The meniscus is a soft rubbery structure between the femur and tibia. There is one on each side of the knee, a medial and a lateral meniscus.
Injury to this structure (A Meniscal tear) is very common.
The function of the meniscus is to act as a...
- Shock absorber.
- And to help with lubrication.
A knee which does not have a meniscus has a significantly higher chance of developing osteoarthritis in the long term. The severity and timing of this arthritis depends on many factors including your age, activity levels, weight and degree of meniscal damage.
History Of Injury
Athletes usually (but not always) tear their meniscus with a specific injury. In older people it can the tear can occur with minimal or no trauma. Tears can be simple or complex and are described according to the type of tear. The meniscus has a very poor blood supply and rarely heals without intervention.
Some people feel a pop in the knee. The injury is not usually severe and most people can continue with sports or at least can walk around without too much pain.
- Swelling usually begins the next day and is usually not severe.
- Pain is usually localised to the side of the knee where the tear is located.
- Locking of the knee is when the knee gets stuck so you can't move it (Usually it can't be straightened because a fragment of the meniscus gets stuck in between the bones).
- Giving way (usually caused by pain rather than true instability).
This can usually be made based on the history and examination alone. An MRI test may be ordered to confirm the diagnosis and to exclude other pathology but this is usually not needed and may delay treatment.
Initial treatment involves Rest, Ice, Elevation and bandaging. There is no urgency to be seen by a surgeon unless you have a locked knee (The meniscus can be damaged when it gets caught between the bones of the knee joint).
The meniscus rarely heals itself (due to its poor blood supply) and treatment for a meniscal tear usually involves an arthroscopy. The torn meniscus can be trimmed or repaired. The decision to repair is based on age, activity levels, occupation and sporting demands. The final decision can not be made until the time of surgery as it depends on the size, site and the quality of the remaining meniscus.
Repair can usually be performed arthroscopically using special devices but one or two additional incisions in the skin may be required. There are advantages and disadvantages of meniscal repair.
- Maintain protective role of meniscus.
- Reduces the risk of arthritis.
- Longer rehabilitation period.
- Longer restriction of work and sport activities.
- Failure of the meniscus to heal (15-20%) because of it's poor blood supply. If it does not heal and is symptomatic you may require a repeat arthroscopy to attempt another repair or cut out the torn fragment.
- Slightly increased risk to vessels and nerves.
- Potential damage to articular surface from some of the devices used.
Overall if a meniscus can be repaired (in the right patient with the right type of tear) it is best to do so as it protects the knee from premature arthritis.