The meniscus is a commonly injured structure in the knee. The injury can occur in any age group. In younger people the meniscus is fairly tough and rubbery, and tears usually occur as a result of a fairly forceful twisting injury. In older people, the meniscus grows weaker with age, and meniscal tears may occur as a result of a fairly minor injury.
What is a meniscus?
It is a crescent shaped piece of cartilage that lies between the weight bearing joint surfaces of the thigh and the shin, and is attached to the lining of the knee joint. There are two menisci in a normal knee; the outside one is called the lateral meniscus and the inner one is called the medial meniscus.
The menisci play an important role as a shock absorber in the knee joint, protecting the cartilage that lies on the surface of the bones from impact. The cartilage surface is a tough, very slick material that allows the surfaces to slide against one another without damage to either surface. This ability of the meniscus to spread out the force on the joint surface as we walk is important because it protects the cartilage from excessive forces occurring in anyone area on the joint surface. Without the meniscus, the concentration of force into a small area on the cartilage can damage the surface, leading to degeneration over time. The menisci also cup the joint surfaces of the thigh and therefore provide some degree of stabilization to the knee.
There are two different mechanisms for tearing a meniscus.
Traumatic tears result from a sudden load being applied to the meniscal tissue that is severe enough to cause the meniscal cartilage to fail and let go. These usually occur from a twisting injury or a blow to the side of the knee that causes the meniscus to be pushed against and compressed.
Degenerative meniscal tears are best thought of as a failure of the meniscus over time. The meniscus becomes less elastic and complaint, and as a result may fail with only minimal trauma (such as just getting down into a squat). Sometimes there are no memorable injuries or violent events that can be blamed as the cause of the tear.
Signs and Symptoms:
The most common problem caused by a torn meniscus is pain. The pain may be felt along the joint line where the meniscus is located or may be more vague and involve the whole knee. Any twisting,
squatting or impacting activities will pinch the meniscus tear or flap and cause pain. Often the pain
may improve with rest after the initial injury, but as soon as aggressive activity is attempted the pain recurs.
Swelling of the joint may occur although meniscal tears by themselves usually don’t cause a large, tensely swollen knee. Typically, low level swelling sets in the next day after the injury and is associated with stiffness and limping.
If the torn portion of the meniscus is large enough, locking may occur. Locking simply refers to the inability to completely straighten out the knee. Locking occurs when the fragment of torn meniscus gets caught in the hinge mechanism of the knee, and will not allow the leg to straighten completely. The torn fragment actually acts like a wedge to prevent the joint surfaces from moving.
There are long term effects of a torn meniscus as well. The constant rubbing of the torn meniscus on the cartilage may cause wear and tear on the surface, leading to degeneration of the joint. The knee may swell with use and become stiff and tight. This is usually because of fluid accumulating inside the knee joint.
Initial treatment for a torn meniscus usually is directed towards reducing the pain and swelling in the knee. Traumatic tear in younger patients would benefit from an early intervention such as arthroscopy and meniscal repair or excision. You may be asked to attend physiotherapy to reduce the pain and swelling and improve the range of movement. If the knee is locked and cannot be straightened out, surgery may be recommended as soon as reasonably possible to remove the torn portion that is caught in the knee joint. Once a meniscus is torn, it will most likely not heal on its own. However, the pain may subside within couple of months. If the pain continues, surgery will be required to either remove the torn portion of the meniscus or to repair the tear. In degenerate tears if the pain is severe, it could be treated with an intra-articular injection of steroid in the first instance.
Meniscal surgery is done using the arthroscope. Two small 1cm incisions are made on either side of the knee to allow the insertion of a small telescope in one side and special instruments on the other side.
In some cases the meniscal tear can be repaired. Sutures are then placed into the torn meniscus until the tear is repaired. Repair of the meniscus is not possible in all cases. Young people with relatively recent meniscal tears are the most likely candidates for repair. Degenerative type tears in older people are not usually repairable. The post operative rehabilitation is much longer after meniscal repair. The patients are generally asked not to put weight through the leg for 6 weeks to protect the repair.
What is involved for you as the patient
Healthy patients are admitted on the day of their surgery. You should inform your surgeon and anaesthetist of any medical conditions or previous medical treatment as this may affect your operation.
It is extremely important that there are no cuts, scratches, pimples or ulcers on your lower limb as this greatly increases the risk of infection. Your surgery will be postponed until the skin lesions have healed. You should not to shave or wax your legs for one week prior to surgery.
After the operation you will be required to stay in hospital for few hours. Occasionally an overnight stay may be required due to the affects of the anaesthetic or an inability to manage crutches.
Patient should start exercising immediately post operatively. A physiotherapist may be needed to supervise muscle contractions, walking and weight bearing. Usually we don’t use any sutures or steristips. If there are sutures they need to be removed at 9-10 days following surgery. Sedentary and office workers could return to work approximately within 1-2 weeks following surgery. Most patients should be walking normally in that time, although there is considerable patient to patient variation.
Driving is permitted when you are able to walk without crutches and the wound have healed generally after 2 weeks unless you had meniscal repair, in that case you will be none weight bearing for few weeks. You must not drive a motor vehicle whilst taking severe pain killing medications.
Return to vigorous activities will be determined by the extent of the damage to your cartilage, meniscus, and the amount of meniscus that requires removal. If minimal damage was present, then you may return to vigorous activities after 4-6 weeks. If significant damage was present, then you may be advised to avoid impact
loading activities in order to prevent the onset of early arthritis developing within the joint.
Complications related to surgery:
As with all operations if at any stage anything seems amiss it is better to call up for advice rather than wait and worry. A fever, or redness or swelling around the line of the wound, an unexplained increase in pain should all be brought to the attention of the surgeon. You can contact your surgeon by telephoning the hospital at which you have had your surgery and speaking to the sister on the ward. She will then contact your doctor and arrange for immediate treatment.