When you have OA of the knee

The joint fluid may lose its ability to protect the joint
Smooth cartilage that normally protects the ends of the knee bones may lose its cushioning effect or become pitted and frayed. Large areas of cartilage may even wear away completely, so the bones scrape painfully over each other
Cartilage breakdown may cause the joint to lose its shape, and the bone ends may thicken and form bony spurs
Fragments of bone or cartilage may float in the joint space, causing further damage and pain
Talk to your health care provider if you think you have OA of the knee.