Osteosynthesis device for the treatment of fractures of the neck of the femur, comprising a femoral stem (1) of rectangular or oblong cross-section, intended to be inserted into the medullary canal of the femur, a cephalic screw (2) intended to be inserted at least partly in the head and neck of the femur, said head screw (2) having a transverse hole (25) for receiving said femoral stem (1), and a compression element (3), which allows said femoral stem and said cephalic screw, said transverse hole (25) comprising two opposite transverse walls, designated respectively "distal" (252) and "proximal" (251), the distance (D) being between the edge called "upper" (252a ) of the distal transverse wall (252) located in the plane of the inlet opening (253) of said transverse hole (25) and the orthogonal projection of the parallel edge called "bottom" (251b) of the transverse wall proximal salt (251) in this same plane of the inlet opening (253) of said transverse hole (25), greater than or equal to the width (L) of said femoral stem (1), characterized in that said distal walls (252 ) and proximal (251) of the transverse hole (25) are inclined in the same direction with respect to the longitudinal axis (X1-X'1) of said head screw (2), and by which the compression element (3) is joined to said head screw (2) and apply a pressure on one of the side faces (14, 15) of said femoral stem (1), so that the other side face (15, 14) of the femoral stem (1) is in contact with the bottom edge (251b) of the proximal transverse wall (251) of the transverse hole (25).Dispositivo de osteosíntesis para el tratamiento de las fracturas del cuello del fémur, que comprende un vástago femoral (1) de sección transversal rectangular u oblonga, destinado a ser insertado en el canal medular del fémur, un tornillo cefálico (2) destinado a ser insertado por lo menos en parte en la cabeza y el cuello del fémur, presentando dicho tornillo cefálico (2) un orificio transversal (25) de recepción de dicho vás
