The menisci are two crescent-shaped pads of cartilage that sit inside each knee joint. They play an important role in stabilizing the knee, easing movement of the knee joint, and absorbing shock from walking and other weight bearing activities.

A meniscus injury is a tear in one of the menisci. This can happen as a result of trauma or age-related degeneration of the knee joint. Symptoms can vary and may include:

This article discusses what a meniscus injury is, including the different types of meniscus tears. It also outlines symptoms, diagnosis, and treatment and provides information on when to contact a doctor.

A close-up image showing the location of the meniscus of the knee.Share on Pinterest
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A meniscus injury is a tear in one of the menisci within the knee. The menisci serve a number of important functions, such as:

  • shock absorption
  • weight transmission during walking
  • stability through preventing the knee from bending and straightening at extreme angles

According to 2021 research, a meniscus tear is a common injury, affecting 61 out of every 100,000 people in the general population. Causes of the injury include trauma and degenerative changes to the knee joint.

Factors that increase the risk of a meniscus tear include:

  • being male
  • being over the age of 40 years
  • playing sports such as skiing or soccer
  • having an occupation that requires frequent squatting or bending

Doctors classify meniscus tears according to their shape and location. The different types of meniscus tear include:

  • Horizontal, or cleavage: These tears run parallel to the flat top of the shinbone and are more likely to occur in people over the age of 40 years who have degeneration of the knee joint.
  • Longitudinal, or vertical: These tears run perpendicular to the flat top of the shinbone and parallel to the long axis of the meniscus.
  • Radial: These run perpendicular to both the top of the shinbone and the long axis of the meniscus.
  • Complex: This is a combination of horizontal and longitudinal tears.
  • Displaced: These tears involve total detachment of a piece of meniscus, or flipping of a part of the meniscus that remains attached.
  • Bucket-handle: These are fragments of complete longitudinal tears that move centrally over the rest of the meniscus.
  • Flap: These are partially detached fragments of horizontal tears.
  • Parrot-beak: These are radial tears that have partially detached fragments.

Additionally, doctors categorize tears according to their location. The outer one-third of the meniscus has a blood supply, and so doctors refer to this area as the red zone. Tears in this area are typically more likely to heal on their own.

The inner two-thirds of the meniscus have only a limited blood supply, which is why doctors call this the white zone. Red-red tears are within the red zone, and red-white tears have central margins that extend into the white zone.

A person may feel a pop when they tear the meniscus.

Common symptoms include:

  • pain
  • swelling and stiffness of the knee joint
  • locking or catching of the knee
  • inability to fully bend and straighten the knee
  • a sensation of the knee giving way

When diagnosing a meniscus tear, a doctor will carry out a detailed medical history and a thorough examination of the knee joint.

The examination includes the following:

  • Inspection: Tenderness along the joint line where the meniscus lies often indicates a tear.
  • Range of motion testing: Pain and limited movement when bending or straightening the knee may suggest a tear.
  • Strength testing: A meniscus tear does not necessarily affect strength.

The above part of the examination does not always lead to a diagnosis. Doctors may use additional clinical tests that assess range of motion in the knee from various positions. These tests include:

  • McMurray test
  • Apley test
  • Thessaly test

However, these may not have the best accuracy.

X-rays are useful in finding other causes of knee pain, but they will not show a meniscus tear. An MRI scan is the method of choice for confirming a suspected diagnosis.

According to the American Academy of Orthopaedic Surgeons, treatment of a meniscus tear depends on the location of the injury, alongside other factors, including a person’s:

  • age
  • activity levels
  • symptoms

Below, we outline some potential treatment options.

