U.S. patent application number 10/506803 was filed with the patent office on 2006-08-24 for longitudinal implant.
Invention is credited to Robert Lange.
Application Number | 20060189982 10/506803 |
Document ID | / |
Family ID | 8183783 |
Filed Date | 2006-08-24 |
United States Patent
Application |
20060189982 |
Kind Code |
A1 |
Lange; Robert |
August 24, 2006 |
Longitudinal implant
Abstract
The longitudinal implant is fastened to bones on either side of
a damaged area through a connecting device. Said implant is
comprised of a filament or fiber composite material and said
connecting device is made of a material harder than said
longitudinal implant. The longitudinal implant is preferably made
of a carbon filament composite material, wherein the filament are
encapsulated in a polymer matrix.
Inventors: |
Lange; Robert; (Paris,
FR) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Family ID: |
8183783 |
Appl. No.: |
10/506803 |
Filed: |
March 6, 2002 |
PCT Filed: |
March 6, 2002 |
PCT NO: |
PCT/CH02/00136 |
371 Date: |
January 14, 2005 |
Current U.S.
Class: |
606/261 ;
606/246; 606/280; 606/286; 606/292; 606/301; 606/328; 606/907;
606/910 |
Current CPC
Class: |
A61B 17/7007 20130101;
A61B 17/6483 20130101; A61B 17/7041 20130101; A61L 31/126 20130101;
A61B 17/7011 20130101; A61B 17/7059 20130101; A61B 17/701 20130101;
A61B 17/7032 20130101; A61B 17/7031 20130101; C08L 71/12 20130101;
A61L 31/126 20130101; A61B 2017/00831 20130101 |
Class at
Publication: |
606/061 |
International
Class: |
A61F 2/30 20060101
A61F002/30 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 9, 2001 |
EP |
018102434 |
Claims
1. Longitudinal implant and connecting device wherein said
longitudinal implant is fastened to bones on either side of a
damaged area through that connecting device, said implant is
comprised of a filament or fiber composite material and said
connecting device is made of a material harder than said
longitudinal implant.
2. Connecting device according to claim 1, wherein the longitudinal
implant is, made of a carbon filament composite material.
3. Connecting device according to claim 1 or 2, wherein the
filaments are encapsulated in a polymer matrix.
4. Connecting device according to claim 3, wherein the filaments
are encapsulated in PEEK or PEKEKK.
5. Connecting device according to any of claims 1 to 4, wherein the
filaments are oriented.
6. Connecting device according to claim 1, wherein the implant
being an elongated plate having a longitudinal slot extending along
a substantial portion of its length.
7. Connecting device according to claim 6, wherein the connecting
device comprising a pedicle screw having an upper section having a
width greater than the width of said slot and exteriorly threaded
portion extending outwardly from said section and extending through
said slot.
8. Connecting device according to claim 7, wherein an interiorally
threaded nut is received by the outer end of said threaded portion
whereby said plate can be grasped between said upper section and
said nut to tightly secure said plate by threading said upper
section.
9. Connecting device according to claim 1, wherein said implant is
a rod or a rail.
10. Connecting device according to claim 1, wherein said connecting
device comprising a screw and a nut which are made of titanium.
11. Connecting device according to claim 1, wherein said implant is
a rail (17) having a rectangular cross section.
12. Connecting device according to any one of claims 1 to 11,
wherein the filaments are woven.
Description
[0001] This invention relates to a longitudinal implant and
connecting device wherein said longitudinal implant is fastened to
bones on either side of a damaged area through said connecting
device.
[0002] In some spinal repair situations, the damaged area of the
spine is spanned by a slotted plate through which pedicle screws
are inserted and fastened to the pedicle bones on either side of a
damaged area. This fixes the spatial distance between the pedicle
bones and therefore fixes the distance between vertebrae so that
the damaged area of the spine can be repaired. In other spinal
situations, the damaged area of the spine is spanned by a rod. At
least two connectors are slidable along the rod connecting pedicle
screws or hooks to the rod. Such a rod and fixation system is
disclosed in EP 0 923 908A (Robert Lange).
