Knee pain can be a common symptom of several types of arthritis, as well as many other conditions or injuries. If your knee stiffness is accompanied by a burning pain and is warm to touch, you may have a gout flare in the knee.
Though gout is most often associated with the big toe, “gout tends to flare in areas that already have arthritis,” says Robert Keenan, MD, a rheumatologist with Articularis Healthcare in Summerville, South Carolina. Although gout can strike in many different joints, “as a general rule, gout works its way up the body. If it’s not treated, it works its way up from the big toe, through the ankle, to the knee, and then to the lower spine and so on.”
Gout can affect both knees, but typically is felt more strongly in one knee — say, where you may have arthritis wear-and-tear to begin with.
Learn more about what causes gout in the knee, as well as ways to treat the pain and prevent it in the future.
What Causes Gout in the Knee?
Gout develops when the body has high levels of uric acid, a normal waste product. This is known as hyperuricemia.
Uric acid is normally excreted through the body via the kidneys, but in some people, levels can remain high and uric acid can start to accumulate and crystallize in various joints. When these uric acid crystals affect the joint in the knee, it can cause gout symptoms in the knee, making the knee joint red, swollen, and hot to the touch. The buildup of uric acid can also impair the knee joint’s full range of motion, which can make it difficult to walk.
A number of factors can influence your risk for gout.
Genes and Family History
Research over the past decade has increasingly identified a link between a genetic predisposition and high uric acid levels. For example, in a 2012 study, researchers looking at a large number of people’s unique genomes (a person’s set of genetic instructions) found that patients with gout often shared a similar variation on a gene that affects kidney function. A 2018 study further identified several genes that influence how the body gets rid of uric acid.
Another factor that contributes to high uric acid levels is taking certain medications, such as diuretics (water pills) for high blood pressure or cyclosporine, an immunosuppressive drug that patients with a transplanted organ take.
Underlying Health Conditions
Health conditions such as obesity, insulin resistance, high cholesterol, heart disease, and kidney disease are linked with gout, and should be looked for in people with gout.
Certain foods and drinks are high in purines, which get broken down into uric acid during digestion. Although avoiding or limiting consumption of foods high in purines may help prevent gout flares, Dr. Keenan notes that that long-term diet changes are not typically enough to adequately control uric acid levels. The impact of diet changes on uric acid levels is usually much lower than that of taking medication to lower uric acid and reduce gout flares and symptoms. High-purine foods include certain seafood, organ meats, alcohol, and sugar-sweetened beverages.
Age and Sex
Other risk factors associated with gout are age and sex, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Gout is more common in men than in women (although women certainly do get gout; it more commonly affects women after menopause). And while gout usually develops in middle age, it can affect younger people too.
People who previously injured their knee joint could be more likely to develop gout in their knee. This is because the injured joint can develop degenerative arthritis or osteoarthritis earlier than it would with aging alone. Osteoarthritis is a type of arthritis that gradually breaks down the cartilage that cushions bones, and this can create an environment where uric acid crystals could more likely deposit.
How Common is Gout in the Knee?
As a general rule of thumb, if left untreated, gout tends to work its way up the body, Dr. Keenan explains.
For example, he cites research that shows 50 percent of patients experience their first gout attack in the big toe. If gout worsens, 35 percent of secondary flares occur in the knee, 40 percent in the midfoot and ankle, 30 percent in elbows and wrists, and 15 percent in fingers.
It’s not uncommon for a person to experience their first gout flare in their knee and, after an X-ray or ultrasound, show signs of gout in the foot, he adds.
Gout can afflict both knees, but typically is felt more strongly in one knee where arthritis from general wear is worse.
Is Knee Pain Due to Gout — or Something Else?
Most people with gout in the knee experience intense pain during a gout attack. Swelling may also be noticeable during an active flare, as well as redness and warmth.
The pain may develop in the night and hurt continuously for up to two weeks before the flare subsides, with the most intense pain in the first 24 hours. But if gout is not treated, typically with medication to lower uric acid levels, gout flares will recur and over time and affect more joints, including the knee.
Doctors can’t say for sure why gout flares occur more often at night but, according to a 2015 study, it might be because your body temperature goes down at night, which could make uric acid more likely to crystallize.
Although the pain of a gout attack is distinct, there may be other reasons for your knee pain you should be aware of.
Pseudogout (Calcium Pyrophosphate Arthritis)
Your knee pain could be caused by buildup of different kinds of crystals called calcium pyrophosphate (the same crystals responsible for calcium kidney stones). Doctors can examine fluid in your inflamed knee to determine if the crystals are uric acid or calcium pyrophosphate.
