OA is an abbreviation of 'osteoarthritis'.
![Outerbridge Grade IV - patellar cartilage fibrillated with exposure of underlying bone in the tibia](/sites/default/files/users/user1/grade-4-cartilage-damage_02_0.jpg)
This is a photograph taken during keyhole surgery. The joint surfaces within the knee showing osteoarthritis breakdown of the usually shiny white joint cartilage - you can even see the yellower bone showing underneath.
What causes OA in the knee?
OA (osteoarthritis) in the knee can be caused by excessive stress on any one part of the joint - such as being overweight, having an incompetent meniscus, poor limb alignment, and injury.
Synonyms:
osteoarthritis
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