Radiological Evaluations Of Salter Innominate Osteotomy In Developmental Dysplasia Of The Hip

ObjectiveA follow-up was carried out to evaluate the radiological outcomings after Salter innominate osteotomy. The developmental characteristics of the hip after operation were observed and the relationship between ages as well as preoperative radiographic parameters and age at operation was discussed.MethodsBasic data of patients admitted in our department for developmental dysplasia of the hip during 1990-2004 was collected. The patients were all treated with Salter innominate osteotomy and followed-up for at least three years. Forty-four patients with sixty-one treated hips had serial radiographic materials. Radiographs taken before operation, six weeks, one year and 2-3 years after operation and in the latest follow-up were selected. Acetabular index, Sharp acetabular angle and center-edge angle of Wiberg were measured and Severin classification was done according to radiographs taken in the latest follow-up.ResultsThe average correction of acetabular index is 14.4°postoperatively. The acetabulum remodels best at 2-3 years after operation when the average acetabular index becomes very close to normal. In the latest follow-up the Sharp acetabular angle is 41.3°which can be regarded as normal. Postoperative center-edge angle is on average 22.9°which increases to 25.3°2-3 years later. In the latest follow-up the average center-edge angle is 26.3°.In the latest follow-up seventeen hips are classified as Severin 1 A, five hips as 1B, twenty-two hips as 2A, seven as 2B,eight as 3, one as 4A and one as 6. The ratio of excellent and good outcomings (SeverinⅠ/Ⅱ) is 84%, while the ratio of moderate and poor outcomings(SeverinⅢ/Ⅳ/Ⅴ/Ⅵ)is 16%. Age at operation has a negative effect on the ratio of excellent and good outcomings; although 70% patients operated after age six have satisfactory outcomings. The SeverinⅠ/Ⅱgroup showed no difference in acetabular index from SeverinⅢ/Ⅳ/Ⅴ/Ⅵgroup, but the acetabular index of the former obviously improved 2-3 years later while that of the latter deteriorated. Significant difference in the Sharp acetabular angle and the center-edge angle can be observed in the latest follow-up.Conclusions1. Salter innominate osteotomy focuses on normalizing the abnormal acetabular direction in DDH children as well as stimulating the development of the acetabulum, which provides a satisfactory middle-term outcoming.2. The acetabulum remodels rapidly during the first three years after operation when AI and CEA develops into normal. Interference should be adopted if this change has not appeared in the first three years.3. The age at operation has a negative effect on middle-term outcoming, which decreases from 89% before age 3 to 70% after age six.