U.S. patent application number 10/035281 was filed with the patent office on 2003-07-03 for laminoplasty with laminar stabilization method and system.
Invention is credited to Khanna, Rohit Kumar.
Application Number | 20030125738 10/035281 |
Document ID | / |
Family ID | 21881695 |
Filed Date | 2003-07-03 |
United States Patent
Application |
20030125738 |
Kind Code |
A1 |
Khanna, Rohit Kumar |
July 3, 2003 |
Laminoplasty with laminar stabilization method and system
Abstract
Fixation devices and methods for stabilization of the lamina
after laminoplasty are described. The device comprises of a plate
with several holes that receive bone fasteners. The plate is curved
at the ends to contour to the vertebral structure and has
appendages to engage the displaced lamina in a fixed position.
Alternatively, the plate has a bone fusion spacer in the middle to
engage and fuse the lamina in the displaced position. Several
methods of dynamically stabilizing the lamina after either the open
door, double door or expansive laminoplasty technique are
provided.
Inventors: |
Khanna, Rohit Kumar;
(Daytona Beach, FL) |
Correspondence
Address: |
Rohit K. Khanna
Suite 460
311 North Clyde Morres Blvd.
Daytona Beach
FL
32114
US
|
Family ID: |
21881695 |
Appl. No.: |
10/035281 |
Filed: |
January 3, 2002 |
Current U.S.
Class: |
606/279 ;
606/286; 606/907; 606/908; 606/909; 606/910 |
Current CPC
Class: |
A61B 17/7071
20130101 |
Class at
Publication: |
606/61 |
International
Class: |
A61B 017/58 |
Claims
What I claim as my invention is:
1. A bone stabilization device for the lamina of the spine after
laminoplasty comprising an elongated plate with curvature at the
ends of the longitudinal axis, downward for fixation to a lamina
and upward for fixation to a facet by means of a screw through bone
screw receiving holes at each end of the said plate
2. The bone stabilization device of claim 1 further including: an
appendage on either end perpendicular to the longitudinal plate
axis and prior to the curvature at both ends to engage between the
lamina and the facet
3. The bone stabilization device of claim 1 further including: a
bone fusion device wherein said plate is attached to the bone
fusion device in the middle with the longitudinal plate edges
allowing for bone fixation
4. A bone stabilization device of claim 1 wherein said plate has a
curved appendage at one end and a straight appendage at the other
end perpendicular to the longitudinal plate axis and prior to the
curvature at both ends
5. A bone stabilization device of claim 1 wherein said plate has a
curved appendage at one end perpendicular to the longitudinal plate
axis and prior to the curvature
6. A bone stabilization device of claim 1 wherein said plate has a
plurality of bone screw receiving holes throughout the plate
7. A bone stabilization device of claim 1 wherein said device is
made from a biocompatible material selected from the group
consisting of titanium, titanium alloys, surgical steel, polymeric
material, ceramic material, resorbable material, polyglyconate, and
hydroxyapatite
8. A bone fusion device of claim 3 wherein said device is made from
either bone, hydroxyapatite or a resorbable material
9. A bone stabilization device for the lamina of the spine after
laminoplasty comprising of an elongated plate with bone screw
receiving holes at the ends wherein said plate has a downward
curvature at both ends to allow for fixation to the lamina via
screws
10. The bone stabilization device of claim 9 further including: a
curved appendage in the middle perpendicular to the longitudinal
plate axis and prior to the curvature at both ends to secure the
lamina
11. The bone stabilization device of claim 9 further including: a
bone fusion device wherein said plate is attached to the bone
fusion device in the middle with the longitudinal plate edges
allowing for bone fixation via bone fasteners
12. A bone stabilization device of claim 9 wherein said plate has
straight appendages in the middle perpendicular to the longitudinal
plate axis and prior to the curvature at both ends
13. A bone stabilization device of claim 9 wherein said plate has a
plurality of bone screw receiving holes throughout the plate
14. A bone stabilization device of claim 9 wherein said device is
made from biocompatible material selected from the group consisting
of titanium, titanium alloys, surgical steel, polymeric material,
ceramic material, resorbable material, polyglyconate, and
hydroxyapatite
15. A bone fusion device of claim 11 wherein said device is made
from either bone, hydroxyapatite, or a resorbable material
16. A bone stabilization device of claim 9 further including: a
L-shaped curvature at the end on both sides to allow for fixation
to the facets by means of bone fasteners
17. A spacer for the lamina of the spine after laminoplasty
comprising of a rectangular shape with concave curved edges
contoured at the longitudinal ends to allow for engagement between
the lamina
18. A spacer for the lamina of the spine after laminoplasty
comprising of a rectangular shape wherein both edges at the end of
the longitudinal axis of the said spacer have a superior cuff to
allow for engagement between the lamina
