The ACI procedure involves two stages. In the first stage, an arthroscopic evaluation of the cartilage defect is conducted. If the defect is suitable for ACI, healthy cartilage cells are obtained from a non-weight bearing area of the patient's bone and cultured in a laboratory for several weeks. In the second stage, a larger incision is made to expose the cartilage damage, and a patch is harvested from the periosteum, a thick tissue covering the shin bone. The patch is then shaped to fit the cartilage defect and sutured in place, with the cultured cells injected underneath it.
One potential complication of ACI is periosteal hypertrophy, which is characterized by scar tissue formation around the edges of the periosteal patch. Other complications such as implant failure, knee infection, and stiffness may also arise. After ACI, patients are typically advised to avoid weight-bearing activities for six to eight weeks to facilitate the adherence of the new cells to the bone, and some degree of limited range of motion may persist.
ACI offers the advantage of using the patient's own cartilage cells, reducing the risk of graft rejection. However, it is a two-stage procedure that requires an open incision, which is a drawback.