Cotyloidplasty in acetabular reconstruction for dysplastic hips

To introduce the osteotomy of acetabular medial wall as a technique to facilitate anatomical implantation and secure fit of acetabular cups for dysplastic hips.Methods Eighteen hip replacements were performed with use of an osteotomy of acetabular medial wall to stabilize the cups in 17 dysplastic patients.The patients were aged from 35～70 years,with an average of 51.4 year.Among all the dysplastic hips,4 were of type Ⅰ,7 of type Ⅱ,4 of type Ⅲ,and 3 of type Ⅳ according to the Crowe criteria.A Ranawat triangle was drawn on the X-ray film,and a supposed optimal rotating center was located.Both of the horizontal and vertical distances between femoral head and supposed rotating center was decreased significantly after operation.Results With medial wall osteotomy,all the acetabular components were placed in the true acetabulum.The diameters of the implanted cups were 44～56 mm with an average of 50.78 mm.Medial bony wall was preserved with an average thickness of 9.5 mm.The horizontal distance was 21.09 mm(12～40 mm) preoperatively and 3.73 mm(-3～10.1 mm)postoperatively,there was statistical difference (t=7.95,P<0.01);whereas the vertical distance was 15.39 mm(5～32 mm)preoperatively and 4.98 mm(-18～26.3 mm)postoperatively,there was also statistical difference (t=3.42,P<0.01).13 acetabular cups were implanted with the medial aspect of their dome beyond the Kohler line.In the cases followed-up more than 3 months,the osteomized site all achieved bony union.Conclusion The medial wall osteotomy technique is a predictable,reproducible procedure for optimal rotating center reconstruction and it may obtain fixation of an uncemented hemispheric acetabular component in a dysplastic hip.11 refs,3 figs.