Can Damaged Knee Cartilage Heal Itself? The Challenges of Cartilage Repair

Knee cartilage injuries can be painful and debilitating, but can the damaged tissue actually heal on its own? The short answer is no. Cartilage damage, whether caused by arthritis or acute injury, is notoriously difficult to treat successfully due to the unique properties of this connective tissue.

Why Cartilage Can’t Heal Itself

Cartilage is composed of specialized cells called chondrocytes that are embedded in a matrix of collagen and proteoglycans. Unlike most other tissues in the body, cartilage does not contain blood vessels, nerves, or lymphatic vessels. This avascular nature is what makes cartilage so smooth and slippery, allowing for nearly frictionless joint movement.

However, the lack of a blood supply also means that cartilage has a very limited capacity for self-repair. When cartilage is damaged, the chondrocytes cannot migrate to the site of injury to begin the healing process. Without the influx of nutrients, oxygen, and reparative cells that a blood supply would provide, cartilage lesions tend to remain static or gradually worsen over time.

Treatment Options for Damaged Cartilage

Because cartilage cannot heal itself, various surgical techniques have been developed to stimulate cartilage repair or replacement. Some of the most common procedures include:

Microfracture

In this procedure, the surgeon makes small holes in the underlying bone to induce bleeding and the formation of a blood clot. The clot contains stem cells that can differentiate into cartilage cells and fill in the defect. However, the resulting tissue is fibrocartilage, which is not as durable as the original hyaline cartilage.

Autologous Chondrocyte Implantation (ACI)

ACI is a two-stage process where a sample of the patient’s own cartilage cells are harvested, cultured in a lab, and then implanted back into the knee to regenerate cartilage. The cells are either implanted under a periosteal patch or seeded onto a collagen membrane.

Osteochondral Autograft Transfer (OATS)

OATS involves taking small plugs of healthy cartilage and underlying bone from a non-weight-bearing area of the joint and transplanting them into the damaged area. This restores the smooth joint surface, but the technique is limited by the amount of donor tissue available.

While these procedures can be effective for treating localized cartilage defects, they are not suitable for the widespread cartilage loss seen in advanced osteoarthritis. In these cases, joint replacement surgery may be the best option to relieve pain and restore function.

In summary, while cartilage has a very limited capacity for self-repair, there are several surgical techniques available to stimulate cartilage regeneration or replace damaged tissue. However, the success of these procedures depends on the extent and location of the cartilage injury. Seeking prompt treatment from an orthopedic specialist is crucial to achieving the best possible outcome.