Sitting between the tibia and femur bones are two menisci, the medial meniscus and the lateral meniscus.
They act as shock absorbers but have other functions as well. Meniscal injuries are common. The medial meniscus is the larger of the two menisci and is less mobile than the lateral meniscus. These factors contribute to the medial meniscus being more prone to tearing. There are a variety of meniscal injuries. The most frequent types are discussed below.
“Bucket handle” tears
These meniscal tears can occur in association with an ACL tear or as an isolated injury. The injury causes a meniscal fragment that displaces into the middle of the knee joint. It prevents the knee from fully straightening or extending, creating so-called “locking” of the knee. In addition to the locking, there is usually pain and swelling. These types of tear are potentially repairable. Early repair often produces the best results in terms of healing of the meniscus.
An injury also causes this type of meniscal damage. With these tears, the flap of meniscus can move and cause pain, mechanical symptoms and irritate the joint. The flap often folds under itself and then causes pain with activity. Usually, this type of tear requires arthroscopic surgery to remove the torn part of the meniscus (called a partial meniscectomy).
An injury, often relatively minor produces this type of rent. Initial treatment may comprise analgesia and avoidance of aggravating activities. If there has been an associated leg weakness, a strengthening program may be helpful. An arthroscopic assessment of the knee may be required if the pain fails to settle. In a younger person, these tears are sometimes repairable. If not, then the torn segment is removed.
Horizontal or “cleavage” tears and splits in a meniscus are common. They occur as the meniscus undergoes degenerative changes that occur with age. They are very commonly associated with knee arthritis. Even though on an MRI scan they are reported as a “tear”, they represent “wear and tear”. Unless there is a displaced component to the tear, they do not require surgery. Previously many of these tears were operated on to “clean out” the knee. There is now a lot of medical evidence that such “cleanouts” do not help. In younger patients, tears of the lateral meniscus, in particular, can be associated with a painful cyst. These frequently require surgery to decompress the cyst and remove the offending piece of meniscus.
Meniscal root avulsions
The meniscus is attached to bone at both the front and back of the tibia. Elsewhere they are attached to the capsule or the lining of the joint. These points of bony attachment are called the meniscal roots or horns. There are two primary varieties. The first variety is a tear of the posterior root of the lateral meniscus that occurs in association with an ACL tear. These require repair at the time of performing an ACL reconstruction. The second occurs at the posterior attachment of the medial meniscus. These occur more frequently in people in their forties or fifties. They may occur with minimal trauma and are characteristically associated with a “pop”. Often the meniscus is extruded from between the two knee bones. As the meniscus no longer functions as it should, it can then relatively rapidly develop arthritis. An individualised approach to the management of these tears is required. These are best repaired arthroscopically in the appropriate circumstances.
Dr Brown has extensive experience and expertise dealing with meniscal injuries and will be able to diagnose and recommend the best treatment options available, including whether surgery will be needed.