Tiderius Carl, Jaramillo Diego, Connolly Susan, Griffey Michael, Rodriguez Diana P, Kasser James R, Millis Michael B, Zurakowski David, Kim Young-Jo
Department of Orthopaedic Surgery, Children's Hospital-Boston, Boston, MA, USA.
J Pediatr Orthop. 2009 Jan-Feb;29(1):14-20. doi: 10.1097/BPO.0b013e3181926c40.
Avascular necrosis (AVN) of the femoral head remains a major complication in the treatment of developmental dysplasia of the hip (DDH) in infants. We performed a retrospective analysis to look at the predictive ability of postclosed reduction contrast-enhanced magnetic resonance imaging (MRI) for AVN after closed reduction in DDH.
Twenty-eight hips in 27 infants (aged 1-11 months) with idiopathic hip dislocations who had failed brace treatment underwent closed reduction +/- adductor tenotomy and spica cast application under general anesthesia. Magnetic resonance imaging of the hips after intravenous gadolinium contrast injection for evaluation of epiphyseal perfusion was obtained immediately after cast application. Patients were followed with serial radiographs for a minimum of 1 year after closed reduction. Presence of AVN was determined by the presence of any one of the 5 Salter criteria by 2 readers. Magnetic resonance imaging was graded as normal, asymmetric enhancement, focal decreased enhancement, or global decreased enhancement by 2 radiologists.
Six (21%) of 28 hips showed evidence of clinically significant AVN on follow-up radiographs. Fifty percent of the hips with AVN, but only 2 of 22 hips without AVN, showed a global decreased MRI enhancement (P < 0.05, Fisher exact test). Multivariate logistic regression indicated that a global decreased enhancement was associated with a significantly higher risk of developing AVN (P < 0.01), independently of age at reduction (P = 0.02) and abduction angle.
In addition to accurate anatomical assessment of a closed reduction in DDH, gadolinium-enhanced MRI provides information about femoral head perfusion that may be predictive for future AVN. At present, it is premature to use the perfusion information for routine clinical use. However, it opens the door to studies looking at repositioning or alternative reduction methods that may reduce the risk of AVN in this higher risk group.
股骨头缺血性坏死（AVN）仍是婴儿发育性髋关节发育不良（DDH）治疗中的主要并发症。我们进行了一项回顾性分析，以观察闭合复位后对比增强磁共振成像（MRI）对DDH闭合复位后AVN的预测能力。
27例（年龄1 - 11个月）特发性髋关节脱位且支具治疗失败的婴儿的28个髋关节，在全身麻醉下进行闭合复位±内收肌切断术并应用髋人字石膏固定。在石膏固定后立即进行静脉注射钆对比剂后的髋关节磁共振成像，以评估骨骺灌注情况。闭合复位后，患者接受系列X线片随访至少1年。由2名阅片者根据5条Salter标准中的任何一条来确定AVN的存在。2名放射科医生将磁共振成像分为正常、不对称强化、局灶性强化降低或整体强化降低。
28个髋关节中有6个（21%）在随访X线片上显示有临床意义的AVN证据。AVN髋关节中有50%显示MRI整体强化降低，但在无AVN的22个髋关节中只有2个显示整体强化降低（P < 0.05，Fisher精确检验）。多因素逻辑回归表明，整体强化降低与发生AVN的风险显著升高相关（P < 0.01），与复位时的年龄（P = 0.02）和外展角度无关。
除了对DDH闭合复位进行准确的解剖学评估外，钆增强MRI还提供了有关股骨头灌注的信息，这可能对未来的AVN具有预测性。目前，将灌注信息用于常规临床应用还为时过早。然而，它为研究重新定位或替代复位方法打开了大门，这些方法可能会降低这个高风险组中AVN的风险。
