Bone screw for the treatment of bone collapses or deformations, in the case of the Charcot foot, and insertion instrument of anti-migration elements into the bone screw
A bone screw for Charcot foot includes a non-threaded intermediate portion between threaded tip and head portions. The intermediate portion is longer than the tip and head portions. The head portion has an outer diameter larger than the intermediate and tip portions. The screw includes at least one transverse hole on the intermediate portion with a circular cross-section which is arranged for inserting a pin to prevent migration of the screw. The screw includes a helical groove on the intermediate portion. The head portion is removably coupled to the intermediate portion by a shape coupling between two profiles which allows only one relative coupling orientation or at least two relative coupling orientations rotated by a specific angular distance with respect to each other. The head portion is coupled to the intermediate portion by a shape coupling between two profiles comprising a radial groove and a radial relief.
1. An improved bone screw for the treatment of bone collapses and deformations in the case of the so-called Charcot foot, comprising a non-threaded intermediate portion spaced between a tip portion and a head portion both of which being externally threaded; wherein the non-threaded intermediate portion is longer than the tip portion; wherein the non-threaded intermediate portion is longer than the head portion; said head portion having an outer diameter larger than said intermediate portion and said tip portion; said head portion having a head seat for coupling a tightening device; said bone screw further comprising at least one transverse hole on the non-threaded intermediate portion, said transverse hole having a circular cross-section at both its inlet and outlet and being arranged for inserting a corresponding at least one pin to prevent the migration of said bone screw when implanted into the bone; said bone screw further comprising a helical groove on the non-threaded intermediate portion; wherein said head portion is removably coupled to said intermediate portion;
wherein said head portion is coupled to said intermediate portion by means of a shape coupling between two profiles, which allows only one relative coupling orientation or at least two relative coupling orientations rotated by a specific angular distance with respect to each other; wherein said head portion is coupled to said intermediate portion by means of a shape coupling between two profiles comprising a radial groove and a radial relief adapted to be inserted within said radial groove.
2. The bone screw according to claim 1 , wherein said shape coupling between two profiles allows two relative coupling orientations rotated by 180° with respect to each other.
3. The bone screw according to claim 1 , wherein one of said head portion and said intermediate portion has a female element with the radial groove; the other between said head portion and said intermediate portion having at least one male element with the radial relief adapted to be inserted within said radial groove when the shape coupling between said male element and said female element is achieved defining two relative coupling orientations rotated by 180° with respect to each other.
4. The bone screw according to claim 1 , wherein one of said head portion and said intermediate portion has a female element defining a polygonal seat, at least a face of said polygonal seat comprising a radial groove; the other between said head portion and said intermediate portion having at least one male element defining a polygonal profile adapted to engage in said polygonal seat, at least a face of said polygonal profile having an elongated radial ridge adapted to slide within the radial groove.