Medial knee pain, localized to the inner side of the knee, is a common complaint that frequently arises during daily activities like walking. This discomfort is often directly related to the mechanical load placed on the joint, increasing as the knee bears weight and moves. The inner compartment of the knee houses cartilage, ligaments, tendons, and bursae, all susceptible to injury or gradual wear. Understanding the source involves categorizing causes into sudden structural injuries, repetitive strain conditions, and long-term joint degeneration.
Structural Causes Related to Injury
Sudden, sharp medial knee pain during walking often points to damage to the Medial Collateral Ligament (MCL) or the Medial Meniscus. The MCL is a broad band of tissue along the inner side of the knee that prevents the knee from collapsing inward (valgus stress). An MCL sprain or tear typically results from a blow or a forceful twisting motion.
When the MCL is injured, walking stresses the damaged fibers, causing pain and instability. Even mild sprains cause tenderness directly over the ligament, aggravated by the side-to-side forces of the gait cycle.
The medial meniscus, a C-shaped piece of fibrocartilage, acts as a shock absorber and distributes weight evenly. A tear causes pain when the knee is compressed or twisted, which occurs with every step. Meniscal pain is felt along the joint line and may include mechanical symptoms like clicking, catching, or locking. During weight bearing, the torn cartilage fragment can become pinched between the femur and tibia, generating sharp pain.
Overuse and Inflammatory Conditions
Pain that develops gradually, rather than from a single traumatic event, often stems from repetitive stress leading to inflammation. One condition is Pes Anserine Bursitis or Tendonitis, which affects the area a few inches below the inner knee joint line.
The pes anserine is the attachment point for three tendons (sartorius, gracilis, and semitendinosus). A bursa cushions these tendons from the shinbone (tibia). Tight hamstring muscles increase tension on this site, causing friction and inflammation (bursitis). This pain is aggravated by activities that increase hamstring load, such as climbing stairs or walking.
Another source of gradual inner knee pain is Medial Plica Syndrome. This involves a fold of tissue (plica) that can become irritated due to repetitive knee bending and straightening. As the knee flexes and extends during walking, the inflamed plica rubs against the thigh bone, causing a snapping, popping, or rubbing sensation and localized pain.
Age-Related Joint Wear
For many adults, especially those over 50, the most common reason for inner knee pain while walking is Medial Compartment Osteoarthritis (OA). OA is a degenerative disease characterized by the progressive deterioration of articular cartilage, the smooth surface on the ends of bones. The medial compartment typically bears the majority of the body’s weight, making it the most frequent site for OA to develop.
As the cartilage wears thin, the space between the thigh bone (femur) and shinbone (tibia) narrows, leading to bone-on-bone friction. Walking exacerbates this pain because it is a weight-bearing activity that compresses the joint.
The pain often includes stiffness in the morning or after prolonged rest, which may ease slightly with initial movement but worsens with prolonged walking or activity. Symptoms can also include a grinding or scraping sensation, known as crepitus, and localized swelling.
The biomechanical stress of walking, particularly the slight inward force known as the adduction moment, is correlated with the progression and severity of pain in medial compartment OA.
When to Seek Help and Initial Relief Measures
While many causes of inner knee pain improve with conservative measures, certain signs suggest the need for a professional medical evaluation. Seek medical attention if the pain is so severe that you cannot bear weight on the leg, or if you heard a distinct popping sound when the pain started.
Other concerning symptoms include significant swelling, persistent redness or warmth, or if the knee feels unstable, buckles, or locks up. If pain does not significantly improve after a week of self-care, consult a doctor or physical therapist.
For immediate, temporary relief of new or mild pain, employ the R.I.C.E. protocol:
- Rest the joint by avoiding activities that cause pain.
- Apply Ice to reduce inflammation.
- Use Compression with an elastic bandage.
- Elevate the leg.
Over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs) can help manage pain and reduce localized inflammation.