PURPOSE This study aims to evaluate (1) the probability to achieve normal pelvic radiographs in children with developmental dysplasia of the hip (DDH) treated by closed reduction and (2) the amount of time needed to achieve normal pelvic radiographs and to assess what factors influence both probability and time to achieve normal radiographic parameters following CR and spica cast immobilization for DDH. METHODS We retrospectively reviewed 436 patients (393 girls, 43 boys; 507 hips) with DDH treated by closed reduction (CR). Tönnis grade, AVN, acetabular index (AI), centre-edge angle (CEA), and Severin radiographic grade were evaluated on plain radiographs. Criteria to rate pelvis radiographs as normal were established. Cox regression was used to evaluate the factors influencing the probability and the time to achieve normal radiographs. RESULTS According to our criteria, 167 hips (32.9%) achieved normal radiographic parameters during follow-up. The overall amount of time to achieve normal pelvis radiographs was 36.1 ± 15.5 months. Patients older than 24 months of age at the time of CR needed longer time to achieve normal radiographic parameters (55.2 ± 28 months) compared with other age groups. Cox regression analysis suggested the overall cumulative probability of recovery increased by 46% at five years following CR, then it tended to plateau with an annual increase less than 5%. Age older than 24 months, bilateral dislocation, pre-operative AI greater than 40°, and AVN were risk factors for reduced probability of achieving normal radiographic parameters. CONCLUSIONS The cumulative probability of achieving normal pelvis radiographs increases linearly during the first five years following CR, then it tends to plateau. Age older than 24 months and Tönnis grade III and IV are associated with longer time to achieve normal radiographic parameters. Age older than 24 months, bilateral dislocation, pre-operative AI greater than 40°, and AVN are risk factors for reduced probability of achieving normal radiographic parameters in children with DDH treated by closed means.

中文翻译：

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影响闭合复位治疗髋关节发育不良儿童骨盆放射学评估的变量：一项多中心调查。


目的本研究旨在评估（1）通过闭合复位治疗的发育性髋关节发育不良（DDH）儿童获得正常骨盆X光片的可能性，以及（2）获得正常骨盆X光片所需的时间，并评估哪些因素影响 DDH CR 和角位石膏固定后达到正常放射线照相参数的概率和时间。方法 我们回顾性分析了 436 例接受闭合复位 (CR) 治疗的 DDH 患者（393 名女孩，43 名男孩；507 髋）。在平片上评估 Tönnis 等级、AVN、髋臼指数 (AI)、中心边缘角 (CEA) 和 Severin 射线照相等级。建立了骨盆X光片正常的评定标准。 Cox回归用于评估影响获得正常X光片的概率和时间的因素。结果 根据我们的标准，167 个髋关节（32.9%）在随访期间达到了正常的放射学参数。达到正常骨盆 X 线照片的总时间为 36.1 ± 15.5 个月。与其他年龄组相比，CR 时年龄超过 24 个月的患者需要更长的时间才能达到正常的放射学参数（55.2 ± 28 个月）。 Cox 回归分析表明，CR 后 5 年总体累积康复概率增加了 46%，然后趋于稳定，年增长率低于 5%。年龄超过 24 个月、双侧脱位、术前 AI 大于 40° 和 AVN 是实现正常放射学参数可能性降低的危险因素。结论 在 CR 后的前五年内，获得正常骨盆 X 光片的累积概率呈线性增加，然后趋于稳定。 年龄超过 24 个月以及 Tönnis III 级和 IV 级与达到正常放射学参数的时间较长相关。年龄超过 24 个月、双侧脱位、术前 AI 大于 40° 和 AVN 是通过封闭方法治疗的 DDH 儿童获得正常放射学参数的可能性降低的危险因素。