What is it?
The menisci, sometimes known as the cartilages, are two crescent-shaped structures found within either side of the knee (medial and lateral) that act as shock absorbers between the ends of the femur (thigh bone) and the tibia (calf). They have a highly specialised structure, allowing them to perform a number of functions which aid knee joint movement, and preserve the articular cartilage.
The functions of the menisci are numerous, and include: acting as shock absorbers; sharing force transmission from the femur to the tibia with the articular surfaces; working as secondary stabilisers; and performing a role to aid lubrication of the knee joint.
It has become evident over recent years that loss of significant amounts of meniscal tissue can cause instability and accelerated wear within the knee. In the past, menisci were routinely removed when damaged, but treatment today is focused on meniscal preservation and reconstruction .
Why does it occur?
Meniscal tears are very common, and there are two main types: acute and degenerative.
In younger patients, meniscal tears can often be as a result of sports injuries, sometimes in combination with ligament tears. In this circumstance, the most cause of injury is twisting on a loaded, flexed knee, causing sheer force within the meniscus and often resulting in an acute tear.
With wear and tear, the fibrocartilage (tough tissue) of the meniscus becomes less robust, and more susceptible to even minor injuries. Getting up from a squatted position or twisting to get in and out of a car have been know to cause this type of degenerative tear.
What are the symptoms?
The symptoms of meniscal tears vary, depending on the pattern of tear within the cartilage. The main symptoms associated with meniscal tears are:
Knee pain. Often felt around the joint line towards the front or back of the knee, on whichever side the torn cartilage is. This can be made worse with twisting or squatting movements.
Swelling. Meniscal tears prompt the knee to produce synovial fluid, leading to an effusion or liquid on the knee.
Instability. Meniscal tears can catch within the knee joint, leading to a feeling of giving way, or locking. Certain patterns of meniscal tear can lead to an inability to fully straighten the leg.
How is it diagnosed?
Your surgeon will be able to assess whether you have a meniscal tear from your history, and an examination. A meniscal tear may present as swelling and tenderness along the joint line, around where the meniscal cartilage sits. Normally, the presence of a meniscal tear will be confirmed with an MRI scan, which will also give your surgeon some indication as to the pattern and location of the tear. This will help with planning the best treatment for your knee.
How is it treated?
Many meniscal tears can be treated without the need for surgery, and simply with rest and some analgesia. This is particularly so for degenerative meniscal tears, where there may also be wear and tear arthritis within the knee. In these circumstances, three months rest would be advised, to see if the symptoms settle.
If this has no effect, and leaving it alone would be detrimental for the knee joint, arthroscopic surgery would be recommended. Depending on the pattern of the tear, its location, and your age, treatment will involve repair using internal sutures, or resection of the torn fragment. There are pros and cons to each of these approaches, and the rehabilitation for each procedure is slightly different. Your surgeon will discuss with you in detail the type of tear you have, and therefore the best course of action in your particular circumstances.
The One Orthopaedics team specialists
Consultant Orthopaedic Knee and Hip Specialist (Tr & Orth)
Knee Specialist FRCS (Orth)
Consultant Orthopaedic Knee and Hip Surgeon FRCS (Tr & Orth)