Mediolateral frog-leg projections of the hip require the femur to be at what angle of abduction?

• A. 20° to 30°
• B. 30° to 40°
• C. 40° to 45°
• D. 50° to 60°

Answer: (C)

In mediolateral frog-leg projections of the hip, the correct angle of abduction for the femur is 40° to 45°. This specific positioning is critical for obtaining a clear and diagnostic image of the hip joint and the surrounding structures.

Abducting the femur at this angle allows the acetabulum and femoral head to be visualized in profile while minimizing superimposition of other structures. This positioning also helps ensure that any pathology related to the hip joint can be more accurately assessed. If the angle of abduction is too shallow or too steep, the resulting image may lead to misinterpretation or might obscure important anatomical details.

Achieving this optimal angle is important for radiologic imaging because it helps to closely match the orientation of the anatomy, ensuring that both the femoral head and neck are demonstrated without distortion. This is especially relevant in trauma assessments or evaluations for conditions such as hip dysplasia, where accurate representation of the joint anatomy is critical for diagnosis and treatment planning.