The inner two-thirds of the meniscus is avascular, meaning it lacks a direct blood supply. This region is commonly referred to as the "white zone."
Understanding Meniscus Vascularity
The meniscus, a C-shaped piece of cartilage in your knee, plays a crucial role in absorbing shock, distributing weight, and stabilizing the knee joint. Its ability to heal after injury is largely dependent on its blood supply, which is not uniform throughout the structure.
The Red Zone: Vascularized Region
The outer one-third of the meniscus is well-vascularized, receiving a direct blood supply from the surrounding synovial capsule. This area is known as the "red zone" due to its rich blood flow. Tears occurring in this region have a higher potential for self-healing or successful surgical repair because the blood supply provides the necessary nutrients and healing factors.
The White Zone: Avascular Region
Conversely, the inner two-thirds of the meniscus lacks direct blood vessels and is therefore avascular. This region is termed the "white zone." Because it does not receive a blood supply, tears in the white zone often struggle to heal on their own. Without the essential blood-borne nutrients and healing cells, the cartilage in this area has very limited regenerative capacity.
The Red-White Zone: Transitional Area
Between the fully vascularized red zone and the avascular white zone lies a transitional area known as the "red-white zone." This region has a diminished blood supply compared to the red zone, but still more than the white zone. Tears here may have some healing potential, though it is less robust than in the pure red zone.
Why Vascularity Matters for Meniscus Tears
The difference in blood supply profoundly impacts the prognosis and treatment approach for meniscal injuries.
- Healing Potential: The presence of a blood supply is critical for tissue repair. Blood brings oxygen, nutrients, and immune cells that are essential for the healing cascade. Without it, the body struggles to repair damaged tissue effectively.
- Treatment Decisions: When a meniscus tear occurs, its location relative to these zones is a primary factor surgeons consider.
- Red Zone Tears: Often good candidates for meniscus repair (suturing the torn pieces back together) due to their healing potential.
- White Zone Tears: Typically treated with meniscectomy (removal of the torn portion) if symptoms are persistent, as repair is less likely to succeed. The goal is often to remove the painful, unstable flap while preserving as much healthy meniscus tissue as possible.
- Red-White Zone Tears: Treatment depends on the specific tear pattern, patient age, activity level, and surgeon's preference, as there's a variable chance of healing.
Overview of Meniscus Zones
| Meniscus Zone | Blood Supply | Healing Potential | Common Treatment Approach (if symptomatic) |
|---|---|---|---|
| Outer 1/3 | Red Zone (Vascular) | High | Meniscus Repair (Suturing) |
| Inner 2/3 | White Zone (Avascular) | Low/None | Meniscectomy (Removal of torn part) |
| Middle 1/3 | Red-White Zone (Partial) | Moderate | Repair or Meniscectomy, depending on tear |
Understanding the vascular anatomy of the meniscus is fundamental for both diagnosis and effective treatment strategies for knee injuries. For further information on meniscus tears and their treatment, resources such as the American Academy of Orthopaedic Surgeons (AAOS) provide comprehensive details.
