A torn meniscus is one of the most common knee injuries. A meniscus lesion (meniscus damage or tear) is an injury to one of the two cartilage discs (menisci) located between the femur and tibia.
If you look at the bone structure of the femur and tibia, you will notice that they are asymmetrical to each other (round thigh and straight lower leg), and their joint surfaces do not fit together. The meniscus compensates for this asymmetry.
Any activity that causes you to forcefully twist or rotate your knee, especially when putting your full weight on it, can lead to a torn meniscus.
The meniscus consists of two fibrous cartilage discs, the inner meniscus and the outer meniscus, which can also be seen in the picture below. The meniscus serves as a kind of “buffer” because they allow an even pressure load, a smooth transmission of force, and help to stabilize the knee joint.
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Causes of a torn meniscus
Causes for meniscus tears range from traumatic (by accident) to degenerative (excessive strain). The percentage distribution of the meniscus tear in the area of the meniscus lesions can be roughly described as follows:
- 50% of meniscus lesions are degenerative. This form of meniscus tear occurs in the course of life due to increased strain, affecting various occupational groups such as professional footballers, tile layers, miners, gardeners, etc., i.e., people with predominantly kneeling occupational activity.
- 40% of meniscus lesions occur as a result of indirect exposure to violence (= secondary traumatic tear formation). Indirect exposure to violence includes sudden hyperextension or flexion of the joint, which unintentionally pinches the posterior meniscus horns. If force is then applied to the trapped meniscus, for example, in the form of a rotation of the lower leg, the meniscus can tear or tear.
- 8% of meniscal lesions are caused by direct force (= primarily traumatic meniscal tears), for example, by traumatic events in the form of bone fractures.
- 2% of meniscus lesions are genetic. There are people with genetically caused malformations of the meniscus. An example of this is the so-called disc meniscus. Cyst formation and increased calcification in the area of the meniscus (chondrocalcinosis) can also lead to meniscus tears in the course of the disease pattern.
Symptoms of meniscus damage
Patients with meniscus damage have pain in the area of the knee joint gap and often have limited mobility in the knee joint. The different causes of a meniscus tear cause different pain symptoms:
Traumatic meniscal damage (accidental) are usually perceived as very painful, while lesions caused by degenerative changes are often difficult to detect even during an examination. Frequently there are twists in the knee that lead to meniscus lesions. For more information, please also read: Twisted knee – What you need to consider
Various examination methods of the treating orthopedic surgeon in case of a meniscus tear help in the diagnosis but also help to exclude other diseases by differential diagnosis (see: Diagnosis)
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The main symptom of a torn meniscus is severe pain in the affected knee.
The underlying disease determines the character of the occurring pain. An acutely occurring meniscus tear, for example, caused by a sports injury, manifests itself in sudden, severe pain. Chronic cartilage wear, which is accompanied by a meniscus tear, is manifested by a gradual worsening of the pain.
In general, the pain usually occurs, particularly during exertion. In the course of the disease, the pain may also occur when standing or sitting for a longer period. The signs of a torn meniscus are usually triggered by cartilage fragments that are located in the joint space and cause the typical pain there.
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Diagnosis of a torn meniscus
During the manual examination for meniscus rupture, the doctor checks the so-called “special meniscus signs” using so-called meniscus tests.
For this, he uses proven standard tests, e.g., standard tests according to:
- Apley – Grinding
In this case, an attempt is made to press the thigh and lower leg joint surfaces together in various ways, for example, in the stretching, bending, and twisting positions. Within the scope of the examination methods, injuries of the outer meniscus can be distinguished from injuries of the inner meniscus.
Various meniscus tests also provide information about the location of the tear. The Payr standard test indicates an injury in the posterior horn area of the medial meniscus when pain occurs.
Every diagnosis of meniscus damage begins with the manual examination by the doctor, as described above. To confirm this diagnosis of meniscus damage, other diagnostic methods are also used.
