Articular cartilage is the material that lines the ends of bones within the joint. It provides lubrication and protection to the underlying bone, and allows smooth motion of the joint. Cartilage has poor blood supply, and once injured, it does not heal readily. Traditionally, there were very few successful treatments for cartilage damage except for joint replacement surgeries. However, emerging technologies have allowed us to successfully perform several types of cartilage repair and cartilage restoration treatments.
Injuries to the articular cartilage can occur in isolation, or in association with other injuries. For instance, ACL injuries, PCL injuries, and meniscus tears are often associated with articular cartilage injuries. Occasionally, malalignement such as “knock knees” or “bow-legged” knees can contribute to cartilage injury. It is important to address the underlying cause of the cartilage injuries where applicable.
The difficulty in cartilage restoration lies in the method through which the body tries to heal cartilage. It does not replace the injured cartilage with new cartilage, but instead replaces it with something known as “fibrocartilage” which is not as smooth and lubricated as regular cartilage.
Microfracture is a technique where the damaged cartilage is removed, and tiny holes are poked or drilled into the underlying bone. This allows the bone to release healing factors that ultimately replace injured area with fibrocartilage. This new cartilage is not as useful as regular articular cartilage, but it has reasonable survival rates up to 5 years.
Autologous Chondrocyte Implantation (ACI)
ACI is a technique where your own cartilage cells are harvested and then replicated in the lab. Once an adequate number of cartilage cells are grown, they are re-implanted in the area of your injured cartilage. A biologic membrane is used to seal the defect and keep the cells in the right place until new cartilage grows. This technique is a good procedure for smaller lesions and injuries where the bone below the cartilage, or the subchondral bone, is not damage. The downside is that it requires two operations – one to harvest the cells, and one to reimplant them.