Repair of cartilage defects in the knee.

The factors to be considered in selecting a technique are the diameter of the chondral defect, the depth of the bone defect, and the knee alignment. As a rough guide, I suggest the following guide to treatment. Chondral defects (without bone involvement) <3 cm in diameter can be treated with microfracture, autologous chondrocyte transplantation, osteochondral autografts, or periosteal grafts. Osteochondral defects <3 cm in diameter and 1 cm in bone depth can be treated with autologous chondrocyte transplantation, osteochondral autografts, or periosteal grafts. Articular defects >3 cm in diameter and 1 cm in bone depth require osteochondral allografts. This is a rough guide to treatment and only the opinion of the author. The greater the bone involvement and the less contained the defect, the greater the need for allograft tissue. Allograft tissue should, however, only be used when the size of the lesion is beyond the other techniques. For all of these techniques, realignment osteotomy should be performed as an adjunct procedure if the lesion is in a compartment under more than physiological compression.