You likely know that arthritis is a broad term that refers to inflammation of the joints. However, it may surprise you to learn that it encompasses more than 100 different conditions that affect the joints themselves and the bones and tissues around them.
While the many types of arthritis often share similar symptoms, including joint pain, swelling, stiffness and limited range of motion, the conditions have different causes and treatments.
“It’s only when you see the patient, ask them questions and examine their joints that you can really understand the complexity and the differences,” explains Frédéric Lavie, M.D., Ph.D., Head of Global Medical Affairs for Rheumatology, Janssen Pharmaceutical Companies of Johnson & Johnson.
Nearly a quarter of American adults are currently living with some form of arthritis, according to the Centers for Disease Control and Prevention. Though everyone experiences it differently, arthritis can cause severe pain and joint disfigurement; some types even affect internal organs. It’s the leading cause of disability in the U.S., according to the Arthritis Foundation.
That’s why Johnson & Johnson is working on innovations to treat certain kinds of arthritis. For Arthritis Awareness Month, here’s an overview of three more common types: osteoarthritis, rheumatoid arthritis and psoriatic arthritis.
What is osteoarthritis?
Osteoarthritis is the most common type of arthritis, affecting 528 million people worldwide. It happens when cartilage, which is the rubbery connective tissue covering the ends of bones in your joints, breaks down.
Historically, osteoarthritis was thought to be a byproduct of aging, according to the Centers for Disease Control. But experts now consider it to be a disease affecting the entire joint that doesn’t necessarily stem from getting older. It’s not just cartilage and bone that are impacted but ligaments, fat and other tissues lining the joint.
Factors that can lead to osteoarthritis include injuries, overuse of joints, age, genetics and obesity. Women are more likely to develop the condition, especially once they reach 50. Though osteoarthritis is associated with older adults, it’s not inevitable; some never develop the condition.
Pain while using the joint, stiffness (especially after a period of rest), swelling, reduced flexibility and hearing the joint click or pop are the most common symptoms. Osteoarthritis can affect any joint but frequently strikes the hands, hips, knees, neck and lower back.
Because it’s a degenerative condition, it typically worsens over time. As cartilage becomes degraded, the bone can change shape or develop small bony growths known as bone spurs on the affected joint, causing pain and increasing the likelihood of disability.
There’s no cure for osteoarthritis, but the pain and inflammation can be managed with over-the-counter or prescription medications—such as pain relievers and nonsteroidal anti-inflammatory drugs (NSAIDs). Exercise and weight loss may also help the condition. But when severe pain and immobility affect someone’s quality of life, joint replacement surgery could be a viable option.
What is rheumatoid arthritis?
Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disorder that impacts 18 million people around the globe, affecting nearly three times as many women as men. It occurs when the immune system mistakes certain healthy cells in the body as invaders and goes on attack. In RA, the immune system attacks the synovium, which is the tissue surrounding a joint that produces fluids to help it move smoothly.
When this happens, cytokines, the signaling proteins that help control inflammation, start to proliferate, Dr. Lavie explains. The inflamed synovium thickens, making the joint red, swollen and painful to move. Over time, this ultimately may lead to structural damage and joint destruction.
Signs of RA include stiffness, pain and swelling in more than one joint. Patients tend to have the same symptoms on both sides of the body, such as both hands or both knees. In some cases, RA affects other parts of the body, causing skin conditions, digestive issues, fatigue, eye problems and heart and lung conditions.
The exact cause of RA is unknown, but it’s likely linked to genetics. It can occur at any age, but the risk goes up as people get older. Some research shows that smoking may raise the risk for RA, says Dr. Lavie.
When it comes to diagnosing RA, doctors rely on blood tests that look for inflammation and antibodies, or blood proteins, that are signs of the condition, Dr. Lavie explains. Physicians might also take X-rays, ultrasounds or MRIs to identify evidence that the joint is wearing away.
To treat RA, doctors typically prescribe disease-modifying anti-rheumatic drugs (DMARDs), which modify the immune system and slow the disease’s progression, says Dr. Lavie.
What is psoriatic arthritis?
Psoriatic arthritis (PsA) is also a chronic autoimmune disease, causing the immune system to attack the body’s healthy tissue, including tissue of the skin and joints. It’s commonly linked with the skin condition psoriasis; about a third of patients with psoriasis develop psoriatic arthritis. Roughly 125 million individuals worldwide have the condition, and it can start at any age, even in childhood.
PsA specifically affects the joints and the “junctions between the bone and the tendon at the vicinity of the joint, what we call enthesis,” says Dr. Lavie. PsA is often found in the hands, feet, wrists, ankles and knees.
Like other forms of arthritis, PsA causes pain, stiffness, swelling and a decline in range of motion. But PsA can also result in silver or gray scaly spots on the scalp, elbows, knees and lower spine, as well as nail depressions or detached fingernails or toenails.
Left untreated, psoriatic arthritis can damage or weaken bones and lead to vision problems, gastrointestinal conditions, shortness of breath and damage to blood vessels and heart muscles.
Like RA, the cause of PsA isn’t known, but it’s believed to be a combination of genetic and environmental factors—such as an infection, for example, that can trigger a flare-up of symptoms. Doctors use blood tests, X-rays, MRIs and a physical exam to diagnose the condition.
Both psoriatic and rheumatoid arthritis can be tough for patients to distinguish, since the symptoms are similar, says Dr. Lavie. But it’s crucial to seek treatment when you notice joint swelling and pain, as all three types of arthritis can lead to long-term joint damage and other health consequences.