19. A spacer of claim 17 wherein said device is made from either
bone, hydroxyapatite, or a biocompatible material suitable for bone
fusion
20. A spacer of claim 18 wherein said device is made from either
bone, hydroxyapatite, or a biocompatible material suitable for bone
fusion
21. A method of stabilizing and fusing the reshaped lamina after a
laminoplasty comprising the steps of: displacing the severed edge
of a lamina at the junction of the lamina and facet, providing a
spacing means with the edges of the said spacing means contoured to
engage the lamina at one end and the facet at the other end, and a
fixation means attached to the said spacing means in the middle
with curvatures at both ends in opposing directions allowing bone
screw placement through one end of the said fixation means to the
lamina and bone screw placement through the other end of the said
fixation means to the facet
22. A method of stabilizing the reshaped lamina after a
laminoplasty comprising the steps of: displacing the severed edge
of the lamina at the junction of the lamina and facet, a fixation
means comprising of a plate with appendages at either ends prior to
the curvature of the longitudinal axis of the said fixation means
to secure the lamina on one side and the facet on the other and
maintain their repositioned shape along with fixation of the plate
to the lamina and facet via bone fasteners
23. A method of stabilizing and fusing the repositioned lamina
after a laminoplasty comprising the steps of: displacing the
severed edges of lamina at the junction of the lamina and facet on
both sides, providing a spacing means with the edges of the said
spacing means contoured to engage between the lamina and facet on
both sides of the vertebra, a fixation means with the said spacing
means attached in the middle contoured to allow bone screw
placement through one end of the said fixation means to the lamina
and bone screw placement through the other end of the said fixation
means to the facet on both sides of the vertebra
24. A method of stabilizing and fusing the reshaped lamina after a
laminoplasty comprising the steps of: displacing both lamina
through severed edges in the middle, providing a spacing means with
the edges of the spacing means contoured to engage the displaced
lamina at both ends, and a fixation means comprising of a plate
with the said spacing means attached at the middle of the fixation
means and the said fixation means comprising of a curvature at both
ends of the longitudinal axis to secure the lamina and/or facets on
both sides with bone fasteners
25. A method of stabilizing the reshaped lamina after a
laminoplasty comprising the steps of: displacing both lamina
through severed edges in the middle, providing fixation means
comprising of a plate with two appendages perpendicular to the
longitudinal axis of the said fixation means spaced apart in the
middle to engage the lamina on either side with the said fixation
means also comprising of curvatures at both ends to secure the
fixation means to the lamina and/or facets on both sides with bone
fasteners
Description
BACKGROUND OF THE INVENTION
[0001] Cervical stenosis with spinal cord compression and
consequent myelopathy is a very common problem encountered by the
spine surgeon. The usual cause of multilevel cervical stenosis is
spondylosis and/or ossification of the posterior longitudinal
ligament. Surgical decompression either through an anterior or
posterior approach can be undertaken.
[0002] An anterior approach usually involves multilevel corpectomy
with fusion and stabilization. The main drawback of this technique
is the increased time and complexity of the procedure as well as
the risk of pseudoarthrosis and accelerated degeneration at the
levels above and below the fusion.
[0003] A posterior approach has traditionally involved a simple
laminectomy, laminectomy with facet fusion, or more recently
laminoplasty. The drawback of a simple laminectomy is the risk of
late clinical deterioration form either kyphosis or postlaminectomy
scar formation. Laminectomy with facet fusion decreases the risk of
kyphosis but it also decreases the range of motion in the spine and
increases the risk of accelerated degeneration at the levels above
and below the fusion.
[0004] Laminoplasty either through open door or double door
technique developed more recently provides greater stability and
range of motion when compared with laminectomy alone. This
technique entails laminoplasty for decompression with laminar
fusion with allo- or autograft bone and/or fixation with a plate.
The principle behind laminar fusion and fixation is that it
maintains the decompression following laminoplasty as well as the
displaced lamina in a fixed position thereby providing
stabilization also.
[0005] U.S. Pat. No. 6,080,157 to Cathro et al. describes an
implant to stabilize the lamina after laminoplasty. A major
limitation of this implant and technique is that a single implant
extends to all the laminoplasty levels and is followed by posterior
autograft fusion thereby disabling the inherent mobility between
the cervical spine levels which laminoplasty attempts to
preserve.
