Figure 21.

Cam morphology demonstrated on axial oblique T1W fat-saturated magnetic resonance arthrogram images of the hip. A) Axial oblique plane at the level where the femoral neck is narrowest. Note bone protuberance at the anterior aspect of the femoral head and neck junction consistent with cam deformity (long arrow). The alpha angle is formed by two intersecting lines: the longitudinal axis of the femoral neck and from the isocentre of the femoral head to the point where sphericity of the femoral head is first lost. An angle greater than 55 degrees is considered abnormal. There is an anterior acetabular labral tear (short arrow). B) Femoral head-neck offset is also measured on the axial oblique plane at the level where the femoral neck is narrowest. Two parallel lines are drawn along the anterior aspect of the femoral head and neck. An offset of < 10 mm is consistent with cam type morphology