股骨近端防旋髓内钉固定治疗股骨转子间骨折的失效原因分析

目的探讨股骨近端防旋髓内钉(PFNA)固定治疗股骨转子间骨折失效的原因及危险因素。方法回顾性分析2013年3月至2018年3月期间天津市第五中心医院骨科采用PFNA固定治疗的568例股骨转子间骨折患者资料。男348例,女220例;年龄为44~93岁,平均74.6岁。根据骨折稳定性将患者分为两组:稳定组424例,骨折AO分型为31-A1型、31-A2.1型;不稳定组144例,骨折AO分型为31-A2.2型、31-A2.3型、31-A3型。比较两组患者的骨折复位质量、内固定失效率及患髋功能等。并应用单因素及多因素二元logistic回归分析PFNA固定治疗股骨转子间骨折失效的危险因素。结果两组患者术前一般资料比较差异均无统计学意义(P>0.05),具有可比性。术后共有19例患者发生内固定失效。失效原因:螺旋刀片退出13例,股骨颈短缩17例,髋内翻畸形14例,螺旋刀片切出14例。稳定组患者的失效率为1.2%(5/424),显著低于不稳定组患者9.7%(14/144)],末次随访时髋关节Harris评分98(95,100)分]显著高于不稳定组患者84(82,87)分],差异均有统计学意义(P<0.05)。两组患者的骨折复位质量比较差异无统计学意义(P>0.05)。多因素分析结果显示:骨质疏松(OR=7.283,95%CI:1.626~32.623,P=0.009)和不稳定型骨折(OR=11.607,95%CI:4.039~33.355,P<0.001)是PFNA固定治疗股骨转子间骨折失效的危险因素。结论不稳定型股骨转子间骨折使用PFNA固定失效率较高,固定后形成杠杆样结构,需由内固定物承受主要应力,杠杆支点位于髓腔内内固定成角部位,负重侧力臂长,失效率高。骨质疏松和不稳定型骨折患者术后需较长的免负重时间。

Failure analysis in proximal femoral nail antirotation fixation for intertrochanteric fractures

Objective To analyze the causes and risk factors for failure of internal fixation with proximal femoral nail antirotation(PFNA)in the treatment of femoral intertrochanteric fractures.Methods A retrospective analysis was conducted of the 568 patients with femoral intertrochanteric fracture who had been treated with PFNA fixation at Department of Orthopaedic Surgery,The Fifth Central Hospital of Tianjin from March 2013 to March 2018.They were 348 males and 220 females,aged from 44 to 93 years(average,74.6 years).According to the fracture stability classification,the patients were divided into a stable group of 424 cases and an unstable group of 144 cases.According to the AO classification,the stable group had type 31-A1 and type 31-A2.1 while the unstable group type 31-A2.2,type 31-A2.3 and type 31-A3.The 2 groups were compared in terms of reduction quality,rate of internal fixation failure,and function of the affected hip.Single factor and multi-factor binary logistic regression analyses were conducted to determine the risk factors responsible for failure of PFNA fixation of femoral intertrochanteric fracture.Results There were no significant differences in the preoperative general data between the 2 groups,showing comparability between groups(P>0.05).Internal fixation failure occurred in 19 cases,which was caused by spiral blade withdrawal in 13 cases,femoral neck shortening in 17 cases,hip varus in 14 cases,and spiral blade cut-out in 14 cases.The failure rate for the stable group was 1.2%(5/424),significantly lower than that for the unstable group9.7%,(14/144)](P<0.05).The Harris hip score at the last follow-up for the stable group98(95,100)]was significantly higher than that for the unstable group84(82,87)](P<0.05).There was no significant difference in reduction quality between the 2 groups(P>0.05).The multivariate analysis showed that osteoporosis(OR=7.283,95%CI:1.626 to 32.623,P=0.009)and unstable fracture(OR=11.607,95%CI:4.039 to 33.355,P<0.001)were risk factors responsible for the failure of PFNA fixation of femoral intertrochanteric fracture.Conclusions PFNA fixation for unstable intertrochanteric fracture can lead to a high failure rate.It forms a lever like structure so that the main stress is shifted to the internal fixation.Its lever fulcrum is located at the angle of intramedullary fixation so that a long arm forms at the load-bearing side,leading to a high failure rate.The weight-free time should be longer for patients with osteoporosis and unstable fracture after operation.