[0006] The present invention is an apparatus for use in
laminoplasty to fuse and stabilize the lamina individually in the
cervical, thoracic or lumbar spine thereby preserving the range of
motion as well as providing stability.
SUMMARY OF THE INVENTION
[0007] The present invention relates a laminar fusion and fixation
system following laminoplasty. This system with the bone fusion
spacer or resorbable fusion graft and plate reduces surgical time
and simplifies laminar fusion and fixation after laminoplasty.
[0008] The bone fusion spacer consists of a bicortical bone graft
with variable length but uniform width and thickness specific for
the cervical, thoracic or lumbar spine. The edges are contoured
with a notch to allow securement to the lamina on one side and the
lateral mass or facet on the other side.
[0009] In another embodiment of the bone fusion spacer, the edges
have a superior cuff or shoulder that allows securement against the
lamina and facet on either sides as well prevent migration of the
bone graft into the spinal canal.
[0010] The resorbable fusion graft has a design similar to the
allograft bone graft but is made of hydroxyapatite or similar
absorbable material which is eventually resorbed and/or replaced
with autologous bone during the fusion process.
[0011] The invention also comprises a plate made of titanium or
similar alloy with magnetic resonance imaging compatibility of
variable thickness which is contoured at the edges to allow
fixation of the laminoplasty and securement of the bone graft. The
contoured design of the plate allows screw placement in the lamina
or spinous process on one side and the facet on the other side.
[0012] In another embodiment the allograft bone or resorbable graft
and plate are constructed as a unit with the bone graft attached to
the plate in the middle through either screws or an adhesive
material.
[0013] In another embodiment, the bone graft and plate are designed
for laminar fusion and fixation following double door laminoplasty.
The bone graft in the middle allows for laminar fusion in the
decompressed position with the plate design bent on either end
securing the graft to the lamina and facet.
[0014] In another embodiment, the plate has appendages that engage
the lamina and facet in a fixed position without the use of a bone
spacer.
[0015] The procedure as would be undertaken with the use of the
laminoplasty fixation system is described as follows. An open door
laminoplasty entails creating a gutter at the junction of the
lamina and medial aspect of the facet on both sides with the use of
a drill. On the side of the laminoplasty opening, the drilling is
carried through into the canal or the opening completed with a
small kerrison rongeur. At the other side, the inner cortex at the
lamina and facet junction is not drilled. The lamina at the open
end is elevated and the spinous process pushed away in order to
create a greenstick osteotomy and allow for the laminoplasty
decompression. Typically, atleast one centimeter of distraction
between the lamina and the facet provides for a good spinal
decompression. In order to maintain the position of the lamina, the
pre-contoured bicortical allograft of appropriate size is
positioned between the lamina and the facet. Stabilization at each
level is then undertaken with placement of the pre-designed plate
with the curved ends to allow one end to secure to the lamina with
a screw and the other end to the facet. Alternatively, the bone
graft pre-attached to the plate can also be used to provide laminar
fusion in the fixed position. In situations where laminoplasty
stabilization without the use of a fusion graft is desired, the
plate with added appendages to secure the displaced lamina is
used.
[0016] Another variation on the open door laminoplasty is the
expansive laminoplasty most suited for the thoracolumbar spine. In
this method, the lamina on either side at the junction of the
facets are drilled and opened. A lateral spinal canal recess
decompression and/or foraminotomy is undertaken and the lamina
replaced with bone graft/plate construct on both sides.
[0017] A trap door or double door laminoplasty is created by
drilling on each side at the laminar and later mass junction the
outer laminar cortex and sparing the inner laminar cortex. The
spinous process is resected and a midline gutter is also created
which extends through the inner cortex which can be opened with a
small kerrison rongeur. The lamina on either side are lifted and
opened creating a greenstick osteotomy on each side. In order to
maintain the decompressed position of the lamina, a plate alone or
a bone graft/plate construct is placed. The plate can either be
fixated with screws to the lamina or the facets. For situations
where laminar stabilization without the use of a fusion graft is
desired, the plate with appendages in the middle is used.
