Saturday, June 20, 2009
The Knee X-ray: The Arthritic Knee
This is an x-ray of a right knee viewed from directly in front.
Notice the gap between the femur and tibia is uneven. The gap is easily seen on the left (the outside of the knee) but just a thin line on the right.
We don't actually have a gap in our knees. The gap seen is due to the cartilage covering the knee that does not show up on x-ray. When the gap is decreased or gone altogether, it indicates the loss of the articular cartilage.
When there is no gap at all it is described as "bone on bone"
Other features to notice are the little spurs of bone on the outside borders of the joint. The 'fish-hook' appearance at the bottom of the femur on the left is easily seen. There are similar, faint spurs on the right. These are called osteophytes.
Where the joint is down to 'bone on bone' there is usually an increased area of white bone, indicating sclerosis, at the very end of the bones. This is where the bone becomes very hard in response to the altered forces through the joint.
This knee would be described as having advanced degenerative changes especially in the medial joint