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Meniscus Crack Types
As already mentioned in the context of the therapy forms, there are different forms of a meniscus tear. Depending on the location of the injury in the meniscus tissue, the following types of tears can be distinguished in the area of the inner as well as the outer meniscus:
- Tear of the basket handle (longitudinal meniscus tear with a displacement of torn meniscus parts into the joint)
- Transverse crack (from free edge to base)
- Flap tear in the posterior or anterior horn (a combination of longitudinal and transverse tear)
- Horizontal crack (longitudinal crack, whereby an upper and lower lip is formed)
The physician can examine the meniscus tear using various examination methods, usually manual examinations, to which x-ray imaging is also added, to determine which form of a meniscus tear is present.
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Magnetic resonance imaging (MRI) of a torn meniscus
At this point, it should only be pointed out that over 95% of meniscus tears can be diagnosed using MRI.
Unfortunately, some meniscus damages cannot be visualized on the MRI, or tears are worse under arthroscopy than is to be assumed on the MRI. Due to the constant improvement of the MRI technique, the error rate in MRI for meniscus tears has decreased significantly.
In the case of a meniscus tear, the MRI of the knee joint is the imaging technique of choice, as it can show the cartilage tissue with the highest accuracy. This is the best way to assess the tear, its location, shape, and extent.
Based on the findings, the optimal therapy for the patient can then be determined. Also, the MRI examination allows the simultaneous detection of concomitant injuries to the knee joint (cartilage damage, cruciate ligament rupture, tear of the outer or inner ligament).
It is not uncommon for other structures of the joint to be damaged in a torn meniscus, such as the cruciate ligaments, the outer or inner ligaments of the joint capsule.
If the inner meniscus is injured, sometimes the inner ligament and the anterior cruciate ligament are injured simultaneously.
This constellation is also called an “unhappy triad.” The MRI examination allows the entire joint to be examined and a complete injury diagnosis to be made. This is the basis on which the individual therapy to be chosen for the patient is based.
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X-ray examination of the meniscus damage
While the X-ray examination is inconspicuous in the case of fresh meniscus injuries and thus hardly provides any information in the context of traumatic damage, it is significant in the case of chronic damage (e.g., permanent occupational strain on the menisci). Bony changes become visible. To exclude possible accompanying bony injuries, an X-ray examination is carried out at least in two different levels.
Sonography (ultrasound examination)
Although ultrasound is not routinely used because other forms of examination are more meaningful, sonography provides information about accompanying ligament injuries.
In particular, swelling, water in the knee, and also hematomas/bruises can be shown well with the ultrasound examination.
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Arthroscopy of the knee
To confirm a diagnosis, an arthroscopy, i.e., a reflection of the knee joint can be performed. While the doctor can make a precise diagnosis of the joint interior, the great advantage of arthroscopy is that under certain circumstances, surgery can be performed immediately. Due to the excellent image quality of the MRI in the case of a torn meniscus, arthroscopy of the knee joint is practically not performed today for diagnostic reasons.
In the “keyhole operation,” the knee is only opened through a small skin incision. A rod, which transmits images from the inside of the joint to a monitor in the operating room using a camera, is inserted into the knee joint through this small incision, and another small incision allows the insertion of a tactile hook, which tests the condition of the cartilage, cruciate ligament, and menisci. This second incision can be used to insert further instruments, so that, for example, exposed parts of the meniscus can be removed directly.
In cases where surgery (knee arthroscopy) is required, additional examinations such as ECG and / or laboratory control of blood values are also necessary.
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Test(s) for a meniscus damage
To diagnose a meniscus tear and to assess the location and extent of the injury, various tests are used.
In a physical examination, the knee joint is moved in different ways, and the reaction of the patient is analyzed. Several different tests are known for the analysis of a meniscus injury.
Even slight pain when performing the tests is sufficient to be able to assess which type of injury is present. Therefore there is no need to fear the development of great pain. The tests can be used to assess meniscus injury and should not be considered as a substitute for diagnostic imaging methods. To make a definite diagnosis and assess the extent of the injury, diagnostic imaging methods are always used and, if necessary, arthroscopy of the knee joint performed.
The so-called Steinmann test must be divided into a Steinmann sign I and a Steinmann sign II.
In the Steinmann Sign I, the knee joint is rotated slightly inwards or outwards by turning the foot. Depending on which rotation causes pain, there is a probability of a torn inner or outer meniscus.
