Joints are spots where two or more bones connect. They are susceptible to pain and discomfort as a result of a number of causes, ranging from the natural aging process to infection. Some of these causes can be eradicated, while some are permanent. Either way, treatment can help make the pain more manageable.

Arthritis

Osteoarthritis is the age-related breakdown of the cartilage that cushions joints, which causes pain, inflammation, swelling and tenderness---particularly in those over the age of 45, according to the U.S. National Library of Medicine. Rheumatoid arthritis causes chronic inflammation of the joints, which can be disabling if not properly managed. Gout, which results from the excessive buildup of uric acid, most commonly strikes the big toe.

Bursitis

Another common cause of joint pain is bursitis, which typically strikes the fluid-filled sacs (bursae) located between the tendons, causing bones to become inflamed. It commonly affects joints in the shoulder, knee, elbow and hip. This condition can be acute or chronic.

Autoimmune Diseases

Autoimmune diseases cause the immune system to mistakenly attack healthy tissue as it would an invading organism, which commonly causes joint pain. Examples include rheumatoid arthritis and lupus.

Infection

Certain infectious diseases can also trigger joint pain. They include Epstein-Barr virus, hepatitis, the flu, Lyme disease, chickenpox, measles, mumps and rheumatic fever.

Bone Conditions

In addition, conditions affecting the bone directly can cause joint pain. Examples include osteomyelitis (bone infection), osteoporosis and osteomalacia (softening of bones), according to the Mayo Clinic

Source:

MedlinePlus: Joint Pain

Mayo Clinic: Joint Pain