Editorial Commentary: Discovery: Progenitor Cells and Endothelial Cells Are Found in the White-White Zone of the Meniscus, But This Does Not Mean That These Tears Heal or Should Be Repaired.

Abstract

More than 35 years ago, the concept of vascular zones of the meniscus was introduced. It has been shown that blood supply is limited to the peripheral 25% of the lateral and 30% of the medial meniscus. This obviously has repercussions with regard to the healing potential of meniscus tears, whether repaired or not. In general, tears that extend into the white-white zone, such as flaps, cleavage tears, and radial tears, are deemed irreparable. However, several recent reports have suggested that radial tears in the white-white zone, when repaired, heal and have good clinical outcomes. Now progenitor mesenchymal cells have been identified in the white-white zones, confirming the potential of the meniscus to heal. However, blood supply was demonstrated only by indirect signs such as the presence of endothelial cells and the presence of endothelial surface markers.