My doctor is sending me to a large university clinic for a second opinion about my knee. MRI shows a deep tear of the cartilage down to the bone. There’s a new way to treat this problem using my own normal cartilage cells. Can anyone have this surgery? Do you have to be a certain age? (I’m only 16 years old).

Autologous condrocyte implantation (ACI) is a fairly new method of repairing full-thickness defects in the articular cartilage of the knee. Studies done in the mid-1990s with small groups of patients were successful enough to suggest this was a good way to treat damage to the knee joint cartilage.

The technique remains under study with larger groups of people. Each surgeon and facility makes their own decision about patients who can have this operation. The usual age for ACI is between 15 and 55 years of age. With continued improvements in this technique, the age limits will probably be expanded over time.

There are other criteria for selection to ensure success. Patients must not be obese. Body mass index is used as a guideline. Anyone considering this surgery must have a BMI less than 30 kg. BMI between 18.5 and 25 is considered a normal weight. A BMI between 25 and 30 is overweight and a BMI above 30 is in the obese range.

Other factors that might exclude you from having an ACI include knee joint malalignment, ligamentous instability, and meniscal tears. Cartilage damage on both sides of the joint called bipolar lesions also prevent patients from having this operation. Likewise lesions with significant bone loss are beyond what this procedure can support in terms of repair.