A burning sensation on the inside, or medial side, of the knee is a specific symptom that often points toward irritation of soft tissues or nerves rather than simple joint aches. The medial aspect of the knee is home to several structures, including tendons, bursae, and sensory nerves, any of which can become inflamed or compressed. This feeling of heat or burning suggests the involvement of structures highly sensitive to irritation, such as a peripheral nerve, or significant inflammation.
Nerve Irritation and Entrapment
The symptom of burning pain is classically associated with nerve involvement, often termed neuropathy or neuralgia. The saphenous nerve, and more commonly its infrapatellar branch, supplies sensation to the skin over the inner knee and is frequently implicated in this type of pain. This branch is a purely sensory nerve, and its irritation can cause intense, burning discomfort in the anteromedial knee region.
Nerve entrapment occurs when the nerve is compressed or restricted by surrounding tissues, which in this area can include tight fascia or the sartorius muscle. This compression can happen due to repetitive movements, such as those involved in running or squatting, or it can be a complication following knee surgery, as post-surgical scarring can tether the nerve. Activities like kneeling or using stairs can exacerbate the pain, and the skin in the affected area might become unusually sensitive to light touch.
Treatment for this condition typically begins with non-surgical methods aimed at reducing inflammation and improving nerve mobility. Physical therapy techniques, such as nerve gliding exercises, are often employed to help the nerve move freely within its surrounding sheath. Local anesthetic and corticosteroid injections may be used to temporarily relieve the pain and confirm the nerve as the source of the discomfort. In rare, persistent cases where conservative treatments fail, surgical decompression may be considered to release the nerve from the entrapping tissue.
Tendon and Bursa Inflammation
A common soft tissue cause of medial knee pain that can present with a burning component is Pes Anserine Bursitis or Tendinopathy. The pes anserine is the collective insertion point for three tendons (the sartorius, gracilis, and semitendinosus) that attach to the shinbone below the joint line. The associated bursa is a fluid-filled sac that acts as a cushion between these tendons and the bone.
Inflammation in this area, known as pes anserine tendino-bursitis, often arises from overuse or repetitive stress. This is common in athletes, such as runners, or in individuals who have recently increased their activity level. Factors like obesity, tight hamstring muscles, or underlying knee osteoarthritis can also increase friction and pressure on the bursa and tendons, leading to irritation.
While the pain is often described as aching or tender to the touch, the significant inflammation that sometimes accompanies bursitis can manifest as a burning sensation. The pain is typically felt specifically on the inner side of the leg, two to three inches below the knee joint, and may worsen with activities like ascending or descending stairs. Differentiating between bursitis and tendinopathy can be challenging, but both are often managed initially with rest, ice, and physical therapy focused on strength and flexibility.
Structural Wear and Tear
Structural causes affecting the medial knee, primarily Medial Compartment Osteoarthritis (OA), can contribute to a burning feeling, especially in advanced stages. OA is characterized by the breakdown and loss of the smooth, protective cartilage that covers the ends of bones. When this cartilage wears away in the medial compartment, it results in bone-on-bone friction and significant inflammation.
The typical pain associated with OA is a deep, chronic ache that worsens with activity and improves with rest, often accompanied by stiffness. However, the advanced inflammation and mechanical irritation from joint degeneration can cause a secondary nerve irritation or intense inflammatory response. This response is what a person perceives as burning, reflecting the severity of the structural damage.
Risk factors for medial compartment OA include increasing age, a history of previous knee injuries, and excessive load on the joint, such as from obesity. The pain may be accompanied by a grating or crunching sound, known as crepitus, as the joint moves. While treatment for OA focuses on managing symptoms through methods like weight loss, low-impact exercise, and anti-inflammatory medications, the specific burning component may need to be addressed by reducing the overall joint inflammation.
When to Seek Professional Diagnosis
While many minor causes of knee pain can be managed with self-care, certain symptoms warrant a prompt evaluation by a medical professional. A professional assessment is necessary if the burning pain is severe, occurred immediately following a significant injury, or makes bearing weight difficult. A knee that suddenly swells, feels warm to the touch, or appears red may indicate a serious inflammatory condition or an infection, such as septic arthritis.
Other red flags include a fever accompanying the knee pain or a feeling of instability, such as the knee buckling or giving way. If the pain persists for more than a few days despite home care, or if it begins to disrupt sleep or daily activities, consult a healthcare provider. A thorough examination, which may involve imaging or other diagnostic tests, is required to accurately determine the specific cause and lead to an effective treatment plan.