What is osteoarthritis?

Osteoarthritis is a type of arthritis that is caused by the breakdown and eventual loss of the cartilage of one or more joints. Cartilage is a protein substance that serves as a "cushion" between the bones of the joints. Osteoarthritis is also known as degenerative arthritis.

Osteoarthritis commonly affects the hands, feet, spine, and large weight-bearing joints, such as the hips and knees.

Causes of osteoarthritis:

Primary osteoarthritis is mostly related to aging. With aging, the water content of the cartilage increases, and the protein makeup of cartilage degenerates. Eventually, cartilage begins to degenerate by flaking or forming tiny crevasses. In advanced cases, there is a total loss of cartilage cushion between the bones of the joints. Repetitive use of the worn joints over the years can irritate and inflame the cartilage, causing joint pain and swelling. Loss of the cartilage cushion causes friction between the bones, leading to pain and limitation of joint mobility. Inflammation of the cartilage can also stimulate new bone outgrowths (spurs, also referred to as osteophytes) to form around the joints. Osteoarthritis occasionally can develop in multiple members of the same family, implying a hereditary (genetic) basis for this condition.

Secondary osteoarthritis is caused by obesity, repeated trauma or surgery to the joint structures, abnormal joints at birth (congenital abnormalities), gout, diabetes, and other hormone disorders.

Obesity causes osteoarthritis by increasing the mechanical stress on the cartilage. In fact, next to aging, obesity is the most powerful risk factor for osteoarthritis of the knees. The early development of osteoarthritis of the knees among weight lifters is believed to be in part due to their high body weight. Repeated trauma to joint tissues (ligaments, bones, and cartilage) is believed to lead to early osteoarthritis of the knees in soccer players.

Crystal deposits in the cartilage can cause cartilage degeneration and osteoarthritis. Uric acid crystals cause arthritis in gout, while calcium pyrophosphate crystals cause arthritis in pseudogout.

Some people are born with abnormally formed joints (congenital abnormalities) that are vulnerable to mechanical wear, causing early degeneration and loss of joint cartilage. Osteoarthritis of the hip joints is commonly related to structural abnormalities of these joints that had been present since birth.

Osteoarthritis symptoms:

Osteoarthritis is a disease of the joints. The most common symptom of osteoarthritis is pain in the affected joint(s) after repetitive use. Joint pain is usually worse later in the day. There can be swelling, warmth, and creaking of the affected joints. Pain and stiffness of the joints can also occur after long periods of inactivity (for example, sitting in a theater). In severe osteoarthritis, complete loss of the cartilage cushion causes friction between bones, causing pain at rest or pain with limited motion.

Osteoarthritis of the knees is often associated with excess upper body weight, with obesity, or a history of repeated injury and/or joint surgery. Progressive cartilage degeneration of the knee joints can lead to deformity and outward curvature of the knees, which is referred to as being "bowlegged." People with osteoarthritis of the weight-bearing joints (like the knees) can develop a limp. The limping can worsen as more cartilage degenerates. In some patients, the pain, limping, and joint dysfunction may not respond to medications or other conservative measures. Therefore, severe osteoarthritis of the knees is one of the most common reasons for total knee replacement surgery.

Osteoarthritis of the cervical spine or lumbar spine causes pain in the neck or low back. Bony spurs, called osteophytes, that form along the arthritic spine can irritate spinal nerves, causing severe pain, numbness, and tingling of the affected parts of the body.

Osteoarthritis causes the formation of hard, bony enlargements of the small joints of the fingers. Classic bony enlargement of the small joint at the end of the fingers is called a Heberden's node. The bony deformity is a result of the bone spurs from the osteoarthritis in that joint. Another common bony knob (node) occurs at the middle joint of the fingers in many patients with osteoarthritis and is called a Bouchard's node. Osteoarthritis of the joint at the base of the big toe of the foot leads to the formation of a bunion. Osteoarthritis of the fingers and the toes may have a genetic or hereditary.