Femoral anteversion measured by ultrasonography and radiography. An anatomic investigation.

Radiographic and real-time ultrasound measurements of femoral anteversion were compared in an anatomic study of 20 dried adult femurs. The real anteversion (AV) angle was determined by biplanar radiography. In four ultrasound measurements, the linear transducer was kept either horizontal or tilted. The measuring lines were either the anterior tangent of the femoral head--greater trochanter or the anterior tangent of the femoral neck. With the tilted transducer, the correlation between the head-trochanter AV angle and the real AV angle was high (r = 0.9452), and slightly less when the anterior neck AV angle was used (r = 0.9142). The clinical relevance is that the tilted transducer technique with the head-trochanter tangent is recommended for AV screening in patients with clinical signs of increased femoral anteversion. In adults 8.5 degrees has to be subtracted in order to obtain an approximation of the real AV angle.