Background: Cartilage tissue engineering using synthetic scaffolds allows maintaining mechanical integrity and withstanding stress loads in the body, as well as providing a temporary substrate to which transplanted cells can adhere. Purpose: This study evaluates the use of polycaprolactone (PCL) scaffolds for the regeneration of articular cartilage in a rabbit model. Study Design: Controlled laboratory study. Methods: Five conditions were tested to attempt cartilage repair. To compare spontaneous healing (from subchondral plate bleeding) and healing due to tissue engineering, the experiment considered the use of osteochondral defects (to allow blood flow into the defect site) alone or filled with bare PCL scaffold and the use of PCL-chondrocytes constructs in chondral defects. For the latter condition, 1 series of PCL scaffolds was seeded in vitro with rabbit chondrocytes for 7 days and the cell/scaffold constructs were transplanted into rabbits’ articular defects, avoiding compromising the subchondral bone. Cell pellets and bare scaffolds were implanted as controls in a chondral defect. Results: After 3 months with PCL scaffolds or cells/PCL constructs, defects were filled with white cartilaginous tissue; integration into the surrounding native cartilage was much better than control (cell pellet). The engineered constructs showed histologically good integration to the subchondral bone and surrounding cartilage with accumulation of extracellular matrix including type II collagen and glycosaminoglycan. The elastic modulus measured in the zone of the defect with the PCL/cells constructs was very similar to that of native cartilage, while that of the pellet-repaired cartilage was much smaller than native cartilage. Conclusion: The results are quite promising with respect to the use of PCL scaffolds as aids for the regeneration of articular cartilage using tissue engineering techniques. ; Ministry of Science (Spain) MAT2007-66759-C03-01 ; Ministry of Science (Spain) MAT2007-66759- C03-02 ; FEDER ; Generalitat Valenciana GVPRE/2008/160 ; Catalan Department of Universities, Research and the Information Society 2005SGR 00762 ; Catalan Department of Universities, Research and the Information Society 2005SGR 00848 ; Instituto de Salud Carlos III (ISCIII) ; Conselleria de Sanitat (Comunitat Valenciana) ; Centro de Investigación Príncipe Felipe (CIPF) ; Martinez-Diaz, S.; Garcia-Giralt, N.; Lebourg, MM.; Gómez-Tejedor, JA.; Vila, G.; Caceres, E.; Benito, P. (2010). In Vivo Evaluation of 3-Dimensional Polycaprolactone Scaffolds for Cartilage Repair in Rabbits. American Journal of Sports Medicine. 38(3):509-519. doi:10.1177/0363546509352448. ; Senia ; 509 ; 519 ; 38 ; 3