Abstract: A set of mobile necks for inserting into the stem (2) of a hip prosthesis, in which the mobile necks are produced with different inclinations and lengths in such a way that their free ends (3i), when inserted in the stem, terminate at nine mutually equidistant points (Pi) arranged in three parallel horizontal rows (R0) in such a way that the lines joining the outermost points delineate a square (Q), the length of whose sides is approximately 15 mm, the diagonal (D) of this square coinciding with the axis (H-H) of a mobile neck (1) set at a neutral inclination, that is neither varus nor valgus, with respect to a plane (ss) essentially perpendicular to the axis of the abovementioned stem (2).

Abstract: A set of mobile necks for inserting into the stem (2) of a hip prosthesis, in which the mobile necks are produced with different inclinations and lengths in such a way that their free ends (3i), when inserted in the stem, terminate at nine mutually equidistant points (Pi) arranged in three parallel horizontal rows (R0) in such a way that the lines joining the outermost points delineate a square (Q), the length of whose sides is approximately 15 mm, the diagonal (D) of this square coinciding with the axis (H-H) of a mobile neck (1) set at a neutral inclination, that is neither varus nor valgus, with respect to a plane (ss) essentially perpendicular to the axis of the above-mentioned stem (2).

Abstract: An assembly including a head and movable neck for preparing the implantation of an artificial hip is described, the head and the movable neck having, respectively, a frustoconical hole and a frustoconical portion insertable therein. The flat end of the frustoconical portion has, coaxially formed or mounted thereon, a cylindrical protrusion having a diameter smaller than that of the frustoconical portion opposite its fiat end and the frustoconical hole has a coaxial, blind, cylindrical extension from the side walls of which an annular protrusion having an internal diameter which produces a slight interference with the diameter of the cylindrical protrusion projects, and the height of the cylindrical extension is greater than or equal to that of the cylindrical protrusion so that, when the latter is inserted over its entire height inside the cylindrical extension, the flat end bears against a concentric shoulder formed on the head around the cylindrical extension.

Abstract: An assembly consisting of an insertion/extraction device and a preparatory instrument or a prosthetic part used in orthopeadic surgery operations. The free end of the said preparatory instrument or that prosthetic part has, formed therein, a first recess able to be engaged in a complementary manner with the end of a modular neck, and a second recess having an axis substantially intersecting the axis of the first recess. The device is provided with a handle having its axis parallel to that of the second recess and having a first terminal portion shaped so as to engage in a complementary manner with the recess, and a second terminal portion adjacent to the first recess and connected to means which are fixed onto the handle and which, when they are operated, perform the coaxial insertion of the portion into the second recess.

Abstract: A hip prosthesis (1) comprising a shank (2) which is inserted into the extremity of the femur (3), in which the longitudinal axis (H-H) of the shank (2) follows a path substantially parallel to the external profile (P) of the head of the femur (3) in the top part of its cervical-trochanter area (3a) is described.

Abstract: What is described is an assembly consisting of a movable neck and a stem for a hip prosthesis, the said movable neck being provided with a tapered part connected in a complementary way to a cavity formed in the said stem. In the assembly according to the invention, a through hole is formed in the movable neck or in the stem, this hole being orientated and positioned so that, when the tip of a pointed tool with its outer walls converging towards the tip, the opposite sides of these walls bear on a surface forming part of the movable neck and a surface forming part of the stem, exerting, by the inclined plane effect, a substantially axial force capable of causing the disengagement of the movable neck from the stem.

Abstract: A description is given of a set of mobile necks for inserting into the stem of a hip prosthesis, in which the mobile necks are produced with different inclinations and lengths in such a way that their free ends, when inserted in the stem, terminate at nine mutually equidistant points arranged in three parallel horizontal rows in such a way that the lines joining the outermost points delineate a square, the length of whose sides is approximately 15 mm, the diagonal of this square coinciding with the axis of a mobile neck set at a neutral inclination, that is neither varus nor valgus, with respect to a plane essentially perpendicular to the axis of the stem.

Abstract: Hip prosthesis structure includes a stem to be inserted into the upper portion of the femur, this stem having in its top a cavity for housing the free end of a shaped neck which carries on its other end a spherical head to be joined to the acetabulum of the hip. The free end of the neck is shaped in the form of two half truncated cones positioned so that they are mirror images of each other and delimited transversely by two bases which are essentially flat and parallel. The half truncated cones are linked to each other by two surfaces which form two recesses inside the planes tangent to the two half truncated cones on opposite sides of the plane which contains their axes, the shape of the cavity being complementary to the solid formed by the two half truncated cones and by the two planes tangent to them.