Q: I have been told that I have knee arthritis, and that when it gets bad enough I will need a knee replacement. I have heard about cartilage regrowth surgery and wonder if I would be a candidate.

A: There are two types of cartilage in the knee. The one that is usually torn in athletes is known as meniscal cartilage, which sits between the femur and tibia. When this cartilage is injured, the torn piece can be sewn back or removed depending on the size and location of the damage and the age of the patient.

The second type is articular cartilage, which lines every bone in our bodies. When it wears thin to the point that raw bone is exposed, this is known as osteoarthritis. If your knee has reached the point where there are multiple areas of full-thickness articular cartilage wear, you ultimately will require joint replacement.

Cartilage regrowth procedures such as microfracture are limited to patients with relatively small, full-thickness defects. True regrowth techniques (cartisal) can be used in younger patients where the rest of the joint is in relatively good condition. It requires at least two surgical procedures, one of which involves a large open incision and at least two months on crutches.

Research is being done with less invasive techniques. This is an exciting area, and I believe our technology will improve drastically in the next five years.

Dr. Harlan Selesnick is in private practice in orthopedic surgery and sports medicine at Doctors Hospital in Coral Gables, and serves as team physician for the Miami Heat and Miami Dade College, among others. The Jock Doc column runs every other week.