The meniscus is the pad of cartilage that sits between the ends of the bones forming the knee joint. There are 2, 1 on each side of the joint, medial and lateral. These act as shock absorbers and help to protect the bearing surface at the end of the bones. When these are damaged or pieces removed with surgery the load transmitted to the joint surface increases and the risk of developing arthritis within the joint increases.
What are the symptoms?
In the acute phase a tear in the meniscus can cause pain in the knee. This usually localises to the side of the knee of the meniscus which has been damaged, medial (inner) or lateral (outer). The knee can also swell to a moderate degree although this usually occurs sometime after the injury. If there has been a large tear to the meniscus the torn piece can fold over into the joint and block the full range of movement, usually stopping knee from fully straightening, This is termed a locked knee. Smaller tears can cause intermittent catching or locking of the knee.
Some tears can cause pain on the side of the knee that has been damaged when the knee twisted or flexes fully.
How is it damaged?
When there is an excessive force placed through the meniscus either through a twist or sudden flexion of the knee a shear force is placed through the meniscus and it can split or tear. In young patients when the meniscus is entirely normal this requires a lot of force and can cause a large tear. In older patients with time the meniscus can weaken through degeneration and tears with much less force. This is a degenerate tear.
How is a tear diagnosed?
Frequently an MRI scan will be used to confirm a tear in the meniscus when the history and examination findings point to this. An MRI is very sensitive at picking up a tear.
What is the treatment?
Not all meniscal tears need surgery and most are treated with physiotherapy, at least in the first instance. A lot of tears are degenerate. This means that the tear occurs in a meniscus which has become weaker with age and has lost some of the fluid from within it that keeps it tough and springy. This is analogous to the worn knees on a pair of jeans that have become thinned and worn with time that split with relatively minimal force. The majority of these will settle with physiotherapy. Surgery for this type of tear is reserved for those that don’t settle within a period of time usually at least three months from the onset of symptoms. Pain killers or anti inflammatories can be taken to help the pain and discomfort. Regular use of an exercise bike can help the knee settle quicker.
For tears that don’t settle arthroscopy or key hole surgery can be offered. In this procedure 2 small cuts are made at the front of the knee. The knee joint is filled with water and a very small camera is used to look inside. Small instruments can then be used to remove the torn part of the meniscus or address any other issues.
When a large tear is sustained in a normal meniscus we will try and repair the meniscus by putting some stitches in it rather than removing the torn part of the meniscus so that its function is maintained. Not all surgeons who perform arthroscopies are able to do this. This is why it is important to see a specialist knee surgeon.
What is the recovery like from an Arthroscopy?
An Arthroscopy is performed as a day case procedure and you will usually be able to go home a few hours later. The incisions are closed with steristrips which can be removed 2 weeks after the procedure. The small incisions need to be kept clean and dry for 2 weeks. You will be walking on the leg straight away, occasionally crutches are needed for a few days. You can usually be back driving within 2 weeks. Time off work will depend on job but for an office worker will usually be 1 week.
If the meniscus is repaired then the recovery is slightly longer as the repair has to be protected while it heals. A brace is often worn for 6 weeks that limits the amount of flexion in the knee.
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