Pseudopathologic fracture of the femoral neck, first reported by Pope in 1981, is a fracture which shows radiolucency in the superolateral subcapital region of the femoral neck that mimics the features of a pathologic fracture. Our purpose was to determine the prevalence of this phenomenon in Japanese patients. Between January 2000 and January 2005, 148 femoral neck fractures were treated in our hospital. Radiographs and medical records were reviewed. Twenty four (16%) of the 148 fractures showed radiolucency in the superolateral subcapital region (pseudopathologic fracture). These included two (6%) out of 33 Garden stage I fractures, none out of 22 Garden stage II fractures, 15 (27%) out of 55 Garden stage III fractures, and seven (18%) out of 38 Garden stage IV fractures. These incidences in each Garden stage were relatively similar to those reported previously, with an exception that no case of stage I with pseudopathologic fracture was found. The mechanisms which cause radiolucency are discussed. Understanding of the appearance of subcapital hip fractures mimicking pathologic fractures and knowledge of the cause of such findings are important for prescribing appropriate treatment and avoiding lengthy, costly laboratory and radiographic workup.
