ObjectiveTo investigate the impact of the Salter innominate osteotomy on the acetabular morphology and direction and the relationship between them in children with developmental dislocation of the hip (DDH) by three-dimensional CT. MethodsBetween January 2013 and January 2015, 51 patients with unilateral DDH were treated. All patients were females with an average age of 2 years and 5 months (range, one year and 6 months to 5 years). All the patients underwent open reduction of the hip, Salter innominate osteotomy, proximal femoral osteotomy, and hip cast immobilization for treatment. The data of three-dimensional CT before surgery and at 1 week after surgery were measured and collected as follows:the anterior acetabular index (AAI), posterior acetabular index (PAI), axial acetabular index (AxAI), acetabular anteversion angle (AAA) of the acetabulum, and the distances of the forward, outward, and lateral rotation of the distal osteotomy fragments. The differences of AAI, PAI, AxAI, AAA between before and after surgeries were compared and the difference values of the data with significant difference results were calculated. The relationship between the difference values and the distances of three different rotation directions before and after surgeries were tested by Spearman correlation analysis. ResultsThere were significant differences in the AAI, PAI, and AAA between before and after surgery (P<0.05), but no significant difference was found in the AxAI between before and after surgery (t=0.878, P=0.384). The difference values of AAI, PAI, and AAA were (4.518±4.601), (4.219±6.660), and (3.919±4.389)° respectively. The distances of the outward, lateral, and forward rotation of the distal osteotomy fragments after surgery were (0.420±0.339), (2.440±0.230), and (0.421±0.311) cm. There was a significant correlation between the three different rotation directions and AAI difference (P<0.05), especialy the outward rotation (r=0.981). There was a correlation between the outward, forward rotation and PAI, AAI differences (P<0.05), and no significant correlation between the lateral rotation and PAI, AAA was found (P>0.05). There was a significant correlation between the forward rotation and AAA difference (r=0.841). ConclusionSalter innominate osteotomy can increase the curvature of the anterior wall of the acetabulum in DDH, but reduce the curvature of the rear wall. At the same time, it can also change the direction of the acetabulum, significantly decrease the acetabular anteversion, but it can not change the depth of the acetabulum. The main factors of the curvature change after Salter innominate osteotomy of DDH is attributable to outward rotation, followed by forward rotation, and the main factor of the acetabular direction change is attributable to forward rotation.