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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains to a spinal stabilization surgical procedure. More
particularly, this invention pertains to a method for implanting a fusion
spinal implant between two vertebrae.
2. Description of the Prior Art
Chronic back problems cause pain and disability for a large segment of the
population. In many cases, the chronic back problems are attributed to
relative movement between vertebrae in the spine.
Orthopaedic surgery includes procedures to stabilize vertebrae. Common
stabilization techniques include fusing the vertebrae together.
Fusion techniques include removing disc material which separates the
vertebrae and impacting bone into the disc area. The impacted bone fuses
with the bone material of the vertebrae to thereby fuse the two vertebrae
together.
As in any surgical technique, it is desirable in back surgery to provide a
procedure which permits rapid post-operative recovery. To this end and to
increase the probability of a successful fusion, spinal implants have been
developed. An example of such a spinal implant is shown in commonly
assigned and co-pending U.S. patent application Ser. No. 07/702,351 filed
May 15, 1991 (claiming priority to Jul. 6, 1989). That patent application
teaches a threaded spinal implant which includes a hollow cylinder into
which bone chips or bone slurry may be placed. The cylinder has holes
extending radially therethrough. The bone material grows through the holes
to fuse with the bone material of the vertebrae.
A threaded spinal implant is also shown in U.S. Pat. No. 5,015,247, dated
May 14, 1991. In addition to teaching a threaded spinal implant, U.S. Pat.
No. 5,015,247 shows a method of implantation including certain tools to
form a bore into which the implant is threaded.
A threaded fusion cage and a method of inserting such a cage is also shown
in U.S. Pat. No. 4,961,740 to Ray et al. dated Oct. 9, 1990 as well as
U.S. Pat. No. 5,026,373 to Ray et al. dated Jun. 25, 1991. The latter
patent teaches preparing a bore for the implant by drilling over a pilot
rod. In addition to the above, spinal implants are shown in U.S. Pat. No.
4,875,915 to Brantigan dated Nov. 7, 1989, German Patent 3505567A1 dated
Jun. 5, 1986 to Vich, U.S. Pat. No. 4,834,757 to Brantigan dated May 30,
1989 and U.S. Pat. No. 4,507,269 to Bagby dated Feb. 27, 1985. The latter
is not a threaded implant but uses a cage or basket which is impacted into
a bore formed between bone to be fused.
When performing back surgery (such as placing implants in a spine) it is
desirable that the surgical procedure be performed as quickly and as
accurately as possible. Accordingly it is an object of the present
invention to provide a surgical procedure for placing an implant in a
spine in a procedure which can be done quickly and accurately.
In addition to the foregoing, it is known to be desirable to place two
implants between opposing vertebrae (although a single implant procedure
may be advisable in some circumstances). In a two implant procedure, bores
are formed on opposite sides of the vertebrae to receive each of the
implants. I have found that in such a procedure, the forming of the bores
can cause misalignment of the vertebrae which is undesirable. Also, prior
art techniques (e.g., drilling over a guide rod) can result in a bore
which does not cut equally into both vertebrae. Accordingly, it is a
further object of the present invention to provide a surgical implant
procedure which assures accurate alignment of the vertebrae throughout the
procedure.
Furthermore, it is an object of the present invention to provide a surgical
procedure that can be performed posteriorly, anteriorly or as a
laparoscopic procedure.
SUMMARY OF THE INVENTION
A surgical method for implanting at least two spinal fusion implants into a
disc space of a disc material which separates two vertebrae is disclosed.
