发育性髋关节发育不良闭合复位后“同心圆复位”演变的系列磁共振研究

Evolution of concentric reduction after closed reduction for developmental dysplasia of the hip: a prospective serial study of magnetic resonance imaging

目的通过系列磁共振影像观察发育性髋关节发育不良(developmental dysplasia of the hip,DDH)闭合复位后同心圆复位情况的演变规律。方法前瞻性收集2014年3月至2015年6月在中国医科大学附属盛京医院小儿骨科经闭合复位治疗,并达到安全、稳定复位的30例(35髋) DDH患儿的影像资料。其中男童6例,女童24例;左髋脱位17例,右髋脱位8例,双侧脱位5例;复位时平均年龄13. 7个月(3. 5～27. 6个月)。平均随访36. 3个月(28. 5～43. 9个月)。通过复位后系列磁共振影像测量关节间隙评估股骨头同心圆复位的情况。在骨盆正位片上测量髋臼指数(acetabular index,AI)和股骨头中心距离差(centre-head distance discrepancy,CHDD)探究髋关节发育情况。结果 35髋中,复位后仅3髋(8. 6%)达到同心圆复位,在术后当时未达到同心圆复位的32髋经石膏及支具制动,复位6个月后,21髋(21/32,65. 6%)自行达到同心圆复位,另11髋在复位后12个月时有6髋(6/11,54. 5%)达到同心圆复位。上方关节间隙,复位后为(3. 51±1. 51) mm,复位6个月后为(0. 79±1. 18) mm,差异具有统计学意义(t=8. 401,P <0. 001);内侧间隙,复位后为(3. 16±1. 17) mm,术后6个月时为(1. 28±1. 20) mm,差异具有统计学意义(t=6. 594,P <0. 001)。复位前AI为(34. 4±5. 3)°,末次随访时为(23. 5±3. 7)°,差异具有统计学意义(t=16. 986,P <0. 001)。单侧DDH(25髋)去除制动后CHDD为(3. 28±4. 31)%,末次随访时为(3. 13±3. 09)%,差异无统计学意义(t=0. 166,P=0. 869)。至末次随访时,8髋出现AVN,均为Kalamchi-MacEwenⅠ型。结论磁共振可清晰观察DDH闭合复位后同心圆复位情况的演变。达到安全、稳定复位的DDH,经术后关节制动,股骨头可逐渐靠港而达到同心圆复位,并可稳定维持复位,但远期效果仍需进一步观察。

Objective To explore the evolution of concentric reduction after closed reduction for developmental dysplasia of the hip(DDH)by a series of magnetic resonance imaging(MRI).Methods From March 2014 to June 2015,the imaging data were prospectively collected for 30 DDH children(35 hips)undergoing safe and stable closed reduction and Spica casting.There were 6 boys and 24 girls with an average age at reduction of 13.7(3.5-27.6)months.The involved side was left(n=17),right(n=8)and bilateral(n=5).The average follow-up period was 36.3(28.5-43.9)months.The joint space was measured by a series of MRI for evaluating the docking status of femoral head.And the values of acetabular index(AI)and centre-head distance discrepancy(CHDD)were measured on anterior-posterior pelvic radiograph.Results Among 35 hips,only three hips became fully concentric immediately after reduction.Twenty-four and 30 hips turned concentric at the end of 6-month immobilization and 1 year after reduction respectively.The superior join space was(3.51±1.51)mm at post-reduction immediately and(0.79±1.18)mm at 6 months after reduction(t=8.401,P<0.001);the medial space was(3.16±1.17)and(1.28±1.20)mm at immediately and 6 months after reduction respectively(t=6.594,P<0.001).The acetabular index was(34.4±5.3)°pre-reduction and(23.5±3.7)°at the last follow up(t=16.986,P<0.001).After removing brace,the CHDD of unilateral DDH(25 hips)was(3.28±4.31)%and(3.13±3.09)%at the last follow up(t=0.166,P=0.869).Eight hips belonged to Kalamchi-MacEwen type I avascular necrosis.Conclusion Achieving safe and stable closed reduction in DDH,a non-concentric hip may be expected to reach concentric by Spica casting.And the docking process of femoral head is distinctly visible on serial images of MRI.