U.S. patent application number 11/255138 was filed with the patent office on 2007-05-24 for bone fixation assembly.
This patent application is currently assigned to EBI, L.P.. Invention is credited to Moti Altarac, Philip Mellinger, Lenny Schaust.
Application Number | 20070118117 11/255138 |
Document ID | / |
Family ID | 38054477 |
Filed Date | 2007-05-24 |
United States Patent
Application |
20070118117 |
Kind Code |
A1 |
Altarac; Moti ; et
al. |
May 24, 2007 |
Bone fixation assembly
Abstract
A bone fixation assembly and associated method. The bone
fixation assembly includes a bone fastener having a head and a
bone-engaging portion, a receiver defining an opening along a first
axis for receiving the bone fastener at a variable angle, and at
least one supporting augment coupled to the bone fastener. The
receiver has an inner articulation surface at a lower portion of
the opening and matingly articulates with the supporting
augment.
Inventors: |
Altarac; Moti; (Irvine,
CA) ; Schaust; Lenny; (Delano, MN) ;
Mellinger; Philip; (Ladera Ranch, CA) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
EBI, L.P.
|
Family ID: |
38054477 |
Appl. No.: |
11/255138 |
Filed: |
October 20, 2005 |
Current U.S.
Class: |
606/270 |
Current CPC
Class: |
A61B 17/7032 20130101;
A61B 17/7037 20130101 |
Class at
Publication: |
606/061 |
International
Class: |
A61F 2/30 20060101
A61F002/30 |
Claims
1. A bone fixation assembly comprising: a bone fastener having a
head and a bone-engaging portion; a receiver defining an opening
along a first axis for receiving the bone fastener at a variable
angle, the receiver having an inner articulation surface at a lower
portion of the opening; and at least one supporting augment coupled
to the bone fastener and matingly articulable with the articulation
surface of the receiver.
2. The bone fixation assembly of claim 1, wherein the at least one
supporting augment includes two separate supporting augments.
3. The bone fixation assembly of claim 1, wherein the articulation
surface is substantially spherical and wherein the supporting
augment has an outer mating surface that is substantially
spherical.
4. The bone fixation assembly of claim 1, wherein a lower end of
the opening is configured for receiving the head of the bone
fastener therethrough.
5. The bone fixation assembly of claim 4, further comprising a
fastener ring, the fastener ring couplable to the head of the bone
fastener such that the fastener ring can be inserted assembled to
the bone fastener from the lower end of the opening.
6. The bone fixation assembly of claim 5, wherein the fastener ring
is supportable on a groove of the supporting augment.
7. The bone fixation assembly of claim 6, wherein the fastener ring
is a split ring.
8. The bone fixation assembly of claim 6, wherein the supporting
augment is shaped for allowing variable angulation of the
fastener.
9. The bone fixation assembly of claim 2, wherein each supporting
augment includes a notch on an upper surface of the augment.
10. The bone fixation assembly of claim 8, wherein each supporting
augment includes two oppositely inclined end surfaces.
11. The bone fixation assembly of claim 9, wherein each supporting
augment is shaped for partial overlapping about the notch during
assembly.
12. The bone fixation assembly of claim 8, wherein the supporting
augment is further shaped for preventing removal of the fastener
when the ring is coupled to the supporting augment and to the head
of the fastener.
13. The bone fixation assembly of claim 1, further comprising a
fastener cap for coupling the head of the fastener to an inner
surface of the receiver.
14. The bone fixation assembly of claim 13, further comprising a
cap ring for coupling the fastener cap and the receiver.
15. The bone fixation assembly of claim 14, wherein the receiver
defines a channel extending along a second axis generally
perpendicular to the first axis.
16. The bone fixation assembly of claim 15, wherein the channel is
shaped for receiving a fixation rod above the fastener cap.
17. The bone fixation assembly of claim 14, wherein the cap ring is
a split ring.
