Bone fixation devices, systems, and methods
A bone fixation assembly may include a male member removably couplable with a female member. The male member may include a male load-sharing feature having at least one male load-sharing surface. The female member may include a female load-sharing feature having at least one female load-sharing surface. The female load-sharing feature may be positioned and shaped to receive the male load-sharing feature therein. In response to a bending load acting on the bone fixation assembly, at least one of the male member and the female member may bend such that, at least a portion of the at least one male load-sharing surface engages with at least a portion of the at least one female load-sharing surface to distribute the bending load between the male member and the female member.
1. A bone fixation assembly comprising:
a male member, the male member comprising:
a male member shaft comprising:
a proximal end;
a distal end; and
a first longitudinal axis;
a first bone engaging feature at the proximal end of the male member shaft;
an external thread portion at the distal end of the male member shaft, the external thread portion having a first length and a first major diameter; and
a male load-sharing feature intermediate the first bone engaging feature and the external thread portion, the male load-sharing feature having a second length and an outer diameter defining at least one male load-sharing surface; and
a female member, the female member comprising:
a female member shaft comprising:
a proximal end;
a distal end; and
a second longitudinal axis;
a second bone engaging feature at the proximal end of the female member shaft;
an internal thread portion having a third length and a second major diameter, the internal thread portion configured to receive the external thread portion of the male member to removably couple the male member with the female member; and
a female load-sharing feature located distal to the internal thread portion and extending between the internal thread portion and the distal end of the female member shaft, the female load-sharing feature having a fourth length and an inner diameter defining at least one female load-sharing surface, the female load-sharing feature positioned and shaped to receive the male load-sharing feature therein;
the inner diameter is slightly greater than the outer diameter to create a very close sliding fit between the female load-sharing feature and the male load-sharing feature.
2. The bone fixation assembly of claim 1 , wherein at least one of the at least one male load-sharing surface and the at least one female load-sharing surface comprises a cylindrical surface.
3. The bone fixation assembly of claim 1 , wherein the male load-sharing feature is configured to slide and rotate within the female load-sharing feature during assembly of the male member to the female member.
4. The bone fixation assembly of claim 1 , wherein at least one of the male member and the female member comprise a low tensile modulus material that is configured to provide a compression force to the bone.
5. The bone fixation assembly of claim 1 , wherein the male member comprises one of:
a male member blind bore;
a male member through bore; and
a self-centering tip.
6. The bone fixation assembly of claim 1 , wherein at least one of the male member and the female member comprises a bone retention feature.
7. The bone fixation assembly of claim 1 , wherein:
the male member comprises a male member head having a first torque connection interface; and
the female member comprises a female member head having a second torque connection interface.
8. A bone fixation assembly comprising:
a male member, the male member comprising:
a male member shaft comprising:
a proximal end;
a distal end; and
a first longitudinal axis;
a first bone engaging feature at the proximal end of the male member shaft;
an external thread portion at the distal end of the male member shaft, the external thread portion having a first length and a first major diameter; and
a male load-sharing feature intermediate the first bone engaging feature and the external thread portion, the male load-sharing feature having a second length and an outer diameter defining at least one male load-sharing surface; and
a female member, the female member comprising:
a female member shaft comprising:
a proximal end;
a distal end; and
a second longitudinal axis;
a second bone engaging feature at the proximal end of the female member shaft;
an internal thread portion having a third length and a second major diameter, the internal thread portion configured to receive the external thread portion of the male member to removably couple the male member with the female member when the bone fixation assembly is implanted in a bone; and
a female load-sharing feature located distal to the internal thread portion, the female load-sharing feature having a fourth length and an inner diameter defining at least one female load-sharing surface, the female load-sharing feature positioned and shaped to receive the male load-sharing feature therein;
wherein, the outer diameter of the male load-sharing feature is greater than or equal to the first major diameter of the external thread portion.
9. The bone fixation assembly of claim 8 , wherein:
the male member comprises a male member head having a first torque connection interface; and
the female member comprises a female member head having a second torque connection interface.
10. The bone fixation assembly of claim 9 , wherein:
the male member head and the female member head comprise first partially spherical surfaces; and
the first bone engaging feature and the second bone engaging feature comprise second partially spherical surfaces configured to mate with the first partially spherical surfaces and allow polyaxial articulation of the first bone engaging feature and the second bone engaging feature with respect to the male member head and the female member head.
11. The bone fixation assembly of claim 10 , wherein at least one of the first bone engaging feature and the second bone engaging feature comprises a washer.
12. The bone fixation assembly of claim 10 , wherein:
at least one of the first bone engaging feature and the second bone engaging feature comprises a bone plate;
the bone fixation assembly further comprises a retention cap configured to couple with the bone plate; and
one or more retention surfaces of the retention cap are configured to engage with at least one of the male member head and the female member head to adjust a space between the first bone engaging feature and the second bone engaging feature.
13. The bone fixation assembly of claim 8 , wherein the inner diameter of the female load sharing feature is greater than or equal to the second major diameter of the internal thread portion.
14. The bone fixation assembly of claim 8 , wherein at least one of the at least one male load-sharing surface and the at least one female load-sharing surface comprises a cylindrical surface.
15. A bone fixation assembly comprising:
a male member formed of a rigid metal, the male member comprising:
a male member shaft comprising:
a proximal end;
a distal end; and
a first longitudinal axis;
a first bone engaging feature at the proximal end of the male member shaft;
an external thread portion at the distal end of the male member shaft, the external thread portion having a first length and a first major diameter; and
a male load-sharing feature intermediate the first bone engaging feature and the external thread portion, the male load-sharing feature having a second length and an outer diameter defining at least one male load-sharing surface; and
a female member formed of a rigid metal, the female member comprising:
a female member shaft comprising:
a proximal end;
a distal end; and
a second longitudinal axis;
a second bone engaging feature at the proximal end of the female member shaft;
an internal thread portion having a third length and a second major diameter, the internal thread portion configured to receive the external thread portion of the male member to removably couple the male member with the female member; and
a female load-sharing feature located distal to the internal thread portion, the female load-sharing feature having a fourth length and an inner diameter defining at least one female load-sharing surface, the female load-sharing feature positioned and shaped to receive the male load-sharing feature therein;
wherein, in response to a bending load acting on the bone fixation assembly after implantation in a bone, at least one of the male member and the female member bend such that, at least a portion of the at least one male load-sharing surface engages with at least a portion of the at least one female load-sharing surface to distribute the bending load between the male member and the female member.
16. The bone fixation assembly of claim 15 , wherein at least one of the male member and the female member comprises a bone retention feature.
17. The bone fixation assembly of claim 16 , wherein the bone retention feature comprises one or more barbs.
18. The bone fixation assembly of claim 16 , wherein the bone retention feature comprises a thread.
19. The bone fixation assembly of claim 18 , wherein the thread comprises at least one of a right-handed thread and a left-handed thread.
20. The bone fixation assembly of claim 18 , wherein the inner diameter of the female load sharing feature is greater than or equal to the second major diameter of the internal thread portion.