The knee is the connection between the thigh bone (femur) and the shin bone (tibia). The joint is stabilized by four ligaments the ACL, PCL, MCL and LCL. The joint is also cushioned by two interior pillow like C-shaped structures called the lateral meniscus and medial meniscus. These lie directly on top of the tibia (shin bone) and are stabilized by the surrounding tissues.
Occasionally, these menisci are torn. This can occur with an acute trauma or with degenerative conditions/cumulative damage. The symptoms of a tear of the meniscus can include pain along the joint line and occasionally clicking, catching or locking of the knee. There may also be some associated swelling of the knee, called an effusion. This is secondary to the injured knee producing an increased amount of joint fluid which distends the knee joint capsule. This often leads to a sensation of fullness and decreased range of motion.
Anatomically, the menisci have a blood supply to the outer third of the C-shaped rings and no blood supply to the inner two thirds of the rings. Secondary to this blood supply, tears on the inner two thirds of the ring will not heal, even with a surgical repair. Because of this, tears on the inner two thirds of the meniscus will usually only be debrided if surgery is necessary. Tears of the meniscus on the outer one third, which has a blood supply usually will heal with a repair and are not usually excised.
The decision for meniscal tear surgery, depends of the patient’s functional demands, the symptoms that the patient is experiencing, the presence of additional knee injuries (arthritis or ligament damage) and whether other appropriate treatments have failed.
Arthroscopic Meniscal Tear Surgery
When a meniscal surgery is necessary, it is usually done as an outpatient with arthroscopic techniques. Two small incisions are made in the front of the knee and through the use of a camera and small instruments inserted through these incisions, the meniscus is debrided or repaired. Upon completion of the surgery the knee will be wrapped in a compressive dressing to keep the swelling down in the knee. Additionally a compressive stocking will be placed on the extremity. This should be worn until normal mobility has returned. Additionally, unless contraindicated, aspirin should be taken daily to help prevent the formation of blood clots in the extremity.