Forest plots of adverse events. In forest plots, no difference for the relative risk corresponds to one. The I
2 for infection was 23%, for symptomatic cartilage loosening was 29%, and for failure, reoperation, and persistent pain was 0%. ACI1, autologous chondrocyte implantation with periosteal membrane; ACI2, autologous chondrocyte implantation with collagen membrane; ACI3, autologous chondrocyte implantation with scaffold; AMIC, autologous matrix-induced chondrogenesis; MF, microfracture; OA, osteoarthritis; OCT, osteochondral transplantation; spheroids refer to chondrospheres.