The supine position with the knee flexed 30° provides good support for the knee and relaxes the tendency of the gastrocnemius muscle to pull the condyles into hyperextension. It has the disadvantage that, for lateral image intensifier use, the limb may need to be lifted up.
Position the patient supine on a radiolucent table with the knee in 30° flexion. The knee is supported by a cushion, or rolled sheets.
It is useful to have a small sandbag just behind the same buttock to prevent external rotation of the limb.