Which projection is commonly used to visualize the patellofemoral joint tangentially with the knee flexed around 70-90 degrees?

Which projection is commonly used to visualize the patellofemoral joint tangentially with the knee flexed around 70-90 degrees?

• A. Settegast
• B. Holmblad
• C. Beclare
• D. Merchant method

Answer: (B)

The main idea is to obtain a tangential view of the patellofemoral joint with enough knee flexion to separate the patella from the femur so the joint space is well seen. The Holmblad method positions the knee in a flexed, weight-bearing-like stance (about 70 degrees) so the x-ray beam can pass along the patellofemoral joint from the side. This tangential orientation minimizes superimposition of the femoral condyles and highlights the articulation between the patella and the femur, which is exactly what you want when assessing patellofemoral tracking or degenerative changes. Other patellofemoral tangential views exist, but they involve different knee angles or patient positions. For example, a view typically done with the knee flexed near 90 degrees and the patient prone can be used, and Merchant’s view uses a different angle around 40 degrees of knee flexion. Beclere (Beclère) is another axial technique with its own positioning. The Holmblad approach aligns best with a 70-degree flexion tangential projection of the patellofemoral joint.

The main idea is to obtain a tangential view of the patellofemoral joint with enough knee flexion to separate the patella from the femur so the joint space is well seen. The Holmblad method positions the knee in a flexed, weight-bearing-like stance (about 70 degrees) so the x-ray beam can pass along the patellofemoral joint from the side. This tangential orientation minimizes superimposition of the femoral condyles and highlights the articulation between the patella and the femur, which is exactly what you want when assessing patellofemoral tracking or degenerative changes.

Other patellofemoral tangential views exist, but they involve different knee angles or patient positions. For example, a view typically done with the knee flexed near 90 degrees and the patient prone can be used, and Merchant’s view uses a different angle around 40 degrees of knee flexion. Beclere (Beclère) is another axial technique with its own positioning. The Holmblad approach aligns best with a 70-degree flexion tangential projection of the patellofemoral joint.