Evaluation of the positional relationship between femoral arteries and distal screws in the proximal femoral intramedullary nail for preventing iatrogenic vascular injury.

<bold>Background and Aims: </bold>Iatrogenic vascular injury associated with distal screw in the intramedullary nail for femoral trochanteric fracture is a rare but serious complication. This study aimed to investigate the positional relationship between distal screws and superficial (SFA), deep (DFA), and perforating femoral artery (PFA) using computed tomography (CT) angiography and to identify the risk factors of vascular injury.<bold>Patients and Methods: </bold>Thirty-eight patients (11 patients who underwent osteosynthesis with proximal femoral intramedullary nail and 27 healthy people) who underwent CT angiography were included. The distance from the great trochanter tip and insertion angle from posterior condylar axis (reference line) of the distal screws were measured, and the presence rates and distances from the femur of each artery within the insertion angle were investigated.<bold>Results: </bold>The distance from the great trochanter tip to the distal screw was 142.5 ± 8.8 mm. The insertion angle from the reference line was 27.3°±15° The measurement points were set at 130, 140, and 150 mm distal from the great trochanter tip, and the assumed insertion angle as 27°±15° Within this angle, the presence rates and distances were 50.8%/34.2 ± 7.0 mm (130 mm), 38.5%/34.3 ± 6.0 mm (140 mm), 30.8%/33.4 ± 6.0 mm (150 mm) in SFA; 12.3%/14.2 ± 3.3 mm (130 mm), 3.1%/13.1 ± 5.9 mm (140 mm), and 0% (150 mm) in DFA; and 0% (130-150 mm) in PFA. The presence rate of DFA increased at the posteromedial area in the thigh, and the distance from the femur became closer.<bold>Conclusion: </bold>Within the angle that distal screws were likely to be inserted, the risk of DFA injury was the highest. Therefore, anatomical reduction of the femoral neck anteversion should be performed so that the distal screw will be inserted towards the anteromedial area in the thigh, and great attention should be paid not to over-drill the medial femoral cortex. [ABSTRACT FROM AUTHOR]