Damage or tears at the outside of the meniscus in the ‘red zone’ are near to a blood supply, which means it is closer to a source of nutrients and as a result is more likely to heal better. It can then be repaired using special sutures by ‘keyhole’ surgery – surgery which uses cuts in the skin only about 1 cm in length. The below image is taken from a small camera inserted into the knee (in a procedure known as ‘arthroscopy’) which shows a meniscus before and after it has been repaired with sutures. Once the meniscus is stitched into place, it allows the body to do the rest of the healing.
Meniscal Repair: On the above left picture, the tear in the meniscus has allowed the meniscus (B) to become loose, which can result in it being caught between thigh bone (A) and the shin bone (C). After meniscal repair (above right-courtesy of SMITH AND NEPHEW), a suture is holding the meniscus in place, preventing it from getting caught between the thigh bone and the shin bone.
If the meniscal tear is far from a blood supply, it will not be able to heal properly because it is not able to get enough nutrients available to start the healing process. The knee specialist will explain what options there are for your knee with regards to meniscal repair or partial meniscectomy. It is hard to predict which tears can be repaired and the final decision is made at arthroscopy