The surgical method includes the steps of distracting one side of the disc
space with a spacer and forming an implant receiving bore in an opposite
of the disc space. After implanting the implant into the opposite side,
the spacer is removed and a bore receiving implant is formed to receive a
second implant.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation view of an implant for use with the method of
the present invention;
FIG. 2 is the view of the implant of FIG. 1 with the implant rotated
90.degree. about its axis;
FIG. 3 is a view taken along line 3--3 of FIG. 1;
FIG. 4 is a view taken along lines 4--4 of FIG. 3;
FIG. 5 is a view taken along lines 5--5 of FIG. 2;
FIG. 6 is a view taken along lines 6--6 of FIG. 3;
FIG. 7 is a cross-sectional side view of an end cap for use with the
implant of FIG. 1;
FIG. 8 is a plan view of the implant of FIG. 7;
FIG. 9 is a top plan view of an alignment guide assembly;
FIG. 10 is an end plan view of the guide assembly of FIG. 9;
FIG. 11 is a side elevation view of a drill tube guide removal handle;
FIG. 12 is a side elevation view of a drill tube guide;
FIG. 13 is a side elevation view of a drill tube planar according to the
present invention;
FIG. 13A is a cross-sectional side view of the planar of FIG. 13;
FIG. 14 is a view taken along line 14--14 of FIG. 13;
FIG. 15 is a side elevation view of a starter vertebral reamer according to
the present invention;
FIG. 16 is a proximal end view of the reamer of FIG. 15;
FIG. 17 is an enlarged side elevation view of a reamer head of the starter
reamer of FIG. 15;
FIG. 18 is a distal end elevation view of the reamer head of FIG. 17;
FIG. 19 is a side elevation view of an end cap inserter according to the
present invention;
FIG. 20 is a distal end view of the inserter of FIG. 19;
FIG. 21 is a side elevation view of a starter alignment guide handle;
FIG. 22 is a side elevation view of a drill tube inserter cap;
FIG. 23 is a view taken along lines 23--23 of FIG. 22;
FIG. 24 is a distal end view of the inserter cap of FIG. 22;
FIG. 25 is a side elevation view of a distraction plug inserter;
FIG. 26 is a side elevation view of a slap hammer;
FIG. 27 is a distal end elevation view of the slap hammer of FIG. 26;
FIG. 28 is a side elevation view of a distraction plug for use with the
present invention;
FIG. 29 is a side sectional view of a drill tube sleeve according to the
present invention;
FIG. 29A is a side elevation view of a sheath for use with the present
invention;
FIG. 29B is a distal end elevation view of the sheath of FIG. 29A;
FIG. 30 is a distal end elevation view of the drill tube sleeve of FIG. 29;
FIG. 31 is a side elevation view of a drill tube for use with the present
invention;
FIG. 32 is a view taken along line 32--32 of FIG. 31;
FIG. 33 is an enlarged side elevation view of a distal end of the drill
tube of FIG. 31;
FIG. 34 is a side elevation view of a final vertebral reamer;
FIG. 35 is an elevation view of a proximal end of the final reamer of FIG.
34;
FIG. 36 is an enlarged view of a reamer head of the reamer of FIG. 34;
FIG. 37 is an end elevation view of a distal end of the reamer head of FIG.
36;
FIG. 38 is a side elevation view of a vertebral reamer guide pin;
FIG. 39 is a plan end view of the guide pin of FIG. 38;
FIG. 40 is a side elevation view of a starter tap;
FIG. 41 is a view taken along line 41--41 of FIG. 40;
FIG. 42 is an enlarged sectional view of thread cutting teeth of the tool
of FIG. 40;
FIG. 43 is a side elevation view of an implant driver for use with the
present invention;
FIG. 44 is an end view of a hub on a distal end of the tool in FIG. 43;
FIG. 45 is a view taken along line 45--45 of FIG. 43;
FIG. 45A is a side elevation view of a shaft of the tool of FIG. 43 showing
an attached collet;
FIG. 45B is a cross-sectional view of FIG. 45A taken along lines 45B--45B;
FIG. 46 is a side elevation exploded view of a vertebral reamer hand
driver;
FIG. 47 is an end elevation view of the tool of FIG. 46;
FIG. 48 is a side elevation view of two vertebrae separated by a disk;
FIG. 48A is a view taken along lines 48A--48A of FIG. 48;
FIGS. 49 and 49A are views similar to FIGS. 48, 48A showing insertion of a
starter alignment guide assembly;
FIGS. 50 and 50A are views similar to FIGS. 48 and 48A showing placement of
