Due to its lack of a direct blood supply, cartilage has a limited capacity for self-repair.
Cartilage, the smooth, shock-absorbing tissue that covers the ends of bones in joints, differs significantly from other tissues in the body due to its avascular nature. This means it doesn't have its own blood supply. This lack of blood vessels is the primary reason why cartilage struggles to heal itself when damaged.
Here's a breakdown of why cartilage self-repair is limited:
- Absence of Blood Supply: Blood carries essential nutrients and repair cells to injured tissues. Without a blood supply, cartilage doesn't receive these necessary components efficiently.
- Limited Cellular Activity: Cartilage contains cells called chondrocytes, which are responsible for maintaining the cartilage matrix. However, chondrocytes have limited migratory and proliferative abilities, meaning they don't readily move to the site of injury or multiply to create new cartilage.
- Type of Damage: The extent of damage influences repair. Small, superficial injuries might trigger a minimal repair response, but larger or deeper injuries are unlikely to heal completely.
Because cartilage repair is so limited, injuries often lead to chronic pain, inflammation, and eventually, osteoarthritis. This is why interventions, such as physical therapy, injections, or surgical procedures, are often necessary to manage cartilage damage and slow down the progression of joint degeneration. In some cases, surgical procedures like microfracture aim to stimulate cartilage repair by encouraging blood flow from underlying bone, but the resulting tissue is often fibrocartilage, which isn't as durable as the original hyaline cartilage.