儿童髋关节真空现象的初步研究

Preliminary study of vacuum phenomenon in pediatric hip joint

目的 探讨儿童髋关节真空现象的发生率和获得髋关节真空现象的最佳X线投照体位.方法 回顾2003年1月至2013年3月于中国医科大学附属盛京医院放射科拍摄的全部儿童髋关节正位片和蛙式位片,拍片患儿年龄0～ 14岁,平均年龄4.2岁.分析髋关节正位X线片或髋关节蛙式位X线片,在股骨头和髋臼之间显示出新月形、线形或者不规则形的放射性透光区的全部X线片均被纳入到本研究序列中.结果 10年间我院放射科共拍摄了16 749例患儿的髋关节X线片,其中仅拍摄髋关节正位X线片者12422例,男性5 912例,女性6510例;拍摄髋关节正位X线片和髋关节蛙式位X线片者4 327例,男性1 537例,女性2790例.在16 749例全部髋关节正位X线片中无髋关节真空现象,总构成比为0.在4 327例髋关节蛙式位X线片中发现258例（321髋）真空现象,总构成比为5.96％;包括1 738例正常髋关节,出现真空现象150例,发生率为8.63％;发育性髋关节发育不良2 360例,出现真空现象98例,发生率为4.15％.258例髋关节真空现象包括150例正常髋关节（58.14％）,98例发育性髋关节发育不良（37.98％）,5例Legg-Calv＆#233;-Perthes病（1.94％）,坐骨嗜酸性肉芽肿、股骨骨纤维发育不良、多发性骨软骨瘤病、先天性髋内翻和股骨颈骨折术后各1例.根据髋关节透光区在关节内所占比例,将321髋分成完全型121髋（37.69％）和部分型200髋（62.31％）.根据髋关节透光区的形态,将321髋分为线形透光区159髋（49.53％）,新月形透光区151髋（47.04％）和不规则形透光区11髋（3.43％）.结论 在髋关节蛙式位X线片中,儿童髋关节真空现象并不少见.与发育性髋关节发育不良患者相比,髋关节真空现象更容易发生于正常儿童的髋关节.与髋关节正位X线片相比,髋关节蛙式位X线片是获得真空现象的更好的投照体位.

Objective To find the accurate incidence of vacuum phenomenon in the hip and the best projection position produced the vacuum phenomenon on plain radiograph of hip in children.Methods All pediatric anteroposterior view and frog-leg position plain radiographs of hip joints were retrieved in our hospital between January 2003 and March 2013.All subjects was between 0 and 14 years old （mean age,4.2 years old）.All the plain radiographs showing the crescent,linear,and irregular lucency between the femoral head and acetabulum were included in the present study.Results A total of 16 749 cases,including 12 422 cases （5 912 boys and 6 510 girls） only taken AP view plain radiographs and 4 327 cases （1 537 boys and 2 790 girls） taken both AP view and frog-leg position plain radiographs,were taken in our hospital between January 2003 and March 2013.None of AP view plain radiographs of hips could find the vacuum phenomenon.Two hundred and fifty-eight cases （321 hips） with vacuum phenomenon of the hips were found only in the frog-leg position plain radiographs of 4 327 cases,and the constituent ratio of vacuum phenomenon in the hip joint is 5.96% in frog-leg position plain radiographs.One thousand seven hundred and thirty-eight normal children were included in 4 327 frog-leg position radiographs,and 150 cases of vacuum phenomenon were included in 1 738 normal children,and incidence of vacuum phenomenon in normal children is 8.63%.Two thousand three hundred and sixty children with developmental dysplasia of the hip （DDH） were included in 4 327 frog-leg position radiographs,and 98 cases of vacuum phenomenon were included in 2 360 children with DDH,and incidence of vacuum phenomenon in children with DDH is 4.15%.258 cases with vacuum phenomenon included 150 cases of normal hips （58.14%）,98 cases of developmental dysplasia of the hip （37.98%）,5 cases of Legg-Calv＆#233;-Perthes disease （1.94%）,and 1 each in solitary eosinophilic granuloma of ischium,polyostotic fibrous dysplasia of the bilateral proximal femur,hereditary multiple exostoses,congenital coxa vara and fracture of femoral neck after surgery.Three hundred and twenty-one hips in 258 cases were classified into complete type （121 hips,37.69%） and partial type （200 hips,62.31%） according to the proportion of lucency area in the hip joints and linear （159 hips,49.53%）,crescent （151 hips,47.04%） and irregular （11 hips,3.43%） lucency according to the shape of lucency area in the hips.Conclusion Vacuum phenomenon of the hip in children is not very rare in frog-leg position plain radiograph.It is easier to find the vacuum phenomenon in normal hip compared to that of developmental dysplasia of the hip.The frog-leg position plain radiograph is a better projection position to obtain the vacuum phenomenon of the hip in children compared to the anteroposterior view plain radiograph.