Articular Menisci: Anatomy, Functions, Injuries, and Treatment

What is a menisci articular?

Articular menisci are specialized C-shaped or crescent-shaped fibrocartilaginous structures found within certain synovial joints, primarily the knee, serving to enhance joint congruence, distribute forces, absorb shock, and facilitate smooth, stable movement.

Understanding Articular Menisci

The term "menisci articular" refers to the menisci in the context of their function within an articulation, or joint. These are not merely pads but highly specialized forms of cartilage, distinct from the smooth articular cartilage that covers the ends of bones. Composed of tough, fibrous connective tissue and cartilage cells (fibrocartilage), menisci are designed to withstand significant compressive and shear forces, acting as crucial intermediaries between bones in a joint. While most commonly associated with the knee, similar structures (though sometimes called discs or labrums) exist in other joints like the temporomandibular joint (TMJ), acromioclavicular (AC) joint, and sternoclavicular joint, all serving a similar purpose of improving joint mechanics.

Anatomy and Location: The Knee's Crucial Role

The most prominent and frequently discussed articular menisci are found in the knee joint, where they play an indispensable role in its complex mechanics. There are two menisci in each knee:

• Medial Meniscus: This meniscus is C-shaped and located on the inner side of the knee. It is more firmly attached to the tibia and the medial collateral ligament, making it less mobile and thus more susceptible to injury.
• Lateral Meniscus: This meniscus is more O-shaped and positioned on the outer side of the knee. It is less firmly attached and more mobile than the medial meniscus, which can sometimes protect it from certain types of forces but also makes it vulnerable to different injury patterns.

Each meniscus has an anterior horn (front part), a posterior horn (back part), and a body (middle part). They are wedge-shaped in cross-section, thicker at their outer edges and tapering to a thin inner edge. The outer one-third of the meniscus, known as the "red zone," has a blood supply, allowing for some healing potential. The inner two-thirds, the "white zone," is avascular, meaning it lacks a direct blood supply, which significantly impairs its ability to heal after injury.

Essential Functions of the Menisci

The presence of articular menisci transforms a simple hinge joint into a more complex, adaptable structure, allowing for the wide range of motions and loads the knee endures. Their primary functions include:

• Load Distribution and Force Transmission: Menisci significantly increase the contact area between the femur (thigh bone) and the tibia (shin bone). Without them, the forces exerted on the knee would be concentrated on a much smaller area, leading to excessive stress on the articular cartilage and subchondral bone. They distribute axial loads, reducing peak pressures on the articular cartilage by up to 50% in some areas.
• Shock Absorption: Acting as cushions, menisci absorb and dissipate impact forces during activities like walking, running, and jumping, protecting the articular cartilage from damage.
• Joint Stability and Congruence: The knee joint is inherently incongruent; the rounded femoral condyles do not perfectly fit the relatively flat tibial plateau. The menisci deepen the tibial plateau, improving the fit between the two bones and enhancing joint stability, particularly during rotational movements.
• Lubrication and Nutrition: Menisci assist in the circulation of synovial fluid, which lubricates the joint and provides nutrients to the articular cartilage, essential for its health and function.
• Proprioception: While not their primary role, menisci contain mechanoreceptors that contribute to proprioception, the body's sense of joint position and movement, aiding in neuromuscular control and coordination.

Common Meniscal Injuries

Given their vital role and exposure to significant forces, menisci are frequently injured, particularly in the knee. Tears can occur due to:

• Acute Trauma: Often seen in athletes, resulting from sudden twisting movements, deep squats, or direct impact while the foot is planted.
• Degenerative Changes: In older adults, meniscal tears can occur with minimal trauma, even from simple actions like standing up or walking, due to the gradual weakening and fraying of the cartilage over time.

Symptoms of a meniscal tear typically include:

• Pain: Often localized to the joint line, especially with twisting or squatting.
• Swelling: May develop gradually over several hours after the injury.
• Clicking, Popping, or Catching Sensation: During knee movement.
• Locking: The knee may get stuck in a bent position, unable to fully straighten.
• Tenderness: Along the joint line.
• Limited Range of Motion: Difficulty fully bending or straightening the knee.

Diagnosis and Treatment Approaches

Diagnosis typically involves a thorough physical examination, including specific orthopedic tests that elicit pain or clicking, and imaging studies. Magnetic Resonance Imaging (MRI) is the gold standard for confirming meniscal tears and assessing their type and severity.

Treatment options vary depending on the tear's location (red vs. white zone), size, type, the patient's age, activity level, and symptoms:

• Conservative Management: For small, stable tears, especially in the red zone, or for degenerative tears with mild symptoms, non-surgical approaches like RICE (Rest, Ice, Compression, Elevation), anti-inflammatory medications, and physical therapy to strengthen surrounding muscles and improve knee stability may be effective.
• Surgical Intervention: For larger, symptomatic, or unstable tears, particularly those causing locking or significant pain, arthroscopic surgery may be recommended. Surgical options include:
  • Meniscectomy (Partial or Total): Removal of the damaged portion of the meniscus. While effective in relieving symptoms, it reduces the shock-absorbing capacity and increases the risk of developing osteoarthritis in the long term.
  • Meniscal Repair: Suturing the torn parts of the meniscus back together. This is the preferred option when feasible, especially for tears in the vascular red zone, as it preserves the meniscus's function and helps protect the joint from future degeneration.

Prevention and Long-Term Joint Health

Protecting your articular menisci is crucial for maintaining long-term knee health and function. Strategies include:

• Proper Warm-up and Cool-down: Prepare your joints and muscles for activity and aid recovery.
• Strength and Stability Training: Focus on strengthening the muscles around the knee (quadriceps, hamstrings, glutes) and improving core stability to support the joint.
• Proprioceptive Training: Exercises that challenge balance and coordination can improve the knee's ability to react to sudden movements.
• Correct Technique: Use proper form during sports and exercise to minimize undue stress on the knee.
• Weight Management: Maintaining a healthy body weight reduces the load on your knee joints.
• Listen to Your Body: Avoid pushing through pain, especially sharp, sudden pain during twisting or squatting movements.

Conclusion: Protecting Your Menisci

Articular menisci are understated yet indispensable components of joint health, particularly in the knee. Their complex fibrocartilaginous structure allows them to perform critical functions in load distribution, shock absorption, and joint stability. Understanding their anatomy and function is paramount for fitness enthusiasts, athletes, and healthcare professionals alike. Proactive measures to protect these vital structures through proper training, injury prevention strategies, and timely, appropriate treatment for injuries are essential for preserving joint function and ensuring a lifetime of healthy, active movement.