J Am Acad Orthop Surg, Vol 16, No 6, June 2008 Marc R. Safran, MD, Hubert Kim, MD and Stefano Zaffagnini, MD Managing articular cartilage injury continues to be a difficult challenge for the clinician. Although the short- and intermediate-term results of autologous chondrocyte implantation appear to be favorable, resources are being directed toward research to improve the technology. One promising area of investigation is the combination of cultured chondrocytes with scaffolds. Clinicians desire techniques that may be implanted easily, reduce surgical morbidity, do not require harvesting of other tissues, exhibit enhanced cell proliferation and maturation, have easier phenotype maintenance, and allow for efficient and complete integration with surrounding articular cartilage. The characteristics that make scaffolds optimal for clinical use are that they be biocompatible, biodegradable, permeable, reproducible, mechanically stable, noncytotoxic, and capable of serving as a temporary support for the cells while allowing for eventual replacement by matrix components synthesized by the implanted cells. Clinical experience is growing with three scaffold-based cartilage repair techniques, each using a different type of scaffold material: matrix-induced autologous chondrocyte implantation, a hyaluronic acidbased scaffold, and a composite polylactic/polyglycolic acid polymer fleece. Clinical results are encouraging. Future directions in scaffold-based cartilage repair include bioactive and spatially oriented scaffolds.