The cause of knee pain can generally be broken down into two main categories. With the first, you’ve experienced an acute injury, such as with a broken bone or a torn ligament. With the second, there is normal wear and tear or stress on the knee, such as with osteoarthritis, patellar syndrome, or tendinitis.

Two of the most common injuries to affect the knee are a torn ACL and a torn meniscus. Both the ACL and meniscus typically act as stabilizers for the knee, so when they become damaged, it causes instability and intense pain. If your pain followed an acute physical injury, you may be suffering from one of these conditions.