Which factor is most important for occurrence of cutout complications in patients treated with proximal femoral nail antirotation? Retrospective analysis of 298 patients

Introduction Mechanical complications, such as cut-out of the head-neck fixation device, are the most common causes of morbidity after trochanteric femur fracture treatment. The causes of cut-out complications are well defined in patients who are treated with sliding hip screws and biaxial cephalomedullary nails but there are few reports about the patients who are treated with proximal femoral nail antirotation. Aim The purpose of this study was to evaluate the most important factor about occurance of cutout complication and also to evaluate the risks of the combination of each possible factors. Patients and methods Overally 298 patients were enrolled in the study. Medical records were reviewed for patients' age, fracture type, gender, anesthesia type and occurance of cut-out complication. Postoperatively taken radiographs were reviewed for tip-apex distance, obtained collo-diaphyseal angle, the quadrant of the helical blade and Ikuta reduction subgroup. The most important factor (s) and also predicted probability of cut-out complication was calculated for each combination of factors. Results Cut-out complication was observed in 14 patients (4.7 %). The most important factor about occurrence of the cut-out complication was found as varus reduction (p: 0.01), the second important factor was found as implantation of the helical blade in the improper quadrant (p: 0.02). Tip-apex distance was found as third important factor (p: 0.10). The predicted probability of cut-out complication was calculated as 45.6 % when whole of the four surgeon dependent factors were improperly obtained. Conclusion Althought obtaining proper tip-apex distance is important to prevent cutout complication in these fractures, if the fracture is not reduced in varus position and helical blade is inserted in the proper quadrant, possibility of cut-out complication is very low even in the patients with high tip-apex distance.