Related topic > Knee anatomy
Each knee has two menisci. They are commonly called “the cartilage”, although this is not strictly accurate. There is one on the medial (inner) side of the knee and one on the lateral (outer) side of the knee. They are C, or crescent shaped, and serve to cup the femur as it sits on the tibia to improve the congruity of the joint. In some ways they act as shock absorbers of the knee. They are made up of a tough, gristly material called fibrocartilage.
The most common problem which arises with a meniscus is a tear. Occasionally the problem can be related to a cyst on the side of the meniscus.
The symptoms from a torn cartilage can range from pain to clicking and catching sensations. A patient may even experience complete locking of the knee. A locked knee arises when a large fragment of cartilage jams in the front of the knee, resulting in an inability to fully straighten the knee. Other associated features of a cartilage tear may be swelling or even a sensation of giving way (though this is usually a sign of ligament damage).
The diagnosis of a meniscal tear is often made on the history of injury.
In the younger adult patient or adolescent there may be a very definite story of a twisting or jarring injury followed by swelling and clunking or locking of the knee. These symptoms are often very well localised and the patient may be able to put his finger on one side of the knee or the other according to which cartilage is torn.
Sometimes cartilage tears are associated with other injuries such as ligament ruptures.
A tear of the meniscal cartilage in a young adult usually occurs with a greater force than in a middle aged or elderly person. The reason for this is that the strength of the cartilage reduces as you grow older. With the natural aging process, the nature of the meniscus cartilage goes from being a very resilient rubbery composition to becoming more brittle and degenerate.
Therefore, in a middle aged or elderly patient a cartilage tear may occur with a relatively minor injury such as rising from a chair, or a minor twisting episode. Indeed sometimes it is difficult for the patient to recall the exact moment at which the cartilage tear occurred, but recent vigorous activity may be relevant e.g. going on a long walk, moving furniture.
The examination of the knee along with the history is a very useful aid to diagnosis.
An x-ray will usually be undertaken even though a cartilage will not show up. This is because it is a simple investigation which can exclude other problems such as arthritis, an injury to the bone, or loose bodies (fragments of bone) in the knee; any of which can mimic the symptoms of a cartilage tear.
Sometimes an MRI scan will be performed to confirm a cartilage tear if there are any doubts. An MRI scan is not always used and will depend on the clinical diagnosis and problems that the patient is having. Even MRI can miss small tears.
Once the diagnosis of a torn meniscus is made you may well require surgery to treat it, as it is uncommon for these tears to heal. This is because in order for something to heal, it requires a blood supply and the meniscus itself has a poor blood supply.
Symptoms from small tears can settle down, however, over about 6 weeks. If symptoms last longer than this, surgery is usually necessary.
Surgery will nearly always take the form of an arthroscopic (keyhole) procedure, called an arthroscopy.
Depending on the nature of the cartilage tear, it will either have to be repaired, or trimmed to a smooth edge ( a partial meniscectomy ).
A small proportion of meniscal tears are suitable for repair. If a tear is treated soon after it occurs and the tear itself lies in the outer part of the meniscus, where there are tiny blood vessels, it may be suitable for repair with special sutures or anchors. In general this is only considered in the relatively younger age group for a number of technical reasons.
More commonly the torn part has to be removed, a partial meniscectomy. This is done using special small punches and cutters via one of the portals (keyhole incisions) at arthroscopy. The amount of cartilage removed depends on the size of the tear. As little as possible will usually be taken out, trying to leave a smooth stable edge of cartilage which will not cause you any further symptoms.
Sometimes, as noted previously, a cleavage tear (a type of splitting tear within the substance of the cartilage usually found in degenerate cartilages) can be associated with a meniscal cyst. This can be painful in itself and may present as a small lump on the outside of the knee. Cysts on the outer (lateral) side of the knee are more common than those on the inner (medial) aspect of the knee. Usually these cysts can be drained into the knee at the time of meniscectomy. Rarely, they may require removal with a bigger cut through the skin directly over the swelling.
***OMEDIX----NEW SUBHEADING CALLED LIGAMENT SUGERY:
Related topic > Knee anatomy
The anterior cruciate ligament (ACL) is one of the main restraining ligaments of the knee (see anatomy). The ACL is sited in the centre of the knee and runs from the back of the femur to the front of the tibia and acts to prevent excessive forward movement of the tibia. The Anterior cruciate ligament’s main role, however, is to keep the knee stable during rotational movements like twisting, turning or side-stepping activities.