[0003] Spinal repair is often times accomplished with hollow cages
in which bone fragments are inserted that will grow to an extent to
fuse the upper and lower vertebrae together at the damaged area. By
fixing and holding the distance between these vertebrae, the bone
in the cages will have time to grow and join the vertebrae
together.
[0004] It is an objective of this invention to provide an elongated
implant and pedicle screw or hook fixation system providing an
increased stability.
[0005] The implant of the device according to this invention is
comprised of a filament composite material- and said pedicle screws
or hooks are made of a material harder than said implant. The
implant provides a surface that has more friction than a titanium
implant. If the implant is a plate having a longitudinal slot, the
plate is placed between a nut and an upper surface of a pedicle
screw. The plate can be squeezed and locked into position because
the squeezing and the increased friction between titanium and the
filament composite material. When all members are titanium, the
required position is not always available and indentations are
often provided along the slot.
[0006] Fixation systems manufactured from metals such as titanium
alloy and stainless steel confound postoperative radiologic
assessments because they are radiopac and can produce artefact. The
use of an implant comprised of a fiber reinforced polymer composite
permits better diagnostic assessment of soft tissue and bone by
normal radiographic methods.
[0007] According to a preferred embodiment of the invention, the
fibers are aligned lengthwise, so that compression will not change
their strength characteristics to any extent even when compressed.
Preferably the fibers or filaments are oriented to resist
biomechanical forces.
[0008] Other advantages and features of the present invention will
be apparent to those skilled in this art reaching the following
specification with reference to the accompanying drawings in
which:
[0009] FIG. 1 is a view of an embodiment of an implant of this
invention;
[0010] FIG. 2 is a section along line I-I of FIG. 1;
[0011] FIG. 3 is a section through an embodiment of the implant
with a different curvature;
[0012] FIG. 4 shows the implant according to FIG. 3 connecting two
pedicle screws;
[0013] FIG. 5 a schematic view of a material block with horizontal
fiber and an implant machined from this block;
[0014] FIG. 6 a schematic view of a material block with a curvature
fiber orientation and an implant machined from this block;
[0015] FIG. 7 a side view of a connecting device of this
invention;
[0016] FIG. 8 a partial section through the connecting device;
[0017] FIG. 9 a side view of an implant testing configuration;
[0018] FIG. 10 and 11 overall views showing rods or rails
connecting two vertebrae of a spinal cord;
[0019] FIG. 12 a perspective view of another embodiment of an
implant of this invention and
[0020] FIG. 13 a section along line XIII-XIII of FIG. 12.
[0021] FIG. 1 and 2 disclose a plate 1 having a longitudinal slot 2
extending along a substantial portion of its length. The plate has
a curvature of about 10.sup.0 as shown in FIG. 2. FIG. 3 discloses
a plate 1' which has a curvature of 20.sup.0.
[0022] The plates 1 and 1' as well as rods 30 and rails 17 are
manufactured from a composite material composed of long filaments
or fibers 18 and 19 encapsulated in a matrix 4 as shown in FIG. 13.
The filaments or fibers 18 and 19 are preferably long carbon
filaments and the matrix is preferably a polymer. Preferably the
carbon filaments or fibers 18 and 19 are encapsulated in the
polymer polyether-ketoneetherketoneketone (PEMKK). PEKEKK is a
known biocompatible polymer. Another possible polymer is
polyetheretherketone (PEEK). PFKEKK is preferred to PEEK because of
its greater physical and chemical resistance properties. These
characteristics impart greater stability to the plates 1 and 1'
rods 30 and rails 17 or other connecting parts during a long-term
implantation.
