Autologous Chondrocyte Implantation for Treatment of Osteochondral Lesions of the Talus

Autologous chondrocyte implantation (ACI) technology and techniques are a rapidly evolving field. There are currently 3 generations of chondrocyte implantation techniques for osteochondral defects. First-generation and some second-generation ACI techniques are in use in the United States, whereas third-generation chondrocyte implantation methods are in the early phases of human clinical trials. ACI is reserved for patients who have failed marrow stimulation. Caveats to this may be the larger osteochondral lesion of the talus (>1.5 cm2) or the presence of significant subchondral cyst (>8 mm), where ACI with “sandwich” bone grafting is more likely to restore the congruity of the articular surface and underlying bone. Complications specific to ACI in osteochondral lesion of the talus include periosteal hypertrophy, capsular adhesion or arthrofibrosis, painful hardware from osteotomy fixation, and lack of graft incorporation. Newer 1-stage techniques that eliminate the need for a second procedure are also promising and less invasive than first-generation procedures. Furthermore, new-generation cell-based therapies eliminate the need for a periosteal patch, and although third-generation techniques are only investigational, it may eliminate complications associated with scaffolds, such as integration, rate of degradation, and biocompatibility. Prospective randomized studies with long-term follow-up are needed to assess the efficacy of ACI in comparison with marrow stimulation.