Ligaments heal much slower than muscles because they lack a direct blood supply.

Ligaments are composed of dense regular connective tissue, primarily made of Type I collagen fibers. Unlike skeletal muscle, which is highly vascularized and receives a constant flow of oxygenated blood, ligaments are considered 'hypovascular.' This lack of direct blood flow is the primary reason for their notoriously slow recovery times after an injury.When a muscle is injured, the body quickly initiates a multi-stage healing process fueled by satellite cells and a robust inflammatory response. In contrast, ligaments must rely on a process called diffusion to receive essential nutrients from the synovial fluid or surrounding vessels. This passive transport is significantly less efficient than the active delivery system found in muscular tissue.Research published in the Journal of Orthopaedic Research highlights that ligament cells, known as fibroblasts, have a much lower metabolic rate than muscle cells. Studies show that while a minor muscle tear might regenerate in 2 to 4 weeks, a Grade II or III ligament sprain often requires 6 to 12 months to regain its full pre-injury tensile strength. In many cases, such as an ACL tear, the blood supply is so poor that the tissue cannot heal on its own at all.The structural integrity of ligaments is also a factor in their slow repair. Because they are designed to withstand high tension, the dense collagen matrix acts as a physical barrier that slows the migration of repair cells to the site of the injury. This biological reality is why orthopedic surgeons often recommend physical therapy or surgical intervention to stimulate blood flow and mechanical stability in damaged joints.