Application of low-invasive local adherent technique to transplant synovial mesenchymal stem cells into cartilage defect. (a) For illustration, the cartilage defect is located on the condyles of the femur in the knee joint. (b) Knee is positioned so that the cartilage defect is faced upward. The synovial mesenchymal stem cell (MSC) suspension is then slowly dripped onto the cartilage defect, and the knee is held stationary for 10 minutes. (c) Knee position is permitted to be changed, and the synovial MSCs have adhered to the cartilage defect. (d) Transplanted synovial MSCs differentiate according to the microenvironment, and the cartilage regenerates.