This trial aims to investigate whether CARTISTEM® can assist in the repair of cartilage damage in the knee compared to standard treatment. CARTISTEM® is a proprietary product of mesenchymal stem cell made from donated human umbilical cord blood. The study is being conducted in conjunction with biotech firms MEDIPOST Co Ltd and Dong A Pharmaceuticals at 10 major teaching hospitals and medical centres in South Korea. Participants will either receive CARTISTEM® (experimental group) or standard treatment (microfracture). Participants will be monitored for complications and changes in their condition for five years post-treatment. The study aims to enrol 103 subjects and is expected to be completed by May 2015.