Knee pain is a common complaint, and discomfort on the inside of the knee can be particularly bothersome. The knee is a complex joint, integrating bones, ligaments, tendons, and cartilage that all work together to facilitate movement and bear weight. Various issues can lead to pain in its medial, or inner, aspect. Understanding the specific causes of this pain can help in identifying potential issues and deciding when to seek medical advice.
Common Injury-Related Causes
Acute injuries frequently result in immediate pain on the inside of the knee. These incidents often involve sudden forces or movements that exceed the knee’s normal range of motion. Two common structures susceptible to such injuries are the medial collateral ligament and the medial meniscus.
Medial Collateral Ligament (MCL) Sprain
The medial collateral ligament (MCL) is a broad, thick band of tissue located on the inner side of the knee. Its primary function is to resist forces that push the knee inward, helping to stabilize the joint. An MCL sprain typically occurs when a direct blow to the outer side of the knee or a strong valgus (inward bending) force stretches or tears this ligament. Common symptoms include pain, swelling, and tenderness along the inner knee, sometimes accompanied by a popping sound. The knee may also feel unstable, especially when bearing weight.
Medial Meniscus Tear
The medial meniscus is one of two C-shaped pieces of cartilage within the knee joint, acting as a shock absorber and helping to distribute weight evenly across the joint. A tear in the medial meniscus often results from twisting the knee, deep squatting, or direct impact. Symptoms can include sharp pain, clicking, or a catching sensation within the knee. Swelling and stiffness may develop gradually, and the knee might feel as though it is locking or giving way.
Inflammatory and Overuse Conditions
Pain on the inside of the knee can also arise from conditions that develop gradually due to repetitive strain or inflammation. These are typically not linked to a single traumatic event but rather to ongoing stress on the knee structures. Several such conditions affect the medial aspect of the knee, including pes anserine bursitis, medial plica syndrome, and adductor tendinopathy.
Pes Anserine Bursitis
Pes anserine bursitis involves inflammation of the pes anserine bursa, a small fluid-filled sac located below the inner knee joint, beneath the tendons of three hamstring muscles. This bursa acts as a cushion, reducing friction between tendons and bone. Inflammation often occurs due to overuse, repetitive motion, or tight hamstring muscles, and it is more common in athletes and individuals with osteoarthritis or obesity. Symptoms include tenderness, swelling, and pain on the inner side of the shinbone, which often worsens with activities like climbing stairs or standing from a seated position.
Medial Plica Syndrome
Medial plica syndrome involves irritation or inflammation of the medial plica, which is a fold in the joint lining of the knee. If a medial plica becomes irritated or thickened, it can get pinched between the bones during knee movement. This can lead to aching pain on the inner knee, a clicking or snapping sensation, and sometimes a feeling of the knee locking. Repetitive flexing of the knee, common in certain activities, can contribute to its irritation.
Adductor Tendinopathy
Adductor tendinopathy can contribute to discomfort in the inner knee area. The adductor muscles are located on the inner thigh, and their tendons attach near the inner knee. Repetitive activities like running or cycling can lead to inflammation or degeneration of these tendons, causing pain that may radiate to the medial knee. This condition is characterized by tenderness along the inner thigh, often exacerbated by movements that engage the adductor muscles.
Degenerative Conditions
Chronic and progressive conditions can also be a source of inner knee pain, often worsening over time. These conditions involve the gradual breakdown of joint components rather than acute injury or inflammation. A prominent example is medial compartment osteoarthritis.
Medial Compartment Osteoarthritis
Medial compartment osteoarthritis is a “wear and tear” condition where the protective cartilage on the inner side of the knee joint gradually deteriorates. As the cartilage wears away, the bones can rub directly against each other, leading to pain, stiffness, and inflammation. Symptoms commonly include pain that worsens with activity, stiffness after periods of rest, and reduced range of motion. Swelling and a grinding or crackling sensation (crepitus) may also be present. This condition is often associated with aging, previous knee injuries, or excessive weight, as these factors increase stress on the joint.
When to Seek Professional Help
Recognizing when to consult a healthcare professional for inner knee pain is important for proper diagnosis and management. While some mild pain may resolve with rest, certain symptoms warrant medical attention. Prompt evaluation can prevent minor issues from becoming more serious or address underlying conditions that require specific treatment.
You should seek professional help if you experience:
- Severe pain that prevents you from bearing weight on your knee.
- Your knee appears visibly deformed.
- Significant swelling, especially if it develops suddenly.
- The knee feels warm to the touch or is red.
- Your knee locks, catches, or feels like it is giving way.
- Pain persists despite rest and home care.
- Numbness or tingling in your leg or foot.