Meniscal injuries

Menisci are shock absorbers and power transmitters in the knee. Meniscus injuries are usually noticeable with knee pain. More about causes, symptoms and therapies

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View into the knee joint: Here are the menisci (shown in red)

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Meniscal injuries - briefly explained

Menisci are fibrous cartilage discs in the knee joint and contribute significantly to the function of the joint. There is an inner and an outer meniscus. The inner meniscus is fused with the inner ligament. As a result, it is less mobile and more frequently injured than the external meniscus. A tear in the meniscus occurs as a result of (sports) injuries or due to signs of wear and tear. Meniscus damage is diagnosed by examination and magnetic resonance imaging (MRI). A tear is usually treated by a "keyhole operation" (arthroscopy, knee joint mirroring) in which the meniscus is either sutured or partially removed. Which method is used depends, among other things, on the location and type of the crack and is determined individually. If the meniscus damage is due to wear and tear, conservative treatment (without surgery) is sometimes possible.

What are the menisci?

Menisci are C-shaped, fibrous cartilage. They lie in the knee joint like a wedge between the articular surfaces of the tibia and femur. There they increase the contact area, distribute the weight, absorb shocks and stabilize the joint. In the human knee there are two meniscuses, which are referred to as the inner or outer meniscus according to their location.

Most people are not consciously aware of these structures in the course of their lives. However, if injuries or overloading occur, the importance of these crescent-shaped cartilage discs becomes apparent.

Anatomical representation of the knee joint

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Background information - the knee joint

The knee joint can be bent and stretched, and also rotated slightly when in a bent position. It is exposed to great stress and at the same time has to offer sufficient mobility. The knee joint is made up of the thighbone (femur), the shinbone (tibia) and the kneecap (patella). The thigh bone and the shin are covered with cartilage tissue, the joint gap is only a few millimeters. The knee joint is stabilized by the surrounding capsule and several ligaments (collateral ligaments, anterior and posterior cruciate ligament). The anterior cruciate ligament arises at the front of the lower leg and pulls back through the knee joint to the thigh. The posterior cruciate ligament runs from the front of the thigh to the back of the lower leg, so the two ligaments cross each other, hence the term cruciate ligament. The menisci consist of cartilage tissue and serve to buffer and rotate as well as to enlarge the joint surfaces. There are two meniscuses (inner meniscus = meniscus medialis and outer meniscus = meniscus lateralis). The inner mensicus has grown together with the inner ligament and is therefore more immobile and prone to injury.

Cause: How does a meniscus injury occur?

The meniscus is stressed daily during movements such as climbing stairs or "crouching". Various sports such as tennis, football or skiing put a lot of strain on him. "The menisci in the human knee correspond to the shock absorber on a car: In an absolute emergency, you can get ahead with defective ones, but they should be intact for good and painless road holding!" Explains Dr. Boris Möbius, Senior Consultant in the Department of Surgery, Trauma Surgery and Orthopedics at the Evangelical Hospital Hubertus in Berlin.

In middle-aged people, the meniscus begins to wear out. Under the weight of the body, the meniscus tissue becomes thinner and thinner over time. This can lead to tears and injuries (mensicus lesions) through little or no force.

"In young patients, mensicus lesions usually arise as part of sports injuries," says Möbius. Injury typically occurs during a twisting and falling movement as well as when bending or stretching quickly. The free edge of the meniscus can get between the joint bodies and tear completely or partially.

Sometimes meniscus tears occur in combination with other knee injuries. The doctor then speaks of an "Unhappy Triad" (unhappy triad). In addition to the inner meniscus injury, the inner ligament and the anterior cruciate ligament are also torn.

Symptoms: what symptoms does a meniscus injury cause?

In the event of a sudden (acute) meniscus tear, for example after an accident, the patient suddenly feels pain in the knee. It often swells up. In the case of medial meniscus injuries, patients usually have pain in the inner joint space, which increases with twisting and flexing loads. In the case of external meniscus injuries, the external joint space is tender on pressure. If part of the meniscus is torn off, this piece can become trapped and lead to painful blockages of the knee joint. Sometimes snapping and cracking noises can be heard when the meniscus tears.

If the meniscus tear is caused by wear and tear, the symptoms are usually less obvious. The patient experiences increasing pain in the knee joint, especially when exercising, and a feeling of instability may also occur.

Forms of the meniscus tears

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TO THE PICTURE GALLERY

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Uninjured menisci

The picture shows the top view of the knee joint.Here the normal position and shape of the menisci can be seen.

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Radial crack

The radial tear runs across the cartilage fibers and extends outward from the inner edge of the meniscus.

© W & B / Szczesny

Flap tear

This is also a transverse crack, which changes its direction in the course and runs parallel to the inner edge.

© W & B / Szczesny

Longitudinal crack

The tear runs in the longitudinal direction, i.e. with the cartilage fibers.

© W & B / Szczesny

Basket handle tear

The tear also runs lengthways, i.e. in the course of the cartilage fibers, which is widening. The outer edge of the meniscus remains and forms the "basket handle". This can slip into the joint space and block the knee.

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Representation of the different blood flow zones in the meniscus (please click on the magnifying glass)

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Classification of meniscus damage (meniscus lesions) according to blood flow zones

In addition to the type of tear (see picture gallery), the blood flow zone of the affected area is also important for further care. The meniscus is divided into three zones. The red zone (well-perfused area, near the capsule), the red-white zone (medium blood flow) and the white zone (poor blood flow).

