Arthritis is the medical word for irritation or inflammation involving a joint, and it is one of the most common chronic medical conditions in the world. According to recent data from the US Centers for Disease Control, 54.5 million adults in the United States (22.7%) have been diagnosed with some form of arthritis by a medical professional (1).
If you have been diagnosed with arthritis, trying to understand what exactly is causing it, and the difference between various types of arthritis can be overwhelming.
In this article, we will review the causes and associated symptoms of two of the most common forms of arthritis: osteoarthritis (OA) and rheumatoid arthritis (RA).
What Are Some Causes of Osteoarthritis?
OA is the most common cause of arthritis in people around the world.
Due to the natural wear and tear that occurs in our joints from ordinary activities of everyday life. As we and our joints age, a cascade of changes take place within the joint (2).
The protective cartilage can wear down and become dried out, leading to damage to the underlying bone. This bone underlying the cartilage can then become weaker and develop cysts. As the joint degenerates, ligaments associated with the joint can undergo degeneration as well. Also, bone spurs (also known as osteophytes) may form around the joint over time.
Characteristic Symptoms of Osteoarthritis
Both OA and RA are diseases that cause pain and discomfort associated with certain joints throughout the body.
Some of the characteristics of OA:
- usually begins later in life (degenerative process)
- affects weight-bearing joints (knees and hips) most commonly
- usually affects joints asymmetrically (e.g., although both hips may experience OA, it’s typical for one to become symptomatic first or is more severe)
- patients with OA are most likely to experience the worst symptoms at the end of the day, after an extended amount of time spent on their feet
What Are Some Causes of Rheumatoid Arthritis?
Rather than a degenerative process like OA, RA is caused by an autoimmune process. This means that RA is caused by the body’s own immune system incorrectly recognizing part of a joint as ‘bad’ or pathologic and attacking it.
Most researchers agree that RA develops as a result of an autoimmune attack against the joint space lining, or synovium (3). This attack causes swelling and inflammation in the joint space, which eventually leads to the breakdown of the synovium lining the joints and affects the tendons and ligaments associated with the joints.
Characteristic Symptoms of Rheumatoid Arthritis
Because RA is an autoimmune condition, some unique characteristics are specific to RA and less likely to be present in OA:
- affects non-weight-bearing joints, such as the hands, wrists, elbows, and usually involves both sides symmetrically
- affected joints are significantly swollen, tender to the touch, and warm (due to the significant inflammation
- may affect areas outside the joints (RA can affect the eyes, heart, kidneys, etc.)
- patients usually complain of significant morning stiffness which may even improve throughout the day
Both OA and RA are two common forms of arthritis that affect millions of Americans every year. Although the symptoms they cause can be similar, OA and RA are two different diseases that cause joint damage in different ways.
Careful attention to your symptoms may help to determine which type of arthritis is affecting your joints.
1. Barbour KE, Helmick CG, Boring M, Brady TJ. Vital Signs: Prevalence of Doctor-Diagnosed Arthritis and Arthritis-Attributable Activity Limitation — United States, 2013–2015. MMWR Morb Mortal Wkly Rep. 2017;66(9):246-253.
2. Man GS, Mologhianu G. Osteoarthritis pathogenesis – a complex process that involves the entire joint. J Med Life. 2014;7(1):37-41.
3. Guo Q, Wang Y, Xu D, Nossent J, Pavlos NJ, Xu J. Rheumatoid arthritis: Pathological mechanisms and modern pharmacologic therapies. Bone Res. 2018;6(1).