Articular cartilage is a complex avascular (no blood supply) tissue which consists of cells called chondrocytes suspended in a collagenous matrix. Articular cartilage lining the ends of the bones that form joints reduces the friction when the bones glide over each other and makes the movements smooth and cushions the joint and acts as a shock-absorber.
This cartilage is subjected to the normal wear and tear and may sometimes get damaged because of injury, causing pain and impaired function. Articular cartilage injuries occur as a result of mechanical destruction of the cartilage such as traumatic injury and direct blow or progressive degeneration such as wear and tear. It is possible for the cartilage cells to heal, but it depends on the extent of the damage and location of injury. However, the healing capacity is very minimal owing to the lack of blood supply.
Degeneration of the cartilage occurs as a progressive loss of structure and function of the cartilage. The process begins with softening of the cartilage which then progresses to fragmentation. As the articular cartilage lining is lost, the underlying bone has no protection against the normal wear and tear and it starts breaking down leading to osteoarthritis.
Cartilage gets damaged often as a result of sports injury and because of the lack of blood supply to it; the potential for repair is very limited. Cartilage injuries that do not involve the bone do not heal and cause degeneration of the joint surface while those injuries in which bone is involved undergo repair by forming fibrocartilage. This fibrocartilage may cover the defect but is not as competent as the articular cartilage to withstand long-term compression forces.
These cartilage defects are often a cause of pain and decreased function. Prompt treatment of these defects with cartilage restoration methods helps prevent development of osteoarthritis.
The methods of cartilage restoration are based on the two principles namely repair and regeneration. "Repair" involves healing of the injured cartilage by replacing it with new cells and extracellular matrix. "Regeneration" refers to replacing the injured cartilage with a new articulating surface that functionally simulates the original cartilage
The surgical procedures for cartilage restoration include:
- Abrasion Arthroplasty
- Autologous Chondrocyte Implantation
- Osteochondral Autograft Transplantation (mosaicplsty)
- Osteochondral Allograft Transplantation