中文摘要：

目的 确定通过髋关节极度外展固定的方法能够引起股骨头骨骺的缺血,明确在持续固定多长时间内这种缺血是可恢复性的.方法 11头出生3～7周的乳猪,双侧髋关节被极度外展固定.持续固定3～72 h以后,对11头乳猪的22个髋关节进行MR扫描,主要扫描序列为Gd增强SE T1WI.扫描完成后1～7天内允许乳猪自由行走,然后再行扫描.分析股骨头骨骺软骨、生长板软骨和二次骨化中心的增强MR表现特征,进行MR表现与组织学发现的比较对照研究.结果 在Gd增强MRI,全部22个股骨头的17个骨骺软骨、8个生长板可见局限性的弱强化或未强化.自由行走1天以后,仅1头可见缺血的完全恢复,另10头7天后才显示缺血完全恢复.结论 在72 h内持续性地髋关节极度外展所引起的股骨头骨骺早期缺血是可恢复的,Gd增强MRI能够检出这种早期可恢复性的缺血.

英文摘要：

Objective To demonstrate that the early ischemia of capital femoral epiphysis induced by hip hyperabduction can be reversal and Gadolinium-enhanced MRI may detect early reversible ischemia. Methods Eleven 3- to 7-week-old piglets were placed in maximal hip abduction bilaterally. After 3 to 72 hours of consistent hyperabduction, gadolinium-enhanced MRI was used for all hips of 11 piglets. After MR imaging was completed all piglets were allowed to ambulate freely for one or seven days and re-imaged. On enhanced MRI the characteristics of epiphyseal and physeal cartilage and second ossification center in femoral heads were evaluated. The comparison between MRI appearances and histological findings was made. Resuits On gadolinium-enhanced MRI, regional decreased or absent enhancement was seen in 17 cartilaginous epiphyses and 8 physes of all 22 femoral heads. The reversal was seen in only one piglet after one day of ambulation and in all rest after 7 days of ambulation. The abnormality was not seen in histologic study after one or 7 days of ambulation. Conclusion The early ischemia of capital femoral epiphysis induced by hip hyperabduction within 72 hours can be reversal and gadolinium-enhanced MRI may detect the early reversible ischemia.