The Steinmann Sign II includes a knock pain test of the joint with the knee stretched and bent. Depending on the points at which a headache can be triggered, the respective meniscus is likely to be injured.
The so-called Apley-grinding test is performed in the prone position. The leg is bent and rotated inwards and outwards once while the examiner applies pressure. Depending on the occurrence of the pain, the attending physician can make a statement about the presumably damaged meniscus.
The Böhler test also allows an assessment of the location of the injury. Here, the lower leg is moved inwards and outwards while the knee joint is stretched at the same time.
During the McMurray test, the treating physician palpates the knee joint gap with one hand and slowly extends the leg with the other hand. By perceiving specific movements in the knee joint as well as the occurrence of unusual noises, an injury of the respective meniscus can be assessed.
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To assess an injury of the inner meniscus, the so-called Payr test is often used. Here, the affected person sits cross-legged while the doctor applies pressure to the knee joint from above. If pain occurs, the probability of damage to the inner meniscus is given.
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Therapy for a torn meniscus damage
Indication for surgery
Not every form of meniscus damages requires surgical treatment. For this reason, the diagnosis of meniscus diseases, including various diagnostic tests, plays an important role.
The location of the meniscus tear is also of decisive importance about the therapy. If the lesion lies in the outer zone, treatment can be conservative, for example, in the form of splint positioning and decongestant medication, possibly in combination with punctures and injections.
However, if the doctor detects a massive rupture, or a so-called “basket handle” (= longitudinal meniscus tear), it is usually necessary to remove the torn off part of the meniscus. Otherwise, the torn off part acts like a foreign body in the joint, which will also damage the cartilage and will cause the clinical picture of arthrosis at an early stage.
Cracks in the area of the capsule border can be treated by menicoplexy if necessary. This menicoplexia can be imagined as “tacking” or “sewing on.” However, since the fibrous cartilage is only weakly supplied with blood and for this reason has only a few metabolic reserves, damage to the meniscus can only rarely “heal.”
Meanwhile, almost all operations in the area of the meniscus are performed arthroscopically. An arthroscopic meniscus operation is much gentler, helps to avoid consequential damage, and to preserve as much meniscus tissue as possible while making maximum use of the surgical treatment. Also, the duration of arthroscopic surgery on the knee is significantly shorter than open surgery on the knee.
In principle, however, the guiding principle applies:
“A torn meniscus should be repaired as early as possible to prevent consequential damage.”
To guarantee an optimal supply of the knee joint in the long term, a dynamic treadmill analysis is recommended. You are welcome to make an appointment at our practice in Frankfurt am Main.
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Bandage for a torn meniscus
In addition to a series of conservative and surgical measures, which can be applied depending on the type of cartilage damage, specific bandages are available to achieve symptom relief in the case of a torn meniscus.
In general, however, bandages cannot heal the injury and only achieve a limited improvement in symptoms. Treatment by wearing a bandage alone cannot be recommended. However, this can be useful, for example, in the period up to the planned operation or as additional pain therapy.
The function of the supports, which can be worn in case of a torn meniscus, is to compress the knee joint. This compression is intended to build up pressure in the joint capsule and thus relieve the meniscus. Depending on the injury and the type of meniscus tear, a bandage, therefore, works more or less well. If foreign bodies are present in the joint space, even an increase in pressure can only have limited success, whereas an increase in pressure with simultaneous arthrosis achieves excellent results in symptom control. Whether a bandage proves to be useful in an individual case should be discussed with the treating doctor.
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Sport in case of meniscus damage
Sport can be connected with a meniscus tear in different ways.
On the one hand, the injury can be caused by certain types of sport and thus be an expression of a sports injury. On the other hand, many patients with a torn meniscus are faced with the question as to when sporting activity can be recommended again.
The individual healing time after a meniscus tear can vary greatly depending on the type and location of the injury and the chosen therapy.
Thus, a recommendation as to when and from which type of sport is appropriate should always be made individually.
Depending on how quickly the cartilage heals, sports activities can usually be recommended again after a few weeks. In general, knee-friendly sports such as swimming or cycling are better than running, which can only be recommended much later.
