The use of the intramedullary nail in extracapsular fractures of the proximal third of the femur is the most frequent stabilization system. In recent years, the biomechanical complications that affect this system have been increasing.A retrospective radiographic study of intertrochanteric fractures was performed followed by an analysis of the biomechanical complications in zone 1 of the cephalic screw. Of the 548 cases, 85 cases (15.5%) of complications were observed, with "back-out" being the most frequent minor complication and "cut-out" the most frequent major complication. 41% of the total fractures correspond to type 31-A2.3 AO / OTA. The basicervical fractures and 31-A2.3 have a high risk of complications.The biomechanical origin that Lenich describes is important to understand as the surgical solution varies depending on whether it is cut-out, cut-in (same origin of the biomechanical failure of the head screw) or cut-through (different origin) to, consequently, resolve them in the right manner