The 4 stages of osteoarthritis are as follows;
1. Acute inflammation caused by trauma to the joint and surrounding soft tissue,
2. General degeneration of cartilage due to chronic friction in the joints with bone on bone contact,
3. Osteophyte formation on articular surfaces which leads to total destruction of cartilage and loss of shock absorbing function, and finally
4. Obstructed subchondral remodeling which causes a breakdown in blood supply leading to painful inflammatory arthritis into localized areas within the joint