Reliability of the computed tomography criteria after closed reduction of developmental dislocation of the hip

Abstract

BACKGROUND: Developmental dislocation of the hip includes femoral head subluxation or dislocation and/or acetabular dysplasia. Closed reduction of the hip should be performed under general anesthesia. Appropriate performance and interpretation of closed reduction are difficult and require experience. The role of computed tomography (CT) in different aspects of treatment of developmental hip dysplasia is well established. It was an accurate way to assess the adequacy of reduction of dislocated hips for patients in spica casts. AIM: This study aimed to assess the role of CT in the evaluation of closed reduction of developmental hip dislocation in infants and children immobilized in spica casts. MATERIALS AND METHODS: This study included 16 patients with 20 involved hips who presented with developmental hip dysplasia. The youngest patient was 12 months old, and the oldest was 24 months old, with a mean age of 19.62 4.27 months. There were 15 girls (93.75%) and one boy (6.25%). There were four patients with bilateral hip involvement (25%), and the right side was involved in five hips (31.25%), whereas the left side was affected in 7 (43.75%) hips. RESULTS: Closed reduction was performed in 20 hips, and according to the post-reduction CT evaluation, the final results were satisfactory in 16 (80%) hips and unsatisfactory in 4 (20%) hips. On the coronal CT cuts, the modified Shentons line gave a sensitivity of 75%, specificity of 81.25%, and accuracy of 80%. Second, the calculation of femoral head coverage on coronal CT cuts showed the highest sensitivity of 100%, specificity of 50%, and accuracy of 60%. Lastly, the posterior neck line identified on the axial CT cuts gave a sensitivity of 75%, specificity of 87%, and accuracy of 85%. On comparing and evaluating the three methods, the method that gave the best level of reliability for the adequacy of the reduction was the posterior neckline (82.23 %), followed by modified Shentons line (78.75%), and finally femoral head coverage (70%). CONCLUSIONS: The posterior neck line is the preferred method to confirm the adequacy of hip relocation on multi-slice post-reduction axial CT.