U.S. patent application number 13/935501 was filed with the patent office on 2013-11-07 for plate with contour.
The applicant listed for this patent is Carbofix Orthopedics Ltd.. Invention is credited to Mordechay BEYAR, Oren GLOBERMAN.
Application Number | 20130296863 13/935501 |
Document ID | / |
Family ID | 44545778 |
Filed Date | 2013-11-07 |
United States Patent
Application |
20130296863 |
Kind Code |
A1 |
GLOBERMAN; Oren ; et
al. |
November 7, 2013 |
PLATE WITH CONTOUR
Abstract
A bone plate formed of a fiber-reinforced polymer composite,
comprising a radiopaque marker that delineates at least a part of
the contour of the plate. In some embodiments, the radiopaque
marker comprises a metal wire section embedded proximal to an edge
of the contour, for example at a distance of 1 mm from an edge of
the contour. In some embodiments, the radiopaque marker extends
along a head portion of the plate, and/or along a stem portion of
the plate. In some embodiments, the metal wire is formed as an
intermittent line. Alternatively, the wire is formed as a
continuous line.
Inventors: |
GLOBERMAN; Oren;
(Kfar-Shemaryahu, IL) ; BEYAR; Mordechay;
(Caesarea, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Carbofix Orthopedics Ltd. |
Herzlia Pituach |
|
IL |
|
|
Family ID: |
44545778 |
Appl. No.: |
13/935501 |
Filed: |
July 4, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13702334 |
Dec 6, 2012 |
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PCT/IB11/52468 |
Jun 7, 2011 |
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13935501 |
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61486280 |
May 15, 2011 |
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61443308 |
Feb 16, 2011 |
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61344182 |
Jun 7, 2010 |
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Current U.S.
Class: |
606/70 ;
606/281 |
Current CPC
Class: |
A61B 17/863 20130101;
A61B 17/8685 20130101; A61F 2/28 20130101; A61B 17/1717 20130101;
A61B 17/862 20130101; A61B 17/8625 20130101; A61B 17/1728 20130101;
A61F 2210/00 20130101; A61B 17/88 20130101; A61B 17/8033 20130101;
A61B 17/866 20130101; A61B 17/8052 20130101; A61B 17/80 20130101;
A61B 17/8863 20130101; A61B 17/7233 20130101; A61B 2090/3966
20160201 |
Class at
Publication: |
606/70 ;
606/281 |
International
Class: |
A61B 17/80 20060101
A61B017/80; A61B 17/88 20060101 A61B017/88 |
Claims
1. A bone implant component comprising a bone plate formed of a
fiber-reinforced polymer composite, wherein the bone plate
comprises at least one radiopaque marker that delineates at least a
part of the contour of plate, said marker comprising a metal wire
section embedded proximal to an edge of said contour.
2. The bone implant component according to claim 1, wherein said
radiopaque marker delineates 60% or more of the contour of the
plate.
3. The bone implant component according to claim 1, wherein said
bone plate comprises a head portion, and said radiopaque marker
extends around at least a part of the contour of the head
portion.
4. The bone implant component according to claim 1, wherein said
bone plate comprises a stem portion, and said radiopaque marker
extends around at least a part of the contour of the stem
portion.
5. The bone implant component according to claim 1, wherein said
radiopaque marker is embedded on a side of said bone plate facing
outward after implantation.
6. The bone implant component according to claim 1, wherein said
radiopaque marker is embedded at a distance of less than 1 mm from
an edge of said contour.
7. The bone implant component according to claim 1, wherein a
radiopaque marker indicates a projection of said implant.
8. The bone implant component according to claim 1, wherein an
arrangement of radiopaque markers is provided to indicate said
implant contour is viewed from a certain direction.
9. The bone implant component according to claim 1, wherein said
radiopaque marker is formed as two continuous wire sections.
10. The bone implant component according to claim 1, wherein said
radiopaque marker is formed as a single continuous marginal
wire.
11. The bone implant component according to claim 1, wherein said
radiopaque marker is formed of one or more of gold, tantalum and
platinum.
12. The bone implant component according to claim 1, wherein said
radiopaque marker has a diameter between 0.2-0.5 mm.
13. The bone implant according to claim 1, wherein said radiopaque
marker is formed as an intermittent line along said contour.
14. The bone implant according to claim 1, wherein said bone plate
is radiolucent.
15. The bone implant according to claim 1, wherein the
fiber-reinforced polymer composite comprises reinforcing fibers
along the length of the plate.
16. The bone implant component according to claim 5, wherein said
radiopaque marker indicates a projection of said implant.
17. The bone implant component according to claim 13, wherein said
radiopaque marker has a diameter between 0.2-0.5 mm.
18. A method for indicating a viewing direction of a bone plate,
comprising: implanting a bone plate according to claim 1,
determining a viewing direction according to a projection of said
implant indicated by said radiopaque marker delineating at least a
part of said contour.
19. A method for positioning a bone plate during implantation,
comprising: orienting a bone plate according to claim 1 based on a
location of said radiopaque marker provided under fluoroscopy.
20. The method according to claim 19, further comprising
determining a location of at least one of a head portion of said
bone plate and a stem portion of said bone plate based on said
radiopaque marker extending along at least a portion of each.
Description
RELATED APPLICATIONS
[0001] This application is a division of U.S. patent application
Ser. No. 13/702,334 filed on Dec. 6, 2012, which is a National
Phase of PCT Patent Application No. PCT/IB2011/052468 having
International filing date of Jun. 7, 2011, which claims the benefit
of priority under 35 USC .sctn.119(e) of U.S. Provisional Patent
Application Nos. 61/344,182 filed on Jun. 7, 2010, 61/443,308 filed
on Feb. 16, 2011 and 61/486,280 filed on May 15, 2011.
[0002] PCT Patent Application No. PCT/IB2011/052468 is also related
to PCT Patent Application No. PCT/IB2010/050225 filed on Jan. 18,
2010.
[0003] The contents of the above applications are all incorporated
by reference as if fully set forth herein in their entirety.
FIELD OF INVENTION
[0004] The present invention in some embodiments thereof, relates
to composite material bone implant components, devices and systems,
and/or to methods for manufacturing and using such components,
devices, and systems, and to surgical instrumentation and
procedures used during implantation. More particularly, but not
exclusively, the invention relates to bone-supporting components
such as bone nails and bone plates, to implant fixation components
such as bone screws and pegs, formed of fiber-reinforced polymer
matrix composites or self-reinforcing polymers, and to tools and
accessories for performing surgery using such components.
[0005] As used herein, the term "bone implants" encompasses, but is
not limited to, hip joints, knee joints, shoulder joints, bone
screws, bone instruments, bone plates, pegs, and intramedullary
nails, including proximal femur nails, typically including screw
holes for receiving bone fixation screws, as well as dental bone
implants.
BACKGROUND OF THE INVENTION
[0006] Bone-supporting components such as bone plates and
intramedullary nails (bone nails) have become a treatment of choice
for the fixation of bone fractures, especially fractures of long
bones (e.g., the humerus, tibia and femur), and in non-broken bones
to prevent fractures. Typically, bone nails are rod-shaped devices
configured and constructed to be secured (interlocked) to a bone
using one or more fixation components which anchor the bone nail
into the bone in order to carry the loads until the bone fracture
is cured.
[0007] Bone plates are generally (but not exclusively) used in
cases that a bone nail can't be used, and are designed for
implantation on the bone surface.
[0008] Implant fixation components include bone screws, rods and
pegs. Bone screws are used for fixation at one or both ends of a
nail or along a bone plate. Implant fixation components generally
referred to as "pegs" are round unthreaded rods (or threaded at one
end), conventionally formed of metal that are usually (but not
exclusively) used to help anchor bone plates to a bone such as the
proximal humerus or the distal radius for fracture fixation. The
rod goes into a hole drilled into the bone.
[0009] In the art, the entire implant is generally constructed from
metal, such as titanium, stainless steel, or a cobalt-chromium
alloy. Although metallic implants provide numerous advantages, they
also have a few drawbacks. Metal construction normally provides
adequate bending strength, thus reducing problems associated with
implant fracture. However, the rigid metal implant creates a
relative high degree of stresses in certain regions of the bone,
while, on the other hand, does not provide for sufficient load
transfer resulting in stress shielding. Both high stress and stress
shielding can cause bone deterioration and resorption, leading to
areas of bone weakness and loss of bone support for the implant
(e.g., intramedullary nails and stem components of joint
replacement systems). In addition, metals may result in artifacts
in CT and MR imaging. In addition metals can mask (i.e., block)
radiation treatment in cancer cases. Furthermore, metals such as
stainless steel and cobalt chromium may cause biocompatibility
problems related to corrosion and sensitization reaction (mainly
due to allergy to nickel).
[0010] Also, conventional metal fixation components, e.g.,
bone-supporting components (e.g., intramedullary nails and bone
plates) and pegs and screws can mask the fracture and limit the
ability of the surgeon to set the fracture correctly. Metal
bone-supporting components and fixation components may also limit
the ability to see the healing process in X-Rays.
[0011] Non-metal implants made of a lighter and more flexible
material, yet having sufficient strength for load bearing, have
been suggested in the past. In particular, composite material
implants, for example formed of polymer reinforced with fibers, are
disclosed in U.S. Pat. Nos. 4,750,905, 5,181,930, 5,397,358,
5,009,664, 5,064,439, 4,978,360 and 7,419,714, the disclosures of
which are incorporated herein by reference.
[0012] U.S. Pat. No. 5,009,664 describes a tubular, curved marrow
nail, made of carbon fibers, which are preferably knit in a
crisscross fashion, saturated in a hardenable plastic, with a
conically tapered distal tip.
[0013] U.S. Pat. No. 5,181,930 describes an implant comprising an
elongated core formed of continuous filament fibers embedded in
thermoplastic polymer. The core is encased within a filler, made of
a non-reinforced polymer which is molded around the core to
proximate the final desired shape of the implant. A sheath,
composed of reinforced fibers embedded in a polymer, is spiral
wound around the filler, at angles (orientations) which may vary
along the implant axis.
[0014] Although known composite material implant technology can
provide several advantages, there are also some limitations. In
contrast to metal, composite material implants are radiolucent,
i.e., do not block most of the radiation coming from x-ray systems
such as fluoroscopy, and hence their implantation and tracking
during follow-up may be difficult. For bone nails or plates,
accurate insertion of the screws into the holes in the nail/plate
is crucial to the success of the operation, especially where no
aiming device is used.
[0015] U.S. Pat. No. 7,419,714 describes a bone screw or plate
formed of a composite of polymer or ceramic material.
[0016] Currently available bone implants, such as bone plates,
include pre-drilled holes for the fixation devices which anchor the
implant to the bone and optionally lock the implant in place and/or
provide for bone fragments compression.
