Knee pain can arise from various conditions, including different types of arthritis and injuries. A burning pain accompanied by knee stiffness and warmth may indicate a gout flare in the knee.
While gout is commonly linked to the big toe, it often flares up in areas already affected by arthritis. According to Dr. Robert Keenan, a rheumatologist, gout can affect different joints and generally progresses upwards in the body if left untreated, starting from the big toe, moving through the ankle, to the knee, and potentially reaching the lower spine.
Gout can impact both knees, but it typically manifests more intensely in one knee, particularly where pre-existing arthritis or wear-and-tear is present.
Let’s delve deeper into the causes of gout in the knee, explore treatment options for pain relief, and discuss preventative measures.
What Triggers Gout in the Knee?
Gout develops when the body has elevated levels of uric acid, a normal waste product. This condition is known as hyperuricemia.
Alt text: Illustration depicting a knee joint affected by gout, highlighting uric acid crystal buildup and inflammation.
Typically, uric acid is eliminated from the body through the kidneys. However, in some individuals, uric acid levels remain high, leading to accumulation and crystallization in various joints. When these uric acid crystals accumulate in the knee joint, it can trigger gout symptoms, causing the knee joint to become red, swollen, and warm to the touch. This buildup can also restrict the knee joint’s full range of motion, making walking difficult.
Several factors can influence your risk of developing gout.
Genetic Predisposition and Family History
Research has increasingly demonstrated a link between genetic factors and high uric acid levels. A 2012 study revealed that individuals with gout often share similar variations in genes affecting kidney function. A 2018 study further identified multiple genes that influence the body’s uric acid elimination process.
Impact of Medications
Certain medications, such as diuretics for high blood pressure or cyclosporine, an immunosuppressant drug for transplant patients, can contribute to elevated uric acid levels.
Co-existing Health Conditions
Underlying health conditions, including obesity, insulin resistance, high cholesterol, heart disease, and kidney disease, are associated with gout and should be considered in individuals with the condition.
The Role of Diet
Certain foods and beverages are high in purines, which are broken down into uric acid during digestion. Limiting high-purine foods may help prevent gout flares, but Dr. Keenan emphasizes that long-term dietary changes alone may not sufficiently control uric acid levels. The impact of diet changes on uric acid levels is usually less significant than that of medications aimed at lowering uric acid and reducing gout flares. Foods high in purines include certain seafood, organ meats, alcohol, and sugar-sweetened beverages.
Age and Sex Influence
According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, age and sex are also risk factors for gout. Gout is more prevalent in men than in women, although women can also develop gout, particularly after menopause. While gout typically develops in middle age, it can also affect younger individuals.
Link to Previous Injuries
Individuals with prior knee joint injuries may be more prone to developing gout in the knee. Injured joints can develop degenerative arthritis or osteoarthritis earlier than expected, creating an environment where uric acid crystals are more likely to accumulate.
Prevalence of Gout in the Knee
If left untreated, gout often progresses upwards in the body, as Dr. Keenan explains.
Research indicates that approximately 50 percent of patients experience their first gout attack in the big toe. If gout worsens, secondary flares occur in the knee in 35 percent of cases, the midfoot and ankle in 40 percent, elbows and wrists in 30 percent, and fingers in 15 percent.
It is not uncommon for individuals to experience their initial gout flare in the knee and subsequently exhibit signs of gout in the foot after diagnostic imaging such as X-rays or ultrasounds.
Gout can affect both knees, but the pain is often more intense in one knee, particularly where arthritis from general wear is more severe.
Alt text: Image showing a foot affected by gout, characterized by redness and swelling in the big toe joint.
Differentiating Gout Knee Pain from Other Conditions
Most individuals with gout in the knee experience severe pain during a gout attack, accompanied by noticeable swelling, redness, and warmth.
The pain may develop at night and persist continuously for up to two weeks before subsiding, with the most intense pain occurring within the first 24 hours. Without treatment, typically involving medication to lower uric acid levels, gout flares will recur and affect more joints, including the knee.
While the exact reasons for more frequent nighttime gout flares are unknown, a 2015 study suggests it may be related to decreased body temperature at night, potentially increasing the likelihood of uric acid crystallization.
While gout pain is distinct, other causes of knee pain should be considered.
Pseudogout (Calcium Pyrophosphate Arthritis)
Knee pain may be caused by the buildup of calcium pyrophosphate crystals. Doctors can examine fluid in the inflamed knee to determine whether the crystals are uric acid or calcium pyrophosphate.
Septic Arthritis
Septic arthritis, an infectious condition, inflames a joint due to bacterial or fungal invasion. It typically affects the knee, hip, or other large joints, and requires prompt treatment with drainage and intravenous antibiotics until the infection clears.
Cellulitis
This bacterial skin infection can cause red, inflamed, and painful knee swelling, resembling gout symptoms. Cellulitis testing involves blood or affected skin examination, rather than fluid extraction, which could spread the infection.
Rheumatoid Arthritis
Joint pain may stem from rheumatoid arthritis (RA), an autoimmune or inflammatory type of arthritis. Unlike gout pain, RA pain is often symmetrical, affecting the same joints on both sides of the body simultaneously. It is also characterized by morning joint stiffness that improves throughout the day. RA commonly starts in the small joints of the fingers and toes, but it can also affect the knees.
Psoriatic Arthritis
Psoriatic arthritis (PsA) is an inflammatory arthritis that can cause pain and swelling in the knees and other joints. PsA is also associated with obesity, high blood pressure, and high blood sugar, common comorbidities in gout. However, individuals with PsA typically exhibit psoriasis and other symptoms like changes to the fingernails and toenails.
Iliotibial Band Syndrome
Inflammation of the iliotibial band, which runs along the outer leg from hip to ankle, can cause pain on the outside of the knee, commonly affecting distance runners or individuals new to exercise.
Previous Injury
Old knee injuries that have caused conditions like tendinitis, bursitis, meniscus tears, or bone fractures can result in pain that may be mistaken for gout.
Diagnosing Gout in the Knee
Dr. Keenan emphasizes the importance of seeking prompt medical attention for any gout-like pain in the knee. While primary care physicians often treat gout, they may not immediately associate knee pain with gout, especially without an active flare during the visit. Visiting a rheumatologist may be beneficial if you have a history of gout flares and are experiencing 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 reviewing your history and examining your knee, your doctor may order blood tests to check uric acid levels and a joint fluid test to check for uric acid crystals. X-rays, MRIs, or CT scans of your knee may also be performed to identify other potential causes of joint inflammation.
Treatment Options 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 typically 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)
- Febuxostat
- Probenecid
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.”