Read more here about symptoms of pseudogout.
This infectious arthritis inflames a joint when bacteria or fungi invade. Typically, septic arthritis affects the knee, hip, or other large joints, and must be treated quickly through drainage and intravenous antibiotics until the infection clears.
Read more here about septic arthritis.
This bacterial skin infection could lead to the red, inflamed, and painful knee swelling that can look similar to symptoms of gout in the knee. Cellulitis testing requires careful examination of blood or affected skin, not fluid extraction, which could spread the infection.
Read more here about cellulitis and other diseases that mimic gout.
Joint pain can be caused by an autoimmune or inflammatory type of arthritis called rheumatoid arthritis (RA). Unlike gout pain, RA pain is often symmetrical — it affects the same joint on both sides of the body at the same time. It is also characterized by joint stiffness that is worse in the morning but lessens as the day goes on. RA typically starts affecting the small joints in the fingers and toes, but can affect the knees.
Read more here about the difference between rheumatoid arthritis and gout.
Psoriatic arthritis (PsA) is a type of inflammatory arthritis that can cause pain and swelling in your knees and other joints. PsA is also linked to obesity, high blood pressure, and high blood sugar, which are common comorbidities in gout as well. However, people with PsA typically also have psoriasis (an inflammatory condition that causes skin rashes and scaly plaques) and other symptoms, like changes to the fingernails and toenails.
Read here to learn about the differences between PsA and gout.
Iliotibial Band Syndrome
The iliotibial band runs down the outer length of your leg from hip to ankle, and repetitive movement, such as bending, can cause the iliotibial band to be inflamed. This causes pain to the outside of your knee and commonly afflicts distance runners or people new to exercise, according to Cedars-Sinai.
Old knee injuries that have damaged your knee and caused conditions such as tendinitis, bursitis, meniscus tear, or bone fractures can cause pain that could be mistaken for gout.
How Doctors Diagnose Gout in the Knee
Dr. Keenan stresses the importance of talking to a doctor right away if you experience any gout-like pain the knee. Primary care physicians often treat gout, but Dr. Keenan warns that your doctor may not immediately associate knee pain with gout, especially if you don’t have an active flare at the time of your visit. For this reason, if may be more beneficial to visit a rheumatologist if you have a history of gout flares and are experience knee pain.
“It’s important to share a thorough history with your doctor to provide clues toward the right diagnosis,” Dr. Keenan recommends. “Take note about how your flare started and how long it lasted. Try to also take note of any foods you ate right before the flare in case they included those high in purines.”
In addition to taking your history and examining your knee, your doctor may also order a blood test to check uric acid levels and a joint fluid test to check for uric acid crystals. An X-ray, MRI, or CT scan of your knee may also be done to help identify other possible causes of joint inflammation.
Treatments for Gout in the Knee
“The goal of gout treatment is to get rid of the uric acid crystals,” Dr. Keenan says. “Once you get rid of the reason for your pain, you will typically regain function and your overall health will improve.”
Gout pain is generally treated in two ways:
- Medications to relieve gout attacks in the short-term
- Preventive medications taken regularly to lower uric acid and stop gout attacks from occurring
While inflammation-fighting drugs (NSAIDs, colchicine, and glucocorticoids) are used to relieve pain during gout flares, different medicines are used to lower uric acid levels to prevent future attacks. These include:
- Allopurinol (the most commonly used medication to lower uric acid levels)
Another medication called pegloticase (Krystexxa) may be recommended for people with chronic gout who have not responded to other uric acid-lowering medication.
For most people, the goal is to get uric acid levels below 6 mg/dL. In some especially severe gout cases, such as when someone has tophi, the goal is a uric acid level below 5 mg/dL.
Allopurinol is the preferred first-line agent for urate-lowering treatment according to recommendations outlined in the 2020 American College of Rheumatology Guideline for the Management of Gout.
Your physician may also discuss certain dietary and lifestyle changes you could take to help control your gout. Dr. Keenan recommends avoiding high-purine foods, alcohol, and sugary drinks as part of this healthy diet. He also says keeping a healthy weight is especially important for people with gout in the knee, as it reduces extra stress on the knee joint.
If left untreated, gout can continue to cause severe pain and may spread throughout your body, resulting in permanent damage to your joints and bones.
“Gout is very common and very treatable,” Dr. Keenan says. “If you experience persistent joint pain in the knee or elsewhere and you are not being treated for it, ask to be referred to a rheumatologist who can more specifically diagnose if your pain is gout.”
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