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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° ± 10.0° versus 22.4° ± 6.8° 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° ± 6.0° versus 46.6° ± 3.1°; 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., Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence., Competing Interests: Disclosure: The authors indicated that no external funding was received for any aspect of this work. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJS/G204)., (Copyright © 2020 by The Journal of Bone and Joint Surgery, Incorporated.)

Background: Recent evidence has suggested that cam morphology may be related to alterations in the capital femoral growth plate during adolescence. The purpose of this study was to evaluate the relationship between capital femoral growth plate extension and cam morphology in a longitudinal radiographic study., Methods: We used a historical, longitudinal radiographic collection to identify 96 healthy adolescents (54 boys and 42 girls) with at least 5 consecutive annual radiographs of the left hip including closure of the capital femoral physis. We reviewed 554 anteroposterior radiographs of the left hip to measure the anteroposterior modification of the alpha angle of Nötzli and of the superior epiphyseal extension ratio (EER), measured as the ratio of extension of the capital femoral epiphysis down the femoral neck relative to the diameter of the femoral head. Measurements were made at 3 points in femoral head maturation corresponding to the Oxford bone age (OBA) femoral head stages 5, 6, and 7/8., Results: There was a mean increase in the anteroposterior alpha angle (10.7° ± 14.0°) and EER (0.12 ± 0.08) between OBA stages 5 and 7/8, corresponding to maturation and closure of the capital femoral physis. There was a positive correlation between the final anteroposterior alpha angle and both the final EER (r = 0.60) and the change in the EER (r = 0.58). A receiver operating characteristic curve generated to predict an anteroposterior alpha angle of ≥78° through the EER demonstrated an area under the curve of 0.93, indicating that an increasing EER had excellent diagnostic accuracy for predicting concurrent cam morphology., Conclusions and Clinical Relevance: Superior epiphyseal extension was directly and temporally associated with an increase in anteroposterior alpha angle and more cam-like morphology. This alteration in the capital femoral epiphysis occurred immediately before physeal closure (OBA stage 7/8). Given the association of epiphyseal extension with activities that increase shear forces across the physis, we proposed that epiphyseal extension may be an adaptive mechanism to stabilize the physis and prevent slipped capital femoral epiphysis., (Copyright © 2016 by The Journal of Bone and Joint Surgery, Incorporated.)

Background: Many radiographic indices that are used to assess adolescents for femoroacetabular impingement rely on an ossified posterior acetabular wall. A recent study identified a secondary ossification center in the posterior rim of the acetabulum, the ossification of which may affect perceived acetabular coverage. The purpose of this study was to characterize ossification of the posterior rim of the acetabulum with use of a longitudinal radiographic study and quantify its impact on the radiographic assessment of femoroacetabular impingement., Methods: In this study, we utilized a historical collection of annual radiographs made in a population of healthy adolescents. Six hundred and twelve anteroposterior radiographs of the left hip of ninety-eight patients were reviewed to identify the appearance, duration, and fusion of the secondary ossification center in the posterior rim of the acetabulum. The center-edge angle was then measured before appearance and after fusion of the secondary ossification center in a subset of ten patients who had <5° of rotation on all radiographs., Results: The secondary ossification center in the posterior rim was identified in seventy-three of the ninety-eight subjects, with no significant difference between the sexes. The mean patient age at the time of radiographic appearance of this secondary ossification center was fourteen years for males and twelve years for females. The mean duration of radiographic appearance was ten months for both sexes. Serial center-edge angles were measured in a subset of ten patients, and they increased during posterior rim ossification by a mean of 4.1°., Conclusions: The secondary ossification center in the posterior rim of the acetabulum (the posterior rim sign) is a common radiographic finding that reliably appears for ten months around the time of triradiate closure. Posterior rim ossification led to a mean increase of 4° of perceived acetabular coverage through the center-edge angle. Given the narrow margin between normal coverage (33° to 36°) and acetabular overcoverage (>40°), the use of radiographs in adolescents with incompletely ossified hips may lead to misinterpretation of acetabular coverage. In patients with open triradiate cartilage, magnetic resonance imaging may be considered for the assessment of femoroacetabular impingement., Clinical Relevance: The posterior rim ossification sign is a normal finding in adolescent hip development and has important implications for the proper evaluation of femoroacetabular impingement., (Copyright © 2015 by The Journal of Bone and Joint Surgery, Incorporated.)