1. Taking a proper weight-bearing AP knee x-ray
Taking a proper weight-bearing AP knee x-ray. To obtain this view, the patient has to be standing with their knees extended (straight) and fully weight bearing on both lower extremities. The radiology technician must direct the beam parallel to the floor and exactly at the level of the joint. Assessing the space accurately also requires that the x-ray beam is truly parallel to the top surface of the tibia. You can only appreciate the open space between two flat, parallel surfaces if your line of sight is parallel to those surfaces. Look down from above, or up from below, and the space disappears. An off-axis x-ray can make an open joint space look closed.
Source: The Knee, Practical Office Orthopedics
Citation: Parks E. Practical Office Orthopedics; 2017 Available at: Accessed: October 29, 2017
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