The meniscus is an important structure in the knee joint and plays a central role in maintaining knee stability. The menisci are composed of fibrocartilage and are located between the femur and the tibia. Their crescent shape allows for optimal alignment of the joint surfaces.
Injuries, such as a meniscus tear, are particularly common and can cause severe discomfort. The anatomy of the meniscus shows that the medial and lateral menisci perform different functions. Degenerative changes can result from wear and tear or sudden stress. Early diagnosis is crucial to prevent secondary damage such as osteoarthritis.
What is the meniscus?
Meniscus is the correct anatomical term for a crescent-shaped piece of cartilage in the knee joint. The knee contains both a medial meniscus (meniscus medialis) and a lateral meniscus (meniscus lateralis). Collectively, these fibrocartilaginous structures are referred to as the menisci.
The crescent-shaped lateral meniscus consists of three sections:
- anterior horn (cornu anterius),
- middle section (Pars media)
- posterior horn (cornu posterius)
The anterior horn attaches the lateral meniscus to the upper and anterior part of the tibia, whereas the posterior horn is connected to the posterior aspect of the tibia. The medial meniscus can also be divided into an anterior horn, a middle section, and a posterior horn.
The medial meniscus is fused to the medial collateral ligament of the joint capsule and is therefore not as mobile as the lateral meniscus.
What is the function of the menisci?
The menisci perform several functions at once. For example, the smooth cartilage surface of these structures reduces the friction that occurs between the femoral condyle and the femoral acetabulum during movements in the knee joint. At the same time, the menisci act as shock absorbers, cushioning movements within the knee joint. This function is particularly important when the knee is under heavy strain, such as during athletic activities.
The medial and lateral menisci also ensure that the articular surfaces of the femur and tibia fit together precisely. This allows weight and pressure to be distributed more evenly across the knee joint. By ensuring optimal distribution of synovial fluid across the articular cartilage, the menisci also promote proper nourishment of the cartilage tissue.
What conditions can affect the meniscus?
Meniscus injuries most commonly affect athletes. High-risk sports include skiing and snowboarding, as well as tennis, handball, and karate. Similarly, people who frequently overexert their knees due to their occupation are more likely to suffer meniscus injuries. Meniscus contusions and tears are among the most common meniscus injuries, with the medial meniscus tearing significantly more quickly than the lateral meniscus.
Like all cartilaginous joint surfaces, the menisci can also be affected by signs of wear and tear. In this process, the meniscus tissue degenerates, becomes increasingly thinner, and eventually tears. Such meniscal disorders occur particularly in the context of osteoarthritis, i.e., joint wear and tear.
In contrast to these acquired injuries, the so-called disc-shaped meniscus is a congenital malformation. This anatomical variant of the menisci, which sometimes occurs on both sides, leads to pain and a snapping sensation in the knee joint.
How are meniscus disorders diagnosed?
Various tests are available when a meniscus injury is suspected. These include, for example, the Apley, McMurray, and Payr tests, in which the doctor moves the lower leg and thigh in different ways. Depending on whether pain occurs when stress is placed on the medial or lateral meniscus, the doctor can infer damage to the corresponding structure.
During the physical examination, the doctor also checks for joint effusion. If the suspicion of a meniscus disorder is confirmed, magnetic resonance imaging (MRI) can be used for further diagnosis. Magnetic resonance imaging allows the ligaments, menisci, and muscles of the knee to be visualized in cross-sectional images. While lighter spots indicate cartilage wear, a light-colored streak suggests a tear.
Arthroscopy is also suitable for a closer examination of the knee joint and, consequently, the menisci. In this procedure, the doctor inserts a small camera into the knee joint through a small incision in the skin. X-rays and ultrasound examinations can also be useful in diagnosing meniscus disorders.
Specialists in the Treatment of Meniscus Injuries
Meniscus surgery is used for the surgical treatment of meniscus injuries. In cases of more extensive or irreparable damage, it is also possible to have a meniscus implant (artificial meniscus) inserted. Specialists in the treatment of meniscus injuries are orthopedic surgeons and trauma surgeons, particularly those with advanced training and specialization in knee surgery.
Conclusion
The meniscus is a crescent-shaped structure that serves as an important shock absorber in the knee joint. The medial and lateral menisci are firmly attached to the joint capsule and consist of strong collagen fibers that enable even pressure distribution across the tibial plateau and the femoral plateau. Injuries to the meniscus, such as a meniscal tear or meniscal tears, often result in meniscal damage and cartilage wear.
Meniscus injuries occur particularly in sports-related injuries and often affect the posterior or medial portion of the structure. The exact type and location are determined through clinical examination and magnetic resonance imaging (MRI). Blood flow plays an important role in this process, as only areas within the well-perfused zone can heal properly.
Treatment aims to preserve the meniscus, for example through meniscal suturing or accompanying physical therapy. In more severe cases, meniscus surgery—such as meniscus resection—is performed. The meniscus is closely connected to the articular cartilage, synovial fluid, and synovial membrane and plays a key role in knee function.
Without treatment, degenerative wear and tear and osteoarthritis can develop over time. Overall, it is clear that the meniscus plays a crucial role in the stability and load-bearing capacity of the knee joint.
FAQ
What is the meniscus, and what is its function?
The meniscus is a crescent-shaped cartilage structure in the knee joint. It acts as a shock absorber, stabilizes the joint, and improves pressure distribution between the femur and tibia.
How does a meniscus tear occur?
A meniscus tear is often caused by sudden twisting movements in the knee or by wear and tear. Sports injuries, in particular, frequently lead to a meniscus tear.
What are the symptoms of a meniscus injury?
Typical symptoms include pain, swelling, and limited mobility of the knee. The patient’s symptoms may worsen when squatting or twisting.
How is a meniscus tear diagnosed?
The diagnosis is made through a clinical examination and imaging techniques such as magnetic resonance imaging (MRI). In some cases, arthroscopy is performed.
How is a meniscus injury treated?
Treatment may be conservative, involving physical therapy, or surgical, such as meniscus repair or meniscus resection. The goal is to preserve the meniscus as much as possible.