Comparison of preoperative radiographic measurements for femoral shaft fractures: a study on canal diameter measurement methods.

Purpose: This study sought to determine the most reliable preoperative method for measuring canal diameter in femoral shaft fractures to optimize intramedullary nailing outcomes.

Methods: We retrospectively analyzed 164 patients treated with intramedullary nailing at University Hospital from October 2017 to December 2019. Each patient's canal diameter was measured using five techniques: simple anteroposterior (AP) radiography, simple lateral radiography, AP scanogram with a scano rod, lateral scanogram with a scano rod, and computed tomography (CT). Error was calculated as preoperative measurement minus actual nail diameter. Interobserver reliability was assessed with Cohen's Kappa coefficient and paired t tests, with subgroup analyses for isthmus fractures and osteoporosis.

Results: CT yielded the smallest error (-0.34 ± 0.87 mm and 0.25 ± 1.39 mm across observers), with Kappa values of 0.61-0.85 indicating substantial reliability. Only CT showed significant error differences for isthmus fractures (p < 0.05). No method differed significantly with osteoporosis (p > 0.05). Preoperative plans adjusted in 18% of scano rod cases due to discrepancies exceeding 2 mm.

Conclusion: CT offers the highest reliability, particularly for isthmus fractures, while scanograms outperform simple radiography, with AP views superior to lateral views. Further investigation is needed into osteoporosis effects on measurement accuracy.