SUMMARY OF THE INVENTION
[0017] There is provided in accordance with an exemplary embodiment
of the invention, a bone implant component comprising bone plate
formed of a fiber-reinforced polymer composite in which the
reinforcing fibers are along the length of the plate,
[0018] wherein the bone plate is radiolucent.
[0019] In an exemplary embodiment of the invention, the component
includes at least one radiopaque marker that delineates at least
part of the contour of plate. Optionally the marker is comprised of
a metal wire.
[0020] There is provided in accordance with an exemplary embodiment
of the invention, a bone-supporting component formed of a
fiber-reinforced polymer composite configured to be anchored by a
plurality of fixation components received in passages therein,
[0021] wherein at least some features of the component not
preformed so that it may be reconfigured by the surgeon during the
implantation procedure by forming the required features.
[0022] In an exemplary embodiment of the invention, the features
are drilled and/or tapped passages, or cut or sawed portions.
[0023] Optionally or alternatively, the component is further
including at least one built-in reconfiguration guide to facilitate
formation of fixation component passages or for otherwise
reconfiguring the bone-supporting component. Optionally, the
reconfiguration guide includes one or more indentations in the
surface of the component. Optionally, the indentations form blind
holes, or blind slots, or elongated blind grooves, or cutting
lines.
[0024] In an exemplary embodiment of the invention, the component
is further including at least one pre-drilled passage for receiving
a fixation component.
[0025] There is provided in accordance with an exemplary embodiment
of the invention, a fixation component for a bone implant formed of
a fiber-reinforced polymer composite having a body and a head at
the proximal end of the body which is integrally formed with the
body,
[0026] wherein the body includes an elongated portion having
longitudinal reinforcing fibers disposed along its length, and
[0027] the head includes reinforcing fibers disposed mainly in a
circular or spiral pattern.
[0028] There is provided in accordance with an exemplary embodiment
of the invention, a bone implant component, formed mainly of
fiber-reinforced polymer composite material comprising:
[0029] a core including elongated reinforcing fibers to resist
mainly bending forces; and
[0030] a sleeve enclosing the core that includes spirally wound
fibers to resist mainly torsional forces. Optionally, the component
is a bone screw.
[0031] In an exemplary embodiment of the invention, the body
further includes chopped fibers of reinforcing material.
Optionally, the chopped fibers are of different lengths and/or are
non-uniformly oriented.
[0032] In an exemplary embodiment of the invention, the reinforcing
fibers of the sleeve are oriented in a spirally wound layer
oriented at 45 degrees relative to the core.
[0033] In an exemplary embodiment of the invention, the sleeve is
formed of two or more spirally wound layers, with alternating
layers oppositely wound at about .+-.45 degrees relative to the
longitudinal axis of the core.
[0034] In an exemplary embodiment of the invention, the composite
material is in the form of pre-impregnated (prepreg) tapes having
the fibers running length-wise along the tape. Optionally, the
cores are formed by layers of prepreg tape disposed one on top of
the other. Optionally or alternatively, the sleeves are formed of
prepreg tapes, wound spirally over the core.
[0035] There is provided in accordance with an exemplary embodiment
of the invention, a composite implant having fibers having
different mechanical properties disposed at different places in the
implant. Optionally, at least 20% of the fibers used in the sleeve
have different strength in tension and different modulus of
elasticity from fibers are used in the cores.
[0036] There is provided in accordance with an exemplary embodiment
of the invention, a composite bone implant component including at
least one radio-opaque marker located at a distal end of the body,
or extending most the length of the body. Optionally, the at least
one marker is formed of metal wires embedded inside the components.
Optionally or alternatively, the at least one marker is formed of a
hollow tube.
[0037] There is provided in accordance with an exemplary embodiment
of the invention, a bone implant kit comprising:
[0038] a bone-supporting component formed mainly of a
fiber-reinforced polymer composite;
[0039] one or more fixation components for the bone-supporting
component; and
[0040] a radiolucent drill guide to facilitate drilling for
insertion of the fixation components. Optionally, the
bone-supporting component includes pre-drilled passages for the
fixation components so that only the bone needs to be drilled
during the implantation procedure. Optionally, the bone-supporting
component is supplied undrilled, and both the bone and passages for
the fixation components are drilled during the implantation
procedure.
[0041] In an exemplary embodiment of the invention, the
bone-supporting component is a radiolucent bone plate.
[0042] In an exemplary embodiment of the invention, the kit
including an arrangement for removing drilling debris created by
drilling for insertion of a bone implant comprising a suction
element configured for connection to a source of suction and for
disposal of a suction port on the suction element adjacent to a
drill bit during drilling; and
[0043] In an exemplary embodiment of the invention, the kit further
includes an arrangement providing irrigation fluid to a drilling
site comprising an irrigation element configured for connection to
a source of irrigation fluid,
[0044] wherein the irrigation element includes a fluid outlet port
configured to be positioned adjacent to a drill bit during
drilling.
[0045] There is provided in accordance with an exemplary embodiment
of the invention, a fixation component for a bone-supporting
component of a bone implant comprising:
[0046] a body including a core, a sleeve surrounding the core, and
a head portion,
[0047] wherein the body is formed of a fiber-reinforced polymer
composite; and
[0048] a further portion formed of a hard material to strengthen
the implant and/or enhance the hardness of the implant and/or to
impart surface properties.
[0049] In an exemplary embodiment of the invention, the further
portion is a layer covering an elongate section of the body or the
entire body. Optionally or alternatively, the further portion is a
metal coating or a metal tape. Optionally, the fixation component
is threaded at least in its distal region, and the metal coating or
tape disposed over the threads. Optionally, the coating or tape is
discontinuous, and does not cover the root portions of the
threads.
[0050] In an exemplary embodiment of the invention, the coating or
tape is continuous, and a portion covering the crown portions of
adjacent threads extends into and overlaps in the root portions
between the threads. Optionally, at least some overlapping portions
are welded.
[0051] In an exemplary embodiment of the invention, the further
portion is an insert at the distal end of the component.
[0052] There is provided in accordance with an exemplary embodiment
of the invention, a bone implant formed of a fiber-reinforced
polymer matrix composite comprising:
[0053] a bone-supporting component;
[0054] a fixation component configured to be received in passages
in the bone-supporting component; and
[0055] a locking element for attaching the fixation component to a
bone-supporting component.
[0056] There is provided in accordance with an exemplary embodiment
of the invention, a bone implant formed of a fiber-reinforced
polymer matrix composite comprising:
[0057] a bone-supporting component;
[0058] a fixation component configured to be received in a passage
in the bone-supporting component; and
[0059] a sleeve between the fixation component and the passage.
Optionally, the sleeve is configured to reduce friction between the
fixation component and the passage. Optionally or alternatively,
the sleeve is threaded.
[0060] There is provided in accordance with an exemplary embodiment
of the invention, a method of treating a bone fracture
comprising:
[0061] positioning a bone-supporting component at a desired
position in relation to a fracture site,
[0062] wherein the bone-supporting component is formed of a
fiber-reinforced polymer composite manufactured without pre-drilled
passages for receiving fixation components; and
[0063] reconfiguring the bone-supporting component to provide
passages for one or more fixation components or other desired
features by removal of material from the bone-supporting component
before or during implantation surgery. In an exemplary embodiment
of the invention, bone fragments are manipulated while viewing
through the component, for example, using an x-ray imager.
Optionally, the bone-supporting component is reconfigured by one or
more of drilling, or tapping, or cutting, or sawing. Optionally or
alternatively, the reconfiguring is performed using a radiolucent
drill.
[0064] In an exemplary embodiment of the invention, the
reconfiguring is performed before or after the bone-supporting
component is positioned at the fracture site.
[0065] There is provided in accordance with an exemplary embodiment
of the invention, a method of manufacturing a fixation component
for a bone implant comprising:
[0066] compression molding a core of relatively straight elongated
fibers within a polymer matrix; and
[0067] machining the core to form a thread. Optionally, the method
includes forming at least one spirally wound layer over the core.
Optionally or alternatively, the pitch of the spirally wound layer
matches the thread pitch. Optionally or alternatively, the method
includes forming a spirally wound profile layer having a cross
section substantially matching said thread.
[0068] In an exemplary embodiment of the invention, the fixation
component is formed of prepreg tapes of fiber-reinforced polymer
composite. Optionally or alternatively, the method includes forming
an external titanium layer on the fixation component.
[0069] There is provided in accordance with an exemplary embodiment
of the invention, a bone implant component formed of a
fiber-reinforced polymer composite having a body and a head at the
proximal end of the body which is integrally formed with the
body,
[0070] wherein the body includes an elongated portion having
longitudinal reinforcing fibers disposed along its length, and
[0071] the head includes a coupling element for coupling the
component to an insertion tool, and is formed with reinforcing
fibers disposed circumferentially or spirally wound around the
coupling element.
[0072] Unless otherwise defined, all technical and/or scientific
terms used herein have the same meaning as commonly understood by
one of ordinary skill in the art to which the invention pertains.
Although methods and materials similar or equivalent to those
described herein can be used in the practice or testing of
embodiments of the invention, exemplary methods and/or materials
are described below. In case of conflict, the patent specification,
including definitions, will control. In addition, the materials,
methods, and examples are illustrative only and are not intended to
be necessarily limiting.
[0073] Implementation of the method and/or system of embodiments of
the invention can involve performing or completing selected tasks
manually, automatically, or a combination thereof. Moreover,
according to actual instrumentation and equipment of embodiments of
the method and/or system of the invention, several selected tasks
could be implemented by hardware, by software or by firmware or by
a combination thereof using an operating system.
BRIEF DESCRIPTION OF THE FIGURES
[0074] Some embodiments of the invention are herein described, by
way of example only, with reference to the accompanying drawings.
In this connection, it is stressed that particular features shown
in these embodiments are by way of example and for purposes of
illustrative discussion. Other embodiments may include other
combinations of features as will be apparent to those skilled in
the art from the drawings and the accompanying description.
