U.S. patent application number 11/264958 was filed with the patent office on 2006-05-04 for bone fusion device.
This patent application is currently assigned to McLuen Design, Inc.. Invention is credited to Gary R. McLuen.
Application Number | 20060095136 11/264958 |
Document ID | / |
Family ID | 36263100 |
Filed Date | 2006-05-04 |
United States Patent
Application |
20060095136 |
Kind Code |
A1 |
McLuen; Gary R. |
May 4, 2006 |
Bone fusion device
Abstract
A bone fusion device provides stability to bones during a bone
fusion period. The bones include, for example, the vertebrae of a
spinal column. The bone fusion device comprises one or more
extendable tabs attached to the bone fusion device by associated
rotating means. The bone fusion device is preferably inserted by
using an arthroscopic surgical procedure. During arthroscopic
insertion of the device, the tabs are pre-configured for
compactness. In this compact configuration, the tabs are preferably
deposed along and/or within an exterior surface of the bone fusion
device. After the bone fusion device has been positioned between
the bones, one or more tab(s) are extended. In some embodiments,
the position of each tab relative to the bone fusion device is
adjustable. Typically, the tabs advantageously position and brace
the bone fusion device in the confined space between the bones
until the bones have fused.
Inventors: |
McLuen; Gary R.; (Port
Townsend, WA) |
Correspondence
Address: |
HAVERSTOCK & OWENS LLP
162 NORTH WOLFE ROAD
SUNNYVALE
CA
94086
US
|
Assignee: |
McLuen Design, Inc.
|
Family ID: |
36263100 |
Appl. No.: |
11/264958 |
Filed: |
November 1, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60624836 |
Nov 3, 2004 |
|
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Current U.S.
Class: |
623/23.47 ;
623/17.11; 623/23.5 |
Current CPC
Class: |
A61F 2002/30411
20130101; A61F 2002/30904 20130101; A61F 2002/3092 20130101; A61F
2002/2835 20130101; A61F 2002/30579 20130101; A61F 2/4455 20130101;
A61F 2002/30492 20130101; A61F 2002/30556 20130101; A61F 2002/30525
20130101; A61F 2/446 20130101; A61F 2002/30538 20130101; A61F
2002/3085 20130101; A61F 2310/00023 20130101; A61F 2/447 20130101;
A61F 2002/2817 20130101; A61F 2250/0009 20130101; A61F 2002/30841
20130101; A61F 2220/0025 20130101; A61F 2310/00976 20130101; A61F
2002/30507 20130101; A61F 2002/30784 20130101; A61F 2250/0006
20130101 |
Class at
Publication: |
623/023.47 ;
623/023.5; 623/017.11 |
International
Class: |
A61F 2/28 20060101
A61F002/28; A61F 2/44 20060101 A61F002/44 |
Claims
1. A bone fusion device for insertion between bones comprising:
first and second ends; an interior cavity deposed between the first
and second ends; an exterior surface; a conduit providing a pathway
from the interior cavity to the exterior surface; and one or more
tabs for bracing the bone fusion device in a space between the
bones, wherein the one or more tabs comprise an adjustable
element.
2. The bone fusion device of claim 1, wherein the adjustable
element is collapsible to a compact position deposed within the
exterior surface such that the bone fusion device has a minimized
form factor.
3. The bone fusion device of claim 1, wherein the adjustable
element is configured for a plurality of positions.
4. The bond fusion device of claim 1, wherein the adjustable
element has a range of motion that is greater than 90 degrees with
respect to the exterior surface of the bone fusion device.
5. The bone fusion device of claim 1, wherein the adjustable
element is configured for a position slightly more than 90 degrees
with respect to the exterior surface.
6. The bone fusion device of claim 1, wherein the adjustable
element comprises an independent extendable tab, wherein the
independent extendable tab is separately configured.
7. The bone fusion device of claim 1, further comprising a bone
graft material pre-deposited into the interior cavity before
insertion of the bone fusion device between the bones.
8. The bone fusion device of claim 1, further comprising a lead
screw driven into the interior cavity, wherein driving the lead
screw into the interior cavity relocates a bone growth material
from the interior cavity to the exterior surface.
9. The bone fusion device of claim 1, further comprising a worm
screw drive mechanism such that driving a lead screw into the
interior cavity modifies the configuration for a tab among the one
or more tabs.
