Meniscus tear

Definition: What is a meniscus and a meniscus tear?

The menisci are initially two crescent-shaped cartilages located between the lower and upper thigh bones. The inner meniscus is located on the inner side and the outer meniscus on the outer side of the thigh bone. 

The menisci serve to stabilise the movement of the knee joint when walking. Here, the menisci function similarly to shock absorbers, because the pressure is distributed evenly over the musculoskeletal system.

The functioning of the meniscus 

The meniscus functions similarly to a shock absorber: namely, it is responsible for healthy balance and biomechanics in the knee joint. The connecting cartilage consists mainly of elastic building blocks, one-third collagen and two-thirds hydrogen.

The inner meniscus differs in that it has a much firmer structure, which is more firmly fused with the joint capsule of the knee joint. The disadvantage is that rotational movements cannot be optimally compensated from the outside. The result is that injuries can occur more frequently.

The outer meniscus is much more mobile in comparison, although the structure is the same. The thicker edge of the menisci is firmly fused to the joint capsule, which additionally stabilises the knee joint. Both menisci stabilise the movement of the knee joint, distribute pressure and cushion shocks. At the same time, they lubricate the joint cartilage and supply it with important nutrients.

Which age group is often affected by meniscus tears? 

Tearing of the meniscus is common in young adults who play ball sports such as football. The increased stress can thus increase the likelihood of a knee injury occurring. 

However, older people with reduced meniscus function are also plagued with mechanical blockages of the knee joint, which are caused by cartilage wear and knee arthrosis. Depending on the length and position of the meniscus, a mechanical blockage of the knee joint can be caused. 

Symptoms: Recognise meniscus tear 

The symptoms of a meniscus tear vary depending on the size and shape of the meniscus damage. Small meniscus tears are not always noticeable immediately. So you may not notice the pain until a few hours, days or even weeks after the injury. When it comes to a meniscus injury, you should experience the following symptoms:

• First and foremost, you should check and assess the pain at the knees and especially during twisting movements.
• You may also hear a popping or cracking sound when the meniscus tears. 
• Visually, you can detect the meniscus tear by the swelling of the knee. 
• It could also be true that you hear a popping or cracking sound when the meniscus tears. 
• A common symptom of meniscus tear is limited motor function and locking of the knee. 
• Furthermore, many people complain about the instability of the knee joint. 

The causes: This is how meniscus damage occurs

Not all meniscus tears are the same, because there are different ways in which the meniscus can tear. A distinction is made between longitudinal, basket-handle, flap, transverse, radial and horizontal tears. The inner meniscus is about five times more frequently affected by injuries than the outer meniscus, which is more loosely attached to the thigh bone.

Traumatic or degenerative meniscus damage 

A meniscus tear is often the result of a violent knee twist, twisting of the knee or simple overloading of the affected area. The causes of sudden tears are not only due to sporting activities, but also to everyday situations.

A basic distinction is made between traumatic (accident-related) and degenerative (wear-related) meniscus lesions. A typical cause of traumatic meniscus injuries is the twisting of the knee joint under load. Here, patients usually immediately feel a shooting and stabbing pain or even a blocking sensation. In fact, primarily younger patients are affected by this meniscus damage.

Degenerative meniscus damage mainly plagues older patients. The symptoms here are usually gradual, but nevertheless acute pain events and blockage phenomena can also occur.

The meniscus tear during sports activities 

Sport involves a lot of movement, so the likelihood of getting injured while doing it is quite high. Especially in contact sports like football, for example, the meniscus tears when the ball is kicked at full speed. Due to the dynamics, the impact with the ball and the shot, the knee joint can no longer react against it. Depending on the impact and the position, the extent of the tear can be larger or smaller.

The meniscus tear at work 

Meniscus tears often occur during everyday activities such as working. This is because the knee joints can also be confronted with high loads here. Frequent bending, such as kindergarten teachers who mostly bend down to the small children, can have a negative impact on the knee joint. Factors such as body weight put additional strain on the knee. Other conditions, such as carrying heavy objects, constantly climbing stairs or being very overweight, also lead to an unfavourable development of the meniscus. Consequently, you are unable to work after the meniscus tear.

Treatment: Therapies for meniscus tears 

There are a few options for treatment against the acute meniscus injury, depending on the degree of cross-linking. If the meniscus tear is large, a surgical treatment approach is often recommended. Smaller damages can ideally be repaired by conservative treatments.

This is the first thing you should do if you notice a meniscus tear

The first signs of a meniscus tear are pain and significant swelling of the knee. Therefore, you should follow the steps below:

• Ideally, put your leg up to rest it.
• Cool the knee area by placing a cooling bag on the affected area at regular intervals. This will help to reduce the swelling.
• Avoid jerky movements and putting pressure on the knee. Kneeling, squatting and activities such as climbing stairs should be avoided immediately.
• Anti-inflammatory painkillers should be taken if the pain is too severe.