[0075] In the drawings:
[0076] FIG. 1 illustrates a composite material intramedullary nail
connected to an insertion handle, in accordance with some
embodiments of the present invention;
[0077] FIG. 2 is a cross-sectional view of the proximal region of
the nail shown in FIG. 1;
[0078] FIG. 3 is an enlarged perspective view of the proximal
region of the nail of FIGS. 1 and 2;
[0079] FIG. 4 is a side perspective view of a fixation component
according to some embodiments of the present invention;
[0080] FIG. 5 is a cross-sectional view showing schematically a
distal section of a bone nail anchored by a bone screw as
illustrated in FIG. 4, according to some embodiments of the
invention;
[0081] FIG. 6A is a generally side perspective view of a fixation
component with a portion that is oversized relative to a passage in
a bone supporting component;
[0082] FIG. 6B is a perspective view showing schematically the
component of FIG. 6A installed in a bone-supporting component;
[0083] FIG. 6C is a cut-away view of FIG. 6B;
[0084] FIG. 6D is an enlarged side-sectional view of the fixation
component of FIG. 6C;
[0085] FIGS. 7A-7D, FIGS. 8A-8C and FIG. 9 illustrate composite
material bone screws, in accordance with some embodiments of the
invention;
[0086] FIGS. 10A-10D illustrate composite material bone screws
having an external coating according to some embodiments of the
invention;
[0087] FIG. 11, FIGS. 12A-12B and FIGS. 13A-13B illustrate
different composite material proximal femur nail and leg screw
configurations, in accordance with some embodiments of the
invention;
[0088] FIG. 14A is a side elevation view of a bone nail that
provides reinforcement at the interface with a bone screw;
[0089] FIG. 14B shows a side view of FIG.14A, rotated 90
degrees;
[0090] FIG. 15 is a side view, including a portion in schematic
partial section, showing the orientation of reinforcing fibers in
the head of a fixation component formed of a fiber-reinforced
polymer composite according to some embodiments of the
invention;
[0091] FIG. 16A is a side view that schematically illustrates
options for radiopaque marking of a bone screw;
[0092] FIGS. 16B-16C are transverse sectional views that
schematically illustrate options for radiopaque marking of a bone
screw;
[0093] FIGS. 17A and 17B are top perspective and longitudinal
cross-sectional views respectively of a bone-supporting implant
component including one or more blind bores or grooves;
[0094] FIG. 18 is a side and top perspective view of a bone plate
in which the shaft includes round bores and elongated slots, and a
targeting guide which may be used to help drill holes in the bone
plate head and/or the underlying bone;
[0095] FIG. 19 is a top and side perspective view of a bone plate
and a drill sleeve for use in drilling holes for fixation
components, and a drill sleeve holder to assist in insertion and
removal of the drill sleeve;
[0096] FIGS. 20A and 20B top and side perspective and vertical
sectional views respectively that illustrate another drill sleeve
670 according to some embodiments of the invention;
[0097] FIG. 21 is a top and side perspective view illustrating a
combined drill targeting guide and fixation device insertion
accessory according to some embodiments of the invention;
[0098] FIGS. 22A and 22B are schematic top views that illustrate
ways to provide for visualization of bone plates under fluoroscopy
during implantation and/or at follow-up in some embodiments of the
invention;
[0099] FIGS. 23A and 23B are assembled and partially exploded views
of some embodiments of the invention which may be used to share the
loads exerted on the nail-handle connection area during insertion
of the nail into the bone;
[0100] FIGS. 24A and 24B are, respectively, assembled and partially
exploded views similar to FIGS. 23A and 23B showing another nail
installation device 770 according to some embodiments of the
invention;
[0101] FIGS. 25A and 25B are partial cut-away views illustrating a
portion of a radiolucent connector 790, coupled to a drill power
unit 792;
[0102] FIGS. 26A and 26B are schematic sectional views that
illustrate embodiments of the invention in which provision is made
for removal of drilling debris; and
[0103] FIG. 27 shows, in flow-chart form, an example of how methods
according to some embodiments of the invention may be
performed.
DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION
Overview of Features of Some Embodiments of the Invention
[0104] The present invention in some embodiments thereof, relates
to composite material bone implant components, devices and systems,
and to methods for manufacturing and using such components,
devices, and systems, as well as to surgical instrumentation and
procedures used during implantation. More particularly, but not
exclusively, the invention relates to bone-supporting components
such as bone nails and bone plates, to implant fixation components
such as bone screws and pegs formed of fiber-reinforced polymer
matrix composites.
[0105] In the following overview, except as otherwise indicated, it
is to be understood that the implants described are all formed
mainly (e.g., at least 50%, 60%, 70%, 80% or intermediate amounts
of the load bearing portions thereof) of a fiber-reinforced polymer
composite.
[0106] An aspect of some embodiments of the invention pertains to a
bone implant component, e.g., a bone nail, a bone screw, or a peg
formed of a core including different fiber directions and/or types
in different parts thereof. In one embodiment, the implant includes
elongated reinforcing fibers to resist mainly bending forces,
optionally in a core thereof. Optionally or alternatively, bone
nails and screws or other fixation elements such as pegs may also
have a sleeve enclosing the core that includes spirally wound
fibers to resist mainly torsional forces.
[0107] In an exemplary embodiment of the invention, an elongate
implant has a length to width ratio of at least 1:2, 1:3, 1:4 or
more.
[0108] In an exemplary embodiment of the invention, the body
includes chopped fibers of reinforcing material. Optionally, the
chopped fibers are of different lengths and/or are non-uniformly
oriented.
[0109] In an exemplary embodiment of the invention, the reinforcing
fibers of the sleeve are oriented, for example, at about (e.g.,
within 5, 10, 20 or intermediate degrees of) 45 degrees relative to
the longitudinal axis of the core. Optionally, the sleeve is formed
of two or more spirally wound layers, with alternating layers
oppositely wound at, for example, .+-.45 degrees relative to the
longitudinal axis of the core.
[0110] An aspect of some embodiments of the invention pertains to
implant components in which different types of fibers having
different mechanical properties are used in different places in the
implant. For example in a nail, longitudinal fibers having high
elongation at break and low modulus of elasticity may be used in
the core. In the sleeve, low elongation to break and high module of
elasticity, may be preferable so the nail will be elastic for
bending and rigid for torsion.
[0111] Optionally, the polymer forming the matrix in the various
embodiments described above is polyetherketoneketone (PEKK),
polyetheretherketone (PEEK), or any other suitable biocompatible
polymer.
[0112] Optionally, the composite material forming the components in
the embodiments described above is in the form of pre-impregnated
(prepreg) tapes having the fibers running length-wise along the
tape. Optionally the cores are formed by layers of prepreg tape
disposed one on top of the other. In some embodiments of the
invention, the sleeves are also formed of prepreg tapes, wound
spirally over the core.
[0113] In some embodiments, all or part of the bone implant is
coated with a material to improve the implant osteo-conductive
and/or osteo-inductive properties, to enhance implant ability to
integrate in the bone and to support bone ingrowth. Optionally, the
coating is formed of porous titanium or hydroxyapatite (HA).
Optionally, in some embodiments, one or more antibiotics to avoid
infection, and/or bone morphogenetic proteins (BMP) may be added to
the coating in the area of the fracture to promote bone
regrowth.
[0114] Optionally, a polymer layer is a bioresorbable or
biodegradable material. Optionally, the layer is formed of
polydioxanone or polycarbonate. These may be used as a coating on
the inside of the fixation component-receiving passages or on the
entire implant to reduce wear of the composite material during
implantation.
[0115] An aspect of some embodiments of the invention pertains to a
bone-supporting component e.g., a bone nail or bone plate,
configured to be processed during or right before surgery. In one
example, the component is sawn. Optionally or alternatively, the
component is drilled, cut, nibbled, tapped and/or notched or
otherwise has material removed thereof during surgery or right
before. Optionally, the processing is decided based on a CT, X-Ray,
MRI or visual observation of a treated area. Optionally, the
component is modified even after implantation, for example, to add
a fixation element (e.g., a screw) therethrough.
[0116] In an exemplary embodiment of the invention, the component
has a plurality of guide locations or pre-designated locations for
processing, for example, in the form of thinned areas, missing
areas and/or grooves.
[0117] In an exemplary embodiment of the invention, the implant is
a plate or nail which is meant to be anchored by a plurality of
fixation components received in passages therein, in which at least
some passages are not predrilled, and the bone supporting component
is configured so that at least some least some fixation device
passages may be drilled by the surgeon during the implantation
procedure. (For simplicity, these are collectively referred to as
"undrilled").
[0118] Optionally, undrilled components include at least one
built-in reconfiguration guide to facilitate formation by the
surgeon of fixation component passages or for otherwise
reconfiguring the bone-supporting component. Optionally, the
reconfiguration guide is an indentation in the surface the
component defining blind holes, narrow-diameter holes, dimples,
blind slots, elongated blind grooves and/or cutting lines.
Optionally, one or more markers (e.g., visual and/or radio-opaque)
are provided to indicate such desired processing locations.
Optionally, markers are arranged as a grid, optionally
rectangular.
[0119] In another example, a nail or other elongate implant is cut
to length, for example, at one or both ends, to match a particular
patient.
[0120] In an exemplary embodiment of the invention, the implant is
drilled while inside the body. Optionally, suction and/or washing
fluid are provided, for example, for removing debris and/or
cooling.
[0121] In an exemplary embodiment of the invention, the implant
includes at least one attachment location, for example, a hole, for
attaching a drill guide or cutting tool guide thereto, during
processing.
[0122] In an exemplary embodiment of the invention, instructions
for processing are provided on or with the implant, for example, in
a packaging. Optionally, one or more size markings are provided on
the implant to indicate the effect of such processing.
[0123] An aspect of some embodiments of the invention pertains to a
bone implant including a bone-supporting component, e.g., a bone
nail or and a fixation component, e.g., a bone screw, each having a
body and/or a head portion at the proximal end of the body which is
integrally formed with the body. In such embodiments, the bodies
include elongated portions having longitudinal reinforcing fibers
disposed along their length, and the heads include reinforcing
fibers disposed mainly in a different direction, for example, in a
circular or spiral pattern.
[0124] An aspect of some embodiments of the invention pertains to
combination of a bone implant including a bone-supporting
component, one or more fixation components for the bone-supporting
component; and a radiolucent drill guide to facilitate drilling for
insertion of the fixation components.
[0125] Optionally, the bone-supporting component includes
pre-drilled passages for the fixation components so that only the
bone is drilled during the implantation procedure. Optionally, the
bone-supporting component is supplied undrilled, and both the bone
and passages for the fixation components are drilled during the
implantation procedure.
[0126] In an exemplary embodiment of the invention, use is made of
the fact that the composite implant is mainly transparent (e.g.,
blocks less than 5%, 10%, 30%, 50%, 90% or intermediate amounts of
x-ray radiation, depending on the implementation) and bone can be
viewed through it. This allows, for example, reduction of a
fracture, drilling in bone and/or processing an implant while the
implant is in the body and using x-ray (for example) to view the
relative locations of bone fragments and the implant. Optionally, a
plurality of implants are aligned, inside the body to each other
and to bone, using such imaging after implantation. Optionally,
non-radiolucent screws are used with such implants.
[0127] An aspect of some embodiments of the invention pertains to a
fixation component for a bone-supporting component of a bone
implant formed of a body optionally including a core, a sleeve
surrounding the core, and a head portion, and a further element
formed of a hard material to strengthen the implant and/or enhance
the hardness of the implant and/or to impart other desired
properties.
[0128] In an exemplary embodiment of the invention, the further
element is a layer covering the head portion or the entire body.
Optionally or alternatively, the fixation component is threaded at
least in its distal region, and the layer is a metal coating or a
metal tape wound over the threads. Optionally, the layer is
discontinuous, and does not cover the root portions of the threads.
