Treatment of extensive chondral and osteochondral defects in the knee remains a challenge. The traditional bone marrow stimulation and osteochondral mosaicplasty are effective but this is indicated only for lesions smaller than 4 cm ² . In addition, while they are offered in young patients, functional deterioration is often observed after 2 years. In contrast, Autologous Chondrocyte Implantation (ACI) has proven to be efficient and durable even in larger lesions. These factors have encouraged our team to consider ACI as a valuable tool, but it was not readily available in Switzerland. In this article, we describe why and how we have developed and refined the technique in our University Hospital for the clinical implementation of this cell-based therapy, performed under a quality assurance system and following good manufacturing practices.