A meniscus tear is a common knee injury. The meniscus is a rubbery, C-shaped disc that cushions your knee. Each knee has two menisci (plural of meniscus)-one at the outer edge of the knee and one at the inner edge. The menisci keep your knee steady by balancing your weight across the knee. A torn meniscus can prevent your knee from working right.
A meniscus tear is usually caused by twisting or turning quickly, often with the foot planted while the knee is bent. Meniscus tears can occur when you lift something heavy or play sports. As you get older, your meniscus gets worn. This can make it tear more easily.
There are three types of meniscus tears. Each has its own set of symptoms.
With a minor tear, you may have slight pain and swelling. This usually goes away in 2 or 3 weeks.
A moderate tear can cause pain at the side or center of your knee. Swelling slowly gets worse over 2 or 3 days. This may make your knee feel stiff and limit how you can bend your knee, but walking is usually possible. You might feel a sharp pain when you twist your knee or squat. These symptoms may go away in 1 or 2 weeks but can come back if you twist or overuse your knee. The pain may come and go for years if the tear isn't treated.
In severe tears, pieces of the torn meniscus can move into the joint space. This can make your knee catch, pop, or lock. You may not be able to straighten it. Your knee may feel "wobbly" or give way without warning. It may swell and become stiff right after the injury or within 2 or 3 days.
If you are older and your meniscus is worn, you may not know what you did to cause the tear. You may only remember feeling pain after you got up from a squatting position, for example. Pain and slight swelling are often the only symptoms.