A burning sensation inside the knee can be a perplexing symptom, often signaling that something is amiss within the complex structures of the joint. This specific type of discomfort can arise from a range of underlying issues, varying in severity from minor irritations to more significant conditions requiring medical attention. Understanding the potential origins of this internal burning is an important step toward addressing the symptom effectively.
Understanding the Sensation
The sensation of burning pain within the knee indicates irritation or damage to nerve fibers, inflammation of tissues, or a combination of both. Nerves contain specialized receptors that detect noxious stimuli, and when activated, transmit signals to the brain interpreted as burning.
Inflammation within the knee joint releases chemical mediators that sensitize peripheral nerve endings, contributing to the perception of pain. Structures like the synovial membrane, which lines the joint, and the cartilage, which cushions the bones, do not have many nerve endings themselves, but their damage can lead to inflammation that affects surrounding innervated tissues. Irritation of major nerves passing through or near the knee, such as the saphenous nerve, can also directly cause a neuropathic burning sensation.
Common Causes of Internal Knee Burning
Inflammatory conditions are frequent culprits behind an internal burning sensation in the knee. Osteoarthritis, a degenerative joint disease, involves the breakdown of cartilage, leading to bone-on-bone friction and subsequent inflammation. Similarly, rheumatoid arthritis, an autoimmune disease, causes chronic inflammation of the joint lining, leading to swelling, pain, and a burning sensation. Bursitis, the inflammation of fluid-filled sacs (bursae) that cushion the joint, and tendinitis, the inflammation of tendons, can also produce localized burning pain.
Nerve irritation or damage can directly cause a burning feeling. Nerve impingement, where a nerve is compressed by surrounding tissues, can lead to neuropathic pain. An example specific to the knee is saphenous nerve entrapment, where the saphenous nerve, a branch of the femoral nerve, becomes compressed as it passes through the adductor canal, resulting in burning pain along the inner side of the knee. Referred pain from issues in the lower back, such as a herniated disc, can also manifest as burning in the knee because nerves originating in the spine supply sensation to the leg.
Injuries and overuse can also contribute to this discomfort. A meniscus tear, particularly chronic tears, can cause intermittent burning due to mechanical irritation and associated inflammation within the joint. Ligament sprains, especially if they result in chronic instability or inflammation, may lead to an ongoing burning sensation. Patellofemoral pain syndrome, characterized by pain around the kneecap, often involves irritation of the underlying tissues and can present as a burning discomfort, particularly during activities that load the kneecap. A Baker’s cyst, a fluid-filled sac behind the knee, can sometimes cause a burning sensation if it becomes inflamed or compresses nearby structures.
When to Seek Medical Evaluation
Seek medical evaluation if the internal knee burning is severe or significantly impacts daily activities.
Prompt medical attention is warranted for sudden inability to bear weight, frequent knee buckling, or giving way. Significant swelling, redness, or warmth around the knee joint suggests acute inflammation or possible infection.
Accompanying symptoms such as a fever or chills alongside knee pain could indicate a joint infection, which is a medical emergency. Visible deformity of the knee or a popping sound at the time of injury followed by burning pain also signals a need for professional evaluation. Numbness, tingling, or weakness extending down the leg or into the foot suggests possible nerve involvement. If the burning pain is rapidly worsening, does not improve with rest, or persists despite several days of self-care measures like R.I.C.E. (Rest, Ice, Compression, Elevation), consult a doctor.
General Approaches to Diagnosis and Management
Diagnosing the cause of internal knee burning begins with a thorough medical history and physical examination. The healthcare professional will inquire about the pain’s onset, duration, and aggravating or alleviating factors, along with any associated symptoms. During the physical examination, the doctor will assess the knee’s range of motion, stability, tenderness, and any signs of swelling or inflammation. This initial assessment helps narrow down potential causes and guides further diagnostic steps.
Common diagnostic tools include imaging studies such as X-rays, which can reveal bone abnormalities, fractures, or signs of arthritis like joint space narrowing. Magnetic resonance imaging (MRI) provides detailed images of soft tissues, including ligaments, tendons, cartilage, and menisci, helping to identify tears or inflammation not visible on X-rays. Blood tests might be ordered to check for inflammatory markers or specific antibodies if an autoimmune condition like rheumatoid arthritis is suspected. Nerve conduction studies or electromyography (EMG) may be performed to evaluate nerve function if nerve impingement is a strong possibility.
Management strategies for internal knee burning are individualized based on the diagnosis. Initial approaches often involve conservative measures like rest and activity modification. Physical therapy is frequently recommended to improve knee strength, flexibility, and stability.
Over-the-counter pain relievers such as NSAIDs or prescription medications may be used to manage pain and inflammation. Injections, such as corticosteroids or hyaluronic acid, can provide temporary relief. Surgical intervention is generally considered a last resort when conservative treatments have failed, addressing specific issues like severe cartilage damage, ligament tears, or nerve decompression.