Meniscus Injuries of the Knee
1. What is it?
The knee joint has 2 menisci, one on the lateral side that is somewhat circular in shape, and a medial one that is ‘C’ shaped. These sit on top of the tibia (shinbone), and help to connect the tibia with the femur (thighbone).
The menisci are made up of fibro-cartilage and serve a number of purposes including: stabilization of the knee joint, load distribution, and shock absorption.
2. What are the causes/predisposing factors of injury?
There are generally two types of meniscus injuries: traumatic or degenerative.
Traumatic meniscus injuries usually involve people that are younger and involved in contact sports. The common mechanism of injury is a twisting or rotation of the upper leg while the foot remains planted and stationary. This causes tearing of the meniscus.
Degenerative injuries are due to wear and tear of the meniscus or repetitive trauma. This creates defects in the structure, which over time may progress to tears or breakdown of the meniscus.
Most meniscus injuries involve the medial side due to its unique anatomy (it is very securely attached to the tibia), and can also involve the anterior cruciate ligament.
3. What are the symptoms?
Usually joint pain and the inability to straighten the knee are classic symptoms of a meniscus injury. Swelling and a painful click when the knee is bent back and forth may also occur. Severe pain may persist if a piece of the meniscus displaces and becomes trapped between the femur and tibia.
4. What can be done to prevent or treat this injury?
Prevention is difficult for both types of injuries. Avoidance of contact spots or sports such as downhill skiing can reduce the risk of traumatic meniscus injuries, but are not a guarantee, since these injuries can occur suddenly without warning during many types of activities. Degenerative injuries occur over long periods of time and are generally not noticeable until a significant amount of damage has already occurred.
Treatment is divided into 2 categories: surgical or non surgical. The type of treatment depends on the severity of the injury which is usually determined by an arthroscopic exam or an MRI.
Conservative treatment is geared towards reducing pain and swelling, and increasing mobility and muscle strength around the knee joint by doing rehabilitative exercises.
Surgical treatment tries to preserve as much of the meniscus as possible to reduce the risk of osteoarthritic changes in the future, but there is sometimes a need to remove broken off fragments or remove sections that may not heal.