Cartilage (Meniscus) Injury

A picture taken at a knee arthroscopy operation showing a torn meniscus. In this case, the meniscus could not be repaired so the torn section was removed.

Confusingly, the term “cartilage” is used to describe the surface of the joint (the articular cartilage) and the meniscus, which lies between the joint surfaces of the knee. The meniscus has an important role in protecting the joint surface, but injury and damage to the meniscus is common and may cause pain and swelling in the knee.  The menisci (there are two menisci, one on the each side of the knee joint) can be damaged by injury to the knee, usually a twisting injury when the knee is bent, causing a sudden sharp pain and swelling of the knee.  Alternatively (and in fact more commonly), the menisci can be damaged by the wear and tear process in the knee, usually (like so may other things), in middle life.  In this case, the knee becomes sore for no apparent reason.  Swelling is variable.  Typically, the knee is sore on crouching and kneeling and if the knee is twisted, such as when walking over rough ground.  

The diagnosis may be made by an examination of the knee, but further tests are often required.  An X-ray bearing full weight on the affected leg, can be useful to identify narrowing of the space between the bones (the joint space), which suggests wear in that part of the knee.  The menisci cannot be seen on an X-ray but can be very effectively examined by an MRI scan, which in most cases would be the investigation of choice.

Tears of a meniscus are usually treated by keyhole surgery on the knee.  This is a day surgery operation under either a local or general anaesthetic.   Whenever possible, the meniscus should be preserved, particularly in acute injuries when it can be sutured with a reasonable chance that it will heal.  Unfortunately, if the meniscus is torn beyond repair, or when the tear is degenerative (as part of a wear and tear process in the knee), partial removal of the meniscus is required. 

Recovery after this operation takes about four to six weeks before you can get back to full activities, including sports.  This may take longer if the meniscus has been repaired.  In most cases, the knee will recover completely, but if  there is underlying wear in the knee, unfortunately knee pain may persist particularly with high impact exercise.

RWN’s view

Keyhole surgery is very effective in treating cartilage (meniscus) damage and in most cases the knee will recover fully. Whenever possible, the meniscus should be repaired but realistically, particularly in degenerative tears of the meniscus, this is not always possible.   When the meniscus has been torn by an injury to the knee, early treatment (within six weeks) is advisable as this represents the best opportunity to repair the meniscus successfully.

I am often asked about the long term consequences of removing part of the meniscus.  It is recognised that if over 20% of the meniscus is removed there is a long term risk of developing arthritis in that part of the knee, but this is a gradual process over 10 years or more.  A great deal of research is being undertaken at present in findings ways to preserve the meniscus and repair the articular cartilage, which hopefully will reduce the long term risk of osteoarthritis.