Ultrasonographic Assessment of Femoral Torsion Angle Based on Tilting Angles of Femoral Neck and Condylar Axis

Abstract Femoral anteversion has been assessed with ultrasound using femoral necktilting angle (FN-TA); however, femoral torsion angle (FTA), which is defined using FN-TA and condylar axis tilting angle, has not been assessed with ultrasound. This study aimed to establish the ultrasonographic assessment of FTA (US-FTA) by comparing data obtained through US-FTA and computed tomography (CT). Twenty-one patients (age range, 38–82 y) with 21 intact hips were included. In the US-FTA, the femoral head and anterior tubercleof the greater trochanterwere used as bony landmarks. The intra-rater and inter-rater reliabilitiesand standard error of measurement (SEM) of US-FTA were 0.994 (SEM 0.93) and 0.994 (SEM 0.94), respectively. A strong agreement was found between FTA variables obtained with ultrasound and CT (R = 0.939, p