10. The bone fusion device of claim 1, further comprising a bone
graft material that is applied after placement of the bone fusion
device between the bones.
11. The bone fusion device of claim 1, further comprising one or
more protrusions configured for engaging the bones.
12. The bone fusion device of claim 1, further comprising a
cylinder.
13. The bone fusion device of claim 1, further comprising a
rectangular shape.
14. The bone fusion device of claim 1, wherein a material of the
bone fusion device is biocompatible.
15. The bone fusion device of claim 1, wherein the bone fusion
device is configured for insertion by using an arthroscopic
procedure.
16. The bone fusion device of claim 1, wherein the bones comprise
vertebral bones.
17. A bone fusion device for insertion between adjacent bones,
comprising: a. a hollow body having one or more holes along a
length of the body; and b. one or more extendable tabs each
attached to the hollow body by a screw, wherein the one or more
extendable tabs are aligned along a surface of the hollow body in a
compact position during insertion into a patient.
18. The bone fusion device of claim 16, wherein the one or more
tabs are individually adjustable to a desired position after
insertion for bracing the bone fusion device between the adjacent
bones.
19. The bone fusion device of claim 18, wherein the tabs are
adjusted by a rotation of the screw.
20. The bone fusion device as claimed in claim 15, wherein an
extendable tab is deposed to lie within the exterior surface of the
bone fusion device such that the bone fusion device has a small
form factor.
21. The bone fusion device as claimed in claim 15, wherein an
extendable tab is attached to the hollow body on an end face.
22. The bone fusion device as claimed in claim 15, wherein the
bones comprise vertebrae, wherein a material of the bone fusion
device is biocompatible.
23. The bone fusion device as claimed in claim 15, wherein bone
graft material is present within the hollow body before insertion
between the bones.
24. The bone fusion device as claimed in claim 15, wherein bone
graft material is applied after insertion and placement between the
bones.
25. The bone fusion device as claimed in claim 15, wherein an
extendable tab has a sharp protrusion configured to engage the
adjacent bones.
26. The bone fusion device as claimed in claim 15, wherein an
extendable tab has threading configured to engage the adjacent
bones.
27. The bone fusion device as claimed in claim 15, wherein an
extendable tab has a textured surface.
28. The bone fusion device as claimed in claim 15, wherein an
extendable tab is coated with a porous material.
29. A method of implanting a bone fusion device between bones, the
method comprising: inserting the bone fusion device between the
bones, wherein the bone fusion device comprises an internal cavity,
an exterior surface, and an extendable tab, wherein the extendable
tab comprises an associated rotating element; pre-configuring the
extendable tab to lie within the exterior surface by using the
rotating element such that the bone fusion device has a minimized
form factor; driving a lead screw into the cavity; and extending
the tab to a desired position by using the rotating element.
30. The method of claim 28, further comprising selecting the
tab.
31. The method of claim 28, wherein extending the tab comprises
turning the rotating element associated with the tab to elevate the
tab.
32. The method of claim 28, wherein the bone fusion device
comprises a worm screw drive mechanism such that driving the lead
screw into the cavity past a predetermine point elevates the tab by
using the rotating element.
33. The method of claim 28, wherein the desired position comprises
an angle of slightly greater than approximately 90 degrees with
respect to an exterior surface of the bone fusion device.
34. The method of claim 28, further comprising before implantation,
depositing a bone graft material into the cavity.
35. The method of claim 28, further comprising applying bone growth
material to the tab after extension, wherein the bone growth
material stimulates regeneration of bone cells in the bones.
36. The method of claim 28, wherein driving the lead screw
relocates a bone graft material from the interior to the exterior
of the bone fusion device.
37. The method of claim 28, wherein the bones comprise
vertebrae.
38. The method of claim 28, wherein inserting the bone fusion
device comprises an arthroscopic procedure.
Description
RELATED APPLICATIONS
[0001] This patent application claims priority under 35 U.S.C.
.sctn. 119(e) of the co-pending U.S. Provisional Patent
Application, Ser. No. 60/624,836, filed Nov. 03, 2004, and entitled
"BONE FUSION DEVICE," which is hereby incorporated by reference in
its entirety.
FIELD OF THE INVENTION
[0002] This invention relates generally to bone fusion devices.
More specifically, the present invention relates to devices for
fusing vertebrae of the spine that can be inserted
arthroscopically.
