ACI and MACI

Regenerative procedures aim to recreate a hyaline-like tissue, thus restoring a biologically and biomechanically valid articular surface with durable clinical results. Autologous chondrocyte implantation (ACI) has been developed two decades ago, and both the production of a hyaline-like articular surface and a satisfactory clinical outcome have been documented at medium-long follow-up. The development of the bioengineering technology further improved this regenerative treatment approach: matrix-assisted ACI techniques (MACI) have been introduced in the clinical practice since one decade, showing to offer similar results but at the same time to overcome most of the concerns related to the first generation ACI. The use of scaffolds to create a cartilage-like tissue in a three-dimensional culture system allows to optimize the procedure from both the biological and surgical point of view. However, despite thousands of patients treated and several published studies suggesting good clinical results and durability of these procedures, at the time being the properties of the healthy cartilage tissue are still unmatched by any available substitute, and both indications and results are still controversial. The role of many variables that may influence the final outcome still need to be clarified to further improve the potential benefits of these biological regenerative procedures.