a distraction plug by use of an inserter;
FIGS. 51 and 51A are views showing the distraction plug in place;
FIGS. 52, 52A are views similar to the preceding views showing placement of
a vertebral reamer guide pin;
FIGS. 53, 53A are views similar to the foregoing views showing placement
and use of a drill tube planar;
FIGS. 54, 54A are views similar to the foregoing views showing placement of
a drill tube;
FIGS. 55, 55A are views similar to the foregoing showing placement of a
drill tube sleeve;
FIGS. 56, 56A are views similar to the foregoing showing preboring of an
implant bore;
FIGS. 57, 57A are views similar to the foregoing views showing a partially
formed bore following the preboring of FIGS. 56, 56A;
FIGS. 58, 58A are views similar to the foregoing views showing final boring
of an implant bore;
FIGS. 59, 59A are views similar to the foregoing showing formation of a
completed bore after removal of the final boring tool of FIGS. 58, 58A;
FIGS. 60, 60A are views similar to the foregoing showing tapping of the
bore formed in FIGS. 59, 59A;
FIGS. 61, 61A are views similar to the foregoing showing the tapped bore;
FIGS. 62, 62A are views similar to the foregoing showing placement of an
implant within a threaded bore;
FIGS. 63, 63A are views showing completed placement of an implant within
the bore;
FIG. 64 is a view showing placement of a drill tube using an end cap
inserter; and
FIG. 64A is a view showing use of a sheath on a drill tube.
DESCRIPTION OF THE PREFERRED EMBODIMENT
1. GENERALLY
Referring now to the several drawing figures in which identical elements
are numbered identically throughout, a description of the preferred
embodiment will now be provided. For purposes of illustrating a preferred
embodiment, a description of the surgical procedure will be given with
respect to an implant 10 such as that shown and described in commonly
assigned and co-pending U.S. patent application Ser. No. 07/702,351. It
will be appreciated that the present surgical procedure can apply to a
wide variety of implants including threaded implants such as those shown
in the aforementioned U.S. Pat. Nos. 5,015,247 and 4,961,740 as well as
non-threaded implants such as shown in U.S. Pat. No. 4,507,269 or other
implants. The term "implant" as used herein may also include bone implants
(e.g., autograft, allograft or artificial bone).
The implant 10 (FIGS. 1-6) is a hollow cylinder 12 having male threads 14
exposed on the exterior cylindrical surface of cylinder 12. The cylinder
includes a forward interior chamber 16 and a rear interior chamber 17
separated by a reinforcing rib 19, a bone slurry or bone chips may be
compacted into chambers 16,17 as will be described.
A first plurality of holes 18 extend radially through the cylinder wall and
communicate with the chambers 16,17. A second (and enlarged) plurality of
holes 21 are disposed on diametrically opposed sides of the implant 10.
A rear end 22 of the implant has a slot 24 which communicates with the
chamber 17. The slot 24 allows the bone slurry or bone chips to be
impacted into the implant 10. A slot 25 is defined by rib 19. The slot 25
is sized to receive the distal end of a tool (as will be more fully
described) to place the implant within a bore formed between opposing
vertebrae.
An endcap 26 (FIGS. 7, 8) is provided to snap fit onto the rear end 12 by
means of snap tabs 27. In a preferred embodiment, the endcap 26 is
polyethylene or some other radiolucent material to permit post-operative
x-ray inspection and determine the adequacy of the fusion after the
implant surgery has been performed.
2. TOOLS
A. Generally
In a preferred embodiment the technique of the present invention will be
performed with a prescribed kit of tools. For the purpose of illustrating
the preferred embodiment, the tools of the kit will now be described. It
will be appreciated that the method of the surgery can be practiced using
a wide variety of tools of different size and shapes.
Each of the tools of a kit necessary to perform the surgery as described in
this application will be separately described. The use of the tools will
become apparent with the description of the method of the invention in
Section IV.3 of this application. Unless otherwise specified, all tools
are formed of stainless steel.