18. A method for spinal fixation comprising: providing a receiver
defining an opening along a first axis for receiving a bone
fastener at a variable angle, the receiver having an inner
articulation surface at a lower portion of the opening; inserting
the head of the bone fastener into the opening; inserting at least
one supporting augment into the opening, the at least one
supporting augment articulable with the articulation surface;
coupling the at least one supporting augment to the head of the
bone fastener; and varying the angle of the bone fastener relative
to the first axis by articulating the at least one supporting
augment relative to the articulation surface.
19. The method of claim 18, wherein coupling the at least one
augment is performed after inserting the head of the bone fastener
into the opening.
20. The method of claim 18, wherein inserting the head of the bone
fastener into the opening includes inserting the head through a
lower end of the opening.
21. The method of claim 20, wherein coupling the at least one
supporting augment to the head of the bone fastener includes
preventing the head of the bone fastener from withdrawal through
the opening.
22. The method of claim 18, wherein coupling the at least one
supporting augment to the head of the bone fastener includes
coupling a retention member to the at least one supporting augment
and to the head of the bone fastener.
23. The method of claim 20, further comprising inserting a cap
through an upper end of the opening for engaging the head of the
bone fastener.
Description
[0001] Various internal fixation devices are known for correcting
and/or stabilizing malformation or other condition of bones,
including long bones and the spine. Such fixation devices can
include elongated rods affixed with bone screws at desired
orientations relative to the bone or spine. Some known bone
fixation devices utilize poly-axial or multi-axial screws for
adjusting the fixation device at a desired orientation.
[0002] Although the existing fixation devices can be satisfactory
for their intended purposes, there is still a need for modular bone
screw assemblies that can provide variable angle orientation, and
which are easy to assemble.
SUMMARY
[0003] The present teachings provide a bone fixation assembly. The
bone fixation assembly includes a bone fastener having a head and a
bone-engaging portion, a receiver defining an opening along a first
axis for receiving the bone fastener at a variable angle, and at
least one supporting augment coupled to the bone fastener. The
receiver has an inner articulation surface at a lower portion of
the opening and matingly articulates with the supporting
augment.
[0004] The present teachings also provide a method for bone
fixation. The method includes providing a receiver defining an
opening along a first axis for receiving a bone fastener at a
variable angle, inserting the head of the bone fastener into the
opening, and inserting at least one supporting augment into the
opening. The at least one supporting augment is articulable with an
inner articulation surface of the receiver. The method further
includes coupling the at least one supporting augment to the head
of the bone fastener, and varying the angle of the bone fastener
relative to the first axis by articulating the at least one
supporting augment relative to the articulation surface.
[0005] Further areas of applicability of the present invention will
become apparent from the detailed description provided hereinafter.
It should be understood that the detailed description and specific
examples are intended for purposes of illustration only and are not
intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The present invention will become more fully understood from
the detailed description and the accompanying drawings,
wherein:
[0007] FIG. 1 is a side view of a bone fixation assembly according
to the present teachings shown with an elongated fixation
member;
[0008] FIG. 1A is a side view of a bone fixation assembly according
to the present teachings similar to FIG. 1, illustrating a variable
angle orientation;
[0009] FIG. 2 is a sectional view of the bone fixation assembly of
FIG. 1 taken along the axis 2--2 of FIG. 1;
[0010] FIG. 3 is an enlarged view of detail A of FIG. 2 shown
additionally in exploded view;
[0011] FIG. 4 is an enlarged perspective view of a receiver of the
bone fixation assembly of FIG. 3;
[0012] FIG. 5 is an enlarged perspective view of a bone fastener of
the bone fixation assembly of FIG. 3;
[0013] FIG. 6 is an enlarged perspective view of a supporting
augment of the bone fixation assembly of FIG. 3;
[0014] FIG. 7 is an enlarged perspective view of a cap ring of the
bone fixation assembly of FIG. 3;
[0015] FIG. 8 is an enlarged perspective view of a cap of the bone
fixation assembly of FIG. 3;
[0016] FIG. 9 is an enlarged perspective view of a fastener ring of
the bone fixation assembly of FIG. 3; and
[0017] FIG. 10 is an end view of the bone fixation device of FIG.
