The Illustrative Overlay Autologous Chondrocyte Implantation (Overlay ACI) Technique for Repair of the Extra-Large Osteochondral Defects

The importance of the subchondral (SC) bone has been well established [1, 2], which makes the osteochondral (OC) lesions distinctly different from the pure chondral lesions. For the treatment of osteochondral lesions, the subchondral bone must be reconstructed properly before the cartilage repair procedure is carried out [3]. Most of these OC lesions are very big in size and are associated with either subchondral bone damage or large SC cysts or a totally separated large OC fragment [4]. The most common non-degenerative etiologies for such large combined osseous and chondral lesions are osteochondritis dissecans (OCD), regional osteonecrosis, and trauma [5]. Prognosis of such lesions is less favorable and has a strong tendency to leave a painful and/or unstable joint causing early-age osteoarthritis. Treating such large lesions with joint-preservation techniques is a big challenge because there are no proven techniques to treat such lesions; they may require multiple surgeries, and still have a doubtful success rate. Goyal [6] discussed the mid-term results of “The overlay ACI technique” and established the technique for the treatment of the extra-large osteochondral lesions where the autologous chondrocyte implantation (ACI) was overlaid over the reconstructed subchondral bone. The purpose of this chapter is to illustrate the case selection and the surgical technique along with a discussion of the long-term results of the Overlay ACI technique.