BACKGROUND OF THE INVENTION
[0003] The spinal column is made up of vertebrae stacked on top of
one another. Between the vertebrae are discs which are gel-like
cushions that act as shock-absorbers and keep the spine flexible.
Injury, disease, or excessive pressure on the discs can cause
degenerative disc disease or other disorders where the disc becomes
thinner and allows the vertebrae to move closer together or become
misaligned. As a result, nerves may become pinched, causing pain
that radiates into other parts of the body, or instability of the
vertebrae may ensue.
[0004] One method for correcting disc-related disorders is to
insert a fusion cage between the vertebrae to act as a structural
replacement for the deteriorated disc. The fusion cage is typically
a hollow metal device usually made of titanium. Once inserted, the
fusion cage maintains the proper separation between the vertebrae
to prevent nerves from being pinched and provides structural
stability to the spine. Also, the inside of the cage is filled with
bone graft material which eventually fuses permanently with the
adjacent vertebrae into a single unit.
[0005] The use of fusion cages for fusion and stabilization of
vertebrae in the spine is known in the prior art. U.S. Pat. No.
4,961,740 to Ray, et al. entitled, "V-Thread Fusion Cage and Method
of Fusing a Bone Joint," discloses a fusion cage with a threaded
outer surface, where the crown of the thread is sharp and cuts into
the bone. Perforations are provided in valleys between adjacent
turns of the thread. The cage can be screwed into a threaded bore
provided in the bone structure at the surgical site and then packed
with bone chips which promote fusion.
[0006] U.S. Pat. No. 5,015,247 to Michelson entitled, "Threaded
Spinal Implant," discloses a fusion implant comprising a
cylindrical member having a series of threads on the exterior of
the cylindrical member for engaging the vertebrae to maintain the
implant in place and a plurality of openings in the cylindrical
surface.
[0007] U.S. Pat. No. 6,342,074 to Simpson entitled, "Anterior
Lumbar Underbody Fusion Implant and Method For Fusing Adjacent
Vertebrae," discloses a one-piece spinal fusion implant comprising
a hollow body having an access passage for insertion of bone graft
material into the intervertebral space after the implant has been
affixed to adjacent vertebrae. The implant provides a pair of
screw-receiving passages that are oppositely inclined relative to a
central plane. In one embodiment, the screw-receiving passages
enable the head of an orthopaedic screw to be retained entirely
within the access passage.
[0008] U.S. Pat. No. 5,885,287 to Bagby entitled, "Self-tapping
Interbody Bone Implant," discloses a bone joining implant with a
rigid, implantable base body having an outer surface with at least
one bone bed engaging portion configured for engaging between a
pair of bone bodies to be joined, wherein at least one spline is
provided by the bone bed engaging portion, the spline being
constructed and arranged to extend outwardly of the body and having
an undercut portion.
[0009] U.S. Pat. No. 6,582,467 to Teitelbaum et al.
entitled,"Expandable Fusion Cage," discloses an expandable fusion
cage where the surfaces of the cage have multiple portions cut out
of the metal to form sharp barbs. As the cage is expanded, the
sharp barbs protrude into the subcortical bone of the vertebrae to
secure the cage in place. The cage is filled with bone or bone
matrix material.
[0010] U.S. Pat. No. 5,800,550 to Sertich entitled, "Interbody
Fusion Cage," discloses a prosthetic device which includes an inert
generally rectangularly shaped support body adapted to be seated on
hard end plates of vertebrae. The support body has top and bottom
faces. A first peg is movably mounted in a first aperture located
in the support body, and the first aperture terminates at one of
the top and bottom faces of the support body. Further, the first
peg projects away from the one of the top and bottom faces and into
an adjacent vertebra to secure the support body in place relative
to the vertebra.
[0011] U.S. Pat. No. 6,436,140 to Liu et al. entitled, "Expandable
Interbody Fusion Cage and Method for Insertion," discloses an
expandable hollow interbody fusion device, wherein the body is
divided into a number of branches connected to one another at a
fixed end and separated at an expandable end. The expandable cage
may be inserted in its substantially cylindrical form and may be
expanded by movement of an expansion member to establish lordosis
of the spine. An expansion member interacts with the interior
surfaces of the device to maintain the cage in the expanded
condition and provide a large internal chamber for receiving bone
in-growth material.
[0012] These patents all disclose fusion cage devices that can be
inserted between vertebrae of the spine in an invasive surgical
procedure. Such an invasive surgical procedure requires a long
recovery period.
