AbstractRemarkable advances have been made in knee replacement. Nevertheless, patients and surgeons still face unsolved problems following implantation of an artificial knee joint. In some cases arthroscopy may serve as a diagnostic or surgical tool. Our experience has shown that arthroscopy is helpful in diagnosing polyethylene wear, fractures of prosthetic components and loosening of the endoprosthesis. Moreover, surgical procedures can be synchronously performed, e.g. lateral release for complete or partial patellar dislocation, parapatellar denervation for retropatellar pain and resection of meniscal remnants or a synovial plica in case of interposed tissue. In contrast to knee infections, early prosthetic infections should be treated with an open procedure.