A meniscus is a structure located in your knee joint that functions as a shock absorber. You have two of them in each knee and they are prone to tearing. When the meniscus is torn, it produces a sharp stabbing pain and sometimes it will cause your knee to click or even lock. Many times swelling is associated with a meniscal tear.
The treatment for a meniscal tear is a knee arthroscopy. That is the procedure where I go in and remove the torn part of the meniscus. On occasion the meniscal tear can actually be repaired or sutured back together but that is only rare. The reason why the meniscal tears are typically not repaired is because the meniscus does not have a good blood supply. So if I place sutures in the meniscus it would just not heal. There is a part of the meniscus that is very vascular and has a good blood supply. If the tear occurs in that area then the meniscus can be repaired versus just removing the part that is torn.
The meniscus has shock absorbing qualities but once it is torn, the area where the tear is located no longer provides any shock absorbency. The only thing the torn meniscus provides is pain.