SUMMARY OF THE INVENTION
[0013] The present invention is a bone fusion device for insertion
between bones that are to be fused together, such as, for example,
the vertebrae of a spinal column. The bone fusion device comprises
one or more extendable tabs. The bone fusion device is in its most
compact state when the tabs are aligned with the body of the device
such that the tabs lie within the exterior of the device. In this
compact form, the bone fusion device is preferably inserted between
the vertebrae by using an arthroscopic procedure. The bone fusion
device of some embodiments is filled with bone graft material. In
these embodiments, the bone graft material is typically relocated
from the interior to the exterior of the bone fusion device by
using a lead screw. After the device has been positioned between
the vertebrae, and the lead screw is inserted to optionally deliver
the bone graft material, selected tabs are extended. Each tab
typically has an associated rotating means. The position of each
tab relative to the bone fusion device is adjustable depending upon
the configuration of the associated rotating means. In this way,
the tabs are advantageously positioned in the confined space
between the vertebrae to help brace the device until the bone has
fused. Further, the tabs of the bone fusion device provide a larger
surface area to which the bones attach and fuse during a healing
period.
[0014] According to an embodiment of the present invention, the
body of the bone fusion device is a round cylinder with end faces.
The bone fusion device has conduits or holes that allow the bone
graft material within the device to flow to the exterior of the
device where the material contacts and grafts to the vertebrae. The
extendable tabs are arranged in various configurations on the
exterior of the bone fusion device, including the end faces.
Preferably, the tabs are attached to the body of the device on more
than one side to optimally brace the device from multiple
directions between the adjacent vertebrae. Alternatively, the bone
fusion device has a rectangular shape with end faces and extendable
tabs attached to multiple exterior surfaces.
[0015] Optionally, the bone fusion device of some embodiments
includes protrusions, threading, and/or sharp features on the
exterior surface and/or the extendable tabs. These features are
configured to engage the adjacent vertebrae to provide a tighter
interface between the device and the vertebrae.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 illustrates a bone fusion device in accordance with
some embodiments of the invention.
[0017] FIG. 2 illustrates a bone fusion device according to an
alternative embodiment of the present invention.
[0018] FIGS. 3A-B illustrate a section of a vertebral column
showing the bone fusion device inserted between two adjacent
vertebrae in place of an intervertebral disc.
[0019] FIGS. 4A-B illustrate a detailed view of the worm screw
drive and the extendable tabs of some embodiments.
[0020] FIGS. 5A-B illustrate the small form factor of some
embodiments.
[0021] FIGS. 6A-B illustrate a cross section view of the small form
factor of some embodiments.
[0022] FIGS. 7A-B are perspective drawings illustrating the tabs
and tab bays of some embodiments.
[0023] FIG. 8 illustrates a process flow in accordance with some
embodiments of the invention.
DETAILED DESCRIPTION
[0024] In the following description, numerous details and
alternatives are set forth for purpose of explanation. However, one
of ordinary skill in the art will realize that the invention can be
practiced without the use of these specific details. For instance,
the figures and description below often refer to the vertebral
bones of a spinal column. However, one of ordinary skill in the art
will recognize that some embodiments of the invention are practiced
for the fusion of other bones, including broken bones and/or
joints. In other instances, well-known structures and devices are
shown in block diagram form in order not to obscure the description
of the invention with unnecessary detail.
[0025] FIG. 1 illustrates a bone fusion device 100 in accordance
with some embodiments of the invention. As shown in this figure,
the bone fusion device 100 has a round cylindrical shape and has
two end faces, including the end face 140. The bone fusion device
100 is preferably constructed from a high strength biocompatible
material, such as titanium, which has the strength to withstand
compressive and shear forces in the spine that are generated by a
patient's body weight and daily movements. The base biocompatible
material is often textured or coated with a porous material
conducive to the growth of new bone cells on the bone fusion device
100.
[0026] Also shown in FIG. 1, the end face 140 has an opening 145
which allows the insertion of bone graft material into the bone
fusion device 100. The bone graft material includes bone chips from
the same patient (autograft), bone chips from a donor (allograft or
xenograft), and/or a synthetic bone matrix. The bone graft material
typically promotes bone growth during a recovery period after the
patient receives bone fusion surgery. As further illustrated in
FIG. 1, the bone fusion device 100 has several conduits or holes
150, which permit the bone graft material to contact the vertebral
bone after the device 100 has been inserted between the vertebrae
of the patient. The bone graft material and the surface texturing
of the device 100 encourage the growth and fusion of bone from the
neighboring vertebrae. The fusion and healing process will result
in the bone fusion device 100 becoming embedded within the two
adjacent vertebrae of the spine which eventually fuse together
during the healing period.
