What is a Meniscus?:
Your knee has two C-shaped cartilage structures which act primarily as shock absorbers within the knee joint. One meniscus is located on the medial (inside) side of the knee, the other is located on the lateral (outside) side of the knee. The outer 1/3 of these menisci have a blood supply (called the red zone) and thus when torn, have the best chance of healing, while the inner 2/3 has no blood supply (called the white zone) and thus no ability to heal.
How is the meniscus injured?
In young athletes, the meniscus is most often injured when the knee is compressed and then twisted. It can also be injured in combination with ligamentous injuries such as an anterior cruciate ligament (ACL) tear.
In older athletes, as the meniscus tends to wear down, sometimes a degenerative tear can occur with very little trauma such as a mild twisting or hyperflexion of the knee. This is frequently found in association with arthritis of the knee joint. Statistics show that around 61 in 100,000 people get a meniscus tear. It is one of the most common injuries seen by orthopedic surgeons treating knee injuries.
How is a meniscus injury diagnosed?:
Often, when a meniscus is torn, the athlete will experience a sudden sharp pain along the inside or the outside of the knee depending on which meniscus is torn. This can be associated with symptoms such as swelling, locking of the knee and pain with extremes of flexion or extension. Your orthopedic surgeon may order an MRI (magnetic resonance imaging) which provides a detailed look at the meniscus tissue. This test is 70-95% accurate in diagnosing a tear and can also be used to look for ligament injuries.
How is a meniscus tear treated?:
Non-Operative treatment - Some patients may choose to try a course of physical therapy and anti-inflammatories. Because the meniscus has such poor blood supply in the inner 2/3, non-operative treatment may only provide a temporary relief of symptoms. Further medical evaluation and surgery may be required if conservative treatment fails.
Operative treatment: This is usually arthroscopic surgery (with a camera) as an outpatient procedure which usually takes around 30 minutes. The torn portion of the meniscus is removed with a combination of a shaver and biting instruments. After the procedure, patients are able to walk the day of surgery and are on crutches for a day or two, followed by a short course of physical therapy. Swelling may last up o 6 weeks and patients are usually back to full activities in 4-6 weeks.
Occasionally, younger patients may have a tear along the periphery of the meniscus which is amenable to repair. Instead of removing a majority of the meniscus, sutures are placed across the tear to try and get that area of the meniscus to heal. This will alter the rehab after surgery in that in order to prevent shear forces across the repair, patients will need to walk with their knee fully extended in a knee immobilizer for about 6-8 weeks.