The purpose of this study was to investigate whether an anteroposterior pelvic radiograph alone is sufficient to confirm hip reduction after conservative treatment or whether MRI could be alternatively performed. A total of 133 children (145 hips) were enrolled. All children were examined by anteroposterior pelvic radiographs and MRI. Three experts interpreted anteroposterior pelvic radiographs and then verified these results on MRI. For patients with inconsistent results between anteroposterior pelvic radiographs and MRI, the continuity of Shenton’s line and Calve’s line was recorded, and the medial clear space of bilateral hips was measured for unilateral cases. There was complete agreement between the three experts in the interpretation of anteroposterior pelvic radiographs of 111 (76.55%) hips; there was disagreement in the remaining 34 hips, with two experts diagnosing satisfactory reduction in 13 hips and dislocation in 21 hips. Assuming that the judgment of two or more doctors on anteroposterior pelvic radiographs was taken as the final result, 17 hips (11.72%) were misjudged. There was no statistically significant difference between the actual in-position group and the actual dislocation group in terms of the continuity of Shenton’s line (P = 0.62) and Calve’s line (P = 0.10) and the medial clear space of bilateral hips (P = 0.08). In children less than 1 year of age with developmental dysplasia of the hip treated conservatively, the use of anteroposterior pelvic radiographs alone to judge hip reduction might result in misdiagnosis and missed diagnosis. MRI could be alternatively used to detect hip reduction after conservative treatment, especially when the doctor was not familiar with ultrasound in the presence of plaster.

本研究的目的是调查单独的骨盆前后位 X 光片是否足以确认保守治疗后髋关节减少，或者是否可以替代进行 MRI。共招募了 133 名儿童（145 髋）。所有儿童均接受骨盆前后位 X 线片和 MRI 检查。三位专家解读了骨盆前后位 X 光片，然后在 MRI 上验证了这些结果。对骨盆前后位X线片与MRI结果不一致的患者，记录Shenton线和Calve线的连续性，单侧测量双侧髋关节内侧间隙。三位专家对111（76.55%）髋的骨盆前后位X线片解读完全一致；剩下的34个髋关节有分歧，两位专家诊断满意地减少了 13 个髋关节和 21 个髋关节脱位。假设以两名或多名医生对骨盆正位片的判断作为最终结果，17髋（11.72%）误判。实际就位组与实际脱位组在Shenton线的连续性方面差异无统计学意义（P  = 0.62）和 Calve 线（P  = 0.10）和双侧臀部内侧间隙（P  = 0.08）。对于1岁以下发育性髋关节发育不良的儿童保守治疗，单独使用骨盆前后位X线片来判断髋关节缩小可能会导致误诊和漏诊。MRI 也可用于检测保守治疗后的髋关节复位情况，尤其是当医生在使用石膏时不熟悉超声检查时。