Measuring femoral neck torsion angle using femoral neck oblique axial computed tomography reconstruction.

PURPOSE

To propose a novel method for measuring the femoral neck torsion angle (FNTA) with femoral neck oblique axial computed tomography (CT) reconstruction.

METHODS

Fifty-five patients (24 females, 31 males; mean age 48.8 years [range, 20-91 years]) were included in the study. CT scans were performed on the left femurs of 27 patients and the right femurs of the remaining 28 patients. The images were analyzed independently by two observers using oblique axial femoral neck CT reconstruction. Intra-observer and inter-observer agreement was calculated as intraclass correlation coefficient (ICC).

RESULTS

FNTA can be measured with high intra-observer (ICC = 0.961) and high inter-observer (ICC = 0.982) agreement. Mean FNTA was slightly larger in women than in men, and the mean left FNTA was slightly larger than the right, but neither difference was statistically significant.

CONCLUSIONS

Femoral neck oblique axial CT reconstruction can be used to obtain accurate measurement of FNTA with good reproducibility. No significant differences were found in FNTA between sexes or sides.