Wound healing of the meniscus

An injury in the well perfused part of the meniscus close to the base of the meniscus is subject to various wound healing processes of varying duration, as is the case everywhere else in our body when injuries occur. First of all, the meniscus tear causes bleeding because tissue has been injured. This bleeding is stopped by the body’s own blood clotting system and a haematoma is formed.

This bleeding releases certain defense cells (leukocytes, monocytes, macrophages) from the vascular system, which in turn release messenger substances, thereby initiating a pain and inflammatory reaction. This first phase of wound healing of the meniscus is called the inflammatory phase and lasts about four to five days. The next phase is called the proliferation phase.

Here the cells begin to produce new connective tissue (collagen), with which the meniscus tear can be closed and filled. This process takes up to ten weeks and is followed by the rebuilding phase. During the rebuilding phase, the connective tissue formed is converted into the actual collagen of the meniscus.

It often takes several months until the entire meniscus tear is healed by new, functionally remodeled tissue. Throughout the entire wound healing process, vessels invade the area of injury, restoring the blood flow to the meniscus. Some studies have shown that meniscus tears that are located in the area of the meniscus not supplied with blood can also heal. The duration and the exact course of the wound healing in this case, however, is not yet exactly clear. It is assumed that the joint capsule and the protective joint fluid can initiate repair processes.

Duration after surgery

The meniscus tear is either caused by an accident and the trauma that accompanies it or it is the result of wear and tear and chronic degenerative processes. Nowadays, a meniscus tear is usually treated surgically by arthroscopy. Only in exceptional cases and in case of additional injury of the ligament apparatus an open surgical procedure is still used.

The type of operation is decisive for the duration of healing and regeneration of a torn meniscus, because in addition to the time required for the sutured meniscus to grow together or for partial removal of the meniscus to heal, the size of the wound surfaces and the risk of wound infection must not be disregarded. After the operation, the patient is able to resume normal activities within a few days. Especially after a partial meniscus resection, the regeneration time is very short.If the meniscus has been surgically sutured, a further sparing period is recommended.

This can be facilitated with forearm crutches and splints to stabilize the knee joint. A rehabilitation should be supported by outpatient physiotherapy, lymph drainage and movement exercises. If these exercises are not carried out, the musculature may decrease, which permanently limits the movement of the knee joint.

The individual healing time depends on the extent of the injury, the surgical technique used and the patient’s compliance with the doctor’s instructions after the operation. The duration of incapacity to work after meniscus surgery depends on the severity and localization of the tear and the surgical technique used, as well as on the patient’s professional activity and the associated stress. If the torn off part of the meniscus was removed during arthroscopy, it is called partial meniscectomy.

After this procedure, depending on the load on the knees at work, the patient can return to work after 1 to 3 weeks. However, if the torn meniscus has been sutured, healing takes much longer, and full weight bearing in physically active occupational groups is only possible again after 6 to 8 weeks. Even in the case of an occupation with office work, the sick leave should last at least 4 weeks.

In some cases, it is advisable to start a slow reintegration into the professional life instead of starting directly with a full working day. These prescribed periods should be observed by employer and employee so that the meniscus tear can heal completely. Otherwise the danger of a renewed tear is high. In addition, the meniscus suture may tear or irritate the wound area, causing swelling and pain.