A burning sensation in the knees indicates an underlying issue rather than a specific diagnosis. While a symptom, its origins vary widely, from minor irritations to more serious conditions. Understanding potential causes can help determine appropriate steps for relief and care.
Understanding the Sensation
A burning sensation in the knee often signals irritation or inflammation within the joint or surrounding tissues. Specialized nerve endings, called nociceptors, detect harmful stimuli like extreme temperatures or mechanical damage. These convert stimuli into electrical signals that travel along sensory neurons to the spinal cord, then to the brain, where they are interpreted as pain. Inflammation releases chemicals that excite these nerve endings, contributing to the burning feeling. This sensation acts as a warning sign that something is amiss within the knee joint.
Common Causes of Burning Knee Pain
One frequent cause of burning knee pain is osteoarthritis, a degenerative joint disease where protective cartilage in the knee wears away. This can lead to bones rubbing together, resulting in pain, stiffness, and a burning sensation. This condition is more common among individuals over 50.
Patellofemoral Pain Syndrome (PFPS), or runner’s knee, often causes burning pain in the front of the knee. It occurs when the kneecap does not align properly with the thigh bone, leading to irritation and inflammation. Overuse or repetitive stress, such as from climbing stairs or squatting, can contribute to PFPS.
Bursitis, the inflammation of small fluid-filled sacs that cushion the joints, can also cause burning knee pain. Inflammation of these bursae, often due to overuse or injury, can cause localized burning and swelling. Prepatellar or infrapatellar bursitis, for example, can lead to burning pain accompanied by noticeable swelling.
Tendinitis involves the inflammation of tendons, which connect muscles to bones. Patellar tendinitis, affecting the tendon below the kneecap, is a common overuse injury, often seen in athletes. This condition typically causes burning pain in the front of the knee, worsening with activity and accompanied by tenderness and swelling.
Less Common but Significant Causes
Nerve impingement or neuropathy can also cause burning knee pain. The saphenous nerve, which provides sensation to the inner knee, calf, and ankle, can become entrapped or irritated. This leads to a burning sensation, tingling, or numbness in these areas.
Meralgia paresthetica, another nerve-related cause, involves the compression of the lateral femoral cutaneous nerve. This condition typically causes burning, numbness, or tingling on the outer thigh, sometimes extending towards the knee. Symptoms are usually unilateral and can worsen with prolonged standing or walking.
Inflammatory conditions like gout and pseudogout can also result in burning knee pain. Gout is caused by high levels of uric acid, leading to crystal formation in joints, including the knee. This typically causes sudden, intense burning pain, along with significant swelling, redness, and warmth. Pseudogout, similar to gout, involves crystal deposits but is caused by calcium pyrophosphate crystals.
Referred pain from the back, such as sciatica, can also present as burning pain in the knee. Sciatica occurs when the sciatic nerve, extending from the lower back down the leg, is irritated or compressed. While commonly affecting the buttocks and back of the leg, the pain, described as shooting or burning, can radiate to the knee.
When to Seek Medical Attention
Seek medical attention if your burning knee pain is severe and limits daily activities. A sudden onset of pain following an injury warrants professional evaluation. Accompanying symptoms such as significant swelling, redness, warmth, or fever and chills are red flags, signaling inflammation or infection. Inability to bear weight on the knee, or if the knee feels like it is locking or giving way, also requires prompt medical attention. If the pain worsens or does not improve with rest over a few days, or if you experience numbness or tingling in the leg or foot, consult a healthcare professional.