Pain on the inside of the knee, also known as medial knee pain, is a common issue. It can stem from various sources, from minor strains to significant structural problems within the joint. Understanding these potential origins helps clarify what the discomfort might indicate about the knee’s health.
Understanding the Anatomy of the Inner Knee
The inner side of the knee, also known as the medial aspect, contains several structures that contribute to its stability and function.
One prominent component is the medial collateral ligament (MCL), a strong band of tissue located on the inner side of the knee joint. The MCL connects the thigh bone (femur) to the shin bone (tibia) and helps prevent the knee from bending inward excessively.
Another structure is the medial meniscus, a C-shaped piece of cartilage found within the knee joint. This cartilage acts as a shock absorber and helps distribute weight evenly across the joint surfaces.
The pes anserine bursa is a fluid-filled sac situated on the inner, lower part of the knee, positioned between the shinbone and the tendons of three hamstring muscles. It functions to reduce friction and cushion movement between these tendons and the bone.
The medial compartment refers to the inner section of the knee joint where the ends of the thigh bone and shin bone meet. These surfaces are covered by articular cartilage, which allows for smooth movement.
Common Causes of Inner Knee Pain
Inner knee pain often indicates several common conditions, each with distinct mechanisms and symptoms. Understanding these specific causes helps clarify the nature of the discomfort.
A frequent cause of inner knee pain is a medial collateral ligament (MCL) injury. This injury typically occurs when the knee is subjected to a direct blow to the outside, forcing the knee inward, or from a twisting motion. MCL injuries can range from a mild stretch (Grade 1 sprain) to a partial tear (Grade 2) or a complete rupture (Grade 3). Individuals often report pain directly on the inside of the knee, tenderness to the touch, and sometimes swelling or a feeling of instability, as if the knee might give way. A popping sensation may be felt at the time of injury.
Another common source of pain is a medial meniscus tear. The medial meniscus can tear due to sudden twisting or rotation of the knee, particularly when the foot is planted, or from the natural wear and tear that occurs with aging. Symptoms often include sharp pain on the inner side of the knee, especially during twisting or squatting movements. People may also experience clicking, catching, or locking sensations in the knee, along with swelling and difficulty fully straightening the leg. The pain may not appear immediately but can develop within 24 hours or more after the injury.
Pes anserine bursitis involves inflammation of the pes anserine bursa, the fluid-filled sac located on the lower inner part of the knee. This condition often results from overuse, such as repetitive knee movements in sports, or can be associated with tight hamstrings, abnormal knee alignment, or osteoarthritis. The pain is typically described as an aching sensation on the inner, lower part of the knee, approximately 2 to 3 inches below the joint line. The discomfort may worsen with activity, such as climbing stairs, or at night, and the area might feel tender or puffy to the touch.
Medial compartment osteoarthritis represents wear and tear of the cartilage within the inner section of the knee joint. This degenerative condition develops gradually as the smooth, protective cartilage covering the ends of the bones wears away, leading to bone-on-bone friction. Symptoms include a persistent aching pain on the inside of the knee that often worsens with activity. Stiffness is common, particularly in the morning or after periods of rest, and the knee may also experience swelling, a reduced range of motion, or a grating sensation. This type of arthritis is common because the medial compartment often bears more weight and stress.
When to Seek Professional Medical Advice
While some inner knee pain resolves with rest and home care, certain signs warrant professional medical evaluation. Consult a healthcare provider if you experience severe pain preventing weight-bearing, significant swelling, or instability. A visible deformity of the knee joint also requires immediate attention.
If you heard a distinct popping sound at the time of injury, or if pain does not improve after a few days of rest, seek medical advice. Pain that significantly interferes with daily activities, sleep, or routine tasks also warrants a doctor’s visit. This article provides general information and is not a substitute for professional medical diagnosis or treatment.