股骨转子间骨折动力髋螺钉内固定失败的危险因素

Risk factors related to failure of dynamic hip screw internal fixation for intertrochanteric fractures

目的 探讨导致股骨转子间骨折动力髋螺钉（DHS）内固定失败的危险因素。方法 分析2000年11月～2003年5月应用DHS治疗的137例股骨转子间骨折患者，男42例，女95例；平均年龄68岁（43～83岁）。平均随访13个月（8～34个月）。其中跌倒等低能量创伤98例，交通伤等高能量创伤39例。选择股骨颈螺钉切出指数、骨质疏松程度及骨折类型作为变量，应用COX模型分析其导致DHS内固定失败的风险比率。结果 本组中15例内固定失败。随切出指数增大，DHS内固定失败发生率增加。骨折分型、骨质疏松程度均与DHS内固定失败相关，转子间骨折不稳定型并伴有骨质疏松者易发生DHS内固定失败。COX模型行多因素分析后发现，切出指数、骨折类型、骨质疏松是转子问骨折DHS内固定失败的独立预后因素。结论 沿股骨头中轴较深地拧入股骨颈螺钉，可减少切出指数，降低内固定失败率。术前应用Singh法评价骨质疏松程度，并根据改良Evans转子间骨折分型确定骨折类型，能够预测术后内固定失败的风险。对于不稳定型且伴有严重骨质疏松的转子间骨折患者，不宜应用DHS内固定治疗。

Objective To investigate the risk factors for failure of dynamic hip screw （DHS） internal fixation for intertrochanteric fractures. Methods A retrospective study was done on 137 cases （42 males and 95 females; with age range of 43-83 years, mean 68 years） with intertrochanteric fractures treated with DHS from November 2000 to May 2003. The follow up averaged 13 months （8 -34 months）. Of all, 98 cases were resulted from low energy trauma and 39 from high energy trauma. Cutting-out index of the lag screw, fracture pattern and osteoporosis degree were selected as variables to identify the correlation between the variables and the mechanical failure. Cutting-out index was used to describe the position of the lag screw ; Singh＇ s classification of the trabecular bone structures in the proximal femur to measure osteoporosis. The fracture patterns were classified according to Evans classification modified by Jesen. Mechanical failures were defined as cutting-out of the lag screw, screw tip in joint space, plate loosening from femoral shaft or implant fracture or bending implant. Multivariable COX model was used to identify and quantify the factors that affect the failure of fixation. Results Of all, 15 cases resulted in failed DHS internal fixation. Risk of the mechanical failure increased with increase of cutting-out index. Fracture pattern and osteoporosis degree related to failed DHS internal fixation. DHS internal fixation easily failed in those with unstable intertroehanterie fractures combined with osteoporosis. Muhivariable analysis of COX model showed that the cutting-out index, fracture patterns and osteoporosis were all independent predictors for failure of DHS internal fixation. Conclusions Deep central placement of the lag screw is ideal to reduce the cutting-out index and decrease failure rate of internal fixation. The use of Evans/Jesen classification and Singh＇s classification on the basis of a pre-operative radiograph allows for a prediction of any post-operative failure of fixation. DHS should not be the first choice for those who have unstable fractures combined with osteoporosis.