Since vertebrae size and disc space size vary from patient-to-patient (and
since such sizes vary along the length of the spine of any given patient),
several sizes of implants 10 are anticipated. Presently, implants 10
having minor outside diameters (D.sub.m) of 3 mm, 5 mm, 7 mm, 9 mm, 11 mm,
13 mm, 15 mm, 17 mm, 19 mm and 21 mm with lengths (L) of 10 mm, 12 mm, 14
mm, 16 mm, 16 mm, 20 mm, 24 mm, 28 mm, 28 mm and 30 mm, respectively, are
anticipated to accommodate various spine locations and sizes. The major
outside diameters (D.sub.M) Of the implants 10 are 2.5 mm larger than the
minor outside diameters D.sub.m.
Several of the tools to be described (e.g., reaming tool 126) are sized for
particular sizes of implants. Namely, the reaming tool 121 must form a
bore sized to receive the implant. Since ten sizes of implants are
anticipated, ten sizes of boring tools 126 are anticipated as will become
apparent to one of ordinary skill in the art.
B. STARTER ALIGNMENT GUIDE HANDLE
The kit of the present invention includes a starter alignment guide handle
28 (see FIG. 21). The handle includes a distal end 30 having an impact
flange 31 and an axially extending threaded stud 32. A proximal end 34 of
the handle is knurled to permit a surgeon to firmly grip the handle 28.
C. STARTER ALIGNMENT GUIDE ASSEMBLY
The starter alignment guide assembly 36 (FIGS. 9 and 10) includes a main
body 40 having a threaded bore 42 sized to receive the threaded end 32 of
handle 28. Extending from the body 40 are parallel pins 44, 46. The pins
are spaced apart by a distance D.sub.1 as will be more fully described.
The pins 44, 46 have stop surface 45, 47.
As mentioned, since human anatomy varies significantly from one patient to
another (and since the sizing of vertebrae varies depending on the
location within the spine), it is anticipated that the kit will require
various sizes of tools. With respect to starter alignment guide assembly
36, it is anticipated that at least ten tools will be provided having pin
spacings D.sub.1 selected to identify a desired spacing of two implants
each of diameters of 3, 5, 7, 9, 11, 13, 15, 17, 19, and 21 mm,
respectively. However, such a kit will only require one guide handle 28
which can be inserted and attached to each of the starter alignment guide
assemblies 36.
The main body 40 is nylon to be X-ray transparent. Also, the body 40 has
curved edges 49 with a radius of curvature to match a radius of a
corresponding drill tube 92. For example, for placing two 13 mm (D.sub.m)
implants 10, a drill tube 92 with an inside diameter of 16.0 mm (for a
D.sub.M of 15.5) is required (the 0.5 mm difference providing clearance).
The edges 49 match the contour of the drill tube 92 and are spaced apart
equal to a spacing of the drill tube when operating on either the right or
left side. As a result, the back surface 43 of main body 40 may be placed
against the spine to outline an area which must be cleared for the
procedure. This aids the surgeon in determining the proper laminectomy
size or required amount of vessel retraction.
D. DISTRACTION PLUG INSERTER
A distraction plug inserter 48 (FIG. 25) is provided and includes a shaft
50 and a handle end 51 which is knurled to provide a secure grip. A distal
end 53 has a threaded shaft 52 extending axially therefrom. End 51 has a
larger diameter than shaft 50 to provide a surface 49 against which slap
hammer 192 (FIG. 26) may strike as will become apparent.
E. DISTRACTION PLUG
A distraction plug 54 (FIG. 28) is provided having a generally cylindrical
body 56 with a tapered forward end 58. The rear end has a reduced diameter
portion 55 terminating at a flange 57 having a diameter the same as the
body 56. A threaded bore 62 is formed through the rear end to receive the
threaded shaft 52 of the distraction plug inserter 48. The body 56 is
knurled to prevent undesired axial movement of the plug 54 after it is
inserted.
