Arch Orthop Trauma Surg DOI 10.1007/s00402-007-0348-1 123 ARTHROSCOPY AND SPORTS MEDICINE Arthroscopic implantation of a three dimensional scaVold for autologous chondrocyte transplantation Wolf Petersen · Sandra Zelle · Thore Zantop Received: 9 March 2007  Springer-Verlag 2007 Abstract The arthroscopic M-ACT technique is applica- ble for defects at the femoral condyle up to 5 cm². The size of the defect has to be assessed with a speciWc scaled, per- cutaneously inserted needle. Then an 8 mm water-stop-can- nula is positioned in a suprameniscal portal. The chondrocyte seeded matrix is trimmed to size the defect. The scaVold is introduced in the joint through the cannula and placed into the defect with a blunt arthroscopic grasp instrument to prevent damage of the scaVold. Then a spe- ciWc drill guide is inserted through an additional anterome- dial portal to place it on the scaVold 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 sub- chondral bone. Then the biodegradable pin (length 16 mm) is placed in the drill guide and carefully hammered into the subchondral bone. The joint is Xexed so that the drill guide can be placed on the posterior end of the scaVold. 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. Keywords Arthroscopic M-ACT technique · Femoral condyle defect · Chondrocyte seeded matrix · Biodegradeable pin Introduction Autologous chondrocyte transplantation (ALT) was intro- duced by Brittberg et al. [2] as a method for the treatment of chondral defects. In a Wrst arthroscopy a small sample of cartilage has to be harvested. The biopsies were digested and the chondrocytes were cultured in vitro to increase the number of cells. After app. 4 weeks the cells were implanted back into the chondral defect. During this surgi- cal procedure an arthrotomy was performed to inject the cells below a periosteal Xap that was sutured to the sur- rounding cartilage. In this study 14 of 16 patients with a femoral defect are presented with good to excellent results [2]. These results could be conWrmed later by prospective clinical studies with a larger number of patients and a longer follow up. However, these studies released some disadvantages of this technique which were associated with the use of periosteum. First, for harvesting the periosteum a large incision was needed. Secondly, for the Wxation of the periosteum with sutures an arthrotomy was performed. Thirdly, Peterson et al. [6] observed hypertrophy of the periosteum in 26 of 101 patients. During the recent years new techniques were developed to eliminate these disadvantages [3, 4]. All these techniques use a biodegradable matrix with seeded chondrocytes instead of the periosteum to cover the defect (Bioseed C™, MACI™, Novocard™, Hyalograft™). With these scaVolds the size of the skin incision was reduced. Another advan- tage of the use of the matrices is that the chondrocytes have fewer tendencies to diVerentiate due to the three dimen- sional culture conditions. Most authors still use an arthro- tomy for the implantation of the cell seeded matrix [2]. There are only few reports about arthroscopic techniques for the implantation of a matrix seeded with chondrocytes [3, 4]. One of these techniques is technically demanding W. Petersen · S. Zelle · T. Zantop (&) Department of Trauma-, Hand-, and Reconstructive Surgery, Westfälische Wilhelms-University Münster, Waldeyerstr, 1, 48149 Münster, Germany e-mail: Thore.Zantop@ukmuenster.de