Some symptoms of arthritis in the knee are swelling and pain that are worse in the morning or after a period of inactivity, stiffness that makes the knee painful to move, and crepitus, says the American Academy of Orthopaedic Surgeons. Crepitus is a creaking or grinding sound in the knee.
Other symptoms are pain that flares up during strenuous activity, a knee that sometimes locks when the patient tries to move it, and a feeling that the knee may give out, says the AAOS. Another symptom is an increase in pain when it rains. The knee hurts when it bears weight, and the pain affects the way the person walks.
Most people with knee arthritis have a type called osteoarthritis, claims AAOS. This condition comes about with the regular wear and tear of living and is fairly common in people over 50. The onset is gradual, and the pain gets worse as time passes.
Rheumatoid arthritis is an autoimmune disease, and it affects several joints, claims AAOS. It usually affects the same joint on both sides of the body. If rheumatoid arthritis impacts the knees, the patient's immune system attacks the synovial membrane over the knee, which causes swelling, pain and stiffness. Though osteoarthritis may affect only one knee, rheumatoid arthritis involves both knees. Post-traumatic arthritis happens after the knee receives an injury.