A 24-year-old volleyball player with anterior knee pain and suspected patellar maltracking needs the patellofemoral joint space shown without superimposition. The patient can flex both knees over the table edge while seated. Which patella projection method best demonstrates the patellofemoral articulation for this patient?
Select an answer to reveal the explanation.
Short Explanation
You can get that sunrise view with both knees flexed over the table edge, making side-to-side comparison easy. The Merchant method opens the patellofemoral space for your maltracking assessment.
Full Explanation
The bilateral Merchant method best demonstrates the patellofemoral articulation tangentially: with the patient seated and both knees flexed about 40 degrees over the table edge, a caudally angled beam opens the space between each patella and femoral trochlea for maltracking assessment and side-to-side comparison. The unilateral Settegast method is also tangential, but its prone position and 90-degree knee flexion do not fit this patient’s seated ability to flex both knees and provide bilateral comparison. An AP knee with full extension superimposes the patella on the femur rather than profiling the patellofemoral joint space. A routine lateral knee with 20 degrees of flexion shows patellar height and effusion, but projects the patellofemoral interface obliquely instead of tangentially. For the exam, distinguish the bilateral seated Merchant positioning from the unilateral prone Settegast positioning. In practice, support the cassette, flex both knees equally, and avoid excessive flexion that could close the joint space.