腰骶段塌陷型结核后凸畸形后路截骨矫形术后内固定并发症的原因分析

Risk factors analyasis of instrument complication after posterior asymmetric vertebral column resection of collapsed tuberculous kyphosis of lumbosacral spine

目的:总结分析腰骶段塌陷型结核后凸畸形患者行后路非对称全脊椎截骨矫形术(posterior asymmetric vertebral column resection,PAVCR)后内固定并发症的原因。方法:回顾性分析2012年1月~2016年12月于我院行PAVCR治疗的45例腰骶段塌陷型结核后凸畸形患者的临床资料。男27例,女18例,平均年龄38.6±17.4岁(22~65岁),平均随访时间36.4±9.8个月(24~66个月)。所有患者术前常规行全脊柱正侧位X线、畸形节段CT、MRI检查,术后随访行正侧位X线检查及腰痛Oswestry功能障碍指数(Oswestry disability index,ODI)评分,必要时行CT复查。根据患者是否发生螺钉松动及连接棒断裂进行分组,比较无内固定并发症组分别与螺钉松动组、连接棒断裂组患者性别、年龄、截骨节段、融合节段、骨密度、远端锚定点数量比、术前、术后(2周)及终末随访局部后凸Cobb角、冠状面侧凸Cobb角、ODI评分。应用卡方检验、Fisher精确检验、独立样本t检验统计分析内固定并发症的原因并提出相应预防策略。结果:9例患者发生内固定并发症,平均发生时间25.4±7.3个月,发生率20%。其中固定远端螺钉松动5例,连接棒断裂3例,固定远端螺钉松动合并对侧连接棒断裂1例。无并发症组与螺钉松动组比较,术后2周局部后凸Cobb角有统计学差异(19.2°±6.3°vs 24.5°±8.7°,P<0.05)、终末随访局部后凸Cobb角有统计学差异(21.2°±6.1°vs 28.4°±8.4°,P<0.05),终末随访ODI评分有统计学差异(11.1±3.6 vs 17.3±4.3,P<0.05)。无并发症组与连接棒断裂组比较,术后2周局部后凸Cobb角有统计学差异(19.2°±6.3°vs 25.6°±7.3°,P<0.05),终末随访局部后凸Cobb角有差异(21.2°±6.1°vs 30.2°±7.9°,P<0.05),终末随访ODI评分有差异(11.1±3.6 vs 19.5±5.8,P<0.05)。无并发症组与螺钉松动组远端锚定点数量构成比有统计学差异(P<0.05),骨密度构成比有统计学差异(P<0.05);无并发症组与连接棒断裂组远端锚定点数量比有统计学差异(P<0.05)。术前局部后凸Cobb角、术前、术后2周及终末侧凸Cobb角、术前ODI、术后ODI三组间比较均无明显差异(P>0.05)。结论:腰骶段塌陷型结核后凸畸形行PAVCR术后存在发生螺钉松动及连接棒断裂的风险,术后残留后凸、远端锚定点数量不足、前中柱融合不良及骨质疏松可能造成腰骶段塌陷型结核后凸畸形术后螺钉松动,而术后残留后凸、中段锚定点缺失、前中柱融合不良与连接棒断裂发生有关。

Objectives:To analyse the risk factors and preventions of instrument complication after posterior asymmetric vertebral column resection(PAVCR)of collapsed tuberculous kyphosis of lumbosacral spine.Methods:45 patients with collapsed tuberculous kyphosis of lumbosacral spine received posterior asymmetric verte-bral column resection from January 2012 to December 2016 in our medical center were analyzed.There were27 males and 18 females with an average age of 38.6±17.4(22-65)years old,and the average follow up was36.4±9.8(24-66)months.Oswestry disability index(ODI),general epidemiological data including age,gender,osteotomy segment,fusion segments,bone mineral density(BMD),lower instrumented vertebra(LIV),and radiologic parameters of coronal and sagittal standing full spine X ray including local kyphosis cobb angle,coronal scoliosis cobb angle at preoperative,postoperative and final follow up were collected.All patients were categorized into rod fracture group,screw loosening group and non-complication group according to the diagnosis criteria of instrument complication.Results:9 cases occurred instrument complication with an average time at 25.4±7.3 months,including simple distal screw loosening in 5 cases,simple rod fracture in 3 cases,screw loosening accompanied with rod fracture in 1 case.The incidence was 20%.There were significant differences between non-complication group and screw loosening group in postoperative local kyphosis Cobb angle(19.2°±6.3°vs 24.5°±8.7°,P<0.05),final follow up local kyphosis Cobb angle(21.2°±6.1°vs 28.4°±8.4°,P<0.05),final follow up ODI(11.1±3.6 vs 17.3±4.3,P<005),distal scew numbers ratio(P<0.05)and BMD ratio(P<0.05).There were significant differences between non-complication group and rod fracture group in postoperative local kyphosis Cobb angle(19.2°±6.3°vs 25.6°±7.3°,P<0.05),final follow up local kyphosis Cobb angle(21.2°±6.1°vs 30.2°±7.9°,P<0.05)and final follow up ODI(11.1±3.6 vs 19.5±5.8,P<0.05),distal screw numbers ratio(P<0.05).There were no significant difference among those three groups in preoperative local kyohosis Cobb angle,preoperative scoliosis Cobb angle,postoperative scoliosis Cobb angle,final follow up scoliosis Cobb angle,preoperative ODI and postoperative ODI(P>0.05).Conclusions:There are risks of screw loosening and rod fracture after posterior asymmetric vertebral column resection(PAVCR)of collapsed tuberculous kyphosis of lumbosacral spine.The risk factors of screw loosening could be postoperative residual local kyphosis,less distal screws,nonunion and osteoporosis.The risk factors of rod fracture could be postoperative residual local kyphosis,absence of middle screws,and nonunion.