The meniscus is a c-shaped, tough piece of cartilage inside the knee joint. It sits between the ends of the thigh bone (femur) and lower leg (tibia), acting as a shock absorber.

We have a medial meniscus on the inner knee and a lateral meniscus on the outer side of the knee. A meniscus is torn when it becomes trapped between the femur and tibia, usually during a twisting motion. It can happen alongside other injuries such as an ACL tear.

In an acute meniscal injury, you may feel a tearing or popping sensation. It is often painful in the early stages: this pain is usually sharp, stabbing, and be pinpointed to the side of the knee where the tear has occurred. Pain comes on rapidly with twisting movements of the knee but often disappears quickly.

Any swelling is usually worst within a few hours of the injury. If the meniscal tear creates a flap of tissue, it can get trapped in the knee causing a catching or clicking sensation. Occasionally the tear can cause the knee to 'lock': this is where you can’t fully straighten your knee. Sometimes it can be ‘unlocked’ by wiggling and twisting the leg although often it needs surgery to remove or repair the jammed cartilage.

If a tear happens in a knee that also has osteoarthritis, you may have an aching pain on that side of the knee (usually the inner side). This is usually worse with exercise and can also be painful at night. The knee will often click and catch.

A GP, physiotherapist or specialist can diagnose a torn meniscus by asking about your injury, examining your knee, and performing an MRI. The MRI shows whether you have a tear, whether it’s repairable and, whether there is any other cartilage or ligament injury.