Meniscus Injury: First Aid Measures

Immediately after a knee injury, you should try to protect the joint and contain the swelling as much as possible. To do this, elevate the injured knee and move it as little as possible. Cool it with ice packs or compresses (caution, do not put ice directly on the skin, but wrap it in a cloth, for example, otherwise there is a risk of frostbite!). In any case, the knee must be examined quickly by a doctor after the accident.

The so-called PECH rule has proven its worth immediately after a sports accident. This stands for:

  • P = pause. Protect the affected area
  • E = ice, so cool
  • C = Compression: Apply an elastic pressure bandage
  • H = elevation of the affected leg

Diagnosis: How is a meniscus injury diagnosed?

The doctor asks about the exact course of the accident. Then he will look at the knee and mechanically examine the menisci using certain twisting and bending tests. "In most cases, the clinical examination is already goal-oriented," says Möbius.

If a meniscus injury is suspected, an X-ray of the knee joint often follows in order to rule out accompanying bony injuries.

If there is a large effusion in the knee joint, the doctor can puncture the knee. Here he takes part of the liquid with a hollow needle in order to relieve the knee and examine the liquid.

The best method for diagnosing meniscus injuries is nuclear spin tomography (also known as magnetic resonance tomography, or MRI for short). With this technique, doctors can precisely visualize bones, cartilage and soft tissues and assess accompanying injuries. Other possible causes of the symptoms must be ruled out, for example a meniscus squeeze and another ligament or cartilage injury.

If, after these examinations, it is still unclear whether a meniscus tear or other meniscus damage is present, the doctor may recommend a knee arthroscopy. In doing so, he can often operate on the meniscus tear.

Therapy: How is a meniscus injury treated?

The treatment of a tear in the meniscus depends on factors such as the size and location of the tear, but also on the patient's age, athleticism and pain.

"Not every meniscus lesion has to be operated on," says the trauma surgeon and orthopedic surgeon. "Small and non-pinching meniscus lesions that cause little or no problems can be cured first with immobilization and then with physiotherapy exercises." In addition, pain relievers such as diclofenac or ibuprofen can be taken temporarily.

Larger and unstable meniscal injuries require surgery. "Painful and, above all, movement-restricting meniscus lesions should not be underestimated," warns the orthopedic expert. They are an urgent reason for an operation, says Möbius, because there is a risk of cartilage damage and thus joint wear (osteoarthritis).

Nowadays the operation can be done in the vast majority of cases by means of an arthroscopy under general or partial anesthesia. The procedure is carried out on an outpatient or inpatient basis, depending on the patient and the injury. Major open knee surgery is usually no longer necessary.

The therapy goal: to preserve as much meniscus as possible

Partial meniscus removal and meniscus suturing are most common in meniscus surgery:

  • Removal of part of the meniscus: If large areas of the meniscus are torn in or torn off, the surgeon removes all damaged and movable parts. The goal, however, is to preserve as much healthy meniscus tissue as possible. If the meniscus has to be removed almost completely, a partial meniscus implant made of collagen may also be considered in individual cases.
  • Meniscus suture: "In younger, very active patients, an arthroscopic meniscus suture - using a keyhole technique - is used," says Möbius of his work. Here the tear is fixed either with a surgical thread or with special small pins. These so-called meniscus arrows (darts) are made of a material that the body can later dissolve.

In many cases, doctors combine both procedures during surgery in order to preserve as much healthy cartilage tissue as possible. "Which surgical procedure is chosen is a very individual decision that is made together with the patient," adds the surgeon. In addition to the type of tear, the location of the injury also plays a role. There are different areas of blood flow within the meniscus. Healing is more difficult in areas with poor blood circulation, which is why a suture is not useful in these areas.

In any case, timely medical therapy is important. If meniscus damage is not treated, it can lead to joint effusions, further cartilage damage due to blockages and joint wear.

Meniscus operation: what is the follow-up treatment like?

"The follow-up treatment depends on the operation performed and the quality of the remaining meniscus," explains Möbius. "After a meniscus suture, the patient has to relieve the operated leg so that the suture can heal in peace."

In the case of a partial removal of the meniscus, it is usually sufficient to use crutches for a few days; in the case of a suture, partial stress and wearing a so-called orthosis for several weeks are to be expected. So-called thrombosis prophylaxis should take place during the time in which the leg cannot be fully loaded. This can be done by injecting low molecular weight heparin into the subcutaneous fat tissue of the abdominal wall or with tablets. It is best for patients to inquire individually with their doctor how much they can put on their knee. Appropriate physiotherapy exercises are important to strengthen the muscles.

Depending on the injury and the operation, the knee movement and sporting activities are slowly rebuilt. A full sporting load should only take place after several weeks with a partial removal, after a meniscus suture at the earliest after three months.

Dr. Boris Möbius

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Consulting expert

Dr. med. Boris Möbius, specialist in surgery, orthopedics and trauma surgery, is the senior consultant in the clinic for orthopedics / trauma surgery and sports medicine at the Hubertus Evangelical Hospital in Berlin.

Swell:

  • German Society for Trauma Surgery (DGU), meniscus lesion (= meniscus tear). Online: http://www.dgu-online.de/index.php?id=279 (accessed on April 15, 2019)
  • German Society for Orthopedics and Trauma Surgery (DGOU), S2k - Guideline Meniscus Diseases, as of 07/15. Online: https://www.awmf.org/uploads/tx_szleitlinien/033-006l_S2k_Meniskus Krankungen_2015-07.pdf (accessed April 15, 2019)

Important note: This article contains general information only and should not be used for self-diagnosis or self-treatment. He can not substitute a visit at the doctor. Unfortunately, our experts cannot answer individual questions.

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