[0023] FIGS. 4, 7 and 8 disclose a pedical plate fixation systems 5
and 5' comprising a plate 1', two bone screws 6 and two nuts 7. The
screws 6 and the nuts 7 are manufactured from steel or medical
grade titanium alloy. Bone screws 6 are common in the orthopedic
arts. The screws 6 are provided with bone engaging threads 6a. and
at its other end a screw segment 6b with a conventional thread. The
thread 6a flairs outwardly to an enlarged portion 6c. The enlarged
portions 6c having a width greater than the width of the slope 2.
The screw segment 6b extending outwardly from the enlarged portion
6c and extending through the slot 2. The nut 7 is received by the
screw segment 6b, whereby the plate 1' can be grasped between the
enlarged portion 6c and the nut 7 to tightly secure the plate 1 by
threading the nut 7 toward the enlarged portion 6c.
[0024] The embodiment according to FIG. 7 is provided with slip
washers 20, 21 and 22 having a planar surface 20a, 21a, 22a and a
concave or convex surface 20b, 21b, 22b. The planar surfaces 20a
and 21a are touching the plate 1' are preferably provided with rips
(not shown), which are depressed in the plate 1' and which prevent
the screw 6 from moving along the slot 2.
[0025] As the carbon-filament composition material of the plate 1
is softer than titanium and at its surface is somewhat rougher than
a titanium surface, the plate 1 can be squeezed between the
enlarged portion 6c and the nut 7. This prevents the screws 6 from
moving along the slot 2 both by depression caused by the squeezing
and the enhanced friction there between.
[0026] The filaments 3 encapsulated in the polymer matrix 4 are
oriented as shown in FIGS. 7 and B. The plate 1 is machined from a
block 8 having a curvature fiber orientation as indicated in FIG.
6. The curvature of the fiber lay-up is the same as the curvature
of the plate I or plate 2. The filaments 3 in the matrix 4 are
therefore aligned lengthwise of the slot 2. The FIG. 5 shows a
block 8' with a parallel curvature lay-up and the in the plate 1'
machined from this block 8' the filaments do not follow the
curvature of the plate 1l and are shorter. With the testing
configuration 10 disclosed in FIG. 9, tests were conducted using
the ASTM provisional standard for spinal implants. This mechanical
testing has shown that the strength of the plate 1 and 1' is
similar to plates made from stainless steel and titanium. The goal
of stabilization has not been sacrified. As material of the plates
1 and 1' is radiolucent, the plates do not interfere with
diagnostic methods.
[0027] As already mentioned, the implant according to this
invention can also be a rod 12 as disclosed in FIGS. 10 and 11 ox a
rail according to FIG. 12 and 13. Two connectors 13 include two
clamping members 14, connecting pedicle screws 15 to said rods 12.
The rods 12 and rails are made from the same material as the plates
1 and 1' and the filaments encapsulated in the matrix are
preferably oriented in axial direction. A rail 17 with a
rectangular cross section as shown in FIG. 12 and 13 is more stable
to rotation than a rod.
[0028] Another advantage of implants manufactured from a carbon
filament composite material is that its strength, flexibility and
hardness can be varied by changing the ratio of filaments to
plastic. It has been found, that "bone growth" is enhanced when it
is under a certain degree of physiological stress. Thus, it will be
desirable to select a composite ratio for the plate to gain the
required degree of stiffness without sacrifying any strength. The
ratio of filaments to plastic is preferably higher than 40%
(weight) and more preferably higher than 60% (weight).
[0029] The filaments of fibers are not randomly embedded, but
oriented in layers A as shown in FIG. A. The layers A can be
parallel to each other and to a surface 23 as shown in FIG. 13. The
layers A may be made up of woven filaments 18 and 19. The filaments
18 are oriented in the axial direction of the longitudinal implant
1, 17 and 30. The filaments 19 are oriented perpendicular to the
axial direction. The filaments 18 and 19 are oriented to resist the
biomechanical forces as for example bending force as shown in FIG.
9. The filaments can also be coiled to resist torsion forces, The
distance D between two layers A is preferably less than 0.5 mm and
preferably about 0.1 mm.
* * * * *