Evaluation of femoral malrotation after intramedullary nailing.

Background: Intramedullary nailing and closed reduction are one of the most important treatment strategies for femoral shaft fractures. Malrotation in the femoral shaft is a complication that requires exact investigations. Here we aimed to evaluate and report the outcomes of malrotation of femur in patients with femoral shaft fractures following antegrade intramedullary nailing.

Methods: In this cross-sectional study, 140 patients who had referred to Shahid-Beheshti Hospital in Abadan, Iran and had undergone antegrade intramedullary fixation for isolated femoral shaft fracture during a 6-year period from 2015 to 2021 were enrolled. Demographic information and disease-related information were collected. During operation, the patients were assessed clinically for malrotation of femur with 90° of the knee flection and with the hip in 0° flexion and then in the postoperative follow-up period, the patient was examined again and a computed tomography scan requested to identify the degree of malrotation of femur and the observers were unaware of the CT scan result at the time of the clinical examination. We also measured the amount of internal and external rotation while the patient in the lying supine position with 90° flexion in the knee and hip joint and lying prone position with hip extension. In CT imaging to determine the amount of malrotation of femur, the angle between a line drawn across the two femoral condyles in the posterior aspect and the femoral neck shows the amount of rotation.

Results: Degree of rotational deformity, less than 5°, 5 to 10° and 10 to 15° was less than 8.6%, 75.7% and 15.7% respectively and did not relate to age, sex, fracture location and activity of the patients (P>0.05). There was a strong linear correlation with the average predictive power between clinically detected torsional deformity in comparison with the CT detected torsional deformity (r=0.333 and P=0.005), which was stronger in women than men (r=0.336 in men and r=0.659 in women) (P<0.05). There was a strong linear correlation with the average predictive power between clinically detected torsional deformity in comparison with the CT detected torsional deformity was observed only in external malrotation of femur (r=0.541 and P=0.001). A poor inverse linear relationship was observed between clinically detected and CT detected torsional deformity with the age of the patients which the correlation of clinically detected was more than the CT detected (r in clinical examination =-0.285 and r in CT measurement =-0.246) (P<0.05).

Conclusion: In this study, there was no femoral malrotation over 15° that was associated with clinical symptoms. However, a CT scan should be performed for accurate diagnosis and necessary measures but it does not seem necessary to perform in all patients.