Nonsurgical treatment

A doctor may recommend one of the following nonsurgical treatment options for people who do not experience persistent symptoms or symptoms of knee locking or swelling:

  • RICE: This acronym stands for the following:
    • Rest: This involves taking a break from activities that cause or exacerbate symptoms.
    • Ice: This involves applying cold packs to the knee for 20 minutes several times per day.
    • Compression: A person should use an elastic compression bandage, which may prevent additional swelling.
    • Elevation: This involves elevating the legs higher than the heart during rest, to alleviate swelling and pain.
  • Nonsteroidal anti-inflammatory drugs: These medications reduce pain and inflammation. Examples include aspirin and ibuprofen.
  • Steroid injections: Drugs in this category also reduce pain and inflammation. An example is a corticosteroid, such as prednisolone. Healthcare professionals administer steroid injections when meniscus tears are degenerative and due to arthritis.
  • Biologic injections: A biologic is any drug derived from or containing material from living organisms. An example is platelet-rich plasma, which some research shows has growth factors that may enhance healing of the menisci. Scientists are currently studying this treatment.

Surgical treatment

If nonsurgical methods do not alleviate a person’s symptoms, a doctor may suggest arthroscopic surgery. This procedure involves inserting a miniature camera and tiny surgical instruments through two or three small incisions in the knee to repair or trim a meniscus tear.

There are two main types of arthroscopic surgery for a meniscus tear: partial meniscectomy and meniscus repair.

Partial meniscectomy involves trimming away the damaged meniscus. It permits immediate weight bearing following surgery and provides a full range of motion soon afterward.

Meniscus repair involves stitching torn pieces of a meniscus back together. After healing occurs, a doctor will recommend a rehabilitation program of exercises to improve range of motion and strength. The recovery time is longer than in the case of a meniscectomy.

A person with a meniscus injury should consult a healthcare professional, such as a physical therapist, before starting an exercise program.

A nonsurgical treatment approach typically involves rest and avoiding activities that trigger symptoms. A physical therapist will individualize a person’s exercise regimen to prevent further injury.

With a surgical treatment approach, exercises are necessary for recovery. Following surgery, a doctor may advise engaging in 20–30 minutes of exercise two–three times per day.

Exercise programs start with an initial routine and then progress to intermediate and advanced routines.

Initial routine

A person’s initial exercise routine may include an exercise called hamstring contractions. To perform this exercise, a person should do the following:

  1. Lie on the back and bend both knees at a 10-degree angle.
  2. Pull both heels into the floor while tightening the muscles on the backs of the thighs.
  3. Hold the position for 5 seconds and then relax.
  4. Repeat 10 times.

Intermediate routine

An intermediate exercise routine may include straight leg raises. To perform this exercise, a person should follow these steps:

  1. Lie on the back, with the unaffected knee bent.
  2. Straighten the opposite knee using the muscles on the front of the thigh.
  3. Slowly raise the extended leg 12 inches from the floor and then slowly lower it back.
  4. Do 5 sets of 10 repetitions.

Advanced routine

An advanced exercise routine may include an exercise that involves partially bending the knee. To perform this exercise, a person should do the following:

  1. Using the back of a chair for support, stand upright.
  2. Bend the unaffected leg, touching the toe to the floor as necessary for balance.
  3. Slowly lower the body, keeping the foot flat.
  4. Return to the starting position.
  5. Relax and do 10 repetitions.

The red zone has a blood supply, and therefore, a meniscus injury in this area may heal on its own. For a simple tear here, doctors may advise a short course of rest and physical therapy to see whether spontaneous healing occurs.

Conversely, since tears within the white zone have only a limited blood supply, they do not heal on their own and do not respond to conservative treatment.

Recovery after a meniscectomy takes 3–6 weeks, and recovery after a meniscus repair takes 3–6 months. Following proper treatment and rehabilitation, people can typically resume their pre-injury activities.

A person should make an appointment with a doctor if they experience any of the following:

  • tenderness in the knee
  • an increase in pain and swelling
  • locking or buckling of the knee
  • redness or streaking at the site of the injury
  • persistent symptoms despite appropriate self-care

A meniscus injury refers to a tear in one of the menisci within the knee. It is a very common injury, especially among people who play sports.

The diagnostic process starts with a medical history and a thorough examination that may include clinical tests. An MRI will confirm a suspected diagnosis.

Nonsurgical treatment may include interventions such as rest, exercises, and medication. If these measures do not alleviate a person’s symptoms, doctors may recommend surgical options, such as a partial meniscectomy or a meniscus repair.

Most people will need to perform exercises following surgery. An individual should seek guidance from a physical therapist about which exercises to perform to assist their healing.