The meniscus is a fibrocartilagenous disc that sits in between the femur (thigh bone) and tibia (shin bone). The meniscus cushions the knee and functions similar to a shock absorber of a car. The meniscus dissipates stress as it is loaded. By doing so, our articular cartilage, or joint cartilage, sees significantly less stress as we walk, run, etc. In addition, the meniscus helps provide stability to our knee.
Twisting movements, buckling episodes, and generalized wear and tear can cause meniscal tears. Tears often cause significant pain from the rubbing of the torn edges together. Occasionally, the torn portion can flip into the knee and block motion.
The only way to definitively take care of the tear is with an arthroscopy. The torn portion either is resected or repaired. The majority of tears are unable to be repaired. All attempts are made to preserve the uninvolved meniscus. Thirty years ago, the entire meniscus was removed during surgery, and we have found this lead to premature arthritis.
Certain meniscal tears are amenable to surgical repair. Typically these are referred to vertical tears, or tears along the fibers of the meniscus. It is necessary for the meniscus to have adequate blood flow to heal a tear. Therefore tears preferably are located in the outer (peripheral) portion of the meniscus. A number of sutures are placed within the knee and are retrieved through a small incision. The knee must be protected for two months following a repair to allow for the meniscus to heal. The quoted healing rate for a repaired meniscus is approximately 70%, and if a meniscus is repaired at the same time as a reconstructed ACL is 90%. Keep in mind these figures are only for appropriate tears with good blood supply. Tears repaired in a portion of the meniscus with poor blood flow would have a substantially higher retear rate.
Steps for meniscus repair:
1) The proper tear is identified
2) Either sutures are placed through the knee and collected through a small incision on the side of the knee or a bioabsorbable implant is placed
3) In this case, a bioabsorbable implant is placed through the torn meniscus and a "stop" on the far side of the meniscus and capsule is deployed.
4) The suture with a knot on the end is collected outside the knee.
5) The knot is tensioned and the meniscus is repaired.