Given the typical (degenerative) etiology of osteoarthritis, how then might a 20 year old person have this condition?
The most likely cause of osteoarthritis in a young person is trauma
Trauma, in turn, can cause arthritis in 3 ways (at least)
- DIRECT DAMAGE Damage to the articular surface directly can of course lead to breakdown.
- Chronic damage inflicted from loose ligaments. In the figure below, you see that (on the left) if the tire is not secured, there will be focal loading on parts of the tire (and tire damage accordingly). Similarly, a loose joint can have eccentric loading on small areas, and in those areas there will be increased pressure (again, recalling P=F/A). This pressure leads to breakdown
- Trauma can disrupt the blood supply, and the arthritis may be from AVN
As shown here, dead bone can collapse leading to deformity of the joint surface
The take home point is that DJD in a young person is possible, but not likely, and should be a diagnosis of exclusion.