Alternatively, the layer is continuous, and the portion covering
the crown portions of adjacent threads extends into and overlaps in
the root portions between the threads.
[0129] Optionally or alternatively, the layer is provided in a
tool-engaging portion, such as an inner hex-shaped socket or
screwdriver receptacle.
[0130] Optionally or alternatively, the layer is provided at an
interface between a fixation component and a second composite or
other material.
[0131] An aspect of some embodiments of the invention relates to a
method of reducing wear, debris and/or damage in a composite
implant or implant system. In an exemplary embodiment of the
invention, locations prone to wear or damage are covered and/or
provided with a metal or polymer layer or element which provides
reduced friction, reduced wear and/or larger or small (e.g., as
desired) wear particles. In an exemplary embodiment of the
invention, the layer is part of a fixation element or a different
implant. Optionally or alternatively, the layer is a separate
component.
[0132] In an exemplary embodiment of the invention, fiber direction
at a location of expected wear is oriented perpendicular to a wear
direction, so as to reduce damage to an implant.
[0133] An aspect of some embodiments of the invention pertains to
formation of a threaded bone screw by compression molding a rod,
optionally from layered prepreg tapes, followed by machining to
form the threads. Alternatively, over the molded core, there is
formed a spiral winding, optionally formed of one or more prepreg
tape layers, and optionally in which winding pitch matches the
desired screw pitch. Optionally, when two or more layers are used
they are wound in alternating clockwise and counterclockwise
orientations.
[0134] Optionally, the screw is further machined to produce the
desired configuration of the thread teeth. Optionally, a profile
winding, for example that has a relatively triangular cross section
is spirally wound around the core.
[0135] An aspect of some embodiments of the invention pertains to
fixation components including a locking element for attaching the
fixation component to a bone-supporting component. Optionally, the
locking element is a spring constructed and configured to expand
radially to engage within the passage. Optionally, the spring is a
locking ring. Optionally the spring is an integral part of a metal
portion of the fixation component. Optionally, the locking element
is formed by a portion that is oversized relative to the passage.
Such a locking element is compressed during installation, and
re-expands after it exits the distal side of the passage.
Optionally the fixation component is slightly larger than the
passage in the supporting implant, and during insertion, is
compressed locally the supporting implant and lock into it.
[0136] An aspect of some embodiments of the invention pertains to
bone implant components that include radiopaque markers.
Optionally, in the case of the fixation component or a bone nail,
the marker is located at a distal end of the body, or extends most
the length of the body.
[0137] In the case of the bone-supporting component such as a bone
plate including a head portion, the radiopaque marker extends
around at least part (e.g., 10%, 30%, 40%, 60% or intermediate or
greater amounts) of the contour of the head portion or head portion
(e.g., when viewed from a side of the implant). Optionally, the
radiopaque marker extends around the entire contour of the bone
plate. Optionally, the radiopaque marker is on the side of the bone
plate facing outward after implantation. Optionally, the contour
marker is within 1 mm or 0.5 mm, of the outer counter. Optionally,
a marker indicating the projection of the implant is provided as
well, for example, a circle or a square, or an arrangement of
markers whose distortion indicates if the implant is viewed from a
correct direction.
[0138] In some embodiments of the invention, the markers are formed
of metal wires, for example, tantalum, gold, or platinum or similar
embedded inside the components. For example a tantalum wire having
diameter of 0.2-0.5 mm is suitable.
[0139] Optionally or alternatively, the marker comprises a
plurality of markers, for example, beads or wire sections.
Optionally, such markers are used to indicate pre-drilled holes or
slots and/or locations for processing.
[0140] An aspect of some embodiments of the invention pertains to a
bone-supporting component, in which opposite ends of fixation
component passage include reinforcing fibers optionally having
opposite U-shaped configurations to help reduce wear and/or
breakage due to forces from a fixation device.
[0141] Alternatively, the cylindrical part of the body is coated
with a material to reduce friction between the body and the
passage. Optionally, the coating is a polymer, for example Teflon.
Optionally, the coating is a ceramic material, for example
alumina.
[0142] In some embodiments of the invention, there is a bearing,
for example, a hollow cylinder or cylinders, between the passage
and the portion of the fixation component body located in the
passage when the device is implanted.
[0143] Optionally or additionally, the surface of the passage bears
a metal coating to help reduce formation of debris during
implantation.
[0144] An aspect of some embodiments of the invention relates to
drilling and fixation component insertion accessories, optionally
provided in kit form together with one or more implants and/or
fixation devices. Such accessories are optionally configured to be
temporarily attached to the implant components to assist a surgeon
in properly positioning and anchoring the components.
[0145] In some embodiments, the accessories include one or more of
a targeting device for drilling holes to anchor the head of a bone
plate, a drill guide for holes to anchor bone nails, and fixation
component insertion guides, or accessories that incorporate one or
more of the described functions. Optionally, the accessories are
formed of metal, or of a radiolucent material, for example, a
polymer. Optionally, the polymer is fiber-reinforced.
[0146] In an exemplary embodiment of the invention, the accessories
are configured to be disposable after a single use, for example,
due to wear or difficulty in sterilization. Optionally, the
accessories supplied pre assembled with the implant.
[0147] In some embodiments of the invention, a bone implantation
system includes one or more fixation components, one or more
bone-supporting components, and one or accessories, for example, as
described above, and may also include a bone nail insertion support
apparatus that is used to share the loads exerted on the
nail-handle connection interface during insertion of the nail into
the bone.
[0148] In an exemplary embodiment of the invention, the accessories
include one or more radiolucent drill guide, optionally configured
for attachment to the composite bone implant. Optionally, the drill
guides are drilled during or before surgery, at a desired angle of
access for the drill. Optionally or alternatively, the drill guides
are formed, for example, using computer-controlled 3D prototyping
tools, for example, based on one or more 3D CT images.
[0149] In some embodiments of the invention, the system also may
include a radiolucent drill connector, one side of which is
configured for connection to a power unit. The other side is
configured for connection to a drilling tool. Optionally, the
connector includes a clutch arrangement to assure the drill bit
operates only when the surgeon holds the power unit and
intentionally engages the clutch, e.g., by pushing the power unit
toward it. Optionally, the connector (or a drill) is not straight,
so that part of the connector (or drill) is not blocking the view
of an x-ray imager.
[0150] In some embodiments of the invention, the radiolucent drill
is a single use device, having in its proximal side, handle,
electric motor, battery, switch and optionally gear, and in his
distal radiolucent side, radiolucent drill bit connector, and
optionally right angle gear such as bevel gear or worm gear.
Optionally, a radiolucent shaft transmits the torque from the motor
or the proximal gear, between the proximal and the distal sides of
the device.
[0151] An aspect of some embodiments of the invention relates to
drilling passages in the bone-supporting component and/or fractured
bones during an implant procedure while applying suction to aid in
removal of drilling debris and/or irrigating. Optionally, a
drilling instrument or tool is contained within a tube that enables
suction of the drilling debris. Optionally, the drilling tool is
cannulated and suction is performed through the cannulation.
Optionally, the suction is performed directly through the
cannulation. Optionally, the suction is performed through a
separate tube located in the cannulation.
[0152] In some embodiments of the invention, the drilling site is
irrigated, e.g., with sterile saline solution during drilling.
Optionally, with a cannulated drilling tool, the cannulation is
used to provide the irrigation fluid, and an external tube provides
the suction. Optionally, the cannulation is used to provide the
suction, and an external tube provides the irrigation fluid.
Optionally, the external tube surrounds the drilling tool.
Optionally, the external tube is completely separate, and is
positioned adjacent to the drilling tool.
[0153] In some embodiments of the invention, where the drilling
tool is not cannulated, separate tubes, either surrounding the
drilling tool, or adjacent to it are used to supply irrigation
fluid and for suction.
[0154] In some embodiments of the invention, irrigation is not
employed, and suction of drilling products is performed
simultaneously from the drilling tool cannulation (with/without an
internal suction tube) and from an external suction tube.
[0155] The irrigation can help cool the implant and surrounding
tissue while drilling is being performed, for example, to reduce or
avoid the risk of damage of patient tissue and/or devices.
[0156] In some embodiments of the invention, a bone implant device
include fixation components and bone-supporting components having
various combinations of features as described above, and as
described in detail below.
[0157] In some embodiments of the invention, implant kits include
fixation components and bone-supporting components and accessories
having various combinations of features, also as described above,
and as described in detail below.
Exemplary Bone Nail Embodiments
[0158] FIG. 1 illustrates schematically in a side view, a
bone-supporting component of an implant, intramedullary nail 10,
for example a humeral nail, connected at its proximal end 12 to an
insertion handle 14. Illustrated nail 10 is configured for use in
treating humeral fractures. However, it should be understood that
this and other embodiments are applicable to other intramedullary
nails as well, such as nails for tibia bones, femur bones, or other
bones. Typically nail 10 is between about 7 and about 12 mm in
diameter. In some embodiments of the invention, the radiolucent
drill is a single use device, for example, having in its proximal
side, handle, optionally electric motor, optional battery, switch
and optionally gear, and in his distal radiolucent side,
radiolucent drill bit connector, and optionally right angle gear
such as bevel gear or worm gear. Optionally, a radiolucent shaft
transmits the torque from the motor or the proximal gear, between
the proximal and the distal sides of the device.
[0159] The proximal region 13 of nail 10 includes two holes 15, 17
positioned in the same orientation for the insertion of screws that
fix the nail to the bone. The distal end 29 of nail 10 includes
three additional holes 19, 21, 23 for bone screws. Other
configurations, numbers, and orientations of screw holes may
alternatively be provided.
[0160] Radiopaque markers 25, 27, optionally made of tantalum or
other suitable metal, are provided near each screw hole to assist
in drilling and screw placement. These are illustrated as
diametrically opposite dots, but can have other configurations, for
example, circles around the holes. Suitable radiopaque materials
include tantalum, gold, platinum, or other biocompatible metal.
[0161] As will be understood, nail 10 is configured to be inserted
into the medullary canal by the surgeon during the implant
procedure with the assistance of insertion handle 14.
[0162] Insertion handle 14 is an example of a suitable device for
performing the actual insertion. Handle 14 comprises a curved
portion 16 and a straight tube 18, which engages with the proximal
end 12 of nail 10. Curved portion 16 is optionally formed of metal
but is preferably formed of composite material to reduce
interference with radiographic visualization during
implantation.
[0163] The process of insertion of nail 10 into the bone may
involve manipulation of the nail-handle assembly and thus may
impose bending and torsional forces on the nail. Therefore, an
inner rod 24, optionally formed of metal, for example, surgical
grade stainless steel is temporarily installed between nail 10 and
handle 14, to strengthen the connection area for bending. Rod 24 is
introduced via a cannulated nail adapter 20 which may be part of
handle 14, or a separate element.
