Osteoarthritis (OA or Degenerative Arthritis)

  • Medical Author:
    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

  • Medical Editor: Catherine Burt Driver, MD
    Catherine Burt Driver, MD

    Catherine Burt Driver, MD

    Catherine Burt Driver, MD, is board certified in internal medicine and rheumatology by the American Board of Internal Medicine. Dr. Driver is a member of the American College of Rheumatology. She currently is in active practice in the field of rheumatology in Mission Viejo, Calif., where she is a partner in Mission Internal Medical Group.

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Quick GuideOsteoarthritis (OA): Treatment, Symptoms, Diagnosis

Osteoarthritis (OA): Treatment, Symptoms, Diagnosis

What causes osteoarthritis?

Primary osteoarthritis, osteoarthritis not resulting from injury or disease, is partly a result of natural aging of the joint. With aging, the water content of the cartilage increases, and the protein makeup of cartilage degenerates as a function of biologic processes. Eventually, cartilage begins to degenerate by flaking or forming tiny crevasses. In advanced osteoarthritis, there is a total loss of the cartilage cushion between the bones of the joints. Repetitive use of the worn joints over the years can mechanically 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. Osteoarthritis is therefore felt to be a result of a combination of each of the above factors that ultimately lead to a narrowing of the cartilage in the affected joint.

Picture of normal and arthritic joints - osteoarthritis
Picture of normal and arthritic joints - osteoarthritis

Secondary osteoarthritis is a form of osteoarthritis that is caused by another disease or condition. Conditions that can lead to secondary osteoarthritis include 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 joint and therefore on the cartilage. In fact, next to aging, obesity is the most significant 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 and army military personnel. Interestingly, studies have not found an increased risk of osteoarthritis in long-distance runners.

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.

Hormone disturbances, such as diabetes and growth hormone disorders, are also associated with early cartilage wear and secondary osteoarthritis.

Medically Reviewed by a Doctor on 7/19/2016

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