Meniscus

The knee menisci are “C”-shaped structures located between the femur and the tibia. They are made of fibrocartilage and there are two menisci in each knee: the lateral meniscus, located on the outer part of the joint, and the medial meniscus, on inner side. The menisci have several functions within the joint. The main one is to increase the contact surface between the femur and the tibia, which decreases the pressure in that region. The menisci also help to stabilize the knee, lubricate and nourish the joint, and provide proprioception, which is the recognition of the body’s position.

Anatomy and Blood Supply of the Menisci

The menisci are made up of fibrocartilaginous tissue, composed mainly of an intertwined network of collagen fibers. The way these fibers are arranged makes the menisci firm and resistant to compressive forces. To make meniscal injuries easier to locate, the menisci are divided into three main parts: anterior horn, body, and posterior horn.

The menisci have a peculiar blood supply. The most peripheral part, close to the knee joint capsule, does receive blood and is known as the red-red zone. The innermost portion of the menisci, close to the center of the knee joint, is avascular, so it does not receive blood supply. This portion of the meniscus is called the white-white zone. The intermediate section is the red-white zone. The blood supply directly impacts the healing potential of meniscal injuries, since injuries in the red-red zone heal more easily.

How the Injury Occurs

Meniscus injuries are very common. They can be degenerative, which occur due to wear and tear, or traumatic, which usually occur after a twisting movement of the knee. Degenerative injuries are associated with aging and can get worse over time. Twisting movements related to acute injuries occur, for example, during sports, especially for those who practice sports that involve rotational movements of the body over the knee or movements that change direction, such as soccer, basketball, handball, wrestling (jiu-jitsu, judo), among other sports.

Meniscus injuries are often associated with other knee injuries, such as ligament injuries, cartilage injuries, etc.

Types of Meniscal Injury

There are different types of menisci injuries, according to the pattern of the tear.

They can be:

Horizontal: more related to degenerative meniscus injuries;

Radial: injuries that have a direction perpendicular to the meniscus fibers;

Longitudinal: injuries that follow the direction of the meniscus fibers;

Complex: injuries in which there is a combination of the previous patterns.

Some meniscus injuries have specific characteristic, since fragments can show up, such as bucket handle injuries, which are more extensive longitudinal injuries, in which the fragment can move to the ineermost region of the joint and become locked; and meniscal flaps, in which small fragments can also cause locking of the knee.

What Are the Symptoms of Meniscus Injuries?

Symptoms related to meniscal injuries vary. Degenerative injuries, which are caused by wear and tear, may cause the patient few or no symptoms or may be painful and cause swelling in the knee.

Patients with traumatic meniscal injuries may have pain located in the knee joint line, between the femur and the tibia.

There are some maneuvers that stimulate the injured area of the meniscus that are performed during the physical examination by the doctor, in order to look for any sign that characterizes the injury.

Specific injuries, such as bucket-handle meniscal tears, can lock the knee.

Necessary Exams

Some imaging exams can help the doctor when there is a suspicion of injury to the lateral or medial meniscus. The main one is magnetic resonance imaging, which provides important information related to the injury, such as its location, type, among others.

Treatment

Most meniscal injuries require non-surgical treatment, based on physiotherapy to improve the inflammatory process and restore muscle balance. However, injuries that do not respond well to non-surgical treatment and some specific types of injuries, such as unstable injuries, meniscal flaps or bucket handle injuries, usually require surgical treatment, by arthroscopy approach.

Surgical treatment can be performed in several ways:

Partial meniscectomy: arthroscopic surgical technique that involves removing part of the meniscus so that the injury can be repaired.

Suturing: arthroscopic surgical technique in which stitches are placed at the site of the meniscus tear so that the injury can stabilize and heal properly.

Root reattachment: technique for correcting specific tears to the posterior root of the medial or lateral meniscus, in which transosseous stitches are placed to fix the injury.

As the menisci have an important function within the knee joint, we try to preserve them whenever possible.

Rehabilitation with Physiotherapy

Patient's rehabilitation with physiotherapy plays a fundamental role in achieving a satisfactory outcome. The treatment is carried out in order to reduce pain and inflammation and to progressively gain range of motion in the knee, improve balance and restore muscle strength in the affected limb.

It is important to note that physiotherapy helps a lot both before and after the surgical procedure.