Variable angle bone fixation device
View Patent ↗A bone fixation element includes a threaded head and a shaft extending along a longitudinal axis from a proximal end to a distal end, an outer surface of the head being one of carburized and nitrided and including a first groove extending into an outer surface of the head along a path interrupting the threading and extending along an angle counter to an angle of the threading.
1. A system for bone fixation, comprising:
an elongated bone implant having a shaft configured for insertion into a bone in an operative configuration and being formed of a ferrite-free implant grade material, an outer surface of the bone implant being one of carburized and nitrided to have a first hardness and to increase a corrosion resistance; and
a bone fixation plate having an opening extending therethrough from a first surface configured to contact the bone in an operative configuration to a second surface located opposite the first surface, the opening being configured to receive the bone implant therethrough, the bone fixation plate having a second hardness;
wherein the first hardness is greater than the second hardness.
2. The system of claim 1 , wherein the bone implant is a bone screw having a threaded head.
3. The system of claim 1 , wherein a head of the bone implant includes a rounded outer profile.
4. The system of claim 1 , wherein a head of the implant includes a substantially spherical outer profile.
5. The system of claim 1 , wherein the opening is a variable angle hole.
6. The system of claim 1 , wherein the first hardness in the range of 67-74 HRC and the second hardness is in the range of 74 HRB-44 HRC.
7. The system of claim 1 , wherein the bone implant is formed of one of an implant quality austensitic stainless steel, cobalt alloys, MP35N, L605, ASTM-F-1058,Elgiloy, Titanium, and titanium alloys.
8. The system of claim 7 , wherein the bone implant is formed of one of Biodur 108 and 316L stainless steel.
9. A bone fixation element comprising a threaded head and a shaft extending along a longitudinal axis from a proximal end to a distal end and formed of a ferrite-free implant grade material, an outer surface of the head being one of carburized and nitrided to increase a surface hardness thereof and including a first groove extending into the outer surface of the head along a path interrupting the threading and extending along an angle counter to an angle of the threading.
10. The bone fixation element of claim 9 , wherein a material of the bone fixation element is selected to be harder than a material of a bone plate through which the bone fixation element is to be inserted.
11. The bone fixation element of claim 9 , wherein the first groove extends along a groove axis perpendicular to the longitudinal axis of the bone fixation element.
12. The bone fixation element of claim 9 , further comprising a notch formed adjacent the distal end of the shaft.
13. The bone fixation element of claim 9 , further comprising a recess in a proximal end of the bone fixation element, the recess configured to engage a driving mechanism.
14. The bone fixation element of claim 9 , wherein the head comprises one of five grooves and eight grooves.
15. The bone fixation element of claim 9 , wherein the shaft is threaded.
16. The bone fixation element of claim 15 , wherein a pitch of threads of the shaft is the same as a pitch of threads of the head.
17. The bone fixation element of claim 15 , wherein the thread of the shaft includes multiple leads.
18. The bone fixation device of claim 9 , wherein the head is substantially spherical.
19. A bone fixation system, comprising:
a bone fixation element comprising a threaded head and a shaft extending along a longitudinal axis from a proximal end to a distal end and being formed of a ferrite-free implant garde material, an outer surface of the head being one of carburized and nitrided to increase a surface hardness thereof and including a first groove extending into the outer surface of the head along a path interrupting the threading and extending along an angle counter to an angle of the threading; and
an elongated bone plate extending along a plate axis and having a plate hole extending therethrough from a first surface to a second surface configured to contact a bone in an operative configuration.
20. The bone fixation system of claim 19 , wherein a material of the bone fixation element is selected to be harder than a material of the bone plate through which the bone fixation element is to be inserted.
21. The bone fixation system of claim 19 , wherein the first groove extends along a groove axis perpendicular to the longitudinal axis of the bone fixation element.
22. The bone fixation system of claim 19 , wherein the plate hole is one of a combination hole and a variable angle hole.
23. The bone fixation system of claim 19 , wherein the second surface of the bone plate comprises a plurality of undercuts.
24. The bone fixation system of claim 19 , wherein the plate hole comprises a first tapered portion adjacent the first surface, a second tapered portion adjacent the second surface and a threaded portion extending between the first and second tapered portions.
25. The bone fixation system of claim 19 , further comprising a notch adjacent the distal end of the bone screw.
26. The bone fixation system of claim 19 , further comprising a recess in a proximal end of the bone screw, the recess configured to engage a driving mechanism.
27. The bone fixation system of claim 19 , wherein the shaft is threaded.
28. The bone fixation system of claim 19 , wherein a pitch of threads of the shaft is the same as a pitch of threads of the head.
29. The bone fixation system of claim 19 , wherein the plate hole is a variable angle hole including a slot extending along a wall of the hole and configured to interrupt threads thereof.
30. A method for treating a bone, comprising:
placing a bone fixation device over a target bone, the bone fixation device extending along a plate axis and having a hole extending therethrough from a first surface to a second surface configured to contact the bone in an operative configuration; and
inserting a bone fixation element through the hole and into the bone, the bone fixation element comprising a threaded head and a shaft extending along a longitudinal axis from a proximal end to a distal end and being formed of a ferrite-free implant grade material, an outer surface of the head being one of carburized and nitrided to increase a surface hardness thereof and including a first groove extending into the outer surface of the head along a path interrupting the threading and extending along an angle counter to an angle of the threading.