[0018] While the inventions described here are specific, any
variations to the described embodiments falls within the scope of
the current invention and the protection granted therein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a cross section of the vertebra
[0020] FIG. 2 is a top view of the bone graft
[0021] FIG. 3 is a side view of one embodiment of the bone
graft
[0022] FIG. 4 is a cross section of the vertebra following open
door laminoplasty with one embodiment of the bone graft
[0023] FIG. 5 is a side view of another embodiment of the bone
graft
[0024] FIG. 6 is a cross section of the vertebra following open
door laminoplasty with another embodiment of the bone graft
[0025] FIG. 7 is a top view of one embodiment of the plate
[0026] FIG. 8 is a top view of another embodiment of the plate
[0027] FIG. 9 is a side view of the plates
[0028] FIG. 10 is a top view of the graft and plate construct
[0029] FIG. 11 is a side view of one embodiment of the
construct
[0030] FIG. 12 is a cross section of the vertebra with the graft
and plate construct in place
[0031] FIG. 13 is a side view of another embodiment of the
construct
[0032] FIG. 14 is a cross section of the vertebra with the graft
and plate construct in place
[0033] FIG. 15 is a cross section of the vertebra with expansive
laminoplasty
[0034] FIG. 16 is a cross section of the vertebra following double
door laminoplasty with one embodiment of the bone graft
[0035] FIG. 17 is a cross section of the vertebra following double
door laminoplasty with another embodiment of the bone graft
[0036] FIG. 18 is a top view of one embodiment of the graft and
plate construct
[0037] FIG. 19 is a side view of the construct
[0038] FIG. 20 is a cross section of the vertebra with the graft
and plate construct in place
[0039] FIG. 21 is a top view of another embodiment of the graft and
plate construct
[0040] FIG. 22 is a side view of the construct
[0041] FIG. 23 is a cross section of the vertebra with the graft
and plate construct in place
[0042] FIG. 24 is top view of another embodiment of the plate
[0043] FIG. 25 is a side view of the plate
[0044] FIG. 26 is a cross section of the vertebra with plate in
place
[0045] FIG. 27 is a side view of another embodiment of the
plate
[0046] FIG. 28 is a cross section view of the vertebra with the
plate in place
[0047] FIG. 29 is a top view of another embodiment of the plate
[0048] FIG. 30 is a side view of the plate
[0049] FIG. 31 is a top view of another embodiment of the plate
[0050] FIG. 32 is a side view of the plate
[0051] FIG. 33 is a cross section of the vertebra with one
embodiment of the plate in place
[0052] FIG. 34 is a cross section of the vertebra with another
embodiment of the plate in place
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0053] A top view of a vertebra is illustrated in FIG. 1 with
vertebral body 1, facet 2, junctions of the facet and lamina 3 and
6, lamina 4, spinous process 5, and spinal canal 7.
[0054] In one embodiment of the bone fusion device as illustrated
in FIGS. 2 and 3, the device has a rectangular configuration with a
top surface 9, longitudinal edge 8, side edge 10, and grooved edges
10 and 11 to allow securement to the lamina and facet.
[0055] For the open-door technique of laminoplasty, a bicortical
opening at the junction of the lamina and facet on one side and a
unicortical groove 6 on the other side with a greenstick fracture
is created for the laminar displacement as illustrated in FIG. 4. A
bone fusion graft 8 is placed between the facet 2 and lamina 4 to
maintain the repositioned shape of the laminoplasty that provides
decompression of the spinal canal 7.
[0056] In another embodiment of the bone fusion device with a
longitudinal side 12 and top surface 13 as illustrated in a side
view in FIG. 5, the edges at the ends are shouldered with superior
cuffs 14 and 16 and edge 15. Following the open-door laminoplasty,
as depicted in FIG. 6, the bone fusion device rests between the
lamina 4 on one side and facet 2 on the other and the shouldered
ends 14 and 16 prevent migration of the graft into the spinal canal
7.
[0057] A plate is also used following the laminoplasty to stabilize
and fuse the displaced lamina in the decompressed position. The
plate has a top surface 20 with several bone screw receiving holes
as illustrated in FIG. 7. Screw holes at the ends 17 and 19 secure
the plate to the lamina on one side and the facet on the other.
Screw hole 18 in the center of the plate can be used to secure the
bone graft to the plate. In another embodiment of the plate as seen
in FIG. 8, there are bone receiving screw holes 21 and 22
throughout the plate 23. As illustrated in FIG. 9, the plates have
curved ends to conform to the anatomy of the lamina following the
open door laminoplasty technique with a top surface 20 and upward
curved end 24 for facet fixation and downward curved end 25 for
laminar fixation.