As will be more fully described, the distraction plug 54 is used to
initially distract opposing vertebrae. The amount of desired distraction
will vary from patient to patient and from spine location to spine
location. Accordingly, it is anticipated that distraction plugs having
diameters D.sub.2 ranging from 3 to 14 mm (by one millimeter increments)
shall be included within the kit. Each of the distraction plugs fits on
the inserter 48 such that only one inserter 48 is required for the kit.
F. VERTICAL REAMER GUIDE PIN
A vertebral reamer guide pin 64 (FIGS. 38 and 39) is provided including a
generally cylindrical body 66 having a tapered forward end 68 and a
reduced diameter threaded rear end 70. The tapered forward end 68 has
three flats 69 that grind away disc material when the pin 64 is secured to
a starter reamer 112 (FIG. 15) as will be described.
As with the distraction plug 54, a wide variety of sizes of guide pins 64
are anticipated to be required in the kit having diameters D.sub.3 ranging
from 3 through 14 mm (increasing by one millimeter increments). For
reasons that will become apparent, it is desired that all of the guide
pins 64 have a threaded stud 70 of identical size.
G. DRILL TUBE GUIDE
A drill tube guide 72 (FIG. 12) is provided including a cylindrical shaft
74 and a distal end 76. The distal end 76 has a predetermined maximum
outside diameter D.sub.4. Provided on the axial face 78 of distal end is a
bore 80 which is threaded and sized to receive stud 70 of the guide pin
64. A proximal end 82 (of diameter D.sub.4) of the drill tube guide has a
threaded bore 81 for purposes that will be described. End 82 terminates at
a flat axial face 83.
In application, various sizes of implants 10 will be required depending on
the anatomical sizing of the vertebrae to be fused. It is anticipated that
implants 10 of ten different major outside diameters D.sub.M will be
required to accommodate a wide variety of applications. Accordingly, the
kit of the present invention will include ten drill tube guides having
outside diameters D.sub.4 to finally prepare bores to receive the three
sizes of implants as will be described. The outside diameters D.sub.4 are
equal to D.sub.M for each matching pair of implant 10 and drill tube guide
72.
H. DRILL TUBE PLANAR
In some applications, it may be desirable to plane a surface of a
vertebrae. For example, tissue may cover the surface of the vertebrae to
be bored. The various tools of the present invention should abut vertebrae
bone to insure that an implant 10 is inserted to a proper depth. A drill
tube planar 84 removes the tissue and provides a flat surface on the
vertebrae bone against which to place tools.
The drill tube planar 84 (FIGS. 13 and 14) includes a hollow tube 86 having
an inside diameter D.sub.5. The distal end 88 of the drill tube planar 84
includes a toothed rasp surface 85 to rasp away bone material as the
distal end 88 is placed against bone and the planar 84 is rotated about
its axis. The proximal end 90 of the planar 84 includes a knurled handle
to permit a surgeon to securely grasp the planar during the planing
operation.
As will be more fully described, in the anticipated method of the present
invention, the planar 84 will slip over the drill tube guide 72 with the
diameter D.sub.4 selected in close tolerance to D.sub.5 (i.e., D.sub.5 is
0.5 mm larger than D.sub.4). As a result, ten planars 84 are required to
fit on the ten sizes of drill tube guides 72.
The planar 84 includes an internal stop 87 positioned to oppose surface 83
of guide 72 when the planar 84 is placed over guide 72. A clean out hole
89 is provided to clean out planar 84.
I. DRILL TUBE
A drill tube 92 (FIGS. 31, 32, and 33) is provided in the form of a hollow
cylindrical tube 94. The distal end 96 of the tube 94 is provided axially
projecting teeth 98. The proximal end 99 of the tube 94 is flared
outwardly for purposes that will become apparent. As will be apparent, ten
sizes of tube 92 are required with inside diameters D.sub.6 to slip in
close tolerance over ten sizes of drill tube guide 72 (i.e., D.sub.6 is
0.5 mm larger than D.sub.4).
The teeth 98 each have a length, T.sub.L, of preferably 3 mm. The valleys
97 are flat to provide stop surfaces to hit bone as teeth 98 are forced
into vertebrae. This helps prevent the drill tube 92 from being forced too
far into bone.
