"The femoral head-neck-shaft angle is influenced by femoral rotation, which might lead to measurement errors if not considered 1,2."
"Due to the susceptibility of angle measurements to rotation and to account for the usual femoral anteversion an internal rotation of the feet of 15°-20° is recommended for the standardised acquisition of the pelvis (AP view) 1."
"Potential measurement errors radiographically caused by external rotation of the femur can cause a change of >10° in the apparent femoral neck-shaft angle with as little as 7° of external rotation of the femur 2."
Expected headings
"Potential measurement errors"