Prognostic Factors in Acetabular Development Following Reduction of Developmental Dislocation of the Hip in Patients under the Age of 24 Months

Abstract

Purpose:The aims of this study are to evaluate the outcome of treatment for developmental dislocation of the hip (DDH) in children under the age of 24 months who underwent open reduction (OR) or closed reduction (CR) and to determine radiologic prognostic factor. Materials and Methods: A total of 90 hips of 88 children under the age of 24 months treated for DDH were included. The treatments for these children were CR in 29 hips and OR in 61 hips. All patients were followed up for more than 5 years. Radiographic evaluations, including acetabular index (AI), Yamamuro's distance a and b, center-edge angle (CEA), sourcil shape, and teardrop shape have been proposed to indicate the degree of DDH. Hips were reclassified according to the Severin criteria (classes I and II, satisfactory; classes III and IV, unsatisfactory). Results: Among the 90 hips, 67 hips (74.4%) were included in the 'satisfactory group', while 23 hips (25.6%) were included in the 'unsatisfactory group'. In the CR group, 23 hips (79.3%) were included in the 'satisfactory group', while 6 hips (20.7%) were included in the 'unsatisfactory group'. In the OR group, 44 hips (72.1%) were included in the 'satisfactory group', while 17 hips (27.9%) were included in the 'unsatisfactory group'. There was no significant difference between the reduction methods. At 1 year follow-up after reduction, the AI improvement in the 'satisfactory group ' (8.1° [23.4%]) was significantly higher than that in the 'unsatisfactory group' (6.7° [18.5%]) (p=0.012). A significant difference of the mean CEA values was observed between the 'satisfactory group' and the 'unsatisfactory group' 3 years after the treatment (p=0.001). Five years after reduction, the V shape of teardrop and the upward shape of acetabular sourcil were observed in 2 hips (3.0%) and 4 hips (6.0%) of the 'satisfactory group', respectively, whereas the corresponding findings were observed in 3 hips (13.0%) and 5 hips (21.7%) of the 'unsatisfactory group', respectively (p=0.023, 0.005). Conclusion:The improvement of AI at 1-year and CEA at 3-year follow-ups, as well as teardrop shape and sourcil shape at 5-year followup, were reliable radiographic prognostic factor of DDH.