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.