J. DRILL TUBE INSERTER CAP
As will be more fully described, the drill tube 92 is secured to vertebrae
by forcing the teeth 98 into the vertebrae bone material. This is done by
impacting the proximal end 99 of the drill tube 92. An inserter cap 100
(FIGS. 22, 23 and 24) is provided in the form of a solid cylinder having
an axial bore 102 with an inside diameter D.sub.9 terminating at a flat
annular face 101. Diameter D.sub.9 is slightly larger than outside
diameter D.sub.4 of drill tube guide 72 (FIG. 12) so that cap 100 can slip
over end 82 of guide 72 with a stop surface 103 opposing end 83 and with
surface 101 opposing flared end 99 of drill tube 92. The cap 100 has an
opposite flat end 104 against which a surgeon may impact. This impacts the
drill tube 92 to force the teeth 98 into the bone of a vertebrae.
K. DRILL TUBE SLEEVE
A drill tube sleeve 105 (FIGS. 29 and 30) is provided in the form of a
hollow tube having a flat distal end and an outwardly flared proximal end
110. Ten sizes of sleeves 105 are required in the kit having outside
diameters D.sub.7 sized to slip within, in close tolerance, the ten sizes
of drill tubes 92. The inside diameter D.sub.10 is selected to be slightly
greater (e.g., 0.5 mm larger) than the minor outside diameter D.sub.m of
the implants 10.
L. STARTER VERTEBRAL REAMER
To start a bore between opposing vertebrae, a starter vertebral reamer 112
is provided (FIGS. 15 through 18). The starter reamer 112 has a shaft 114.
A reamer head 116 is secured to the distal end of the shaft 114. An axial
face of the reamer 116 has a threaded bore 118 sized to receive the
threaded shaft 70 of the vertebral reamer guide pin 64. A proximal end 120
has an outwardly flared hub 122 to act as a positive stop against flare
110 of the drill tube sleeve 106 as will be more fully described. A shaft
124 extends from the distal end. The reamer 116 includes cutting blades
117 that provide both end cutting and side cutting into bone as the
starter reamer 112 is rotated about its axis.
To accommodate ten sizes of implants, ten sizes of vertebral reamers 112
are included in the kit. The reamers 112 have outside diameters D.sub.11
equal to the minor outside diameters D.sub.m of the implants 10.
M. FINAL VERTEBRAL REAMER
A final vertebral reamer 126 (FIGS. 34 through 37), is provided for
completing a bore started by the starter vertebral reamer 112. The final
reamer 126 includes a shaft 128. A distal end of the shaft is provided
with a reamer end 130 having side and end cutting blades 131. A proximal
end of the shaft is provided with an outwardly flared hub 132. Extending
from hub 132 is an axial shaft 134. For reasons given with respect to
starter reamer 112, ten sizes of final reamers 126 are required with the
kit. The outside diameter D.sub.12 of final reamer 126 equals the minor
outside diameter D.sub.m of implants 10.
N. VERTEBRAL REAMER HAND DRIVER
To operate reamers 112 and 126, a hand driver 136 (FIGS. 46 and 47) is
provided. The hand driver includes an axial bore 138 to receive either of
shafts 124 or 134. The hand driver 136 also includes a manually engageable
handle 140 to be actuated by a surgeon performing the surgery of the
present invention.
The handle has an enlarged barrel portion 137 with radial grooves 139. With
one hand, a surgeon puts axial pressure on handle 140 and with the other
hand the surgeon rotates barrel 137 with fingers in grooves 139. Thus, the
surgeon can securely turn a reamer secured to the driver 136.
Radial bores 141,143 extend through barrel 137 to receive set screws to fix
a shaft 124 or 134 received within bore 138.
O. BONE TAP
In the event a threaded implant is utilized (as is the case in the
preferred embodiment of the present invention), the bores for the implant
are partially prethreaded. To prethread, a bone tap 142 (FIGS. 40 through
42) is provided, having a shaft 144. At the distal end of the shaft 144 is
a tapping head 146 having tapping threads 148. Near the proximal end of
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