Red Zone of the Menisci

The vascular portion of the meniscus is called the "red zone," in distinction to the in the avascular portion, or "white zone." Tears in the red zone are far more likely to heal than tears of the white zone; therefore, tears in the red zone may be treated meniscus-preserving techniques, while tears in the white zone are typically treated by means of débridement.

Some have suggested that the more peripheral area of higher signal intensity in the meniscus represents the red zone. Recent work, however, has shown that the entire meniscus, including the vascularized red zone, appears as low signal on MR images. In addition, intravenous contrast does not help differentiate the red zone from the white zone.

The only way to determine if a tear is in the red zone, therefore, is to guess. It has been suggested that the red zone may be considered as the peripheral 10%–15% of the meniscus. The figure shows a tear in the peripheral posterior horn of the medial meniscus, and was assumed to be in the red zone.

References

Hauger O, Frank LR, Boutin RD, Lektrakul N, Chung CB, Haghighi P, Resnick D. Characterization of the "red zone" of knee meniscus: MR imaging and histologic correlation. Radiology. 2000 Oct;217(1):193-200.