The biological factors leading to the deterioration of cartilage in osteoarthritis are not entirely understood. Many experts believe that osteoarthritis results from a genetic susceptibility that causes some biological response to injuries to the joint, which in turn leads to progressive deterioration of cartilage. In addition, the body's ability to repair cartilage decreases with increasing age.
Additionally, joint damage from injuries or recurrent stress to the joint is the starting point in the osteoarthritis disease process. Osteoarthritis sometimes develops years after a single traumatic injury to or near a joint. Patients with knee injuries may be up to five times more likely to have osteoarthritis in the injured knee than those without injuries, and patients with hip injuries may be more than three times more likely to develop arthritis in the injured hip.
The pain of osteoarthritis typically begins gradually and progresses slowly over many years. In fact, people under age 40 may have the condition with no symptoms at all.
Osteoarthritis is commonly identified by the following symptoms:
- Pain that worsens during activity and gets better during rest. This is the most common symptom of osteoarthritis. As the disease advances, the pain may occur even when the joint is at rest.
- Pain is generally described as aching, stiffness, and loss of mobility. The symptoms are often worse when resuming activities after periods of no activity.
- The pain may be intermittent, with bad spells followed by periods of relative relief.
- Pain seems to increase in humid weather.
- Some people have muscle spasm and contractions in the tendons.
- Osteoarthritis in the knee may cause a crackling-like noise (called crepitus) when moved.
In addition to medication, lifestyle changes and physical therapy, severe cases of osteoarthritis may require surgery to replace or repair damaged joints.
Common surgical options include:
- Arthroscopic surgery to trim torn and damaged cartilage and wash out the joint
- Cartilage restoration to replace the damaged or missing cartilage in some younger patients with arthritis
- Change the alignment of a bone to relieve stress on the bone or joint (osteotomy)
- Surgical fusion of bones, usually in the spine (arthrodesis)
- Total or partial replacement of the damaged joint with an artificial joint (knee arthroplasty, hip arthroplasty)