What Is Osteoarthritis?by Jerilyn Covert Health Writer
Everyone’s joints wear down with age. That’s life! But for some, the damage can lead to osteoarthritis (OA). “A joint is where two bones meet, allowing movement of our body,” explains Soo Kim, M.D., medical director of the Johns Hopkins Musculoskeletal Center in Baltimore. “Between those bones is cartilage that acts as a cushion. As we get older, or with trauma, that cushion gets worn out or damaged.” Without cushion, the bones begin to rub together, causing pain, inflammation, and sometimes bony growths. While you can’t stop the process, read on to learn how to slow it down and manage the pain.
OA = Damage to Joint Cartilage
Unlike most of the body’s tissues, which can regrow when damaged, cartilage has a very limited blood supply, hampering its ability to regenerate, says Dr. Kim. As cartilage breaks down, it loses collagen and proteoglycans, molecules responsible for the spongy, cushion-y qualities that allow it to absorb force, says Clifton Bingham, M.D., director of the Johns Hopkins Arthritis Center. It becomes dry and flaky, and small pieces may break off, irritating the thin tissue lining the joint (synovium) and leading to painful inflammation, Dr. Bingham says.
It Can Happen to Large and Small Joints
Any joint can be affected by OA—the most common form of arthritis, in fact—but it typically occurs in joints that experience the most stress and repetitive movement, such as joints in the hand (especially the joint near your fingertip, the middle finger joint, and the base of the thumb) as well as the weight-bearing joints of the knees, hips, and spine, says Dr. Kim. Joints that have been previously injured have increased risk of developing OA—so if you blew out your knee playing soccer in high school, it’s at higher risk for OA later in life than your other knee.
It Hurts, Especially When You Move
Symptoms tend to develop slowly, and may come and go, says Dalit Ashany, M.D., a rheumatologist at the Hospital for Special Surgery in New York City. Generally, they’re worse in the evening, simply because you’ve been using your joints all day. If cartilage wears completely away and bones start grinding against each other in OA, the pain may start to feel more “mechanical” or sharp than what you experience with RA, says Dr. Kim, and it will always happen with movement, regardless of the time of day.
Pain Can Take on a Few Different Forms
Disintegration of cartilage triggers the release of chemicals that cause a pain response. You may feel an “achy” or “throbbing” sensation in your joint, says Dr. Kim, particularly when you move it. Hip OA can be tricky, though—pain may show up elsewhere, like in the groin, buttocks, front of the thigh, or lower back. OA (particularly of the knee) can also cause a grating or crackling sensation known as crepitus.
It’s Not the Same as Rheumatoid Arthritis
While OA does cause some inflammation, it’s typically not enough to produce the same amount of redness, warmth, and swelling found in more inflammatory forms of the disease, like rheumatoid arthritis (RA). That’s because RA is an autoimmune disease, meaning it affects the immune system, so inflammation levels will be much higher.
It’s Hard to Get Moving in the Morning
Experiencing “stiff” joints upon waking up in the morning, or after sitting for prolonged periods, is a classic symptom of arthritis, says Dr. Kim. Weirdly, though movement can exacerbate OA pain throughout the day, it actually improves stiffness in the morning. But an inflamed synovial membrane can take a little longer to work. Because inflammation levels tend to be lower in OA than in RA, morning stiffness tends not to last as long—OA lasts less than 30 minutes, while RA usually lasts longer, says Dr. Kim.
You May Develop Bony Growths
When cartilage wears away, bone cells are activated to create new bony growths—called osteophytes—along the existing bone, says Bill Robinson, M.D., chief of immunology and rheumatology at Stanford Health Care. As a result, the shape and contour of the bone can change. Most bony growths are not noticeable at first, except on an X-ray. But over time, you may notice the joint feels harder and looks bigger than it used to, Dr. Robinson says.
X-rays Help Diagnose OA
Your medical history, a physical exam, and X-rays will be needed to help diagnose OA, says Dr. Kim. During the exam, the doctor will look at your joints and move them to test what movements produce pain. (If movements that compress the joint cause pain, OA is likely, says Dr. Kim.) X-ray images can reveal if the space between the bones is getting narrower—a sign of cartilage loss. An MRI usually isn’t needed, but can provide more detailed images of tendons and surrounding tissues—useful if your doc wants to look for early signs of degeneration, says Dr. Kim.
Meds Can Help Ease Pain
OA can’t be reversed. But treatments can reduce pain and help you stay active. For some, oral pain medications like Tylenol (acetaminophen) or nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen may help, says Dr. Kim. Those who can’t take oral NSAIDs (due to heartburn, stomach ulcers, or kidney or liver disease) may consider a prescription topical NSAID like diclofenac, says Dr. Ashany. OTC topicals, like lidocaine or capsaicin (an extract from chile peppers!), applied over the joint may help as well, says Dr. Ashany.
Injections Can Also Bring Relief
If oral or topical treatments don’t work, your doctor may suggest injecting corticosteroids or hyaluronic acid (a gel that mimics joint fluid), says Dr. Kim. Steroids can be injected up to three times a year, and may provide several months of pain relief, says Dr. Ashany. Hyaluronic acid injections are typically done once a week for about a month, and may provide relief lasting up to six months.
Nondrug Therapies? You Guessed it: Exercise and Weight Loss
Strengthening the muscles around the affected joint can take the stress off it, says Dr. Kim. Lifting weights is a great option, though depending on your pain level you may prefer low-impact exercise like swimming or aqua aerobics. And maintaining a healthy weight is key: Every 1 pound of extra body weight puts up to 4 pounds of stress on the joints, says Dr. Kim, and also promotes inflammation. In fact, says Brian Feeley, M.D., an orthopedic surgeon at UCSF Health in San Francisco, higher-BMI patients with OA who lose even a moderate amount of weight can delay joint-replacement surgery for years.
Down the Road, Surgery May Be Necessary
Once non-surgical options have been exhausted, joint-replacement surgery might be your best bet for pain relief, says Dr. Feeley. That’s when the damaged part of the joint is removed and replaced with metal or plastic parts creating a buffer between your bones so they no longer rub together. “It doesn’t restore you to a point in time where you had no injury,” Dr. Feeley notes. “But most patients are happy with the results.” Patients younger than 55 or who are extremely active may be candidates for a different type of surgery called osteotomy, where the hips or knees are surgically realigned by removing or adding bone, says Dr. Feeley.