The Epiligament-The Main Donor of Cells and Vessels during Healing Of the Collateral Ligaments of the Knee

Abstract

Ligaments are composed of dense connective tissue and attach bones in joints. The thin connective tissue sheath, covering these fascicles is called endoligament and is connected to a more vascular connective tissue structure that envelopes the entire ligament and is referred to as epiligament. The tissue of the epiligaments is composed of different cell types such as: fibroblasts, fibrocytes, adipocytes, neurovascular bundles, and a multitude of collagen fibers, disposed in different directions. The main structural protein of epiligament is collagen type I. Collagens types III and V were also found in the structure of epiligament. Type I collagen is the main collagen in normal and healing ligaments. The ligament repair requires presence of collagen type III. Collagen type V is associated with collagen type I and regulates the collagen fibril diameter. Knowledge of variation of cells and collagen types of epiligament in normal and injured ligaments is crucial for understanding of the healing process.