I damaged the cartilage in my left knee playing football. I've had one operation on that knee. It looks like I'll need another soon. The surgeon is talking about doing a cartilage transplant. They'll take healthy cartilage cells and put them in the hole in my bad knee. Will a second operation work okay when it's already been operated on once?

The procedure you are having is called autologous chondrocyte implantation (ACI). Autologous refers to the fact that the surgeon is harvesting your own tissue. Chondrocyte is the medical term for cartilage cell.

ACI is one of three new methods used to regenerate joint tissue. It can be used when the defect is 2.5 cm2 or less in size. Some studies show that even larger defects in patients with more symptoms are less likely to have good growth of normal hyaline-like tissue. Hyaline tissue is the type of cartilage that lines the inside of the knee joint.

Previous surgery and patients with older defects are less likely to regenerate normal joint (hyaline) cartilage. But these factors do not necessarily exclude you from having the procedure.

Your surgeon will have a better idea how to advise you after taking a look at the damaged area. This is usually done during the arthroscopic exam. The exam may be done before or as part of the ACI harvesting procedure.