow-up was thirty-six months (range, eight to one hundred and sixty-eight months), and the mean age of the patients was fifty-one years (range, twenty-nine to eighty years). Twelve hips were classified as type I; twenty-four as type II; seven as type III; and one as type IV, according to the criteria of Crowe. The horizontal location of the center of the hip (the distance along the interior drop line extending lateral or medial from the inferior point of the teardrop to the perpendicular line dropped from the center of the femoral head) was measured.

RESULTSThere were 24 acetabular components that were placed in the centralized position and the other 20 in no deepen placement post-operatively. At the most recent follow-up, the mean Harris hip score was 90.2, 86.3 for the centralized position and the undeepen placement hips respectively, there was a significant difference between these two groups.

CONCLUSIONSIn order to obtain the stability of acetabular component, deepen acetabular reaming is necessary for the most acetabular dysplasia in THA. In this way the anatomical rotational center can be obtained medially and lowly. The excellent long-term function will be maintained.