Clinical features

A torn meniscus will usually cause pain on the side of the knee that is localized to the meniscus (at the level of the joint line between the femur and tibia). Swelling of the joint may occur although meniscal tears by themselves usually don't cause a large, tensely swollen knee. However, some swelling can occur the day after the injury and there may be associated stiffness.

Sometimes the knee becomes "locked" in a bent position and is quite painful with attempts to straighten it. This is often caused by the mechanical blockage of the joint from a displaced bucket handle type meniscal tear. The torn fragment actually acts like a wedge to prevent the joint surfaces from moving, hence the knee appears locked.

Any twisting, squatting or impacting activities will pinch the meniscus tear or flap and cause pain. Often the pain may improve with rest after the initial injury but as soon as aggressive activity is attempted the pain recurs. Meniscal tissue doesn't heal (with the exception noted above) due to its lack of a blood supply, so symptoms are persistent until the tear is treated.

The diagnosis of a tear is made based on the history and joint line findings. A doctor can often stress and manipulate the knee joint in a way that provokes the meniscal tear to snap or cause pain which makes the diagnosis likely. Other times an MRI scan will be obtained to visualize the meniscus and assess its integrity. A good MRI scanner has a very high accuracy rate in determining if a tear is present.