[0164] As shown in FIG. 2, rod 24 is configured to penetrate into a
bore 34 at the proximal end of the nail. Optionally the diameter of
the bore 34 is in the range of 2 to 5 mm. Optionally, rod 24
extends beyond the proximal hole 15 in the nail. Following nail
introduction part way into the bone, the inner rod 24 is
removed.
[0165] According to bench testing performed by the inventors, inner
rod 24 improved the bending properties of the nail-handle
connection area.
[0166] FIGS. 2 and 3 are respectively enlarged sectional and
perspective views of the proximal region 13 of the nail 10
illustrated in FIG. 1. As shown in FIGS. 2 and 3, the nail includes
a threaded end-portion 30, to which the nail adapter 20 is
connected, and a connection detail 32 at proximal end 12 having
slots 40 configured to engage matching protrusions at the end of
insertion tube handle tube 18 when it is connected to the nail 10
(see also FIG. 3).
[0167] One or more radial slots and complementary teeth may be
provided. However, according to bench testing performed by the
inventors, increasing the number of the slots in the connection
detail (and the complementary teeth at the handle end), leads to
improved torque transfer.
[0168] By way of example, as shown in FIG. 3, connection detail 32
includes seven radial slots 40a, 40b, 40c, etc., although other
numbers and shape of slots are also feasible. Optionally, the slots
40 are positioned so that the distance between at least two
adjacent slots 40a and 40b is different than the distance between
other adjacent slots, thus providing only a single orientation of
connecting the nail to handle 14, and helps assure introduction of
the nail into the bone in the correct orientation.
[0169] The connection detail 32 (shown enlarged in FIGS. 2 and 3)
may optionally be produced by machining or during the compression
molding process by which the composite nail is formed. Forming
connection detail 32 by compression molding may be advantageous in
terms of cost reduction.
[0170] FIG. 3 also illustrates the proximal end 12 of a composite
material humeral nail 10. By way of example, the diameter of nail
proximal region 13 may be in the range of about 10 to 12 mm for a
nail shaft 38 having a diameter in the range of about 7 to 9 mm.
The nail is connected to its insertion handle via a thread (not
shown) at its proximal end.
[0171] FIGS. 2 and 3 also show screw holes 15, 17. Holes 15, 17 may
be threaded, or optionally, they may be unthreaded. A radiopaque
marker 36 is also shown at the proximal end of the nail.
[0172] Following nail implantation, a nail cap (not shown) may be
introduced (e.g., screwed) into the threaded bore 30 at nail
proximal end, in order to prevent bone growth into bore 30.
Pre-Drilled and Undrilled Bone-Supporting Component
Configurations
[0173] In FIGS. 1-3, bone nail 10 is shown with the passages for
the bone screws pre-drilled during manufacture. In some embodiments
of the invention, however, the bone nail, and also bone plates as
described below, are supplied undrilled, or optionally, with a few
screw holes or other passageways, for example, for initial
anchoring. The reconfiguration guides facilitate formation during
the implantation procedure of passages in the bone-supporting
component for the fixation components or for otherwise shaping the
bone-supporting component at the optimum locations and orientations
for the particular fracture and patient anatomy. In addition,
especially where small implants are involved, the option of not
having unnecessary screw holes may contribute to the strength of
the bone-supporting components.
[0174] Optionally, undrilled bone-supporting components include
built-in reconfiguration guide areas e.g., indentations or
depressions in the component surface that form blind grooves or
slots, or blind holes or cutting lines. These built-in
reconfiguration guides help prevent sliding of the drilling tool,
particularly as a hole is started. Optionally, the implant is
provided with several such reconfiguration guides located at
positions in the implant that would not compromise the required
implant biomechanical properties following drilling, for example,
along the center line of the nail shaft or bone plate.
[0175] Exemplary built-in reconfiguration guides are described
further below.
Exemplary Composite Materials
[0176] In some embodiments of the invention, bone-supporting
components and fixation components as described herein are formed
of fiber reinforced polymer matrix composites. As an example, the
composite material may be a fiber-reinforced polymer matrix, in
which the polymer matrix is formed of polyetherketoneketone (PEKK),
polyetheretherketone (PEEK), or other suitable polymers).
[0177] The reinforcing fibers may alternatively be formed, for
example, of carbon or of a ceramic material, such as glass. The
fibers may be of a diameter in the range of about 5 to about 10
microns for carbon fibers. Optionally, the carbon fibers are AS4,
IM7, or IM10 Made by Hexcel Inc. Stamford Conn., U.S.A. Carbon
fibers may optionally constitute about 60% to about 70% by volume
of the composite.
[0178] Elongated components such as pegs, screws, and bone nails
are optionally formed with a core in which the reinforcing fibers
run longitudinally to resist mainly bending loads, and a sleeve
enclosing the core, formed of one or more spirally wound layers for
resisting mainly torsional loads. The core diameter is selected
according the specific application of a particular implant.
[0179] Optionally, the sleeve is formed of two or more oppositely
wound helical layers, for example, in which adjacent layers are
wound at .+-.45 degrees relative to the core longitudinal axis.
Winding over the core at .+-.45 degrees provides for maximal
torsional stiffness (compared to other degrees of winding), as the
fiber strain in those configurations is maximal per torsional angle
of the nail.
[0180] Optionally, an additional outer layer is provided, as
described below.
[0181] According to some embodiments, the core and the sleeve are
constructed from pre-impregnated (prepreg) tapes of carbon
fiber-reinforced polymer, preferably a thermoplastic polymer such
as PEEK.
[0182] The prepreg tapes are available in the form of straight
layers, during winding of each prepreg tape, the radius of
curvature of the tape changes to conform to the winding diameter of
the core. During winding, the filaments at the inner portion of the
tape (i.e., with the smallest radius) become slightly folded. Thus,
upon application of torsion, the filaments at the outer portion of
the tape are stretched and can resist the torsional moment, while
the inner filaments are not yet stretched. The inner filaments are
only under tension upon exertion of higher torsional moments. In an
embodiment of the invention, reducing the thickness (height) of the
prepreg tape results in winding in which substantially more fibers
are stretched earlier (i.e., upon application of lower torsional
moment), and thus more efficient torsional stiffness is achieved.
Optionally the thickness of the prepreg for winding is in the range
of 0.05 to 0.2 mm, preferably 0.1 mm or less.
[0183] In an embodiment, the entire thickness of the winding
(sleeve) remains substantially the same, while the thickness of
each wound tape is decreased and the number of wound tapes is
increased. Alternatively, decreasing the tape thickness, and thus
improving the torsional stiffness, enables reducing the thickness
of the winding sleeve on one hand, and increasing the diameter of
the bone implant device longitudinal core (without increasing the
diameter of the entire device), on the other hand. Therefore, this
feature may contribute not only to the torsional stiffness of the
device, but also to its bending performance.
[0184] The tapes intended for winding over a component core may
also be manufactured as a helix, with the same (or approximate)
radius of curvature of the required final winding radius.
[0185] Further exemplary details concerning the nature and use of
prepreg tapes may be found in International Application
PCT/IB2010/050225 which is incorporated herein by reference.
[0186] In some embodiments of the invention, at least some of the
individual reinforcing fibers are at least partially coated. Such a
coating can improve the strength of the implant, and/or may improve
adherence of the polymer to the reinforcing fiber element. In an
exemplary embodiment of the invention, a metal coating, for
example, a titanium coating is used. In another exemplary
embodiment of the invention, carbon with different crystalline
properties (e.g., diamond, graphite, amorphous carbon, etc.), is
used to coat the reinforcing fibers within the polymer matrix
and/or the entire implant (for example, a diamond-like carbon
coating). In an exemplary embodiment of the invention, the coating
layer thickness is, for instance, less than 0.1 micron. In an
embodiment, the coating totals in a relatively small amount of
material, which does not adversely affect the implant properties
under MR/CT imaging.
[0187] In some embodiments of the invention, different types of
carbon fibers may be placed in different places in the implant to
get advantage of different properties and/or different cost of the
fibers. For example, fiber IM10 is stronger in tension 6,964 MPa
compared to fiber AS4: 4,500 MPa but fiber IM10 is also less
flexible having tensile module of 303 GPa relative to 231 GPa of
fiber AS4. Accordingly in implant such as but not limited to nail,
screw or plate, to get more flexibility for bending fiber type AS4
may be used in the core, and to get more torsional stiffness, IM10
will be used for the winding.
[0188] Typically, the polymer matrix is the weakest element in the
composite. Optionally, the matrix may therefore include chopped
fibers of carbon or other reinforcing material, which may improve
bending performance. Optionally, the chopped fibers have different
orientations in the matrix. Optionally, the chopped fibers are of
various lengths within a range of about 0.1 to about 3 mm, and may
constitute between about 1% and about 10% of the composite volume.
The chopped fibers may be embedded into the prepreg tape, during
manufacturing of the prepreg.
[0189] Alternatively chopped fibers may be added between the layers
of the prepreg. Optionally, polymer material may be removed from
the prepreg tape by heat and pressure.
[0190] Prepreg tapes are normally available in thickness not
smaller than 0.2 mm. When calculating the strain required to
initiate tension in the filaments at the inner portion of a tape
with thickness of 0.2 mm which is helically wound (at 45 degrees)
over a longitudinal core having a diameter of 8.5 mm, the strain is
2.3%. The strain at failure for a carbon fiber such as HEXCEL IM7
is about 1.9%. This means that for a tape of 0.2 mm thickness, the
fibers in the outer surface of the tape are torn while the inner
layer of the tape has not yet straightened and thus has not yet
participated in the winding resistance to torsion.
[0191] Similar calculation for tape thicknesses of 0.1 mm and 0.05
mm results in strain values of 1.1% and 0.58%, respectively. In an
embodiment of the invention, the ratio between the diameter of the
device longitudinal core and the thickness of the helical tape is
larger than 40, optionally larger than 70, optionally larger than
100 or 150. Strain at failure is the strain at which the fiber
breaks. Using small thickness prepreg tape, and more windings, will
share the stress along all the cross section area of the tape, and
add torsional strength.
Exemplary Bone Screw and/or Peg Embodiments
[0192] FIG. 4 is a generally side perspective view that illustrates
an example of a fixation component 100 which may be used as a peg
or screw to anchor a bone-supporting component such as a bone
plate, or as a bone screw for a bone nail. One or more pegs or
screws 100 are configured to extend through passages in a bone
plate, and into holes drilled in the bone under the plate, as
described below.
[0193] Bone screws and pegs are optionally formed of the same
materials as the bone nails described in connection with FIGS. 1-3,
and/or by a similar compression molding process, except that pegs
do not need a sleeve to resist torsional forces.
[0194] Optionally, the composite material bone screw also comprises
material that reduces the friction with the bone. Examples of such
material are SiO2, PTFE, etc. The material may be added as powder,
particles and/or other forms. Metal particles, such as titanium,
may also be added to increase the device strength and to provide
visualization under imaging (e.g., fluoroscopy).
