A meniscus injury develops when there is damage to the special cartilage that lines the knee joint. Tears may develop suddenly due to an injury, or come on gradually over time due to wear and tear.
A meniscus tear causes pain, swelling, stiffness, instability and sometimes locking (where the knee gets stuck in one position).
It can take a long time to recover from a torn meniscus as the blood supply to the region is generally poor, resulting in slow healing.
The meniscus is made up of thick, crescent shaped bits of cartilage that line the knee on either side of the joint. There are two parts, the medial meniscus, on the inner side of the knee and lateral meniscus, on the outer side of the knee.
The meniscus acts as a shock absorber and ensures there is correct
weight distribution through the knee. Medial meniscus tears are the most common as more force tends to go through the inner side of the knee, resulting in medial knee pain.
A meniscal tear tends to occur either suddenly from a specific injury or gradually due to wear and tear:
A meniscus injury usually happens during sporting activities e.g. football, rugby and skiing. Usually they occur when the foot is fixed (e.g. studs in the ground) and the knee is slightly bent and then twisted by a sudden turn initiated either by you or by a force to the outside of the knee.
Medial meniscus tears are more common than lateral meniscus tears and often the medial collateral ligament (MCL) is injured at the same time – see MCL Tear.
Cartilage tends to become more brittle with age and everyday use of the knee can cause a meniscus injury. Often this affects the edges of the meniscus which get frayed and torn. Symptoms may gradually build or they may be triggered by a particular event e.g. twisting the knee awkwardly. Meniscal tears are also a common feature of knee arthritis.
There are four types of meniscal tear shown in this diagram:
a) Normal meniscus: shows what a normal meniscus looks like
b) Longitudinal Tear: tear that happens along the length of the meniscus
c) Bucket Handle Tear: tear where part of the cartilage detaches from the tibia leaving a flap of cartilage
d) Radial Tear: tear that starts at the outer edge of the cartilage and comes inwards
e) Degenerative changes: the cartilage wears away losing its smooth surface becoming brittle and thin
1) Knee Pain: With a meniscus injury there is often a
lot of pain in the knee, especially when trying to straighten it fully
or when bearing any weight though the leg. Activities such as stairs and squatting are often painful.
2) Knee Swelling: this usually develops gradually over the first 48 hours after an injury. If there is wear a tear in the meniscus, swelling may fluctuate
3) Locking: With a more severe meniscus injury there may also be locking of the joint – where the joint gets stuck and can’t move further. The meniscus tear is the most common cause of knee locking.
Locking can occur for two reasons:
a) True locking – this is where something gets stuck inside the knee joint, usually a small fragment of cartilage (see bucket handle tear above). Often if you move the leg around for a bit the knee then unlocks as the cartilage fragment moves out of the way
b) Pseudolocking – this usually occurs due to pain. If performing a movement is particularly painful, the body will often prevent itself from moving further to try and make sure no more damage is done.
Unfortunately, torn knee cartilage is not very good at regenerating. Tissues require a good blood supply to heal and whilst blood capillaries do feed the outer edges of the meniscus, the central parts of the meniscus are avascular (have no blood supply). This means they can’t properly heal. There are two options with meniscal tears:
If it is a small meniscus injury, rehab aims to reduce pain and swelling and improve muscle strength. The most appropriate course of action is:
(Protect, Rest, Ice, Compress and Elevate) for a few days and then a
rehab programme to strengthen the knee and regain any loss of movement
and function. Visit the PRICE treatment section to find out how to use the different elements safely and effectively.
2) Exercises: Building up the strength of the muscles surrounding the knee joint helps to reduce the amount of weight going through the knee and therefore through the cartilage, and can really help to reduce the effect of a meniscal tear. Muscle weakness of the glutes and kneecap muscles often causes excess force to go through the medial meniscus resulting in an injury, so strengthening these muscles can particularly help. Visit the meniscus injury exercises section for simple exercises you can do at home to recover.
3) Ice: Ice can really help to reduce the pain and swelling associated with a meniscus injury which helps to speed up healing. Visit the ice treatment section for the most effective ways to apply ice.
4) Tubigrip: This is an elasticated compression bandage that can help in the short term to reduce swelling and to provide some support to the knee. Long term use is not advised as it can result in weakening of the muscles. Visit the tubigrip section to find out more about how it works and how to get the right size for you.
5) Knee Brace: Knee braces provide much more stability than tubigrip, so can be really useful, especially if the knee feels unstable. Usually a basic advanced brace basic or advanced knee brace will provide enough support. If your meniscus injury is associated with a ligament injury you may need an Elite brace.
If exercises haven’t resolved the knee pain from your meniscus injury,
your doctor may advise surgery. Most surgery for meniscal tears is
performed arthroscopically (keyhole surgery). This is where they make two
or three small holes around the knee and a camera is inserted into the knee. The surgeon will remove
any debris (torn bits of cartilage) and sew up tears where possible as shown in the video here from the American Academy of Orthopedic Surgeons.
The aim is to preserve as much of the
cartilage as possible since it won’t regrow. You can usually go home the same day.
Following meniscus injury surgery, it is important to exercise to regain full strength, movement and balance at the knee.
If a meniscus injury isn’t sounding quite like your knee pain, visit the Knee Pain Diagnosis section for help with diagnosing your knee problem.