The knee is the most frequently injured joint in the body and is essentially a hinge joint between the femur (upper/thigh bone) and tibia (lower/shin bone). It may be injured by direct trauma or indirect trauma, such as sudden stops and pivoting motions which can occur during sports and even everyday life. The “hinge” is supported by 4 major ligaments; anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL) and the lateral collateral ligament (LCL). There are two cartilage structures in the knee known as the medial and the lateral meniscus. These are like hard rubber shock absorbers and serve to allow the flatter tibial surface to conform to the rounder femoral surface. Essentially, the medial and lateral meniscus “cup” the rounded femoral surface.
Tears in the meniscus occur most commonly with twisting injuries as well as frequently along with injuries to the knee ligaments. Rarely does a meniscus tear occur in an area where it can spontaneously heal, therefore, symptomatic meniscus tears frequently require surgery in order to eliminate the pain and dysfunction. When a meniscus tears, it can become unstable and frequently catches or gets pinched as the femur glides back and forth on the tibia. Pain is therefore not necessarily constant with these injuries and, in fact, it is more common to have “episodes” of pain or certain movements that consistently elicit a painful catch.
It is important to realize that meniscus “tears” can also occur as arthritis begins to affect the knee joint. While we call these tears, frequently this just represents a natural breakdown of the meniscal cartilage as the arthritis begins to erode the cartilage in general. These types of tears frequently do not need surgery as management of arthritic symptoms will generally minimize any meniscus symptoms. It is important for your surgeon to determine which type of tear you have, as degenerative tears may not respond as dramatically to surgery as a traumatic tear. Further, these tears are not dangerous nor do they cause further damage to the knee. Occasionally, surgery may be a consideration when degenerative tears of the meniscus do not respond to symptomatic treatment and cause prominent mechanical symptoms.
Surgical treatment involves a procedure called knee arthroscopy. Your surgeon will make 2-3 small incisions on your knee the size of a pencil and insert a camera to visualize the tear. Special micro instruments are then used to either remove the damaged part of the meniscus or place stitches into it. The majority of tears do not occur in the region where the meniscus has good blood supply. What this means is that the tear does not have healing capacity and therefore an attempt at repair may not be successful; in these situations, removal of the damaged segment of meniscus is performed and symptoms typically rapidly improve. If the tear occurs in the vascular zone, a repair may be performed. In some cases, this can be done through the same tiny incisions. In certain tears, a larger incision on the side of the knee may be necessary to complete the repair. The recovery depends heavily on whether a repair or partial removal is performed. In a repair, the repair needs to be protected and so a period of minimal walking/crutch use is often recommended. It may be several months before the knee is ready for vigorous activity and sports. On the other hand, if a partial removal is performed, usually you will be allowed to walk on it immediately and, depending on the activity, return to sports and normal activities may occur within 2-6 weeks.