Patient with intermittent left-sided groin pain for several months.
MR arthrography of the left hip
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A severe cam-type deformity is present in this patient with femoroacetabular impingement. There is also a small labral tear at the superior portion of the hip joint. The articular cartilage is intact.
In the axial HASTE images over the proximal and distal femur a femoral retroversion can be seen, i.e. the axis of the femoral neck is oriented more posteriorly than the distal reference line connecting the dorsal border of the femoral condyles.
Measurement on axial HASTE images (proximal and distal femur):
The amount of femoral anteversion is calculated by combining the measurements from the proximal and distal femur: The distal reference angle (24°) is subtracted from the proximal reference angle (20°), which results in a femoral anteversion of -4° (i.e. a femoral retroversion).
Femoroacetabular impingement (FAI) and femoral retroversion
In this patient, both the cam-type deformity and the femoral retroversion contribute to a decreased internal rotation of the hip joint. Cam-type femoroacetabular impingement is associated with decreased femoral anteversion (or even femoral retroversion, as in this case). Because there is a wide range of femoral anteversion values both in the healthy population and in patients with femoroacetabular impingement, it is recommended that femoral anteversion is assessed individually in all patients with suspected femoroacetabular impingement.