Our knees are subjected to constant stresses and strains in our daily activities. From walking to soccer, the risk to injuring the knee meniscus is ever present and it is a common injury requiring treatment. Consultant Orthopaedic Surgeon Dr Tho Kam San explains more...
What is the meniscus?
The meniscus is a C-shaped piece of fibrocartilage located in between the thigh and leg bones, cushioning the joint surface from excessive wear and tear. There are two meniscii in each knee, the medial meniscus, and the lateral meniscus.
A large part of the meniscus has no blood supply and thus when damaged, is usually unable to undergo the normal healing process that occurs in most of rest of the body. In addition, with age, the meniscus begins to deteriorate, often developing degenerative tears.
However, the outer part of the meniscus is endowed with blood supply coming from its outer rim. Tears near the outer edge are amenable to repair and studies seem to show that if a repair is possible, the long-term outcome is better for the patient because of a decreased risk of arthritis later in life.
How is the meniscus torn?
The meniscus is usually injured by the force of rotating the knee while bearing weight. This occurs commonly during soccer, squash and tennis.
If the tear is small, the meniscus stays connected to the front and back of the knee and is stable. If the tear is large, it is usually unstable and the meniscus flap will flop in and out of the knee joint. The severity of symptoms of a tear greatly depends on its location and extent.
What do I feel when my meniscus is torn?
Invariably one will feel some pain, particularly when the knee is straightened or bent. If the pain is mild, you may be able to continue walking around.
Severe pain will occur if a fragment of the meniscus gets trapped between the femur (thigh bone) and the tibia (leg bone), giving a sensation of locking.
The knee may swell soon after injury if blood vessels are disrupted, or swelling may occur several hours later if the joint fills with fluid produced by the joint lining as a result of inflammation.
Occasionally, an injury that occurred in the past but was not treated becomes painful months or years later, particularly if the knee is injured again. The acute symptoms of meniscal injury may disappear on their own after a period of rest but they frequently persist or return and require treatment.
How do I know if I have a meniscus tear?
Your description of the injury and the onset of pain and swelling are important. Your doctor will perform a physical examination and may order x-rays of the knee. This is to exclude possible bony injuries.
The examination involves a test in which the doctor bends the knee, and then rotates the leg outward and inward while straightening it. Pain or a click suggests a meniscal tear. An MRI can be helpful to confirm the diagnosis but this is not always necessary.
What's next doc?
Appropriate treatment really depends on the symptoms and severity of the tear. Acute treatment includes RICE therapy, i.e. rest, ice, compression and elevation.
Anti-inflammatory medication is useful to reduce the swelling and pain. If the tear is small and the pain and other symptoms go away, your doctor will prescribe a muscle-strengthening programme with the physiotherapist.
Should the tear be large, and especially if the knee is locked, your doctor may advise surgery to treat the tear. This is done arthroscopically (well done) and the meniscus can be sewn back in place if the injury is in an area with a good blood supply.
Most young adults are able to return to active sports after meniscus repair.
If the tear is in an area with a poor blood supply, a small portion of the meniscus will have to be removed to even the surface. In some cases, the entire meniscus may have to be removed.
This is bad news as osteoarthritis is more likely to develop in the knee if the meniscus is removed. The loss of cushioning function increases the contact pressure on the joint surface exponentially and the cartilage gets worn down prematurely.
The guiding principle for meniscus surgery is repair if possible and conserve at all times.
Is there life after losing my meniscus?
Although the loss of part or most of the meniscus heralds increased wear of the knee joint, all is not lost. The main aim is to preserve the cartilage as much as possible and as long as can be.
For a start, strengthen your knee joint muscles (i.e. quadriceps and hamstrings) with a good exercise programme which your therapist or trainer will draw up.
Regular oral cartilage supplements like glucosamine have been shown to help repair worn out cartilage. One must also avoid excessive pressure on the knee. This does not mean you cannot pursue your usual exercises.
Wear good shoes, run on softer grounds (e.g. stadium tracks), cross train (alternate between swimming, cycling with pounding exercises) and have sufficient rest in between.
In more uncomfortable instances, oral anti-inflammatory medication may be required. Your doctor may also inject joint lubricants into your knee to reduce the friction, quite similar to our car engines and this procedure can be repeated whenever necessary. In the event if your knee is not straight, realignment surgery to your knee can help reduce excessive stress on one part of the joint.
What are the latest advances in the treatment of meniscus loss?
The permanent solution to the loss of meniscus is to replace it. Unfortunately, our meniscus does not regenerate, just like our adult teeth.
To replace the lost meniscus a procedure called a meniscus allograft transplantation can be performed where the surgeon replaces the meniscus with one from a cadaver. The missing meniscus can also be replaced with an artificial graft made from collagen. The collagen acts as a frame for a new meniscus to grow over.