Most of the blood supply to the menisci originates from the superior and inferior branch- es of the medial and lateral geniculate arteries, which are fed, in turn, by the popliteal artery.

These vessels give branches that sup- ply the capillary bed of the perimeniscal tis- sue. The perimeniscal vessels are oriented in a circumferential pattern with radial branch- es extending into the meniscus along its periphery (Fig. 7).

A 5-mm thick frontal section of the medial com- partment of the knee is shown after vascular per- fusion with India ink and tissue clearing. Branching radial vessels from the perimeniscal capillary plex- us (PCP) can be seen penetrating the peripheral border of the medial meniscus. The central regions are avascular. F = femur, T = tibia.
(Reproduced with permission from Arnoczky SP, Warren RF: Mi- crovasculature of the human meniscus. Am J Sports Med 1982; 10:90-95.)

These vessels penetrate the outer 10% to 30% of the adult meniscus, a region referred to as the “red zone” of the meniscus. The inner 70% to 90% of the cartilage is avascular and referred to as the “white zone.” The posterolateral aspect of the lateral meniscus at the popliteal hiatus is devoid of vascular branches entering its peripheral margin.

Synovial branches of the middle geniculate artery also supply the meniscal horns, but these have limited penetration within the meniscus and end in capillary loops. The cells in the white zone derive their nutritional supply from a combination of diffusion and fluid flow induced by joint loading and motion. These meniscal zones are crucial in predicting the success of meniscal healing and repair after injury. Repairs with- in the red zone, as might be expected, are more apt to heal than repairs within the inner or white region of the meniscus. Of course, a healing response can begin only if there is the potential for vascular ingrowth, so repairs within the white zone are apt to fail unless a blood supply is provided.