A Preliminary Study On The High Risk Factors With Nonunion Femoral Neck Fractures

Background：Due to the special anatomical femoral neck, whethertreated by operation or conservative treatment, nonunion rate after femoralneck fracture is10%-34%, the rate of avascular necrosis is30-50%. Fracturenonunion are basically needed for re-operation, bone-graft or jointreplacement therapy, while one third patients of postoperative osteonecrosis ofthe femoral head have no symptoms or only mild symptoms, so the severity offracture nonunion should be paid more focus on the femoral head necrosis.Therefore, to study on risk factors of nonunion of the femoral neck fracturefollowing internal fixation, analyzing the influencing factors and puttingforward the concept of high risk nonunion population with femoral neckfractures and early intervention has important significance.Methods：One thousand three hundred and twenty three patients withfemoral neck fractures were reviewed who had been treated with cannulatedscrews in our hospital from January2003to January2011, in which ninehundred and sixty five cases with complete data met the inclusion criteria.Five factors, namely patients’age, gender, mechanism of injury (whether highenergy injury or not), type of fracture (with or without displacement), medicalcomorbidities [American Society of Anesthesiologists Physical Score(ASAS)grade] for fracture healing effects were statistically analyzed by applyingLogistic multiple regression methods, to research the high risk factors whichlead to femoral neck fracture nonunion.Results：All patients were followed up for1~7.8years, average3.2yearsof follow-up. In965patients,830cases healed (the healing rate was86%),135cases was with nonunion of fracture (the nonunion rate was14%), thetime for diagnosis with6to12months postoperatively. Quantitaive assay ofthe factors affecting healing of femoral neck fractures was ranged as follows: medical comorbidities (ASAS grade), injury mechanism (whether highenergy injury or not), fracture type (with or without displacement), genderand age. The classification probability equation for Logistic regressionlogitP=-8.714+0.493sex+0.322age+1.083fracture type+1.588injurymechanism+2.234medical comorbidities.Conclusion： Five factors including patients’ age, gender, injurymechanism, facture type, medical comorbidities and their correlation withfracture nonunion have a certain effect, and these factors exists between themutual influence. The study of the equation fully illustrates this point, and alsoinspired us to propose the concept of nonunion of femoral neck fracture inhigh-risk population: over50years of age, female, fracture displacement, highenergy injury, ASAS grade above III. This can guide our clinical work, theoverall situation of patients should be taken into account for the treatment offemoral neck fracture, including reasonable surgical options from thephysiological age. We can do one-stage bone grafting intervention forhigh-risk population, in order to improve the fracture healing rate; or a indirectjoint replacement to avoid the re-operation for nonunion patients after internalfixation, which has positive significance to improve the treatment effect offemoral neck fractures.