[0195] FIG. 5 illustrates in a schematic sectional view use of
component 100 specifically as a bone screw for an intramedullary
nail 106. Bone screw 100 is configured to attach to a bone 104 on a
proximal side 104a, to extend through a passage 105 in a bone nail
106, and to attach to the bone at 104b on the side opposite to the
bone nail. The passage 105 may be round as shown in FIGS. 1-3, or
one or more passages may also be formed as longitudinal slots (no
shown) to facilitate longitudinal positioning, for example, of a
bone nail, which is then optionally firmly anchored by screws in
round holes.
[0196] Referring still to FIGS. 4 and 5, fixation component 100
includes an attachment element, e.g., a threaded proximal end 102,
configured to engage with the outer surface of a bone plate, or the
proximal side 104a of a bone 104 in which a bone nail 106 has been
implanted.
[0197] As further illustrated in FIGs, 4 and 5, the distal end 112
of body 108 is also optionally threaded. In the case of a bone
screw, threads 112 engage with bone 104 on the distal side 114 of
bone nail 106 at 104b (see FIG. 5) to immobilize bone nail 106 in
the desired location and orientation, which are determined by the
surgeon when the bone is drilled. Optionally, in the case of a bone
peg, distal end 112 may be unthreaded. Optionally, threaded
proximal end 102 may be replaced or supplemented by a locking
element on body 108 that engages with the passages in the bone
nail.
[0198] At the proximal end 116 of fixation component 100, a
coupling element 118 is provided for engaging an insertion tool.
Coupling element 118 is shown as a hexagonal recess 120 in a screw
head 121, but any other suitable and desired shape, for example,
Phillips head, axial crown, slotted, hexalobe, etc. may
alternatively be provided. Recess 120 may alternatively be
internally and/or externally threaded. As will be understood, the
configuration of recess 120 optionally matches the connation end of
the insertion tool.
[0199] Referring still to FIGS. 4 and 5, the head 121 and body 108
may be an integral structure formed, for example, by compression
molding of the fiber-reinforced polymer composite material.
Alternatively, head 121 may be formed a suitable biocompatible
metal such as stainless steel or titanium into which composite body
108 is molded.
[0200] Friction forces associated with body loads can sometimes
lead to abrasion at interfaces between the bone nail and the bone
screw which produces polymer and/or fiber debris. To minimize or
avoid this, the fixation components are advantageously constructed
to reduce friction between the fixation components and the passages
in the bone-supporting components. Alternatively or additionally,
the components may be fabricated to have sufficient strength to
resist the forces at the interface.
[0201] One way to accomplish this is shown in FIG. 5, in which one
or more sleeves 122 are fitted into passage 105 in bone nail 106.
Sleeve 122 may be used to change the type of friction in the
interface from sliding friction to rolling friction. This
arrangement is particularly, but not exclusively, suitable for bone
nails and bone screws, where the bone screws are anchored at one or
both ends in the bone.
[0202] Additionally, or in the case of pegs, alternatively,
resilient locking elements may be provided. These are coupled to
the body, and configured to engage the passages only over a small
area and thereby reduce wear and creation of debris.
[0203] Locking elements may take various forms, among which are
spring elements coupled to the fixation component, and constructed
and configured to expand radially to engage with the passage upon
insertion.
[0204] One suitable arrangement is shown in FIG. 4. As illustrated,
at the distal end of proximal threaded portion 102, there is a
groove 124 in which a resilient split ring element 126 is
positioned. This can be formed of any suitably strong and resilient
material, including but not limited to a reinforced polymer
composite material. As will be understood, split ring 126 is
compressed in the passage in the bone-supporting component so that
the restoring force anchors the fixation component.
[0205] Another suitable arrangement is shown in FIG. 6A. Here,
fixation component 300 is free of threads in its proximal region
304 and is threaded only at its distal region 306. Locking element
308, also in the form of a resilient split ring, is fitted in a
groove 320 at the proximal end of the threaded portion 306.
[0206] Another locking arrangement for use with pegs and/or bone
screws is illustrated in FIGS. 6B-6D. In contrast to fixation
components 100 and 300 shown in FIGS. 4 and 6A, fixation component
300A includes an enlarged thread 309 installed in bone-supporting
component schematically illustrated at 311. FIG. 6C is a cut-away
view of FIG. 6B, and FIG. 6D is an enlarged sectional view of FIG.
6C.
[0207] As illustrated in FIG. 6D, a thread 309 at the proximal end
of threaded portion 306 is made oversize relative to the other
threads and relative to the passage 310 in bone-supporting
components 311 so that the composite material of the enlarged
thread(s) must compress as it is installed through passage 310.
[0208] In some other embodiments, a bone screw may be metal-coated,
or coated with a polymer such as a bioresorbable or biodegradable
material to reduce wear during implantation, or for other purposes,
as in the case of bone nails, and employing the same coating
materials.
[0209] For example, coating may be provided to strengthen and/or
improve the hardness of the implant. In an exemplary embodiment of
the invention, the screw is coated with one of the following
materials: titanium nitride (TiN) [E. Lugscheider, S. Barwulf, M.
Riester, H. Hilgers, Magnetron sputtered titanium nitride thin
films on thermoplastic polymers, Surface and Coatings Technology
116-119 (1999) 1172-1178; and H. S. Kim, H. J. Jung Kim, Detorque
force of TiN-coated abutment screw with various coating thickness
after repeated closing and opening, J Korean Acad Prosthodont:
Volume 45, Number 6, 2007], titanium aluminum nitride (Ti--Al--N),
diamond like carbon (DLC), ceramic material or other suitable
material. In an embodiment of the invention, the coating is
performed using physical vapor deposition (PVD) technique
[Rahamathunnisa Muhammad Azam, Mari Tanttari, Tommi Kaariainen,
David Cameron, Coatings on Composites, Lappeenranta University of
Technology, Faculty of Technology, Department of Mechanical
Engineering, Research Report No. 74, ISBN 978-952-214-504-8, ISSN
1459-2932, Mikkeli 2007], optionally following preparation of the
surface of the implant (e.g., grid blast, bombardment of argon
ionized ions, etc.). In an embodiment of the invention, more than
one material is used for the coating, for example a first coating
layer of titanium and a second coating layer of ceramic material.
In an exemplary embodiment of the invention, the thickness of the
coating layer is in the range of a few microns. In an embodiment of
the invention, coating of the bone implant is conducted in order to
improve the implant osteo-conductive and/or osteo-inductive
properties, thus to enhance implant ability to integrate in the
bone and to support bone ingrowth. Such coating may be, for
example, porous titanium or hydroxyapatite (HA). In an embodiment,
the coating is added using a vacuum plasma spray (VPS) technique,
optionally following preparation of the surface of the implant [as
described, for example, in S. W. Ha, A. Gisep, J. Mayer, E.
Wintermantel, H. Gruner, M. Wieland, Topographical characterization
and microstructural interface analysis of vacuum-plasma-sprayed
titanium and hydroxyapatite coatings on carbon fibre-reinforced
poly(etheretherketone), Journal of Materials Science: Materials In
Medicine 8 (1997) 891-896; and S. Beauvais, O. Decaux, Plasma
Sprayed Biocompatible Coatings on PEEK Implants].
[0210] With any of the spring locking arrangements described, and
the arrangement of FIGS. 6A-6D, a mechanism is optionally provided
for removing the fixation component if necessary. One suitable way
is shown in FIG. 6A. Here, head 314 includes a plurality of notches
316 at the proximal end 318 of head 314 in which a removal tool may
be engaged.
[0211] FIGS. 7A-7D illustrate other exemplary embodiments of
composite material bone screws. FIG. 7A shows a side elevation of a
bone screw 140; FIG. 7B is a proximal end perspective view of FIG.
7A. FIGS. 7C-7D are schematic sectional views of the distal region
141 of bone screw 140.
[0212] Screw 140 comprises a head 142 at its proximal end, with
connection means to engage with insertion/removal instruments (not
shown). Connection means may be of any conventional shape, for
example, an internally or externally threaded hexagon, Phillips
head, axial crown, slotted, hexalobe, etc. The hexalobe
configuration may be advantageous in resisting damage due to
application of torsion by the insertion device.
[0213] The distal end 144 of screw 140 is tapered 144 and comprises
cutting edges 150 to provide for self-tapping. The screw 140 also
comprises thread 146 at a desired pitch along its length. The screw
140 is made, for example, from a fiber reinforced polymer, a
material that is radiolucent under imaging such as fluoroscopy, as
described in more detail below.
[0214] FIG. 7B illustrates a screw that comprises a core 112 made
of relatively straight elongated fibers 114 within polymer matrix
116. In an exemplary embodiment of the invention, the screw is
manufacture in two main steps--compression molding, during which a
composite material rod is generated, and machining, during which
the screw thread 118 is created. As can be seen in the figure, the
fibers in the thread 120 are cut due to the machining process.
Having only straight longitudinal reinforcing filaments at its core
contributes to the screw bending properties. On the other hand, the
short, non-sequential fibers at the screw thread compromise the
thread resistance to shear forces. Therefore, this combination of
screw features may be beneficial for screw applications that mainly
require bending strength, such as screw intended to interlock an
intramedullary nail.
[0215] FIG. 7C illustrates a screw that is entirely (i.e.,
including its thread 122) produced by compression molding. In some
embodiments, a fiber reinforced polymer material, for example in
the form a rod, is pressed (under heat and pressure) into a mold
that forces the material to fold at and into designated areas
(e.g., the thread areas), thus creating a thread 122. This
optionally results in a composite material screw that comprises
folds of the elongate fibers 124 and fibers 126. This screw
configuration may be beneficial for applications that require high
pullout strength forces but less bending strength, for example,
screws used with bone plates, as described below.
[0216] FIG. 7D illustrates a screw that comprises a core 128 made
of relatively straight elongated fibers 130 within polymer matrix
132, produced, for example, by compression molding. Over core 128,
a helically winding 134 in one direction of fiber reinforced
polymer is added, optionally in a manner in which winding pitch is
equivalent with the desired screw pitch. Optionally, the helical
winding 134 is made of prepreg tape/s of fiber-reinforced polymer,
so that tape width is compatible with the desired width of the
screw teeth. Optionally, the screw is further machined to produce
the desired configuration of the thread teeth 136. Optionally, a
profile winding 134, for example that has a relatively triangular
cross section is helically wound around the core 128. Such a thread
may be advantageous, for instance, upon threading of the screw into
the cortical bone.
[0217] Optionally, in embodiments illustrated in FIG. 7D, two
helically wound tapes may be employed. Optionally, one is wound
clockwise and the other counterclockwise for example, at .+-.45
degrees relative to the longitudinal axis of the core.
[0218] When assessing the above-described screw designs, it is
expected that a screw which comprises a core of straight
longitudinal reinforcing filaments and machined thread, may be
beneficial for applications requiring mainly bending strength, such
as for screws intended to lock intramedullary nails to the
bone.
