Arthroscopic Surgery of the Knee

Torn Cartilage (Meniscus)

Torn Anterior Cruciate Ligament (ACL)

TORN CARTILAGE
(TORN MENISCUS)

The meniscus, or cartilage, is a crescent-shaped cushion between the bones of the knee.  Each knee has two such cartilages, one on the inner side, and one on the outer side.  With certain movements of the knee, with a twisting injury to the knee, or sometimes as a natural degenerative process, the cartilage can develop a tear.  Once it is torn, the cartilage has very little ability to heal on its own, because the cartilage material has limited blood supply.  The torn part of the cartilage moves about abnormally when the knee is used, and often catches between the bones as they move, causing pain, clicking, popping, swelling, and sometimes even locking the knee in a bent position.

Diagnosis of a torn cartilage can sometimes be made based on symptoms and physical examination.  X-rays are usually done to rule out other joint problems, but the cartilage itself is invisible to the X-ray.  An MRI scan is often helpful in confirming the presence of a cartilage tear.

It is rare for healing of a torn cartilage (meniscus) to occur without surgery.  Without treatment most patients will have persistent problems with the knee.

With arthroscopic surgery, the torn meniscus can be directly visualized, and at the same operation, the damaged tissue can be repaired or removed.  Some tears near the edge of the cartilage can be repaired successfully using the arthroscope.  However, many tears will not heal, even if repaired, because of the lack of blood supply in the meniscus; so the damaged tissue is removed, and the defect is contoured to preserve as much of the remaining healthy meniscus as possible.

The surgery is usually done under general anesthesia (the patient is asleep), although spinal anesthesia can be used if the patient and anesthesiologist prefer.  This surgery is done as an outpatient, and walking is permitted  immediately after surgery, in a protective brace (knee immobilizer).  Many patients also use crutches for comfort during the first few days after surgery.

A return visit is scheduled 2-4 days after the surgery, at which time the brace and sutures are removed, and normal activities are gradually resumed during the next few weeks.  Most patients are able to resume their usual activities within 4-6 weeks after the surgery.

A tear of the anterior cruciate ligament is most often seen after a sports injury, in which a major twisting or strain injury has occurred.  There is usually a painful pop, followed quickly by swelling in the knee.

Although it is possible for some to walk, run, and even participate in demanding sports after a torn ACL, many patients are bothered by recurrent episodes of "giving way" and instability, which may warrant surgical treatment.

Direct repair of the ACL is not usually technically successful, because of the poor healing and high stresses on the ligament.  Therefore, when surgical treatment is chosen, the ligament is reconstructed with tissue taken as a graft from elsewhere about the knee.  Most commonly, part of the hamstring tendons or patellar tendon (a large tendon attached the kneecap) is used as graft material.
 




The graft is placed at the location of the torn ACL, and is attached to bone by absorbable screws.  Most of the procedure is carried out through small incisions using the arthroscope, with an additional 1-2 inch incision to obtain the graft.








Arthroscopic ACL reconstruction is often done as an outpatient, though sometimes an overnight hospital stay may be needed.  The knee is protected in a brace for about 6 weeks after ACL reconstruction, but some weight bearing can be started soon after surgery.  Return to unlimited sports activity should be delayed for several months, however, as the reconstructed ligament requires at least 6 to 9 months to mature and reach its maximum resistance to reinjury.