The conservative meniscus tear exercises and therapies

After the doctor has diagnosed the meniscus tear, treatment can begin. Depending on the degree of cross-linking, the damage can be treated surgically or conservatively. For the conservative treatment of the meniscus tear, there are the following treatment options:

• The movement therapy guided by physiotherapy.
• Consuming anti-inflammatory painkillers.
• Conventional knee supports or orthoses. 
• Weight reduction if obesity is the trigger of the disease. 

The conservative method has the great advantage that the function of the meniscus can be better preserved. In addition, the risk of developing knee arthrosis is significantly lower than after partial removal of the meniscus.

Surgical meniscus tear treatment: meniscus smoothing, meniscus repair or meniscus transplantation

In addition to the conservative treatment of the meniscus tear, there is the option of surgical treatment. Here there is the option that the damaged parts of the previously torn meniscus are sutured or removed. The position of the tear is decisive for the treatment procedure that is ultimately carried out:

• When removing the damaged parts of the torn meniscus, it is first frayed and cut away. The surface of the meniscus can then be smoothed. In technical terms, this procedure is called meniscus smoothing or partial resection . 
• If the meniscus is only slightly torn, the meniscus can be repaired, also called a meniscus suture. Here, the meniscus is sewn together with the help of small instruments.
• In a few cases, the meniscus is not only removed but also replaced straight away. This method is only used if the meniscus is too damaged. So if the entire meniscus is affected, it can be replaced by a meniscus transplantation with the help of a donor meniscus. In addition to this transplantation, surgery can also be performed with a biological tissue substitute. The meniscus replacement is sewn into the cleaned deficit and consists of either collagen or polyurethane, which is gradually replaced by the body's own tissue.

• The parts with good blood supply (red markings) heal better. Therefore, the treatment method of meniscus repair can take place here.
• The situation is different in the part of the menisci that is not supplied with blood (the white area). If this region of the meniscus is torn, the next treatment step is meniscus smoothing. 
• In the case of areas that are only partially supplied with blood (the white-red areas), the attending physician usually decides which method is appropriate.

Surgical treatment of the torn meniscus has the disadvantage that you will probably need a longer recovery period to fully recover. The risk of developing knee osteoarthritis in the following years is more likely than with conservative treatment.

How does a knee endoscopy work

If the doctor decides on surgical treatment, the operation is always performed within the framework of a knee endoscopy (arthroscopy). This requires two to three small incisions on the knee. This allows a special endoscope (arthroscopy) to be inserted.

This contains a camera with a light and a cannula. With the help of this technique, an assessment of the degree of injury and surgical methods can be determined.

Through the other incisions, surgical instruments for cutting, gripping and suturing are inserted, which are needed to perform the operation.

Aftercare and rehabilitation: The three phases of healing

Preoperative: Surgical knee arthroscopy rarely brings complications. The length of the operation is decided on the basis of the degree of injury. To prevent blood clots, venous thrombosis and pulmonary embolism, anti-thrombosis injections and thrombosis stockings are usually administered before the operation.

Post-operative: The rehabilitation phase after surgical treatment of meniscus tears also depends on the treatment method: meniscus repair or meniscus smoothing. If the meniscus is sutured, it could tear again if the grace period is disregarded. Therefore, you should first take it easy after the knee arthroscopy and, if possible, cool down.

Rehabilitation after meniscus straightening

The rehabilitation of the meniscus smoothing is carried out in three phases after consultation with your treating doctor:

1. Phase: Already three weeks after the surgical intervention, the leg can be loaded with body weight. In order to minimise pain or possible damage, a walking aid is recommended.
2. Phase: Four to six weeks after the partial meniscus removal, the leg is stabilised with sports sessions on the ergometer or bicycle. Knee-straining movements should be avoided as far as possible during this phase.
3. Phase: Six weeks after surgery, most sports activities should be possible again. However, consultation with the treating doctor or physiotherapist should take place in advance.

Rehabilitation after meniscus suture

The rehabilitation of the meniscus suture also takes place in three phases after consultation with your treating doctor, but they start much later:

1. Phase: Six weeks after the operation, you should only put weight on your leg with the help of a walking aid. First, gentle physiotherapy is introduced for rehabilitation, during which the knee should be moved passively. The aim of this therapy is that the leg can be fully stretched and bent again at a 90-degree angle.
2. Phase: In the seventh to fourteenth week, the knee can already be loaded with the entire body weight. The goal in this phase is to gently load the knee, which will then lead you back to your everyday life.
3. Phase: From the fourteenth week onwards, sporting exercises and light sports can be undertaken again after consultation with your doctor.

The less common treatment for a meniscal tear is transplantation, which is similar to meniscal suturing in terms of the rehabilitation process. Since this procedure also involves further surgical steps to create the biological tissue replacement, the rehabilitation could take a significantly longer time. It is therefore important to discuss further steps with your doctor.