Focal chondral or osteochondral lesions of the knee are common lesions involving either the cartilage layers or the cartilage layers and the subchondral bone. Despite their heterogeneous clinical presentation, they are important risk factors for the premature development of osteoarthritis. Therefore, early detection of osteochondral lesions and focal cartilage defects is crucial. In symptomatic (osteo-)chondral lesions, numerous therapeutic strategies, ranging from conservative treatment to surgical procedures such as marrow stimulation, osteochondral autograft transplantation, or autologous chondrocyte implantation are available. Musculoskeletal radiologists should be familiar with these surgical procedures, the evaluation of the postoperative findings as well as the possible complications when interpreting postoperative imaging studies. This review article describes the different surgical approaches to focal osteochondral lesions of the knee with emphasis on postoperative imaging findings and the pitfalls possibly encountered by the radiologist.