Meniscal cartilage tears are a very common knee injury. Anyone at any age can tear a meniscal cartilage, however, athletes and participants in contact sports are at higher risk.
What is a meniscus?
The knee is the largest joint in the body and one of the most complex. Three bones meet to form the knee joint: the thighbone (femur), shinbone (tibia) and the kneecap (patella). The meniscus is a small C-shaped piece of tissue, often referred to as ‘the cartilage’, which sits between the femur and tibia in the knee joint. There are two menisci in each knee, the outer lateral meniscus and the inner medial meniscus, which is more commonly injured. The meniscus acts as a shock absorber in the knee joint to soften the impact of the joint when walking, running or bending.
How does a meniscal tear happen?
The most common mechanism for a meniscal tear to occur is during a twisting injury to the knee joint with the foot planted on the ground. Squatting and direct sporting injuries are also common ways the meniscus can tear.
Older people are more likely to have degenerate meniscal tears. The meniscus becomes weaker with increasing age and a trivial injury such as a minor twist when getting out of a chair can result in a torn cartilage.
What are the symptoms of a meniscal tear?
At the time of the injury you may hear or feel a pop or rip. The knee does not necessarily swell and most people can still weight bear and walk on their injured knee.
The most common symptoms are:
- Pain – typically felt on the inner or outer part of the knee as the torn fragment catches in the knee joint with movement.
- Locking – the knee may not go fully straight when a piece of torn meniscus becomes trapped in the joint blocking movement. The joint may feel as though it is catching.
- Giving Way - the sensation of the knee giving out and feeling unstable as the torn piece of meniscus affects knee movement.
A knee specialist can often diagnose a torn cartilage during a consultation involving a medical history and physical examination of the knee joint.
X-rays do not show the meniscus, but can exclude other causes of symptoms such as arthritis and material floating around the knee known as ‘loose bodies’.
A MRI scan can be performed to look at the soft tissues of the knee joint and can be used to detect most torn menisci.
What treatment is needed?
If a torn meniscus is diagnosed and the knee remains problematic despite a period of rest and simple painkillers following the injury, then surgery may be required.
The meniscus does not have a very good blood supply and many meniscal tears do not have the ability to heal.
The most common form of treatment is an arthroscopy, keyhole surgery, to the knee to trim away the torn piece of meniscal cartilage. This procedure is performed as a day case and is very successful at removing the loose and torn cartilage and reducing the symptoms. Following this surgery patients can usually weight bear straight away, return to driving at around two weeks and are often back to normal full activities at six weeks.
The normal meniscus does have a protective function to the knee joint and it is important to leave as much non-injured meniscus as possible.
However, in special circumstances, mainly if the tear is in the outer periphery of the meniscus where there is a better blood supply, and often in younger patients a meniscal repair can be undertaken. This again involves keyhole surgery, but instead of removing the torn piece of cartilage, stitches are used to repair the tear. Following a meniscal repair activities and weight bearing must be restricted for six weeks to allow the cartilage to heal and sports should be avoided for three months.
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Information provided by Richard Goddard, Orthopaedic Consultant