Medial Knee Pain and Swelling

By Ben Benjamin, PhD

Question: The medial collateral ligament is contiguous with the knee joint, and therefore causes the knee joint to swell when injured?

Answer: True.

A medial collateral ligament tear can occur at point A, B or C. The more closely a ligament is associated with a joint, the more it signals the joint to swell when injured.

This knowledge comes in handy when other structures on the medial side are injured, but cause no swelling. For instance, if one of the medial hamstrings is injured, causing pain at the medial knee, no swelling occurs. This also is true when the portion of the patellar tendon mechanism (the patella retinaculum or the medial quadriceps expansion) on the medial side is injured, causing pain when climbing stairs.

There are several potential causes of knee swelling associated with medial knee pain. The most common cause is a medial collateral ligament sprain. A sprain of the coronary ligament, which holds the medial meniscus in place, is another possible cause. Of course, there may be a more serious injury causing the swelling, such as a torn meniscus, a sprained cruciate ligament or a loose piece of cartilage or bone trapped inside the joint. It's important to note that knee swelling is not indicative of a strained muscle or patellar tendon.