Knee pain, particularly on the inner side (medial aspect), can arise from various structures and conditions. This area of the knee involves several components that provide stability and movement. Understanding the potential origins of this pain is a first step toward finding relief and appropriate management.
Key Structures of the Inner Knee
The inner knee houses several key structures that can contribute to pain when injured, including the medial collateral ligament (MCL). The MCL is a band of tissue on the inner side, connecting the thigh bone (femur) to the shin bone (tibia), and it stabilizes the knee joint against inward forces.
The medial meniscus, a C-shaped cartilage, sits between the femur and tibia on the inner knee. It acts as a shock absorber, distributes weight, and contributes to knee stability and smooth movement.
The pes anserine bursa is a fluid-filled sac located on the inner knee, about two inches below the joint line. It cushions the tendons of three muscles—the sartorius, gracilis, and semitendinosus—where they attach to the shin bone, reducing friction during knee movement.
Primary Conditions Causing Inner Knee Pain
Injuries to the medial collateral ligament (MCL) are a common cause of inner knee pain, often from a direct blow to the outside of the knee or a sudden twisting motion. These injuries range from a grade 1 sprain (stretching) to a grade 3 tear (complete rupture). Symptoms include pain, tenderness along the inner knee, and sometimes swelling, often worsening with knee movement.
Medial meniscus tears are another common cause of discomfort on the inner knee. These tears can occur acutely from a forceful twisting injury, often from a planted foot and twisting knee, or gradually due to age-related cartilage degeneration. Individuals may experience pain, swelling, a catching or locking sensation, and difficulty fully extending or bending the leg.
Medial compartment osteoarthritis is a degenerative condition where inner knee cartilage wears away. This causes increased friction between the bones, leading to pain, stiffness, and reduced mobility. Pain often worsens with activity and improves with rest; individuals might notice a grinding sensation or swelling. It progresses slowly.
Pes anserine bursitis is inflammation of the pes anserine bursa, causing pain and tenderness on the inner knee, a few inches below the joint. This inflammation often arises from overuse, repetitive activities like running or cycling, or direct trauma. Osteoarthritis, obesity, or tight hamstrings can also contribute. Pain is usually localized and may worsen with activities like climbing stairs or sleeping on the affected side.
Other Potential Sources of Inner Knee Pain
Medial plica syndrome is irritation or inflammation of a plica, a fold in the knee’s synovial membrane. Plicae can become symptomatic if repeatedly irritated by repetitive knee movements. This can cause clicking or tenderness on the inner knee.
Pain originating from the hip or lower back can sometimes be perceived in the inner knee, known as referred pain. Conditions like hip osteoarthritis or nerve compression in the lumbar spine can cause knee discomfort, even if the primary problem is elsewhere. It often follows a nerve pathway and may not have local knee swelling or tenderness.
Stress fractures in the tibia (shin bone) can also cause inner knee pain, especially in athletes or those who suddenly increase activity. These tiny cracks develop from repetitive stress when bone remodeling cannot keep up. Pain typically worsens with activity and subsides with rest.
Nerve entrapment, less common, can cause inner knee discomfort if nerves are compressed or irritated. For instance, the saphenous nerve can become entrapped in the thigh or knee. This can cause burning pain, numbness, or tingling on the inner knee or lower leg.
Understanding When to Seek Professional Help
Knowing when to consult a healthcare professional for inner knee pain is important for accurate diagnosis and effective treatment. Persistent pain not improving with rest or self-care warrants medical evaluation. Significant swelling, warmth, or redness also indicates professional assessment.
Seek immediate medical attention if pain is severe, you cannot bear weight, or the knee feels unstable or gives way. A clicking, popping, or locking sensation preventing full knee movement also suggests professional diagnosis. While understanding causes is helpful, a healthcare provider can conduct a thorough examination and recommend imaging or tests to pinpoint the discomfort’s source and guide treatment.