Purpose： The aim of this study was to investigate the incidence of Z-effect after dual lag screw intramedullary nailing systems and risk factors contributing to this effect. We hypothesized that long nails provide mo...Purpose： The aim of this study was to investigate the incidence of Z-effect after dual lag screw intramedullary nailing systems and risk factors contributing to this effect. We hypothesized that long nails provide more neck strength due to a longer lever than short nails and are therefore less likely to develop a misbalance of a higher head compressive strength than neck compressive strength, Methods： In this retrospective cohort study 103 patients treated operatively with a dual lag screw intramedullary nailing device for （sub）trochanteric hip fracture were included, We analysed patient charts regarding patient and operation characteristics. Furthermore we conducted radiologic mea- surements within the 2-year follow-up period to investigate the quality of fracture fixation, implant failure and predictors for Z-effect. The re-operation risk was investigated with multivariate regression analysis, Results： The incidence of （reversed） Z-effect in this study was 9% （n 80）; 6 out of 7 Z-effects occurred in the short nail group, which was not significant. Patients who were treated with a long nail had a significant larger number of complications in comparison with the short nail group （median 2 vs 0,5, p = 0.001）. The long nail group received more often erythrocytes blood transfusions （82% vs 31%, p 〈 0.01） and had a longer hospital stay （13 vs 21 days, p 〈 0.05）. Migration of lag screws （p 〈0.05） and unstable fracture type （p 〈 0.05）, were risk factors for re-operation. The re-operation rate within 2 year after surgery was 21%, of which one fourth was due to a Z-effect. Conclusion： The nail length was not associated with the development of a Z-effect. Migration of lag screws after intramedullary nailing is common and a risk factor for re-operation.展开更多
文摘Purpose： The aim of this study was to investigate the incidence of Z-effect after dual lag screw intramedullary nailing systems and risk factors contributing to this effect. We hypothesized that long nails provide more neck strength due to a longer lever than short nails and are therefore less likely to develop a misbalance of a higher head compressive strength than neck compressive strength, Methods： In this retrospective cohort study 103 patients treated operatively with a dual lag screw intramedullary nailing device for （sub）trochanteric hip fracture were included, We analysed patient charts regarding patient and operation characteristics. Furthermore we conducted radiologic mea- surements within the 2-year follow-up period to investigate the quality of fracture fixation, implant failure and predictors for Z-effect. The re-operation risk was investigated with multivariate regression analysis, Results： The incidence of （reversed） Z-effect in this study was 9% （n 80）; 6 out of 7 Z-effects occurred in the short nail group, which was not significant. Patients who were treated with a long nail had a significant larger number of complications in comparison with the short nail group （median 2 vs 0,5, p = 0.001）. The long nail group received more often erythrocytes blood transfusions （82% vs 31%, p 〈 0.01） and had a longer hospital stay （13 vs 21 days, p 〈 0.05）. Migration of lag screws （p 〈0.05） and unstable fracture type （p 〈 0.05）, were risk factors for re-operation. The re-operation rate within 2 year after surgery was 21%, of which one fourth was due to a Z-effect. Conclusion： The nail length was not associated with the development of a Z-effect. Migration of lag screws after intramedullary nailing is common and a risk factor for re-operation.