[0027] As further illustrated in FIG. 1, several tabs 131, 132,
133, 134, 135, and 136 are distributed along the round cylindrical
body of the bone fusion device 100. These tabs 131-136 are each
attached to the bone fusion device 100 by a respective rotating
means 111, 112, 113, 114, 115, and 116. The rotating means 111-116
is typically a turn screw type assembly. When the bone fusion
device 100 is inserted into the patient's body, the tabs 131-136
lie along the body of the device 100, as shown by the dotted
outlines 121-126 of the tabs. Thus, the unextended tabs 121-126 of
the bone fusion device 100 provide a compact assembly that is
suitable for insertion into the patient's body through an
arthroscopic surgical procedure. An arthroscopic procedure is
considered minimally invasive and has certain advantages over more
invasive conventional surgical procedures. In an arthroscopic
procedure, a smaller surgical incision is employed as compared to
the size of the incision required for conventional invasive
surgery. Moreover, arthroscopic procedures minimize or eliminate
the need for excessive retraction of a patient's tissues such as
muscles and nerves, thereby minimizing trauma and injury to the
muscles and nerves and further reducing the patient's recovery
time.
[0028] After insertion of the device 100 into the space between the
patient's vertebrae, the surgeon selectively extends particular
tabs 131-136 by rotating each selected tab's respective rotating
means 111-116. The more each rotating means 111-116 is rotated, the
farther its respective tab 131-136 elevates and extends outward
from its initial position 121-126 along the body of the device 100.
Each tab's 131-136 position is individually adjustable so as to
optimally brace the device 100 between the vertebrae. Due to the
compressive forces commonly associated with spinal column
vertebrae, some embodiments include a range of motion for each tab
that is slightly greater than 90 degrees. It was particularly
discovered during the reduction to practice of the present
invention, that the tabs of these embodiments are preferably
rotated to an angle that is slightly more than about 90 degrees
with respect to the surface of the bone fusion device. The tabs
extended in this configuration were found to be capable of
withstanding the greatest amount of compressive force.
[0029] Preferably, the tabs 131-136, when extended, abut tightly
against the surfaces of the vertebrae that are immediately adjacent
to the bone fusion device 100. In some embodiments, the tabs
131-136 have sharp protrusions along the length of the tab for
engaging the adjacent vertebrae, while the tabs 131-136 of some
embodiments have screw-type threads for screwing into and engaging
the vertebrae. Optionally, the tabs of some embodiments have
surface texturing to encourage and enhance the growth of new bone
on the tabs 131-136. This surface texturing is often similar to the
surface texturing used on the main body of the device 100.
Regardless of their texturing and/or particular physical
characteristics, the tabs 131-136 advantageously wedge the bone
fusion device 100 in a fixed position between the vertebrae and
provide a larger surface area with which the adjacent vertebrae
fuses during the healing period. Moreover, bone growth material,
such as protein, is typically applied to the tabs 131-136 to
stimulate the regeneration of bone cells needed for bone fusion.
The application of bone growth material is described further in
relation to FIG. 4.
[0030] In an alternative embodiment of the invention, the tabs of
the device 100 have sharp ridges or threads which bite into the
adjacent vertebrae, further helping to brace the device between the
vertebrae. It will be readily apparent to one skilled in the art
that there are a number of variations for the body and the tabs
131-136 of the bone fusion device 100. For instance, the bone
fusion device 100 employs different numbers and/or configurations
of tabs in different embodiments. Hence, the tabs 131-136 depicted
in FIG. 1 are merely exemplary. Moreover, the tabs 131-136 are
located anywhere over the exterior surface of the bone fusion
device 100, in a variety of orientations. Specifically, the tabs
131-136 are preferably arranged such that when they are extended,
the tabs 131-136 act to stabilize the bone fusion device 100
against the vertebrae from several points and directions.
Typically, the tighter the bone fusion device 100 is wedged between
the adjacent vertebrae by the tabs 131-136, the more stability the
device 100 provides to the vertebrae and the spine of the patient.
