Once the smooth articular cartilage is damaged, it does not repair. Small defects can be treated using a variety of techniques, either arthroscopically or through a small open procedure. Larger areas of damage require more complex open operations. Sometimes these operations may need to be combined; for example if the knee is mis-alignment then an osteotomy may need to be added to any cartilage regeneration surgery. Once the damage becomes widespread, then the knee has arthritis and joint replacement surgery is usually indicated once pain and restriction of activity is severe.
There are a variety of options available for restoring lost articular cartilage and keeping your own knee going as long as possible, and details of these can be found below: