Ligaments

Ligaments are bands of dense regular connective tissue that connect bones at joints, providing stability and guiding joint movement. They help limit excessive motion and help maintain proper alignment during activity. Ligaments are primarily composed of parallel collagen type I fibers, with fibroblasts, elastin in smaller amounts, and proteoglycans. Their collagen fibers are organized to withstand tensile forces in the directions most commonly experienced.

Ligaments vary in location and structure. Some lie inside a joint capsule, while others lie outside it. Major examples include the knee’s anterior and posterior cruciate ligaments, and the medial and lateral collateral ligaments. Ligaments attach to bone at entheses, where the tissue transitions to fibrocartilage to better absorb stress.

Functionally, ligaments serve as passive stabilizers, limiting undesired directions of movement, guiding joint kinematics, and contributing to proprioceptive feedback through specialized nerve endings. They work together with muscles, tendons, and the joint capsule to maintain stability during movement and at rest.

Injury to ligaments, such as sprains or tears, results from overstretching or sudden forces. Healing is slow due to limited blood supply, and treatment ranges from rest and rehabilitation to, in some cases, surgical reconstruction. Aging can reduce ligament elasticity and vascularity, affecting strength and healing potential over time.