This invention relates to a device for osteosynthesis of fractures of the extremities of the femur. This device is of the type comprising a plate in which holes are provided for the passage of screws intended to be inserted into the bone to make the parts of fractured bone and the plate solid.
In the device according to the invention, the end of the plate to be applied against one of the extremities of the femur exhibits a widening to provide for three holes which form an isosceles triangle while the rest of the plate forms, with the median plane of the extremity, an obtuse angle between 160.degree. and 175.degree..
This arrangement, therefore, makes possible a very good application of the plate against the diaphysis and the corresponding extremity of the bone that it fits perfectly.
Further, the triangle arrangement of the holes in the end of the plate applied against one of the ends of the bone makes possible a peripheral attachment in triangulation in the femoral neck or head for the upper extremity of the femur and in the femoral condyles for its lower extremity.
Another advantage of the invention is that the heads of the screws to be inserted in the holes are shaped as truncated cones and the holes are complementarily configured. This arrangement makes possible a solid and proper attachment of the femoral head in the cervical fractures, a solid hold with a possibility of correcting the varus in per-, inter- or sub-trochanteric, or even trochanterodiaphyseal fractures for the extremity of the femur.
According to yet another characteristic of the invention, in the center of the triangle formed by the three conical holes in the enlarged end of the plate is a threaded hole for insertion of an auxiliary screw that is used for attaching a disk whose outer diameter makes it possible to partially cover the conical heads of the screws inserted in said three conical holes.
This disk assures the holding of the three screws under consideration and prevents their backward movement during the compression under load of the fracture.
Preferably this disk is elastic to make possible the passage of the screw heads and the backward movement of the screw heads if they were to come in contact with the cortical of the femoral head.
This arrangment, therefore, has the advantage of increasing the mechanical behavior of this device by taking all the advantages of one-piece mountings, while avoiding the risks of deterioration by perforation of the corticals of the femoral head and keeping the simplicity of a screwed-on mounting.