Joint pain, or arthralgia, is a common medical complaint that can stem from a variety of causes and conditions. Here’s an overview:

Arthritis

One of the most common causes of joint pain is arthritis. The two main forms of arthritis are osteoarthritis (OA) and rheumatoid arthritis (RA).

According to the American College of Rheumatology, OA is most common in adults over age 40. It progresses slowly and tends to affect commonly used joints like the:

• wrists
• hands
• hips
• knees

Joint pain due to OA results from a breakdown of the cartilage that serves as a cushion and shock absorber for the joints.

The second form of arthritis is RA. According to the Arthritis Foundation, RA affects about 1.5 million Americans. It more commonly affects women than men.

It can deform and debilitate the joints over time. RA causes pain, inflammation, and fluid buildup in the joints as the body’s immune system attacks the membrane that lines the joints.

Other causes

Joint pain can be caused by:

• bursitis, or inflammation of the cushioning pads around joints
• lupus
• gout
• certain infectious diseases, such as mumps, influenza, and hepatitis
• chondromalacia of the patella, or a breakdown of the cartilage in the kneecap
• an injury
• tendinitis, or inflammation of the tendon
• an infection of the bone or joint
• overuse of a joint
• cancer