Osteoarthritis is a chronic (long-lasting) disease, the most common form of arthritis.14

OA is a degenerative joint disease that can affect joint cartilage, bone, ligaments, and other tissues. OA typically develops over time, but it can develop much more rapidly after injury to a joint. The knees, hips, and shoulders are among the joints most commonly affected by OA.

OA symptoms often include joint pain, stiffness, swelling, limited range of motion, clicking or popping sounds, and instability.14,16

There is no cure for osteoarthritis, but there are treatment options available to help reduce pain, improve function, and in some cases, delay disease progression.14

Stages of Knee Osteoarthritis

Inside an osteoarthritis (OA) joint

  1. Normal cartilage: Provides a smooth surface, allowing bones to move easily across each other.
  2. Synovial fluid: Lubricates and provides shock absorption during activity, because it contains a high concentration of hyaluronic acid.
  3. Bone in a normal joint: Provides strength and support for the body’s tissues and organs.
  4. Eroded cartilage: If completely worn away, bones may painfully scrape against each other.
  5. Osteoarthritic synovial fluid: Degeneration from OA leads to lower production of hyaluronic acid and poorer functional quality.
  6. Bone in a joint with OA: Contains osteophytes, also called bony spur growths.

Learn more about the causes of osteoarthritis, the symptoms, and diagnosis.