Injuries to the ACL typically occur during a non-contact twisting movement and a popping sensation can often be felt or heard. Immediate swelling often occurs due to bleeding into the knee (a haemarthrosis). Other injuries to the knee can occur at the same time including meniscal tears (cartilage) or damage to the joint surface.
The ACL also provides important information to the muscles around the knee (proprioception), which are involved in protecting the knee during activities. These ‘balancing’ mechanisms are reduced when the ACL is injured although some of this function can be restored with an appropriate exercise programme supervised by a sports physiotherapist.
If the ACL is torn the knee is likely to give way with twisting activities and if this is associated with knee swelling, it is likely that damage has been done to the joint surface and/or meniscal cartilage. Continued damage will eventually result in osteoarthritis.
The symptoms of patients with an injury to the ACL include a feeling of instability or giving way. They may involve swelling and pain. Typically this will be with twisting activities, however a small proportion of patients become so unstable that even simple activities may cause giving way. There are also a small proportion of patients who are able to return to pivoting activities without giving way.
A ruptured ACL can normally be diagnosed from the history of the injury and confirmed with specific tests at the time of your examination. The diagnosis can be difficult in some cases (especially fresh injuries where examination may be too uncomfortable and those with other injuries to the knee); in these cases the diagnosis can usually be confirmed by MRI scan. A torn ACL cannot be seen on x-ray.
Surgery is not required for all ACL injuries. Some patients with this injury choose to alter their lifestyle in order to avoid activities which make the knee give way. A small proportion of patients are able to continue with their activities without major problems. These "copers" are typically (but not always) patients with lower physical activity levels, who do not participate in pivoting/twisting activities.
Conservative treatment of an ACL injury involves a supervised physiotherapy programme concentrating specifically on:
- Strength – all muscles around the knee must be strengthened especially the hamstrings. These muscles can then take over some of the ACL’s role in knee stability.
- Balance and proprioception - as the ACL has an important role in providing information to the muscles and brain about the position of the knee joint, specific re-training of other nerves is performed to help compensate.
Functional Knee Braces are sometimes prescribed to help patients with damaged ACL’s. Their benefits are not fully understood although they may help with proprioception (see above). They are expensive and may not provide much in the way of support to knee stability.
***OMEDIX---PROVIDE LINK TO ACL RECONSTRUCTION SWARM VIDEO
Following an ACL rupture your surgeon may decide, after discussion with you, that reconstruction is appropriate.
ACL reconstruction is the commonest ligament reconstruction performed around the knee. ACL reconstruction is an attempt to replace the stabilizing function of the anterior cruciate ligament. The ACL reconstruction procedure involves removing the remains of the damaged ACL and replacing it with another form of soft tissue, called a graft. A number of grafts are available for use to replace the ACL.
The two commonest graft techniques are to use two “hamstring tendons” – the semitendinosus and gracilis muscle tendons – or a so called BTB (bone tendon bone, or patella tendon graft). The preference of the Yorkshire Knee Clinic Surgeons is to use hamstring grafts as first choice. The evidence in the medical literature is that there is little or nothing to choose between these two main grafts in terms of results.
Other grafts are available in more unusual situations.
Anterior cruciate ligament reconstruction is usually performed using arthroscopic (keyhole) surgery. There is however a small (4 to 5 cm) incision below the knee where the tendons for the graft are harvested from. The basic technique of anterior cruciate ligament reconstruction is to identify the correct insertion points on the femur and tibia for the ACL. At these insertion points tunnels of an appropriate size to match the graft are drilled through the bone. The graft is then pulled up through the bone and is secured using either screws, pins, staples or other specialised anchoring devices.
ACL reconstruction may be performed either as day case or overnight surgery.
In patients who are having the operation for appropriate reasons and who comply with rehabilitation (6-8 months), there is a 90 to 95% chance of a good result: that is, where stability is restored enough for the patient to undertake activities, including sports, that they were previously unable to.
Complications include infection (1% significant), nerve damage (a numb patch of skin, quite common over a small area, but rarely a problem), stiffness (uncommon) and failure of the graft due to re-injury or unexplained failure.