The tabs 131-136 of the embodiments described above are critical to
insure that the device 100 is not dislodged, since movement of the
device 100 could cause serious injury to the patient, and
especially because the inserted device is situated near the
patient's spinal cord.
[0031] FIG. 2 shows an alternative embodiment of the bone fusion
device 200. As shown in this figure, the bone fusion device 200 of
some embodiments has a rectangular shape. Similar to the round
cylindrical shaped bone fusion device 100 shown in FIG. 1, the
rectangular bone fusion device 200 has two end faces, including the
end face 245 visible in FIG. 2, and multiple tabs 211, 212, 213,
214, 215, 216, 217, and 218 that are attached by rotating means to
the exterior surface. The rotating means are screw type assemblies
in some embodiments. The tabs 211-218 are also selectively extended
after insertion of the bone fusion device 200 between the
vertebrae. As before, the insertion of the bone fusion device 200
and the extension of the selected tabs 211-218, are typically
performed by a surgeon during an arthroscopic surgical procedure.
The procedure of some embodiments is further described in relation
to FIG. 8. The rotation of a respective rotating means associated
with each tab 211-218, individually adjusts the position of the
associated tab 211-218 such that the device 200 is firmly braced
between the two adjacent vertebrae. One skilled in the art will
recognize that the tabs 211-218 are distributed over the exterior
surfaces of the bone fusion device 200 in a variety of
configurations, which include the ends and the surfaces of the
device 200 that are not readily visible in FIG. 2. Moreover, as
mentioned above, different numbers of tabs 211-218 are distributed
over each surface of the bone fusion device 200 of different
embodiments. In some embodiments, the surfaces of the bone fusion
device 200 and/or the tabs 211-218, are coated with a porous
surface texturing which promotes bone growth.
[0032] Preferably, the end face 245 has an opening 240, which
provides access to a cavity within the interior of the bone fusion
device 200. In some embodiments, bone graft materials, such as the
bone chips and/or the synthetic bone matrix that were mentioned
above, are pre-loaded into the cavity within the bone fusion device
200 through the opening 240. Several conduits or holes 250 in the
bone fusion device 200 permit the bone graft material to flow from
the interior cavity to the exterior surfaces of the device 200 that
are in contact with the vertebral bone. Typically, the bone graft
material is relocated from the interior cavity to the exterior of
the bone fusion device 200, after the device 200 has been
positioned between the vertebrae. However, in some embodiments the
bone graft material is delivered to the site of the bone fusion
device 200 by arthroscopic means that originate external to the
device 200. Regardless of the delivery means, the bone graft
material and the surface texturing of the bone fusion device 200
encourage bone growth and fusion with the adjacent vertebrae that
are in contact with the device 200. As bone fusion and healing
progresses, the bone fusion device 200 preferably becomes embedded
within the two fused vertebrae of the spine.
[0033] FIG. 3A illustrates a section of a vertebral column that has
a bone fusion device 300 positioned between two vertebrae 330 and
335. As shown in this figure, the bone fusion device 300 is
positioned in a location where an intervertebral disc would
normally reside. A flexible disc is typically sandwiched between
the two vertebrae of a normal healthy spinal column. For instance,
the normal, healthy disc 340 is sandwiched between the vertebrae
337 and 330. However, for the spinal column illustrated in FIG. 3,
the intervertebral disc that normally resides between the vertebrae
330 and 335 has been excised and surgical insertion of the bone
fusion device 300 has replaced the disc as the supporting structure
between the vertebrae 330 and 335.
[0034] FIG. 3A further illustrates that the damaged disc that is
normally sandwiched between vertebrae 330 and 335 has been totally
removed. However, complete removal of the disc is not necessary in
order to use the bone fusion device 300 of some embodiments.
Typically, only as much of the disc needs to be excised as is
required to permit the placement and positioning of the bone fusion
device 300. Additionally, a sufficient amount of the disc is
typically removed that allows access to the rotating means 311,
312, 313, and 314, which control the extension of the tabs 321,
322, 323, and 324, of the bone fusion device 300. As mentioned
above, additional numbers and configurations of the tabs are
distributed over the exterior surfaces of the bone fusion device
300, including the surfaces that are not visible in FIG. 3A.
