FASTENING DEVICES, SYSTEMS, AND METHODS
A method of preventing bone blowout may include forming a hole in a bone, the hole having a bone hole diameter, and inserting a bone fastener into the hole. The bone fastener may include a shaft having a minor diameter and a helical thread. The helical thread may be disposed about the shaft and may include a first undercut surface and a second undercut surface. The first undercut surface may be angled toward one of the proximal end and the distal end of the shaft, and the second undercut surface may be angled toward the other one of the proximal end and the distal end of the shaft. The minor diameter of the shaft may not be greater than 5% larger the bone hole diameter.
1 . A pedicle bone fastener comprising:
a shaft comprising:
a proximal end;
a distal end;
a longitudinal axis; and
a minor diameter;
a helical thread disposed about the shaft along the longitudinal axis between the proximal and distal ends of the shaft, the helical thread comprising:
a first undercut surface; and
a second undercut surface, wherein:
the first undercut surface is angled toward one of the proximal end and the distal end of the shaft;
the second undercut surface is angled toward the other one of the proximal end and the distal end of the shaft; and
the minor diameter of the shaft is constant.
2 . The pedicle bone fastener of claim 1 , further comprising:
an attachment feature coupled to the proximal end of the shaft and configured to be secured to an implement.
3 . The pedicle bone fastener of claim 2 , wherein the attachment feature comprises a polyaxial head having a first semi-spherical surface.
4 . The pedicle bone fastener of claim 3 , wherein the implement comprises a discrete tulip having a second semi-spherical surface configured to engage the first semi-spherical surface of the polyaxial head to secure the discrete tulip to the polyaxial head at any of a variety of relative orientations.
5 . The pedicle bone fastener of claim 4 , wherein the discrete tulip further comprises:
at least one opening; and
a locking member configured to secure a rod received through the at least one opening to the discrete tulip.
6 . The pedicle bone fastener of claim 2 , wherein the attachment feature comprises an integrated tulip having at least one opening configured to receive at least a part of the implement therethrough.
7 . The pedicle bone fastener of claim 6 , wherein the implement comprises a rod receivable through the at least one opening of the integrated tulip, and wherein the integrated tulip comprises a locking member configured to secure the rod to the integrated tulip.
8 . A method of preventing bone blowout comprising:
forming a hole in a bone, the hole having a bone hole diameter; and
inserting a bone fastener into the hole, the bone fastener comprising:
a shaft comprising:
a proximal end;
a distal end;
a longitudinal axis; and
a minor diameter; and
a helical thread disposed about the shaft along the longitudinal axis between the proximal and distal ends of the shaft, the helical thread comprising:
a first undercut surface; and
a second undercut surface, wherein:
the first undercut surface is angled toward one of the proximal end and the distal end of the shaft;
the second undercut surface is angled toward the other one of the proximal end and the distal end of the shaft; and
the minor diameter of a main portion of the shaft is not greater than the bone hole diameter to reduce a radial outward load force imparted on the bone and prevent bone blowout.
9 . The method of claim 8 , wherein the minor diameter of the main portion of the shaft is equal to the bone hole diameter.
10 . The method of claim 8 , wherein the minor diameter of the main portion of the shaft is less than the bone hole diameter.
11 . The method of claim 10 , wherein the minor diameter of the main portion of the shaft is between 0 mm and 0.1 mm less than the bone hole diameter.
12 . The method of claim 10 , wherein the minor diameter of the main portion of the shaft is at least 0.1 mm less than the bone hole diameter.
13 . The method of claim 10 , wherein the minor diameter of the main portion of the shaft is at least 0.2 mm less than the bone hole diameter.
14 . The method of claim 8 , wherein the minor diameter of the main portion of the shaft is constant.
15 . A bone fastener comprising:
a shaft comprising:
a proximal end;
a distal end;
a longitudinal axis; and
a minor diameter;
a helical thread disposed about the shaft along the longitudinal axis between the proximal and distal ends of the shaft and defining a major diameter of the bone fastener, the helical thread comprising:
a first undercut surface; and
a second undercut surface, wherein:
the first undercut surface is angled toward one of the proximal end and the distal end of the shaft; and
the second undercut surface is angled toward the other one of the proximal end and the distal end of the shaft; and
a ratio of the major diameter to the minor diameter is less than 1.50.
16 . The bone fastener of claim 15 , wherein the ratio of the major diameter to the minor diameter is less than 1.25.
17 . The bone fastener of claim 15 , wherein the ratio of the major diameter to the minor diameter is less than 1.10.
18 . The bone fastener of claim 15 , wherein the ratio of the major diameter to the minor diameter is less than 1.05.
19 . The bone fastener of claim 15 , wherein at least a portion of the bone fastener is configured to be received with an intramedullary canal of a bone.
20 . The bone fastener of claim 19 , further comprising an attachment feature at the proximal end of the shaft configured to be adjustably secured to an implement.