Arthroscopic implantation of a three dimensional scaffold for autologous chondrocyte transplantation.

The arthroscopic M-ACT technique is applicable for defects at the femoral condyle up to 5 cm(2). The size of the defect has to be assessed with a specific scaled, percutaneously inserted needle. Then an 8 mm water-stop-cannula is positioned in a suprameniscal portal. The chondrocyte seeded matrix is trimmed to size the defect. The scaffold is introduced in the joint through the cannula and placed into the defect with a blunt arthroscopic grasp instrument to prevent damage of the scaffold. Then a specific drill guide is inserted through an additional anteromedial portal to place it on the scaffold in a perpendicular angle. The position of the drill guide should not be changed during the next two steps. It may be helpful to hold the matrix in place with a probe inserted through the cannula. A 1.5 mm K-wire is drilled at least 16 mm into the subchondral bone. Then the biodegradable pin (length 16 mm) is placed in the drill guide and carefully hammered into the subchondral bone. The joint is flexed so that the drill guide can be placed on the posterior end of the scaffold. Another hole is drilled with the K-wire and a second pin is inserted. Finally the stability of the matrix is tested with a probe and the joint is mobilized.