[0035] Preferably, during the insertion and placement of the bone
fusion device 300, the tabs 321-324 are deposed in a position
aligned along the body of the bone fusion device 300, such that the
tabs 321-324 lie substantially within the exterior surfaces of the
device 300. In some embodiments, the tabs 321-324 are flush with
the exterior surface. In these embodiments, the form factor of the
bone fusion device 300 is configured to be as compact as possible.
For instance, the form factor of some embodiments has a diameter of
approximately 0.28 inches and a length of approximately 1.0 inch.
In contrast, the form factor of these same embodiments has a
diameter of approximately 0.48 inches when the tabs 321-324 are
fully extended.
[0036] By minimizing the space occupied, the bone fusion device 300
is advantageously inserted arthroscopically into the patient's
body. If instead, the device 300 were inserted in its fully
extended form, a larger surgical incision would be required, and a
greater displacement of the muscles and nerves would be needed.
However, its compact form factor allows the bone fusion device 300
to be inserted by advantageously utilizing minimally invasive
arthroscopic techniques. Then, the tabs 321-324 of the bone fusion
device 300 are extended after arthroscopic insertion to optimally
increase the form factor and brace the device 300 between the
vertebrae 330 and 335. In some embodiments, selected tabs 321-324
are extended.
[0037] While the particular embodiment described above has a
rectangular shape, it will be readily apparent to one skilled in
the art that the cross-section of the bone fusion device 300 has
different shapes in various embodiments. For instance, a more
circular bone fusion device such as the device 100 illustrated in
FIG. 1, or a device having another shape is employed in conjunction
with a set of extendable tabs that are located in various
configurations in additional embodiments of the invention. For
instance, some embodiments have four rows of tabs, where each row
is positioned on a side of the bone fusion device. In some of these
embodiments, each row preferably has four tabs. Such an embodiment
is further described in relation to FIG. 7 and is illustrated in
its inserted form in FIG. 3B. As shown in FIG. 3B, a first set of
four tabs 311-314 lock the bone fusion device 300 against the
vertebra 330, while a second set of tabs 315-318 lock the bone
fusion device 300 against the vertebra 335.
[0038] FIG. 4A illustrates the bone fusion device 400 of some
embodiments in further detail. As shown in this figure, the bone
fusion device 400 includes an interior cavity 405 for the insertion
of a lead screw 415, and one or more tabs 431 each deposed in a tab
bay 421, 422, 423, 424.
[0039] The tab bays 421-424 allow the tabs 431 to lie flush and/or
within the exterior surface 420 of the bone fusion device 400 when
not extended. Also when not extended, the tab 431 and tab bay 421
provides a conduit 450 from the interior cavity 405 to the exterior
surface 420 of the bone fusion device 400, such that the bone graft
and/or growth material within the interior cavity 405 has a
directed path to the exterior surface 420. Typically, the insertion
of the lead screw 415 forces the material within the interior
cavity 405 to relocate to the exterior surface 420.
[0040] The tab 431 includes a rotating means 411 and gear teeth
455. When the tab 431 is not extended, the gear teeth 455 provide a
series of passive grooves by which the lead screw 415 traverses the
interior cavity 405. Typically, the tab 431 remains fixed as the
lead screw 415 is screwed into the interior cavity 405. In these
embodiments, the threading of the lead screw 415 does not address
or affect the gear teeth 455 during the insertion of the lead screw
415.
[0041] However, the gear teeth 455 do employ the threading of the
lead screw 415 when the lead screw 415 has been fully inserted into
the cavity 405, in some embodiments. For instance, in a particular
implementation of the invention, the lead screw 415 is driven into
the cavity 405, until it reaches an endcap 406. The endcap 406
allows the lead screw 415 to continue rotating in place, but does
not allow the lead screw 415 to continue its forward progress
through the cavity 405. When the lead screw 415 of these
embodiments rotates without making forward progress, the rotating
lead screw's threading contacts and engages the gear teeth 455 of
each tab 431. Accordingly, the motion and angle of the spiraling
threads, when applied against the gear teeth 455, causes the tabs
431 to elevate and extend. The combination of the gear teeth 455 on
the tabs 431 and the inserted lead screw 415, is referred to, in
some embodiments, as a worm screw drive mechanism.
[0042] In an alternative embodiment of the worm screw drive
mechanism, the rotating means 411 is turned to raise the tab 431.
In these embodiments, the rotating means 411 for the tab 431
typically comprises a turn screw type mechanism such that when the
rotating means 411 is turned, the gear teeth 455 drive or rotate
against the stationary threads of the inserted lead screw 415.