2.
DESCRIPTION OF VARIOUS ASPECTS
[0018] The following description is merely exemplary in nature and
is in no way intended to limit the invention, its application, or
uses.
[0019] Referring to FIGS. 1, 1A, and 2, an exemplary variable angle
bone fixation assembly 100 is illustrated according to the present
teachings. The bone fixation assembly 100 can include a receiver
102 defining an opening 118 along a first axis "X", and a bone
fastener 104. The bone fastener 104 can be assembled on the
receiver 102 for variable angle angulation relative to the first
axis X on an angulation cone of angle .alpha., as illustrated in
FIG. 1A. The bone fastener 104 can include a head 108 and a
bone-engaging portion 106, which can be shaped as a screw or other
anchor, as shown in FIG. 5. The bone-engaging portion 106 can
include, for example, a plurality of threads 107 and an anchoring
tip 109. The head 108 can include a circumferential exterior groove
111 for engaging a retention member, such as a fastener ring 112,
shown in FIG. 9, as discussed below.
[0020] Referring to FIGS. 3-10, the receiver 102 can include two
substantially parallel arms 126 extending in a direction away from
the fastener 104. The arms define a channel 128 along a second axis
"Y" generally perpendicular to the first axis X. The channel 128
can be shaped to receive an elongated fixation member 130, such as,
for example, a spinal fixation rod or other fixation bar, as shown
in FIG. 1. The interior surface of the arms 126 can include a
thread pattern or other interlocking form 132, such as a
helically-wound interlocking form similar to the one disclosed and
described in U.S. Pat. No. 6,726,689, filed Sep. 2, 2002, the
disclosure of which is incorporated herein by reference. It will be
appreciated that other thread forms can also be used. The
interlocking form 132 can mate with a closure member (not shown)
having a corresponding interlocking form for securing the fixation
member 130 in the receiver 102 such that radial splaying of the
arms 126 can be operatively resisted.
[0021] Referring to FIGS. 3-6, the receiver 102 can include an
articulation surface 120 at a lower portion of the opening 118 and
adjacent a lower end 122 thereof. The articulation surface 120 can
articulate with a corresponding curved exterior surface 124 of one
or more discrete supporting augments 110. The conforming
articulating surfaces 120, 124 can be portions of generally
spherically surfaces or other surfaces that can provide desired
variable angle fixation. Each supporting augment 110 can include a
curved interior surface 125 which can be shaped to conform to at
least a portion of the head 108 of the bone fastener 104. Referring
to FIG. 6, in one aspect, each supporting augment 110 can include
upper and lower substantially planar surfaces 143a, 143b, first and
second oppositely inclined substantially planar end surfaces 140a,
140b, and an upper curved cutout or notch 136 adjacent to first end
surface 140a. The upper surface 143a can define a sharp corner 145b
with the second end surface 140b, and a blunt or rounded corner
145a with the first end surface 140a.
[0022] The supporting augments 110 can be positioned relative to
each other such that upon assembly each of the first and second end
surfaces 140a, 140b of one supporting augment 110 can mate with the
second and first end surfaces 140b, 140a, respectively, of the
other supporting augment 110, thereby completing an annular curved
surface with a 360-degree circumference. The shape of the
supporting augments 110 can be defined for ease of assembly and
angulation during assembly. For example, during assembly, the
supporting augments 110 can be positioned such that the sharp
corner 145b of each supporting augment 110 rides on the notch 136
of the other supporting augment 110, such that the supporting
augments 110 overlap partially, and the overall size/volume of the
resulting configuration is smaller during assembly than the size of
the assembled supporting augments 110.
