Meniscus Tear

The meniscus is a structure in the knee joint that spans and cushions the space between the femur (thighbone) and the tibia (shinbone). There are two menisci in each knee – one on the inside (the medial meniscus) and one on the outside (the lateral meniscus).

Each is made of strong fibrocartilage and is shaped like a crescent or the letter “C.” These menisci look like suction cups that are carefully moulded to the shape of the joint surfaces of the femur and tibia.       

The menisci with their crescent shape are interpose between the femur (above) and the tibia (below)

They act as a shock absorber and provide a smooth surface for your knee to glide on. A tear in the meniscus prevents your knee from rotating, causing pain and locking. Injuries to the meniscus are common, particularly among athletes.

However, most of the meniscus tissue has no vascular supply and is unable to heal except if the tear is located at the extreme periphery of the crescent. This means that in general, a meniscus tear has a natural evolution towards worsening. Also, with ageing, the meniscus tissue has the tendency to dehydrate and degenerate, becoming weak and exhibiting what is called “degenerative” tears.

What does the meniscus do?

The shape and size of the meniscus allows it to serve several functions. When you stand up, your weight is borne evenly through your legs and down to your knees. The stress this weight places on the knee becomes even higher while walking, kneeling, running, and jumping. The meniscus transmits the load of your weigh evenly across the knee joint. This load-sharing function helps to prevent knee injuries and is extremely important to the good health of the knee.

An injury to the meniscus can affect the knee’s ability to function normally. The most common type of meniscus injury is a meniscal tear.

Different types of meniscus tear

What causes a meniscal tear?

There are two basic types of meniscal tears. 

  • A traumatic meniscal tear often happens when an athlete quickly turns the body, pivoting on the knee while the foot is planted on the ground. 
  • A degenerative meniscal tear is caused by wear over time, and usually affects older people.

Traumatic tears

usually occur during forceful twisting of the knee and are common among players of contact-pivot sports such as soccer, basketball, martial arts, etc. They can also occur during any activity involving knee twisting. Less often, repetitive kneeling or rising from a squatting position while lifting can lead to a tear.

Degenerative (non-traumatic) tears

Degenerative or atraumatic tears usually in older populations and are caused by biology and degeneration and breakdown of the meniscal structure. People with degenerative tears may have twisted their knee and accelerate the tear. The treatment for a degenerative tear may be very different from that of a traumatic tear.

What are the symptoms of a torn meniscus?

The key symptom of a meniscus tear is pain in the knee joint. A locking or catching sensation may also be felt in the knee, and it will often become inflamed (swollen). There may also be a feeling of weakness in the leg and a sense of the knee buckling or “giving way.” This is because displaced, fragmented tissue from a torn meniscus and swelling in the knee can affect the thigh muscles.

Pain is usually felt in the knee above the meniscus while bearing weight on the knee and/or when twisting, turning, or pivoting, such as while getting in and out of a car. Walking up or down stairs may be particularly painful and may also cause increased swelling in the knee.

Following a meniscus tear, simple walking and other activities that do not require twisting, pivoting, rapid change of direction are generally well-tolerated. Tears can progress over time, but the rate of progression is gradual and variable. Pain is the watchdog. If a tear worsens, there will generally be associated symptoms of increased pain. Progressive meniscus loss can increase the risk that a person will develop degenerative knee wear. So, it is important to get a diagnosis and seek treatment early.

How is a torn meniscus diagnosed?

Your doctor will ask about your symptoms and the circumstances of your injury and conduct a physical examination. Radiological imaging studies will be ordered to confirm a diagnosis: X-rays will help rule out bone injuries, and high-resolution magnetic resonance imaging (MRI) studies will help reveal the type and location of the tear.

MRI scan showing a vertical tear (red arrow) going through the medial meniscus that is normally homogeneously black.

What type of doctor treats meniscus tears?

If you suspect your meniscus is torn, it is important to be evaluated by a physiotherapist, a primary care sports medicine physician, or an orthopaedic surgeon who specializes in sports medicine. 

Will a meniscus tear heal on its own?

As stated before, the meniscus has a limited blood supply and, therefore has limited ability to heal on its own. Only the outer one-third of the meniscus contains blood vessels required for healing. This is known as the “red zone.” A lesion located in the red zone is accessible to repair

The inner two-thirds of the meniscus does not have blood supply and is also known as the “white zone.” Most meniscus tears that affect the white zone cannot heal on their own and need to be trimmed.

What is the treatment for a torn meniscus?

Nonsurgical treatments, such as oral anti-inflammatory medications and rehabilitation with a physical therapist may help some people with a torn meniscus. Other patients will need surgery, usually either a trimming or repair of the meniscus. Treatments may also depend on whether the tear is traumatic or degenerative.

Non-surgical options

A non-operative physical therapy treatment program will often focus first on reducing pain and maintaining the full motion of the knee. After the initial injury pain has decreased and the knee motion is restored, treatment may move to muscle strengthening. Plasma-rich platelet (PRP) injections may be beneficial to selected patients.

Degenerative tears without separated meniscal fragments can often be treated without surgery through conservative treatment.

Fragmented degenerative tears and most acute, traumatic tears will need surgery.

Surgical options

If surgery is required, a knee arthroscopy is most common. This is what is called “keyhole” surgery with most of the time two or three minimally invasive incisions. The surgeon visualizes the inside of the knee using an arthroscope, fitted with a fibreoptic camera, and uses specific surgical instruments. These instruments allow careful trimming (removal) of the torn meniscal fragments or, for some cases, a repair of the meniscal tear with sutures.

Since the meniscus has an important role in the long-term health and function of the knee, the surgeon will always attempt to retain the healthy meniscal tissue. If the tear occurs in a part of the meniscus with a good blood supply, in a young patient, then a repair may be performed.

Knee arthroscopic surgery

Knee arthroscopic surgery

Meniscal repair with stitches

How long does it take to recover from meniscus tear surgery?

The time that may be required to achieve a complete recovery after surgery will depend on the injury and the extent of meniscal surgery necessary. If a meniscus tear is repaired, then limited weightbearing with crutches may be required for approximately four to six weeks. On the other hand, if the torn portion of the meniscus is removed, then protected weightbearing may only be required for a few days.

A well-directed rehabilitation plan is important to achieve an excellent result. The early rehabilitation will focus on achieving full knee motion and reducing the swelling from surgery. After this, the focus will be on restoring muscle strength. The treating physician and physical therapist or athletic trainer will carefully guide the rehabilitation after surgery.