In a diagnostic anteroposterior (AP) knee radiograph, which of the following should NOT be demonstrated?

In a diagnostic anteroposterior (AP) knee radiograph, the image is meant to provide a clear view of the knee joint and its components in a standardized position. A correctly taken AP radiograph should demonstrate symmetric femoral and tibial condyles, with the patella appropriately superimposed over the distal femur, allowing for an assessment of alignment and joint integrity.

The open femorotibial joint space is also an essential aspect of the imaging, as it indicates no significant overlapping of the femur and tibia and can help rule out conditions such as joint effusion or arthritis.

Distortion of bone structures, however, should not be present in a quality radiographic image. Ideally, the radiograph should be as accurate as possible and free from distortion, providing a precise representation of the anatomical structures. Distortion can hamper diagnosis as it may misrepresent the true anatomy of the knee, leading to potential misinterpretation of any existing pathology. Thus, not demonstrating distortion is critical for an accurate evaluation of the knee joint.