[0023] Referring to FIGS. 3, 6 and 9, each supporting augment 110
can also include a circumferential interior groove 134 shaped for
partially receiving the fastener ring 112. The fastener ring 112
can be a substantially flat and compliant split ring with an outer
boundary 113 and an inner boundary 115. In assembly, at least a
portion of the outer boundary 113 of the fastener ring 112 can be
engaged with the interior groove 134 of the supporting augment 110.
The inner boundary 115 of the fastener ring 112 can engage the
exterior groove 111 of the head 108 of the bone fastener 104.
[0024] Referring to FIGS. 3, 7, and 8, the bone fixation assembly
100 can also include a cap 116, which can engage an upper portion
of the head 108. The cap 116 can include a circumferential exterior
cap groove 117 for engaging a cap ring 114. The cap ring 114 can be
a compliant split ring and can be positioned in engagement between
the cap groove 117 and an interior groove or slot 119 defined in
the receiver 102. Pressing the cap 116 against the head 108 of the
bone fastener 104 with the fixation member 130 can prevent
angulation of the bone fastener 104 relative to the receiver 102,
thereby retaining the fastener 104 in a fixed orientation.
[0025] The bone fixation assembly 100 can be assembled during or
before the surgical procedure. Generally, the head 108 of the bone
fastener 104 can be inserted first into the opening 118. At least
one supporting augment 110 can be inserted into the opening 118,
and coupled to the head 108 of the bone fastener 104. The angle
.alpha. of the bone fastener 104 relative to the first axis X can
then be varied by articulating the supporting augment 110 relative
to the articulation surface 120.
[0026] In one exemplary aspect, the fastener ring 112 can be
assembled on the exterior groove 1 11 of the head 108 of the bone
fastener 104. The head 108 with the fastener ring 1 12 thereon can
be inserted into the receiver 102 through the lower end 122 of the
opening 118, and can be pushed above its final seating position to
facilitate assembly, as necessary. The supporting augments 110 can
then be inserted from an upper end 123 of the receiver 102 and can
be pushed toward the fastener ring 112 while the bone fastener 104
is pulled down, until the supporting augments 110 engage the
fastener ring 112 and the bone fastener 104 is seated in engagement
with the receiver 102. In this position, the bone fastener 104 can
freely angulate relative to axis X, but can not be removed from the
receiver 102 either through the lower end 122 or through the upper
end 123. For facilitating insertion the supporting augments 110 can
be arranged with partial overlapping therebetween, as discussed
above. In another aspect, the supporting augments 110 can be
inserted into the receiver 102 through the lower end 122 of the
opening 118, and manipulated into engagement with the fastener ring
112.
[0027] The cap 116 with the cap ring 114 can be inserted from the
upper end 123 of the receiver 102 such that the cap ring 114
engages the interior slot 119 of the receiver 102. For a particular
application, such as spinal fixation, a rod or other longitudinal
fixation member 130 can be positioned along the channel 128 and
pressed against the cap 116 with a compression member (not shown).
Pressing the cap 116 against the head 108 with the compression
member secures the bone fastener 104 in a desired orientation.
[0028] It will be appreciated that the modularity and shape of the
various parts of the bone fixation assembly 100 can provide a
compact (non-bulky) bone fixation device, which can be easily
assembled during the surgical procedure, or can also be at least
partially pre-assembled. Furthermore, the bone fixation assembly
100 can be easily configured for accommodating various surgical
situations at the site of operation as desired by the surgeon.
[0029] The fixation assembly can be formed from biocompatible
materials, such as, for example, metallic materials.
[0030] The foregoing discussion discloses and describes merely
exemplary arrangements of the present invention. One skilled in the
art will readily recognize from such discussion, and from the
accompanying drawings and claims, that various changes,
modifications and variations can be made therein without departing
from the spirit and scope of the invention as defined in the
following claims.
* * * * *