Definition outer meniscus tear
A torn or ruptured meniscus is a tear of the meniscus of the knee joint. A tear of the outer meniscus is much less common than a tear of the inner meniscus. This is due to the fact that the inner meniscus has a C-shape on the one hand and on the other hand is firmly attached to the inner ligament of the knee, which means that it has only very limited mobility, resulting in a higher risk of injury. The outer meniscus, on the other hand, is more in the shape of a sickle and is not so strongly connected to its surroundings. This allows it to move more freely and thus better avoid damage caused by accidents.
Severity and origin
Both in the case of an external meniscus tear and an internal meniscus tear, different degrees and different forms of tear can be distinguished. – Grade 1 of the external meniscus tear: central, punctiform tear,
- Grade 2 of the external meniscus tear: horizontal tear, which however does not reach the meniscus surface,
- Grade 3 of the external meniscus tear: band-shaped tear up to the surface of the meniscus,
- Grade 4 of the external meniscus tear: multiple tears. The forms include the basket handle tear (tear along the longitudinal course of the meniscus, whereby parts of the meniscus tear off and slide into the joint space, thus causing pain), the transverse or radial tear and the flap tear (a combination of transverse and longitudinal tear).
With the help of clinical examinations it is possible to determine whether the outer or inner meniscus is affected and what type of meniscus tear is present. The most valuable diagnostic imaging option is the MRI examination of a torn meniscus. In many cases, the MRI can show the location and severity of the injury and plan the therapy according to the meniscus tear.
There are various causes for an external meniscus tear, but most often this injury is the result of a long-term degenerative disease of the knee joint. In this case, the knee has already been pre-damaged by permanent stress, which means that in the end, it does not take much to cause a meniscus tear. The second most common trigger of an external meniscus tear is an accident (trauma), for example in sports such as football or skiing.
While the knee joint is relatively well protected against shock loads, it is susceptible to injuries caused by a twisting trauma. The outer meniscus is at high risk of tearing if the knee joint is rotated inwards. It is not uncommon, however, to find no direct cause for this injury.
Diagnosis of a torn outer meniscus
The diagnosis of an external meniscus rupture is essentially made by two diagnostic measures: In the examination, the experienced physician can put the inner or outer meniscus under pressure by means of various meniscus tests. In a healthy meniscus, a meniscus test does not cause any complaints. If there is an outer meniscus lesion, the meniscus test is usually positive.
How well the external meniscus tear can be detected by the doctor depends on his abilities and the age of the meniscus tear. The meniscus test is false negative, especially in the case of older meniscus tears. In order to confirm or disprove the result of the meniscus test, an MRI is usually carried out after the examination of the affected person if a meniscus tear is suspected.
An MRI is a radiation-free examination in which the soft tissue and cartilaginous structures of the knee joint can be displayed particularly well. Also the MRI does not offer a 100% certainty of the diagnosis of a meniscus tear. Especially in the case of small degenerative (age-related) tears, a meniscus tear can also be overlooked in the MRI.
- Examination by the doctor (ideally by a sports orthopaedic specialist)
- Imaging examination procedures (the best examination for meniscus tears is the MRT)
Patients with a torn outer meniscus complain above all about pain that is usually stabbing or pulling. Typically, these are strongest in the area of the outer knee joint gap, but can also occur diffusely in the knee, which is difficult to localize. In some patients, mobility in the knee joint is also restricted.
Especially the extension of the lower leg and squatting are difficult. If a piece of the torn meniscus has become trapped in the joint, the knee may even be completely blocked. In some cases, these complaints are accompanied by swelling.
In the case of a degenerative outer meniscus tear, any symptoms may be completely absent for a long period of time. The type of treatment chosen for a torn outer meniscus depends on many different factors (including age, sporting activity, extent of the complaints, individual needs or wishes of the patient). However, some form of therapy must be carried out under all circumstances, since cartilage is only capable of self-healing to a very limited extent and there is a high risk of consequential damage such as knee joint arthrosis if an outer meniscus tear remains untreated for a longer period of time.
In the case of minor damage, conservative treatment is usually attempted at first. Adequate physiotherapy can lead to complete healing for many people. More severe damage, on the other hand, usually requires surgical treatment.
The method of choice here is arthroscopy, which can be performed using various surgical techniques. With timely treatment, the prognosis of an outer meniscus tear is very good. Complications during surgery are rare with this procedure. The knee joint must be gradually regained under medical or physiotherapeutic supervision, but in most patients, depending on the severity of the injury, choice of treatment and individual condition, the joint is fully recovered after about 6 to 8 weeks. However, it may be necessary to wait a little longer before putting more strain on the knee again, for example through certain sports.