The menisci are 2 c-shaped structures within your knee that act as load distributors.
Without them the contact pressure on the cartilage which lines your bones within the knee increases by about 200% - which in turn leads to osteoarthritis. The menisci (more so medial) are commonly torn in twisting injuries of the knee.
The torn meniscus can get trapped in between the hinge that is your knee and can cause pain, swelling, locking (inability to fully straighten the knee) and giving way. It is usually diagnosed with an MRI scan unless the clinical features are very obvious. Key-hole surgery (arthroscopy) is the best way of assessing and treating the tear. I try to maintain as much meniscus as possible during key-hole surgery (arthroscopy). If the edge the meniscus is torn, the frayed edge can be trimmed and contoured with excellent results and minimal risk of developing arthritis. However, if the meniscus is split in 2 then I am able to repair the meniscus using a special instrument and sutures.
The instrument that I use to repair the meniscus product.
Diagram showing how it works
The end product
Click here to find out more about meniscal repair. Trimming away the meniscus in this case would place the knee at increased risk of arthritis. Unfortunately it is not always possible to save the meniscus but I try to whenever I can.