[0219] The screw produced by axially pressing comprises folded
reinforcing fibers in its core, and thus may have lower bending
performance, however, the resistance of its thread to shear forces
may be enhanced (as the reinforcing fibers at the thread are not
damaged during manufacturing, and therefore may be preferred when
high pullout strength is required). This screw design may be
preferred, for example, for screws intended to lock plates to the
bone (where screw pullout from the bone is the failure mode).
[0220] The screw thread created with profile winding is expected to
be advantageous during threading of the screw into the cortical
bone, as the orientation of the fibers in the thread component in
this screw design matches the thread pitch, and thus provides for a
strengthened thread with potential for less wear upon screw
threading.
[0221] Reference is now made to FIGS. 8A-8C, which schematically
illustrate a bone screw 160 having a separate distal end component
162 made of a material that is harder than body 164 of the screw
160 and optionally harder than cortical bone. FIG. 8A illustrates
assembled bone screw 160, while FIGS. 8B and 8C illustrate the bone
screw components164 and 162, respectively, prior to their
assembly.
[0222] The distal end component 162 may optionally be made of
ceramic material, such as zirconia which also does not interfere
during MRI, or a metal such as titanium. Screw body 164 is formed
from fiber-reinforced composite material as described above.
Optionally, the body is formed using the distal end as a mold.
[0223] Enhanced distal-end hardness may be useful to improve
self-tapping capability, and/or to reduce the possibility of damage
to the distal end during screw introduction into the bone.
[0224] As shown in FIGS. 8B and 8C, the interface 166 between the
distal end component 162 and the screw body 164 is optionally
configured to provide for torsion transferring while preventing the
distal end component 162 from tearing off the screw body 164.
Interface 166 is shown as hexagonal, but optionally, other
non-circular geometric shapes may be employed.
[0225] Optionally or additionally, distal end component 162
includes undercut portion in the internal side of this bore to help
assure firm connection of the distal end component 162 to the screw
body 164. By melting the composite into the undercut, 162 will be
axially locked into 164.
[0226] FIG. 9 illustrates another embodiment of a bone screw 170 in
which a distal end 172 exhibits enhanced hardness and self-tapping
capability. Here, distal end 172 includes one or more inserts, one
of which is shown at 174, that serve as the thread-cutting tool.
Insert(s) 174 are made of material with higher hardness than that
of the rest of the screw and than that of the cortical bone, for
example ceramic or metal material. Connection of the insert to the
screw is achieved using adhesion means and/or (optionally) a
non-circular geometric connection that prevents tear-off of the
insert from the screw.
[0227] FIGS. 10A-10D schematically illustrate other embodiments of
a composite material screw exhibiting enhanced hardness. FIG. 10A
is a schematic longitudinal cross-section of one such embodiment.
Optionally, as shown in FIG. 10A, in cases where the coating
material has a limited elongation before break, the coating over
screw 250 is not continuous, but rather limited to the crown
portions of threaded teeth 254, i.e., the thread portions that
penetrate into the bone, while the root areas 256 between the teeth
are not coated.
[0228] Discontinuous coating may be also applicable to other
portions of a composite implant.
[0229] FIG. 10B is a side elevation view of a screw that is a
variation of the screw of FIG. 10A, generally labeled 280. FIG. 10C
is a cross-section of a FIG. 10B taken along line A-A. FIG. 10D is
an enlarged view of area B in FIG. 10C. Screw 280 differs from
screw 250 in that the entire length of screw 280 is covered by a
coating 282. This may be desirable to increase the hardness of all
the screw parts that may be in contact with bone. Optionally, the
coatings of root portions 284 between the threads are overlapped,
as indicated at 286, for example, by extensions of the coatings of
the adjacent crown portions of the thread, or by overlapping the
tape as it is wound over the threads. Optionally after winding the
metal tape with overlap 286, the internal and external side of the
overlap may be welded at least partially along the spiral overlap.
Optionally the tape is welded using a pulsed laser or a continuous
laser beam.
[0230] FIG. 11 schematically illustrates a portion of a proximal
femur implant 180, including the stem 182 of an intramedullary
femoral nail 183, and a leg screw 184. The nail 182 is inserted
into the medullary canal of the femoral bone, and the leg screw 184
is introduced, via a passage 188 in the nail 182, into the femoral
neck and head of the bone. The proximal femur implant 180 is
intended to treat or help prevent fractures in the proximal area of
a femoral bone. The components of implant 180 are made of a fiber
reinforced polymer composite material, optionally including other
materials, such as metal (for example, titanium), and/or are coated
with a non-composite material as described above.
[0231] At its proximal end 186, nail 183 comprises a connector,
e.g., an internally threaded portion, configured to engage with an
insertion tool, and, after insertion, to receive an end cap to seal
the proximal end and prevent bone ingrowth.
[0232] Along its distal region 185, nail stem 182 may be tapered.
In its proximal region, in addition to passage 188 for bone screw
194, there may be provided one or more additional passages for
additional bone screws or bone pins. These may be oriented
transversely relative to nail stem 182, and function to lock the
nail to the bone and/or to provide additional rotational
stability.
[0233] Passage 188 is threaded, along at least part of its length,
shown at 190, which is configured to engage a complementary thread
192 at the proximal end 194 of the leg screw 184. The distal end
196 of the leg screw 184, which is inserted into the femoral head,
is threaded at 198, to allow firm fixation within the cancellous
femoral head. The thread 198 may be self-tapping. Optionally, the
distal thread 198 and the proximal thread 192 of the leg screw 184
have the same pitch. The leg screw 184 may be cannulated (not shown
in the figure), to allow its introduction into the bone over a
guide wire. At proximal end 194, the leg screw 184 comprises a
connector (not shown in the figure), configured to engage with the
screw insertion tool. Optionally thread 198 may be coated with
metal.
[0234] The different threads of the implant 180 may be produced
using various processes, such as machining, axial pressing, and/or
profile winding, as in previously described embodiments.
[0235] FIGS. 12A and 12B are side elevation and longitudinal
cross-section views, respectively, representative of some
embodiments of a composite material proximal femur implant,
generally illustrated at 200. Implant 200 comprises an
intramedullary femoral nail 202, and leg screw 204 which is
inserted into the femoral neck and head through a passage 212.
Implant 200 also includes a sleeve 206, located in passage 212
between nail 202 and leg screw 204.
[0236] At its proximal end 208, nail 202 includes a coupling
element 210 element similar to the one described in FIG. 3
configured to engage an insertion tool. In some embodiments,
proximal end 208 is internally threaded to receive an end nail cap
as in the embodiments described in connection with FIG. 11.
[0237] Along its distal region, nail 202 may be tapered as in FIG.
11. Passage 212, at least along part of its length optionally
includes a threaded portion 214 configured to engage a matching
thread on the outer surface of the sleeve 206. Sleeve 206 enables
sliding of the leg screw 204 in relation to the nail 202. This
arrangement is intended to prevent a phenomenon called cut-out,
referring to the subsidence of the femoral head and protrusion of
the leg screw out of the femoral head.
[0238] The sliding of the leg screw 204 in sleeve may optionally be
limited, for instance by a tool inserted from nail proximal end 208
and engages a locking element 216 that limits the leg screw 204
movement to a pre-defined travel. Locking screw 216 is passing
through a window in sleeve 206, and enters a slot in the leg screw
204. The length of the slot limits the sliding.
[0239] Reference is now made to FIGS. 13A and 13B, which are side
elevation and longitudinal cross-sectional views, respectively, of
a composite material proximal femur implant 230. The implant 230
comprises an intramedullary femoral nail 232, a leg screw 234 and a
sleeve 236, located between the nail 232 and the leg screw 234.
Implant 230 is generally similar to implant 200 described in
connection with FIGS. 12A and 12B, and the details will not be
repeated in the interest of brevity.
[0240] Implant 230 differs from implant 200 mainly in that sleeve
236 is longer than nail passage 242. Optionally, the sleeve 236
protrudes from both ends of the nail passage 242. Having a longer
sleeve may be advantageous in some embodiments, as the leg screw
234 experiences lower bending moment in this configuration.
[0241] Various embodiments of implants 180, 200, and 230 share
several features. For example, one or more of the following
features may be provided in the implants described herein or in
other composite implants:
[0242] a) leg screws 184, 204, and 234 may be cannulated, to allow
introduction into the bone over a guide wire;
[0243] b) at their respective proximal ends, the leg screws include
connectors configured to engage with screw insertion tools;
[0244] c) implants 180, 200, and 230 are made of a composite
material, as detailed above, and may optionally include metal
components and/or may be partially or completely coated with metal
or other non-composite material;
[0245] d) sleeves 216 and 236 may be made of metal such as
titanium, ceramic material, or composite material with reinforcing
fibers oriented and/or configured to carry the load exerted on the
bone, as described in connection with FIGS. 12A and 12B.
[0246] e) nails 183, 202, and 232 may include additional passages
(not shown), configured to accept anti-rotational pins. These may,
for example, be of smaller diameter than the passages for the bone
screws, and may be located parallel to- and above the respective
leg screw passages.
[0247] f) the longitudinal stem of the nail may be expanded
following its introduction into the medullary bone canal, in a
manner that allows abutment of at least part of nail outer surface
to the inner wall of the bone canal for example, in a similar
manner to that described in WO 0154598 (U.S. Pat. No.
6,127,597).
[0248] g) the implants may include at least one radiopaque marker
e.g., a tantalum thread, ring, dot, pin, etc. (not shown), as
discussed hereinafter. Optionally, a passageway, for example, for a
guide wire is made or includes a radiolucent material, for example,
in the form of a wire or hollow tube.
[0249] FIGS. 14A and B illustrate a possible solution to a
reinforcement problem that may exist due to high local stresses
causing deformation for example, in the stem of a proximal femur
nail in applications such as illustrated in FIGS. 11-13. FIG. 14A
shows a sectional view of the proximal end 502 of nail 500. FIG.
14B shows a side view of FIG. 14A, i.e., rotated 90 degrees.
[0250] Stress can be especially severe in the edges of the leg
screw hole of the stem, due to the high moment applied by the leg
screw on the hole. Orienting the reinforcing fibers longitudinally
or helically does not eliminate the deformation.
[0251] According to some embodiments of the invention the problem
is alleviated by orienting the reinforcing fibers in a way that
converts the compression reaction into tension of the fibers in the
stem. FIG. 14A shows the points of greatest stress 504 and 506 due
to bending of bone screw 508. At these locations, the reinforcing
elements 510 and 512 are configured in a U-shape and an opposed
U-shape at ends 514 and 516, respectively, of passage 518.
Reinforcing elements 510 and 512 are oriented preferably in planes
perpendicular to the main axis of the screw 508, where leg screw
508 bears most forcefully in passage 518. In this way, the
compression reaction due to the leg screw 508 load is converted
into tension of the fibers.
