The MCL, or medial collateral ligament, is the band of tissue on the inside of your knee that connects your thighbone to the bone of your lower leg and keeps the knee from bending inward.
This ligament can be stretched or torn to the point where the knee joint becomes unstable. Injuries to the MCL are usually caused by a force that pushes the knee sideways. These are often contact injuries, but can also occur while doing activities with lots of stop-and-go movements, jumping, or weaving.
Symptoms of a torn or sprained MCL include swelling, bruising, or pain. The pain may increase after some time and it might become harder to bend the knee.
On average, it takes about six weeks for an MCL injury to heal with rest, ice, and anti-inflammatories. Your doctor may suggest that you use crutches and wear a knee brace, while reducing your activities for a few weeks.
A more severe tear may need surgery, but this usually isn’t done unless other parts of the knee are injured as well. Surgery also requires months of rehabilitation to regain strength, range-of-motion, and balance.