The incidence of periprosthetic fractures is increasing because of the increasing age and the rising number of joint replacements. Elderly patients are endangered because of a higher rate of co-morbidity such as osteoporosis or cardiovascular diseases. The treatment of periprosthetic fractures depends on these preconditions and has to solve the problem after an exact analysis of the fracture. An understanding of the biomechanical principles and risk factors is necessary for an effective treatment. Intraoperative and postoperative periprosthetic fractures will be discussed with emphasis on classification and treatment. The aim has to be an early functional postoperative treatment with partial/full weight bearing in order to avoid postoperative complications. In discussing the scope of periprosthetic fractures, the site, incidence, treatment and outcome of periprosthetic fractures of the hip and knee will be outlined.