Do your knees feel stiff and achy when you wake up in the morning or after you’ve been walking a while? You might wonder if it’s arthritis. Most symptoms of knee arthritis come on gradually. You might notice pain or stiffness after a workout or when you first get out of bed in the morning that gradually improves as you move around. The symptoms may come and you might chalk it up to exercising too hard. However, knee arthritis can also come on suddenly, though this is less common than a gradual onset.
But there’s something you might not know. Arthritis isn’t a single entity; there are over 100 distinct types of arthritis, but they all have something in common. Each damages joints to varying degrees. The symptoms can be mild or, less often, severe. Certain types of arthritis are more likely to affect the knee joints, too. Here are five you should know about.
Osteoarthritis
This is by far the most common type of arthritis that affects the knee joint, and other joints in the body. How common is osteoarthritis? Around a third of adults over the age of 65 have it in their knees, although not all have symptoms. Osteoarthritis is due to the breakdown of the articulate cartilage that surrounds the ends of bones and helps cushion the bones and reduce friction when the bones move. It’s a degenerative process, although scientists now believe that there’s an inflammatory component to osteoarthritis too.
Why does osteoarthritis cause pain and stiffness? As the cartilage breaks down because of degeneration and inflammation, the bones have less cushioning to keep them from rubbing against each other. You might notice the gradual onset of knee pain after activity. At first, the discomfort may get better with rest, but if it progresses, you might have stiffness and pain much of the time. You might also find climbing stairs and standing for long periods of time triggers symptoms.
People with osteoarthritis of the knees also complain of knee stiffness when they first wake up in the morning that gradually clears as they move around. If it’s osteoarthritis, the stiffness and discomfort usually resolve within 30 minutes after awakening and moving around. In more severe cases, there may be slight swelling around the affected knee and the knee might feel warm to the touch. However, warmth and swelling are less common than with other types.
Post-Traumatic Arthritis
Post-traumatic arthritis is a sub-type of osteoarthritis brought on by a prior injury to the knee. Once you’ve injured a knee, you’re more prone to develop arthritis in the knee joint. The symptoms are similar to osteoarthritis but affect only the knee with a previous injury. However, you may also experience weakness in the knee, reduced range-of-motion, or the knee may buckle. The most common types of injury that lead to post-traumatic arthritis are a fracture or a ligament tear in the knee.
Rheumatoid Arthritis
A less common type of arthritis that affects the knee is rheumatoid arthritis, an inflammatory type of arthritis. However, rheumatoid arthritis is more likely to affect other joints too, including the fingers, hands, and wrists, and cause pain, stiffness, and swelling. Rheumatoid arthritis has a genetic component and is two to three times more likely to affect women than men. It also often appears at a younger age relative to osteoarthritis, often striking between the ages of 30 and 50.
Unlike osteoarthritis, which frequently affects one knee, rheumatoid arthritis is more likely to affect both knees, as opposed to one, and multiple joints in the body. People with rheumatoid arthritis are also more likely to experience systemic symptoms such as fever, fatigue, and anemia. Because rheumatoid arthritis is an inflammatory disease, that’s autoimmune, it can affect organs too. For example, people with rheumatoid arthritis have a 50% greater risk of developing cardiovascular disease. The reason? Rheumatoid arthritis has a strong inflammatory component and inflammation can damage other tissues in the body, including the inner walls of blood vessels.
Reactive Arthritis
Reactive arthritis is a type of joint inflammation triggered by another infection, usually an infection of the intestinal tract or urinary tract. For example, people sometimes develop reactive arthritis after a bout of food poisoning. Some sexually transmitted diseases can also cause reactive arthritis. Research shows reactive arthritis is more common in people under the age of 40 than older people, and there’s a genetic tendency to develop arthritis after an infection.
The knees are the most common site where reactive arthritis develops, although the ankles and feet can also be affected. If you have reactive arthritis, you might experience pain or stiffness in your knees, ankles, back, and other joints. Some people experience inflammation of the conjunctiva of their eyes or a skin rash.
Fortunately, reactive arthritis usually goes away on its own, although the symptoms can last up to a year after they begin.
Gouty Arthritis
Gouty arthritis is another relatively common form of arthritis that can cause swelling and stiffness in the knee joints, although the most common joint involved is the big toe. Gouty arthritis is caused by monosodium urate crystals depositing in the joints, leading to inflammation. Most people who develop gouty arthritis have an elevated uric acid level. It’s more common in men and in women after menopause. You’re less susceptible before menopause because it’s easier for your body to eliminate excess uric acid.
How do you know if your knee pain is gouty arthritis? Only a health care professional can tell you for sure, but if it’s gouty arthritis, your joints might feel red, painful, swollen, and warm to the touch. It’s also not uncommon to have pain in more than one joint when you have gout.
The Bottom Line
Don’t try to guess what kind of knee pain you have. It’s best to get a medical evaluation, especially if you have problems bearing weight, redness, swelling, or your knee is giving out. Some forms, like reactive arthritis of the knee and gouty arthritis, are self-limited, but gouty arthritis can keep coming back. Rheumatoid arthritis and osteoarthritis are usually chronic. Even if you have healthy knees, take care of them, by exercising in the proper shoes and by keeping your weight down, and strengthening your quadriceps.
References:
- org. “Difference Between Osteoarthritis and Rheumatoid Arthritis”
- com. “Arthritis in the knee: What you need to know”
- Am Fam Physician. 2011 Jun 1;83(11):1287-92.
- Am Fam Physician. 2011 Dec 1;84(11):1245-52.
- Mayo Clinic. “Reactive Arthritis”
- Johns Hopkins Arthritis Center. “Symptoms and Diagnosis of Gout”
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