[0058] In order to simplify the technique of laminoplasty and
provide laminar fusion as well as stabilization, a pre-assembled
construct with the plate attached to the bone fusion device is used
as illustrated in FIGS. 10, 11, and 13. The plate has a top surface
27 with a curved edge pointing superiorly 30 and inferiorly 31. The
bone screw holes at the both ends 28 and 29 allow the plate to be
secured to the bone with screws. The bone fusion graft 26 has
notches at the ends 32 as seen in FIG. 11, whereas in another
embodiment in FIG. 13, the bone fusion graft 33 has shouldered ends
35 with a superior cuff 34. The plate and fusion device construct
is placed as seen in FIGS. 12 and 14 following an open-door
laminoplasty. The bone fusion devices either 26 or 33 rest between
the facet 2 and lamina 4 with the plate 27 secured to the lamina
with a screw 37 and to the facet with a screw 36.
[0059] For the expansive laminoplasty technique as illustrated in
FIG. 15, the plate and bone fusion construct is used on both sides.
On one side, the bone graft 38 rests between the facet 42 and
lamina 43 with the plate 39 securing the construct, whereas on the
other side, the bone graft 40 rests between the facet 44 and lamina
45 with the plate 41 securing the construct.
[0060] The trap door laminoplasty technique as shown in FIGS. 16
and 17 involves removal of the spinous process and creation of
unicortical laminoplasty grooves 46 and 47 at the junction of the
lamina and facet on both sides. The displaced lamina are then
maintained in that position with a bone fusion construct 8 or 12.
In one embodiment of the bone graft and plate construct for use in
this laminoplasty technique as illustrated in FIGS. 18 and 19, the
plate with a top surface 51 has downward angled ends 52 and 53 and
is attached to the bone graft 50. The plate has bone screw
receiving holes 48 and 49 that allow fixation of the plate to the
lamina on both sides. FIG. 20 illustrates the construct in place
with the laminar grooves 46 and 47, bone graft 50 and the plate 51
with bone screws 62 and 63 securing the construct to the
lamina.
[0061] In another embodiment of the bone graft and plate construct
for the trap door laminoplasty technique as illustrated in FIGS. 21
and 22, the plate has a top surface 59 with bone screw holes 54 and
58 for fixation to the facets and screw holes 55 and 57 for further
fixation to the lamina if needed. The plate also has curved ends 60
and 61 contoured for fixation to the facets. The bone fusion device
56 is attached to the plate in the center. FIG. 23 illustrates the
construct in place with the bone graft 56, plate 59 and the plate
fixated to the facets through bone screws 64 and 65.
[0062] For the technique of open-door laminoplasty, stabilization
without laminar fusion can also be undertaken with the use of the
plates as illustrated in FIGS. 24, 25, and 27. The plate has a top
surface 66 with bone screw holes at the ends 67 and 68. The ends
have a superiorly angled curve at one end 69 and inferiorly angled
at the other 70. In one embodiment as seen on the side view in FIG.
25, there is an inferiorly pointing curved hook 72 to engage the
lamina at one end and a straight appendage 71 pointing inferiorly
at the other end to secure to the facet. In another embodiment of
the plate as seen in FIG. 27, there is only one appendage pointing
inferiorly 72 at the end prior to the downward curvature of the
plate. The implanted construct is seen in FIGS. 26 and 28. The
plate is secured to the lamina 4 via bone screw 37 and facet 2 via
bone screw 36. The hook 72 secures the lamina in the displaced
laminoplasty position. As seen in FIG. 26, the additional straight
appendage 71 at the facet end allows the plate to rest on the facet
2.
[0063] For the trap-door technique of laminoplasty, stabilization
without laminar fusion is undertaken with the use of the plates
alone. In one embodiment of the plate as illustrated in FIGS. 29
and 30, the plate has a top surface 73 and screw holes at both ends
74 and 75. The appendages 75 and 76 secure the displaced lamina and
the curvatures at both ends 74 and 77 allows attachment to the
lamina. The implanted plate is shown in FIG. 33 with bone screws 87
and 88 securing it to the lamina on both sides.
[0064] In another embodiment as illustrated in FIGS. 31 and 32, the
plate is curved at the ends 83 and 86. The plate has a top surface
82 with bone screw holes 79 and 80 for laminar fixation and holes
78 and 81 for facet fixation on both sides. The appendages 84 and
85 secure the displaced lamina. The implanted plate is shown in
FIG. 34 with bone screws 87 and 88 securing it to the facets on
both sides.
REFERENCES
[0065]
1 U.S. Patent Documents 6080157 Jun. 27, 2000 Cathro 6241771 Jun.
5, 2001 Gresser
* * * * *