Surgical Hospital :: Orthopedic Surgery

Meniscus surgery, fixation and resection

When people suffer an injury to their knee they often damage their meniscus.
When damaged the meniscus will create pain especially when bending the knee or twisting it.
Some patients will experience that their knee actually locks and swells.

A damaged meniscus can easily be treated by arthroscopic surgery (key-hole surgery) by which it can either by fixated using an absorbable device or the damaged part of the meniscus is removed. Normally the patient will be fully weight bearing the same day as he or she is operated, and will regain normal function after 3-6 weeks depending on the severity of the damage to the knee. If we look at the construction of the meniscus we will see a huge difference between the meniscus on the inside of the knee and the meniscus on the outside.

The inner meniscus is the meniscus which in more than 90 % of all knee accidents is being damaged. Fortunately since the inner meniscus is shaped as a half-moon and that the femoral bone is convexo meaning rounded and the tibial bone is also rounded but downwards. This makes a very big area for the inside of the joint to deliver to pressure when loading the knee. This is the main reason for patients who suffer a meniscus injury not to suffer from osteoarthritis within just a few years time.
Opposite on the outside of the knee; when the meniscus on the outside of the knee is damaged this is a very serious condition since this meniscus is round and by its shape prevents the knee from putting a very heavy load to a very small area since the femoral bone which is also round on the outside but the tibial bone at this place is rounded upwards leaving the patient to develop osteoarthritis very quickly when having a damaged outer meniscus.

Why do some menisci heal and others do not?

The one main reason for why some menisci heals and others do not is due to the vascular condition of meniscus. The other main reason is the type of lesion to the meniscus.

According to vascular conditions: The outer third of the meniscus (referred to as red area) has a 100 % vascular condition. This means that all lesions with the possibility to heal (depending on the type of lesion) will eventually heal when fixated during operation by an absorbable device. The middle third of the meniscus (referred to as red/white area) has a vascular condition of 65 to 70 %. The inner third of the meniscus (referred to as white area) has a minimum of vascular condition and the possibility to heal in this area is near to zero.  The overall possibility for conservative spontaneous healing is about 40 - 60 % within 6 weeks where the patient should avoid twisting and bending the knee. If the patient suffers from pain and eventually locking/impingement after more than 6 weeks he will need to be operated by arthroscopic surgery.

This brings us to the other main reason for why a damaged meniscus heals or not. If a meniscus has tear to it being vertical (meaning upside-downside) and being in the red or red/white area it can be fixated during operation by an absorbable device and if so the meniscus will heal with a success rate of 70 %. If the meniscus suffers from a horizontal lesion this lesion is not doable for fixation since it is two layers of the meniscus who moves independently opposite the vertical lesion where the parts are pushed together. The horizontal lesion will have to be removed until normal meniscus tissue appears. One will always try to keep as much of the meniscus as possible to avoid the development of osteoarthritis or at least delay it as much as possible. If  the patient has a lesion which can be fixated he will have to wear a brace for two weeks, and avoid bending the knee more than zero to 90 degrees for 8 weeks after the operation. This is due to the meniscus moves forward and backwards when loading the knee and when the knee is flexed more than 90 degrees the meniscus slides backwards and actually lays 7-10 mm outside the tibial bone where it initially would lock the knee when being damaged. When fixated the fixation will brake if loaded on the tibial bone at its border. Therefore the patient is not allowed to put load on the knee with more than 90 degrees of flexion before after 12 weeks. By this regimen 70 % of all fixated meniscus will heal reducing the risk for the patient to develop osteoarthritis in the future. Again even if the meniscus is just partly removed related to the lesion, this will avoid the cartilage to be partly damaged due an impinged meniscus which is also going to reduce the risk of osteoarthritis since the cartilage is intact.

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