{Reference Type}: Case Reports {Title}: Atypical Vancouver B1 Periprosthetic Fractures: The Unsolved Problem. {Author}: Vicenti G;Solarino G;Ottaviani G;Carrozzo M;Simone F;Zavattini G;Zaccari D;Buono C;Bizzoca D;Maccagnano G;Moretti B; {Journal}: Geriatr Orthop Surg Rehabil {Volume}: 14 {Issue}: 0 {Year}: 2023 {Factor}: 1.924 {DOI}: 10.1177/21514593221145884 {Abstract}: Atypical femoral fractures (AFF) are stress or insufficiency fractures induced by low energy trauma or no trauma, frequently correlated with prolonged bisphosphonate therapy. The diagnosis follows major and minor criteria, originally described by the Task Force of the American Society for Bone and Mineral Research in 2010 and updated in 2014. However, the definition of AFFs in the report excluded periprosthetic fractures. When atypical fractures occur close to a prosthetic implant the situation become critical, the surgical treatment is often demolitive and supported by medical treatment. Moreover, acute ORIF as a first line treatment is frequently burdened by a high failure rate , and often a stem revision is required as second line treatment. The healing process is long and difficult with poor functional results and impairing outcomes. We present a case treated at our institution of a 78 year old woman with a history of a femoral atypical periprosthetic fracture, complicated by multiple surgical revisions. Its arduous management reflects all the difficulties that these type of fractures could present to the surgeon, while its good final result may teach us how to approach them in a correct way.