Painful chondral defects of the knee are very difficult problems. The incidence of these lesions in the general population is not known since there is likely a high rate of asymptomatic lesions. The rate of lesions found during arthroscopic exam is highly variable, with reports ranging from 11 to 72 % Aroen ( Examples of current attempts at cartilage restoration include marrow stimulating techniques, ostochondral autografts, osteochondral allografts, and autologous chondrocyte transplantation. Current research in marrow stimulating techniques has been focused on enhancing and guiding the biology of microfracture and other traditional techniques. Modern advances in stem cell biology and biotechnology have provided many avenues for exploration. The purpose of this work is to review current techniques in marrow stimulating techniques as it relates to chondral damage of the knee.