This trial aims to assess the benefit of implanting a product made from the patient's own mesenchymal stem cells for cartilage repair. The study is being conducted by the Osaka University Medical School and the Osaka Hospital Medical Centre for Translational Research and proposes to enrol six patients from September 2012. For each participant, a product will be made from their own mesenchymal stem cells that will then be introduced to the fluid surrounding the joint. Participants will be monitored for complications and changes in clinical condition, including evidence of cartilage repair.