Similarly, due to the angle of the stationary lead screw's spiral
threads, the gear teeth 455 cause the tab 431 to elevate and extend
above the exterior surface 420 of the bone fusion device 400.
[0043] As mentioned above, the tabs 431 of some embodiments have a
range of motion that exceeds 90 degrees with respect to the
exterior surface 420 of the bone fusion device 400. Accordingly,
FIG. 4B illustrates the tab 431 extended slightly past 90 degrees,
which is the optimum position to withstand the compressive force
exerted on the vertebrae of some embodiments.
[0044] FIG. 5A illustrates a closed view of the small form factor
for a bone fusion device 500 in accordance with some embodiments.
As shown in this figure, the bone fusion device 500 has a tab 531
that is not extended and lies within the exterior surface of the
device 500. In contrast, FIG. 5B illustrates the form factor for
the bone fusion device 500 with the tab 531 extended, as described
above. Similarly, FIG. 6A illustrates a cross section view of the
bone fusion device 600 having a small form factor, while FIG. 6B
illustrates the cross section view with the tab 631 extended.
[0045] FIG. 7A is a perspective drawing illustrating the bone
fusion device 700 with four tab bays on four opposite sides of the
device 700, according to some embodiments of the invention. As
described above, a tab is deposed in each tab bay and secured by a
rotating means. For instance, the tab 731 is deposed in the tab bay
721 and secured by the rotating means 711. Also shown in FIG. 7A, a
lead screw 715 is preferably driven into the cavity. As described
above, the lead screw 715 provides the thread by which the gear
teeth 755 elevate the tabs 731-733. Accordingly, FIG. 7B
illustrates the bone fusion device 700 with the tabs 731-733
elevated.
[0046] FIG. 8 is a process flow diagram that summarizes the
insertion and use of the bone fusion device according to some
embodiments. As shown in this figure, the process 800 begins at the
step 805 where a small, minimally invasive surgical incision is
performed. The small incision is typically only large enough to
permit entry of an arthroscopic surgical tool. Then, the process
800 transitions to the step 810, where the bone fusion device is
inserted through the small incision and delivered to a region
between two vertebrae that are to be fused together. Insertion and
delivery of the bone fusion device are preferably performed by
using arthroscopic tool(s).
[0047] At the step 815, the bone fusion device is positioned in the
region where bone fusion is to occur, also typically by using one
or more arthroscopic tool(s). Once the bone fusion device is
positioned in the region between the two vertebrae, the process 800
transitions to the step 820, where the lead screw is inserted and
driven into the bone fusion device. The lead screw is typically
driven into a cavity in the center of the bone fusion device.
Preferably, the cavity contains a bone growth material comprising
collagen and/or a matrix for the promotion of bone growth.
Accordingly, insertion of the lead screw into the cavity causes the
bone growth material to be relocated from the interior cavity to
the exterior surface of the bone growth device. The bone fusion
device of some embodiments has a particular pattern of conduits or
pores that extend from the interior cavity to the exterior surface
for facilitating the relocation of bone growth material to
particular locations at the exterior of the device. For instance,
some embodiments have pores that facilitate the relocation of bone
growth material to particular tabs.
[0048] At the step 825 of the FIG. 8, the tabs are selectively
extended to lock the bone fusion device in place in the region
between the two vertebrae. The tabs of some embodiments are
extended by using the worm screw drive mechanism described above in
relation to FIG. 4. Once the selected tabs are extended and the
bone fusion device is secured in place at the step 825, the
surgical tools are removed from the patient, and the small incision
is sutured. Then, the process 800 concludes.
[0049] As mentioned above, the small incision and minimally
invasive (arthroscopic) surgical procedure advantageously promote
health and rapid recovery by the patient. Preferably, bone growth
occurs around the bone fusion device and particularly at the
locations of the extended tabs, such that the bone fusion device is
further secured by the bone growth, which further promotes a
superior, robust bone fusion result.
[0050] The present invention has been described in terms of
specific embodiments incorporating details to facilitate the
understanding of principles of construction and operation of the
invention. Such reference herein to specific embodiments and
details thereof is not intended to limit the scope of the claims
appended hereto. It will be apparent to those skilled in the art
that modification may be made in the embodiments chosen for
illustration without departing from the spirit and scope of the
invention.
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