The knee is made up of several structures – bones, cartilage, tissue lining, lubricating fluid with ligaments, muscles and tendons supporting the joint. This is not unique to the knee. All joints are made up of multiple structures. One of the often overlooked parts of the knee is the menisci. These are two cartilage “shock absorbers” that can become injured or even torn. It weakens and wears down with age but tears can occur even in younger people, particularly in professional sportspeople.
What is a torn meniscus?
A torn menisus is where there is a tear in one or both of the wedge-shaped cartilages in the knee joint. The menisci are important for cushioning and stabilizing the knee. Tears tend to arise with twisting of the knee, usually while playing sports.
Meniscal tears can be treated surgically or non-surgically. If the tear is not severe and limited to the outer parts of the menisci where there is an adequate blood supply then surgery may not be necessary as it can heal on its own. However, tears in the inner two-thirds cannot heal and require surgery.
Causes of Menisci Tears
It is important to understand the position and structure of the menisci as it is relevant to how tears occur and the symptoms that arise. The knee joint is where three bones meet – the femur of the thigh, tibia of the lower leg and the patella (kneecap). The round ends of the femur (thighbone) known as the femoral condyles are separated from the articular surface of the tibia (shinbone) by wedge-shaped cartilages known as the menisci (singular ~ meniscus).
The menisci are mainly made up of collgen fibers. This gives it a firm but rubbery texture. It plays a crucial role as a shock absorber, helping the knees withstand force that is placed on it with walking, running or jumping. The healthy knee with intact menisci have an approximately 20% better shock absorbing capacity than knees where the menisci have been surgically removed. The menisci play an important role in knee joint stability.
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How does a meniscus tear occur?
Menisci tears are more common when playing sports. It tends to occur when a person is running and suddenly changes direction which results it twisting the leg at the knee. It can also occur with repeated squatting. These tears may also arise with trauma to the knee as may occur with contact sports.
Older people are more prone as the menisci wekanes with age thereby making a tear more likely to occur. High impact activities like sports may not be involved in meniscal tears in the elderly. Any twisting of the leg can result in a tear. It is estimated that as many as 4 in 10 people over the age of 65 years have meniscal tears.
There are different types of meniscal tears, classified according to the direction of the tear and where the tears occur in the menisci. This includes:
- Horizontal tears
- Longitudinal tears
- Oblique flap tears, also known as parrot beak tears
- Radial tears
- Root tears
Complex tears are a combination of more than one of the above tears. Most meniscal tears occur at the same time as other injuries to the knee or leg, such as with an anterior cruciate ligament (ACL) injury.
Signs and Symptoms
The signs and symptoms of a meniscal tear are often not as specific and obvious at the time of the tear. A popping sound or locking of the knee may first occur but severe pain may not be present initially. In fact a person with a meniscal tear may be able to continue with physical activity involving the affected leg, and may even be able to continue playing the sport. Pain along with other symptoms may develop as late as 2 to 3 days after the injury as the inflammation worsen.
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The signs and symptoms of a torn meniscus includes:
- Knee pain, including pain at the back of the knee sometimes.
- Swelling of the knee may or may not be present.
- Limited range of motion (bending and straightening at the knee joint).
- Locking, catching and/or clicking of the knee.
It is important to differentiate between a torn meniscus and other types of knee injuries such as an anterior cruciate ligament (ACL) injury or a fracture. Therefore it is important to seek professional medical attention.
Treatment of Meniscus Tears
Once a meniscal tear has been confirmed, there are several options depending on the type of tear and severity. Not all meniscal tears require surgery. However, some degree of intervention is required as most meniscal tears will not heal on its own. The choice of treatment must be discussed with a medical professional. Attempting to manage a meniscal tear with medical supervision can lead to complications which may permanently affect knee function.
The R.I.C.E. approach to managing a meniscal tear is necessary, even if surgery will be required in due course.
- Rest. It is important to stop all activities that will place more strain on the knee. Even after the acute symptoms resolve, running and jumping should be avoided as far as possible for several days to a few weeks.
- Ice. Apply ice packs to the knee can help minimize inflammation following the injury and also assist with easing inflammation that is already present.
- Compression. A bandage or sleeve can be helpful to control swelling. Other devices like a knee brace should only be used if approved by a medical professional.
- Elevate. Prop up the leg whenever possible. A pillow or some other object can be placed under the ankle or heel when sitting or lying down.
Physical therapy and exercises prescribed by a physical therapist are important for rehabilitation. Medication may be prescribed for both non-surgical management as well as after surgery. These drugs include:
- Non-steroidal anti-inflammatory drugs (NSAIDs) helps to reduce inflammation thereby easing pain and swelling.
- Analgesics are used to manage pain (both surgcial and non-surgical cases) and after surgery.
There are two surgical options – repair the menisci or remove the damaged menisci. The menisci are spared as far as possible and surgical repair is undertaken whenever possible. Most severe meniscal tears cannot be adequate repaird surgical and instead the menisci are removed (meniscectomy. Although a meniscectomy may have a shorter healing time compared to surgical repair, surgery can affect knee support and stability in the long term.