An Overview of Osteoarthritis

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Rheumatology consultation, Doctor examining a patients shoulder
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Osteoarthritis is the most common type of arthritis. It develops when cartilage, the flexible tissue that allows bones in a joint to glide over each other, breaks down. Osteoarthritis causes pain, stiffness, and swelling of the affected joints. While it is most common among adults over age 65, people of any age can develop it.

Osteoarthritis is sometimes referred to as wear-and-tear arthritis. Other names include degenerative joint disease, degenerative arthritis, DJD, and osteoarthrosis.

Symptoms

Osteoarthritis can affect joints in the hands and fingers, hips, knees, feet, and spine.

Common symptoms include:

  • Joint pain or tenderness
  • Stiffness
  • Limited range of motion
  • Joint swelling or enlargement
  • Crepitus (crackling or grinding of the joints)
  • Joint deformity or malalignment

Based on X-ray evidence, the distal and proximal interphalangeal joints of the hand are most commonly affected by osteoarthritis, though they may not be associated with typical symptoms. 

The hips and knees are the next most common sites of osteoarthritis and are almost always symptomatic. The first metatarsal phalangeal and carpometacarpal joints also are common sites of osteoarthritis observed on X-ray.

The shoulder, elbow, wrist, and metacarpophalangeal joints are rare sites of osteoarthritis unless related to injury, trauma, or occupation.

Causes

Osteoarthritis has long been explained as the result of the breakdown of cartilage in one or more joints.

Cartilage is composed of 65 percent to 80 percent water, collagen (fibrous proteins), proteoglycans (proteins and sugars that interweave with collagen), and chondrocytes (cells that produce cartilage). This hard, but slippery tissue serves as a cushion between the bones of joints, allowing for movement and shock absorption.

When cartilage loss occurs, joints can deteriorate to the point of rubbing bone against bone. Changes in structures that surround joints (muscles and tendons), fluid accumulation, and bony overgrowth (osteophytes or bone spurs) can develop, leading to severe chronic pain, loss of mobility, and disability.

While the aforementioned explanation of wear and tear (cartilage degeneration) is not inaccurate, it is incomplete. Many other factors play a role in the development of osteoarthritis, and they may be genetic, metabolic, environmental, or traumatic.

In a joint affected by osteoarthritis, all joint tissues are affected, not just the cartilage.

Risk Factors

Osteoarthritis, one of more than 100 types of arthritis and related conditions, is the most prevalent type of arthritis. In the United States, about 27 million people live with the condition. There are certain factors that increase your risk of developing it.

  • Aging: Prevalence of osteoarthritis rises significantly after age 50 in men and after age 40 in women. According to the American College of Rheumatology, 70 percent of people over the age of 70 have X-ray evidence of osteoarthritis.
  • Female gender: Hand and knee osteoarthritis is more prevalent in women than men. The prevalence of hip osteoarthritis is essentially equal in men and women.
  • Injury to joints: After a joint injury occurs, post-traumatic osteoarthritis can develop, typically within 10 years.
  • Occupational activity: With occupations that require intense joint loading (e.g., lifting, kneeling, climbing), especially of a repetitive nature, there is an increased risk of developing osteoarthritis.
  • Overweight or obesity: Excess body weight adds burden to weight-bearing joints. Interestingly, being overweight increases the risk of hand osteoarthritis, too, suggesting a metabolic connection.
  • Genetic predisposition: Studies have associated certain gene variations with an increased risk of developing osteoarthritis.

    By 2030, approximately 20 percent of Americans will be over 65 years old and at high risk for developing osteoarthritis.

    Diagnosis

    Early, accurate diagnosis of osteoarthritis is key in getting proper treatment. Your doctor must determine if you have osteoarthritis or one of the many other types of arthritis.

    It can be difficult to determine when osteoarthritis onset occurs and which joint tissues are affected early on unless there is a traumatic event that can be pinpointed, such as a torn ligament.

    While magnetic resonance imaging (MRI) studies can detect early structural changes consistent with osteoarthritis, conventional X-rays are routinely ordered—at least initially. But, by the time there is X-ray evidence of osteoarthritis, the disease can be quite advanced.

    X-rays reveal cartilage loss, joint space narrowing, subchondral sclerosis, subchondral cysts, and osteophytes. MRI images can reveal subtle changes to cartilage, synovitis, bone marrow lesions, and degenerative changes within soft tissues. 

    As osteoarthritis progresses, the entire joint may become involved, causing the component parts to fail.

    The prognosis for someone with osteoarthritis is difficult to predict. Not everyone with the condition progresses at the same rate, responds to a particular treatment modality the same way, or develops severe symptoms if in early or mild stages.

    Treatment

    There are many options for treating osteoarthritis. Your doctor will work with you to develop a treatment plan that is right for you.

    Treatment for osteoarthritis may include:

    Lifestyle changes are also important in helping to improve osteoarthritis. They may include:

    Coping

    A diagnosis of osteoarthritis can be unnerving, but there are steps you can take to feel better, both physically and mentally. Follow your treatment plan and reassess regularly to ensure it's working for you.

    Gentle exercise can help strengthen and improve your range of motion. It also helps you maintain a healthy weight. But also rest when you need. Ask family and friends for help, make adjustments at work if necessary, and listen to your body.

    A Word From Verywell

    Understanding that osteoarthritis is more than simply a consequence of aging or worn out joints is important. There are factors that increase the risk of developing this condition, some of which are modifiable. While your joints will certainly get mileage with age, the consequences of wear and tear are somewhat within your control.

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    Article Sources

    • Osteoarthritis Epidemiology and Risk Factors. The Johns Hopkins Arthritis Center. Updated April 25, 2012.
    • Osteoarthritis. Handout on Health. National Institute of Arthritis and Musculoskeletal and Skin Diseases. April 2015.

    • Paul E. Di Cesare et al. Chapter 98. Kelley's Textbook of Rheumatology. Elsevier. Ninth edition.
    • Richard F. Loesner. MD. Pathogenesis of Osteoarthritis. UpToDate. Updated June 21, 2016.