A lateral knee radiograph shows the femoral condyle overlapped with the joint space. Which adjustment will correct this error?

• A. X-ray tube angulation
• B. Lateral rotation of the knee
• C. Flexion of the knee
• D. Receptor position

Answer: (A)

When a lateral knee image shows the femoral condyle overlapping the joint space, the projection isn’t aligned with the knee’s axis. The beam is tilted relative to the knee, causing one condyle to project over the joint space instead of the posterior surfaces being superimposed. The fix is to adjust the X-ray tube angle (tilt) so the beam angles appropriately with the knee’s plane, producing true lateral superimposition of the posterior femoral condyles and opening the joint space correctly. Keep the knee flexed around 20–30 degrees and the receptor placement stable, but modify the tube angulation until the condyles are superimposed and the joint space is accurately depicted.