Secondary Surgery and Residual Dysplasia Following Late Closed or Open Reduction of Developmental Dysplasia of the Hip

Background: Outcomes studies following successful closed reduction of late-detected developmental dysplasia of the hip (DDH) reveal high rates of secondary reconstructive surgery with limited comparative data demonstrating lower rates of residual dysplasia with open reduction. The purpose of this study was to compare long-term outcomes, with regard to radiographic evidence of residual dysplasia and secondary reconstructive procedures, between late closed and late open reduction for DDH in patients 6 to 24 months of age at reduction. Methods: We identified all patients between 6 and 24 months of age who underwent closed or open reduction for DDH between 1980 and 2008 and were followed until at least 10 years of age. Outcomes included radiographic measurement of acetabular dysplasia after triradiate cartilage closure, development of osteonecrosis, and the need for secondary procedures for residual dysplasia. Results: One hundred and four hips underwent index closed reduction and 54 hips underwent index open reduction. There was no significant difference in the age at reduction (p = 0.07). Among the 116 hips for which initial anteroposterior pelvic radiographs were available, most closed reductions (55%) were performed in International Hip Dysplasia Institute (IHDI) grade-III hips whereas most open reductions (71%) were performed in IHDI grade-IV hips. Analysis of the hips that did not undergo a secondary procedure showed that those with an index open reduction had a greater lateral center-edge angle (mean and standard deviation, 27.2 degrees +/- 10.0 degrees versus 22.4 degrees +/- 6.8 degrees in the closed reduction cohort; p = 0.02), lower femoral head extrusion index (22.2% +/- 8.9% versus 26.0% +/- 6.2%; p = 0.04), and lower Sharp angle (43.3 degrees +/- 6.0 degrees versus 46.6 degrees +/- 3.1 degrees; p = 0.002) at triradiate closure. There was no difference in the prevalence of osteonecrosis (Bucholz-Ogden grades II, III, and IV) between the closed and open reduction cohorts (22% versus 19%, respectively; p = 0.60). Secondary procedures were performed more frequently after closed reduction than after open reduction (47% versus 30%, respectively; p = 0.03). Conclusions: In patients with late reduction of DDH, closed reduction was associated with increased residual dysplasia and it was associated with a higher rate of secondary surgery in those >12 months old despite a decreased severity of displacement based on the IHDI classification. Additional, prospective studies with assessment of functional outcomes are needed to validate these findings.