Osteoarthritis, also known as degenerative arthritis, is a disease which may arise in any human joint. Over 100 specific types of arthritis have been identified by medical science. Osteoarthritis is classified as a rheumatic disease, meaning that it is an affliction that is isolated to the particular joint structure without attacking any other organ or bodily system.

Osteoarthritis is the general description of the progressive breakdown and loss of cartilage in the joint: there are a number of factors that may contribute to both the origin and the development of the condition. Joints are created in the human musculo-skeletal system where two or more bones meet. All bones consist of hard mineral compounds, primarily those including calcium, the mineral that gives bones their hard surface and density, with a measure of the protein collagen present to provide a measure of elasticity to the bone surface to permit the structure to absorb impact. At the joint, the epiphysis (the area at the end of every bone), is coated with cartilage, a protein substance that provides both cushioning and a reduced friction surface on which the other joint bones can move more readily. These coverings are known as articular cartilage.

There are two general types of osteoarthritis. Primary osteoarthritis does not have a specific cause and is generally attributable to the aging of the body. For many people, the wear and tear to their joints from the repetitive nature of human movement causes the cartilage in the joints to thin over time. Pieces of cartilage fiber tend to peel away from the surface of the bone structure, and where the cartilage thins bone spurs may occasionally develop, further limiting joint movement. Primary osteoarthritis is also known as rheumatism.

Secondary osteoarthritis arises from specific and definable physical circumstances. Hereditary causes occur in people born with unequal leg length or similar structural imbalances that tend to create unequal stresses on weight-bearing joints during movement. These stresses will often cause damage to the cartilage in the affected joint. These alignment or structural deficiencies particularly contribute to the formation of osteoarthritis in the joints of the foot, knee, hip, or lower spine.

Another circumstance the leads to secondary osteoarthritis is sports injury, in which excessive force is directed into a joint and will often cause the cartilage to tear or to partially tear. The most common cartilage tear injuries in sport occur in the knee. A torn knee cartilage often occurs in conjunction with other injuries to the knee structure, such as the patella (knee cap) or one of the ligament structures.

Secondary osteoarthritis also occurs in the obese, those persons who are overweight, which places a significantly greater strain on all weight-bearing joints, rendering the joint more vulnerable to injury.

The symptoms of secondary osteoarthritis are pain in the affected area, accompanied by swelling and limited mobility in the joint. Persons who have sustained longer term cartilage loss in the knees often appear bow legged, due to the fact that the cartilage, having thinned on the epiphysis, has created a narrowing in the space between the femur and the tibia and fibula. The bow-legged appearance is the result of the bones meeting at a different angle than when the epiphysis had optimal cartilage covering. The loss of knee cartilage is the most common basis for total knee replacement surgery in North America.

X-ray showing finger joints which have been immobilized with pins to remedy severe osteoarthritis.

Osteoarthritis often occurs in the regions of the spine that support movement, particularly the cervical spine, the seven vertebrae that support the neck and the skull, and the lumbar spine, the lower back region located above the pelvis. In the joints formed by the individual vertebrae in these areas, when cartilage is reduced, bony spurs, which are composed of the same calcium and mineral material used to build and repair bones, will tend to form on the surface of the vertebrae. These spurs interfere in the natural motion of the spinal joints, and the spurs will sometimes irritate the spinal nerves that emanate from the spinal cord, causing significant pain.

Other than the history communicated by the patient to an examining physician, the primary diagnostic tool available to determine the extent of osteoarthritis is x-ray technology. The x-ray results will reveal where there is either an observable loss of cartilage, a narrowing of joints spaces, or the presence of bone spurs.

The treatment options for the relief of osteoarthritis are limited. If the cartilage is capable of being repaired, arthroscopic surgery may be employed to both suture the damaged cartilage as well as to remove free-floating particles of cartilage in the joint, that may further impair its movement through becoming lodged in the space between the bones of the joint. There have been a number of successful, yet experimental surgeries performed in recent years where new cartilage was successfully cultivated outside of the body and then injected into the joint to encourage a re-growth in the damaged area.

In many cases, the subject will obtain relief from over-the-counter medications such as acetaminophen, or nonsteriodal anti-inflammatory drugs (NSAIDs) such as ibuprofen, or the more powerful NSAIDs, Cox-2 inhibitors, that block the development of the inflammation-causing enzymes at the site of the injured cartilage. A more immediate anti-inflammatory procedure is the injection of a corticosteroid such as cortisone directly into the affected joint.

As there is no certain restorative treatment for cartilage that has been thinned away from the interior of the joint, athletes who suffer from the affects of osteoarthritis often must reduce both the frequency and the intensity of their activities to manage the pain of this condition.

SEE ALSO Bone, ligaments, tendons; Calcium; Minerals; Osteoarthritis.