It is also decided whether there is chronic cartilage damage in the knee or whether the meniscus tear has been caused by an injury.
Injury-related cartilage damage usually occurs in younger, sporty people, and the healing time is correspondingly shorter than in the case of a meniscus tear, which occurs due to osteoarthritis of the knee.
The type of therapy chosen has a significant influence on the moment at which the knee can and should be partially or fully loaded again.
For example, loading is usually possible again shortly after partial removal of the cartilage, whereas the knee should be treated and protected for a much more extended period after cartilage transplantation.
Special exercises during post-operative treatment can be useful and should be carried out according to the recommendations of the doctor and physiotherapist.
A general ban on sports can, therefore, not be imposed, as such a lack of movement tends to damage the healing process as well as the mobility in the knee joint.
In addition to the question of when the knee can be loaded again, depending on the prevailing disease, adjustments to the type of sport performed should be made if necessary.
Sports that are generally associated with a very high knee joint load should be avoided if possible, even after a successful therapy. This is especially true for patients suffering from osteoarthritis of the knee joint since the strain can also cause the destruction of existing cartilage tissue and cause further complaints.
Anatomy of the meniscus damage
The meniscus consists of two crescent-shaped fibrocartilage discs, which are positioned between the upper and lower leg to compensate for the incongruity (inequality) of the articulating bones, as mentioned above, and thus to transfer impacts evenly to the cartilage of the lower leg. Also, the meniscus distributes the synovial fluid, which is particularly responsible for protecting the cartilage tissue, as it causes cartilage discs to slide over each other without friction. It also supplies the cartilage tissue with nutrients and is responsible for the removal of waste products from the joint space.
Morphologically (concerning the cellular structure), a distinction is made between the meniscus base, which is in more direct connection with the joint capsule (red zone), the medial meniscus area (red light zone), and the white marginal zone. Vessels penetrate through the red zone to the middle third of the meniscus (marked light red). The white edge, on the other hand, does not show any vessels. It is supplied by the synovial fluid (= synovial fluid). These findings have a great impact on the chances of healing various meniscus injuries. While there are good chances of healing for the red and light red area due to the supply through the vessels, a meniscus tear in the area of the white edge is much more difficult to treat. A healing in the actual sense (restoration of an uninjured meniscus) is not possible in this zone.
Since the cartilage is an important component of the knee joint, which can be damaged especially by torn/torn menisci, the function of the cartilage is discussed here:
The cartilage is a supporting tissue consisting of water-rich cartilage cells (= chondrocytes) and so-called intercellular substances (basic substance, fibers). Depending on the nature of the intercellular substance, a distinction is made between
- hyaline cartilage
- elastic cartilage
- fibrous or connective tissue cartilage
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While cartilage can be found in many areas of the body, hyaline cartilage, but also fibrous or connective tissue cartilage (= mixture of collagen and hyaline cartilage), is of particular importance for the knee area. If the cartilage has been used up due to heavy wear or injuries, the body can neither repair nor re-synthesize this cartilage tissue. The medical profession then speaks of the clinical picture of arthrosis (more information on this can be found in the definition of arthrosis).
The menisci dampen shocks in the knee joint. In the area of the knee joint, the meniscus contributes in a special way to protecting the cartilage. The meniscus absorbs shocks but also specially stabilizes the knee in cooperation with the cruciate ligaments. In MRI video sequences, it could be proven that especially the ligament connections of the menisci are needed for the shock-absorbing function. Loosened/torn ligament connections can thus be held jointly responsible for meniscus tears, which under certain circumstances can develop from superficial meniscus tears. The yellow arrow points to a healthy meniscus.
Torn or torn menisci destroy the cartilage tissue by not being able to exercise the shock absorber function to the full extent. An arthrosis of the knee joint as a severe consequence can and will occur sooner or later.
Studies have shown that meniscus injuries, regardless of their cause, occur more frequently in the area of the inner meniscus. The area of the posterior horn is particularly susceptible to injuries (about 75% of all injuries of the medial meniscus affect the area of the posterior horn).
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