[0252] FIG. 15 is a schematic side view of a fixation component 560
that illustrates a solution to another reinforcement problem that
may exist due torsional stresses of a fiber-reinforced head 562 of
a bone screw. The torsional forces resulting during insertion are
supported by adding a ring 564 of circumferentially or spirally
wound reinforcing fibers 566.
[0253] FIGS. 16A is a side elevation view, and FIGS. 16B and 16C
are longitudinal cross-sectional views taken along line A-A in FIG.
16A, that illustrate two options for radiopaque marking of a
radiolucent fixation component such as a bone screw generally
denoted at 440 in FIG. 16A. To provide for visualization of the
screw under fluoroscopy during the implantation procedure, and/or
post-operative follow-up, a metal wire 452 is incorporated into the
screw along its longitudinal axis (see FIG. 16B). Optionally, the
wire is made of tantalum.
[0254] Alternatively, as illustrated in FIG. 16C, two radiopaque
wires or pins 454 and 456, are provided only at the proximal and
distal ends, respectively, of screw 440. These, too, may optionally
be formed of tantalum.
[0255] It is to be understood that other shapes, e.g., dots or
rings, and different sizes, locations and materials may be
applicable for marking the radiolucent bone screw.
[0256] It should be noted that if some of the reinforcing filaments
of the bone implant are at least partially coated, adding a
radiopaque marker to provide visualization of the radiolucent
implant under fluoroscopy during insertion may not be necessary. It
may be desirable, however, to limit the coating so that it does not
interfere with post-operative visualization.
[0257] FIGS. 17A and B respectively illustrate top perspective and
side sectional views of a bone plate 600 demonstrating several
features, one or more of which may be provided in one or more
embodiments of bone-supporting components, i.e., bone nails and
bone plates.
[0258] Bone plate 600 includes a head portion 602 and a stem or
shaft portion 604, both of which are configured and sized according
to the particular bone for which plate 600 will be used. In the
Figure, a proximal Humerus plate is shown. Head portion 602
includes an array of bores 606 and stem portion 604 includes a line
of bores 608 spaced longitudinally along a midline of the stem.
These are configured to receive the fixation components. The number
and spacing of bores 606 and 608 are optionally determined, for
example, like the size and configuration of the plate itself,
according to the particular bone for which the plate will be
used.
[0259] Stem portion 604 optionally includes a line of transversely
extending depressions 610. The purpose of depressions 610 is to
reduce the area of contact between the bone and the plate.
Reduction of the contact area may also assist in maintaining the
integrity of the fixation. In some embodiments, this may also be
achieved by the spacing and size of the depressions.
[0260] According to some embodiments of the invention,
bone-supporting components, including bone nails and bone plates,
are manufactured and provided to the user without some or all screw
holes. Instead, the holes are formed by the surgeon during the
implantation. As shown in FIGS. 17A and 17B, implant 600 may
include one or more blind bores or grooves or other indentation
and/or protrusions in the stem, which do not penetrate the entire
implant thickness. For example, they may extend 10 to 20% of the
thickness of the plate stem. Alternatively, they may extend more,
for example, 50%, 70% or more, for example, being narrow-diameter
holes.
[0261] The blind grooves cooperate with drilling tool and fixation
component insertion accessories as described below, and help to
position and grip the drilling device while the surgeon drills
holes through the grooves. This allows the surgeon to insert the
fixation components devices in the optimal locations and
directions/angles. Since these may vary from case to case, the
surgeon has the flexibility to address the need of each case
individually and to provide for more efficient and safe fixation.
In addition, where small implants are involved, the option to have
only the number of screw holes for the particular application may
contribute to the strength of the implant. Optionally, an
attachment location, for example, a notch or hole is provided for
attaching an adjustable tool guide to help guide a tool during
reconfiguration of the implant (e.g., by drilling or cutting).
[0262] In FIGS. 17A and 17B, the blind bores in stem 604 are
represented schematically at 606 as circular, but in some
embodiments, there may be provided a different shape that can keep
the drill bit in place during drilling.
[0263] Optionally, the implant is provided with several such
grooves, which are located at positions and/or in directions of the
implant that do would not compromise the required implant
biomechanical properties following drilling.
[0264] Optionally, the bone implants are manufactured and provided
to the user with at least one screw hole, while the other required
screw holes are created during the surgery.
[0265] In some embodiments of the invention, bone nails are also
manufactured with a longitudinally extending row or other suitable
arrangement of blind grooves, either round or elongated as
described above in connection with FIGS. 17A and 17B. It is also to
be understood that both bone nails and plates may be provided with
pre-drilled through-holes (as in the embodiments described in
connection with FIGS. 2 and 3) in some embodiments of the
invention.
[0266] Also in some embodiments, through-holes may be threaded (not
shown) for attachment of accessories used during drilling and
fixation-component insertion, and/or for locking the fixation
component head to the bone-supporting component as now to be
described.
[0267] Referring now to FIG. 18, there is shown a bone plate 640,
including a head, 642, and a stem or shaft 643. The figure also
illustrates a targeting guide 652, and a drill sleeve 656. Stem 643
of bone plate 640 includes round bores 644 and elongated slots 650.
These may be blind, or extend though the plate as previously
described.
[0268] Targeting guide 652 is a drilling accessory which may be
used to help drill holes in head 642 and/or the underlying bone for
receiving one or more fixation devices. Targeting guide 652
includes an array of holes, some of which may be oriented obliquely
to bone head 642. Targeting guide 652 is attached to head 642 by
one or more targeting screws 654, which are held in place by
threads (not shown), Optionally the targeting guide 652 has one pin
(not shown), that enter into a hole in the implant, in addition to
the screw 654.
[0269] By using targeting guide 652 made of polymer, with implant
made of composite material, during the surgery it is possible to
see under fluoroscopy very clear view of the fracture, and reduce
it more accurately, and place the screw more accurately. Optionally
targeting guide 652 made of polymer such as PEEK. Optionally
targeting guide 652 is supplied pre-assembled on the implant.
Optionally targeting guide 652 is intended for single use.
[0270] FIG. 19 shows further details of drill sleeve 656. This is
an accessory for use in drilling holes for fixation components to
be inserted in the stem 642 of a bone plate 640. Drill sleeve
includes a lower portion 658 configured to be received in one of
the bores 644 and 650 in bone plate stem 642. This may optionally
be threaded to match complementary threads in one of the circular
bores 644, or may be dimensioned for a friction fit.
[0271] Drill sleeve 656 also includes a skirt or shoulder portion
660 that limits insertion depth into the bore.
[0272] FIG. 19 also shows a drill sleeve holder 662 to assist in
insertion and removal of drill sleeve 656. This includes a handle
664, the distal end of which includes a fitting 666 configured to
engage a complementary bore 668 in drill sleeve 656.
[0273] FIGS. 20A and 20B illustrate another drill sleeve 670.
According to some embodiments of the invention. These are top
perspective and vertical sectional views respectively. Drill sleeve
670 differs from drill sleeve 656 of FIG. 19 in that it includes an
elongated portion 672 and a knob 674 at its proximal end to
facilitate handling the device. The distal end 678 of elongated
portion 672 (see FIG. 20B) is threaded to engage complementary
threads (not shown) in one of the bores 644 in bone plate stem
642.
[0274] Elongated portion 672 may take various forms in embodiments
of the invention. The form illustrated in FIGS. 20A and 20B is a
spiral spring 676 which allows torque transfer from the knob 674 to
screw and unscrew distal part 678, while preventing transfer of
bending forces, thus reducing the chance of damage to the bores or
the internal threads.
[0275] Optionally, elongated portion 672 may be formed of
oppositely wound concentric springs, i.e., one spiraled clockwise,
and the other spiraled counterclockwise.
[0276] FIG. 21 illustrates a combined targeting guide and fixation
device insertion accessory 680. This includes three components: an
insertion guide 682 for insertion of a fixation-component, a drill
guide sleeve 684, and a K-wire sleeve 686. A K-wire is optionally
used before drilling, to get idea about the drilling direction.
[0277] In use, accessory 680 is assembled with insertion guide 682
and drill guide 684 connected together and inserted into a hole in
a targeting device 652.
[0278] All the accessories described in connection with FIGS. 18-21
may be formed of metal or of a polymer, optionally a
fiber-reinforced polymer composite.
[0279] It should also be understood that other configurations of
drill and fixation-device insertion guide accessories, including
such accessories that are configured for disposal after a single
use, are also within the scope of the invention. It should also be
understood that, in some embodiments of the invention, implantation
may be done without using the drill sleeve as described above.
[0280] FIGS. 22A and 22B are schematic top views that illustrate
ways to provide for visualization of bone plates under fluoroscopy
during implantation and/or at follow-up in some embodiments of the
invention. In FIG. 22A, a bone plate 700 is shown that includes a
head 702 and an elongated stem portion 704. A radiopaque marker
shown here as a series of short marginal wire sections 706 extends
around the edges of head 702 and the distal end 708 of stem portion
704.
[0281] FIG. 22B shows a variation in which the wire sections 710
extend along the entire contour of bone plate 700.
[0282] The markings may take optionally various forms, for example,
two longitudinally continuous wire sections formed of tantalum or
other suitable metal in the embodiment of FIG. 22A, or a single
continuous marginal wire in the case of the embodiment of FIG. 22B.
For example, tantalum wire having diameter of about 0.2 to about
0.5 mm may be used, and located about 1 mm from the implant edge.
Use of a radiolucent bone plate allows an advantageous method of
assisting the surgeon in positioning of bone fragments for optimum
healing, and following the progress of post-operative healing.
[0283] FIGS. 23A and 23B are assembled and partially exploded
perspective views of some embodiments of the invention illustrating
a design for a bone nail insertion support apparatus 750 which may
be used to share the loads exerted on the nail-handle connection
area during insertion of the nail into the bone.
[0284] In FIG. 23A, insertion apparatus 750 is shown enclosing the
connection interface between a bone nail 752 and a handle tube 754.
Insertion apparatus 750 includes a housing comprised of two
complementary parts 756 and 758 that cover the connection
interface. These are optionally connected to each other by a screw
760 (refer also to FIG. 23B), that is received in holes 762, 764 in
parts 756 and 758, respectively, as well through the lower hole 766
at the proximal end of nail 752. Hole 764 has a thread and screw
760 is inserted through hole 762, and nail hole 766 and threaded
into hole 764. The latter will also be used for insertion of a
fixation-component. Optionally, the screw 760 is provided already
connected to one of the parts 756. A pin 768 in the other part 758
is configured to be inserted into a hole in the handle tube 769.
Torque is transmitted through pin 768 to part 758, and then to the
screw 760 and nail 752. In this manner, part of the torque is
transmitted from the handle to the nail.
[0285] Optionally, insertion apparatus 750 may also be configured
to enable the use of one insertion apparatus with nails of
different diameters.
[0286] During operation, the nail 752 is connected to the handle
tube 754 via the nail adapter (not shown in the figure), and then
apparatus 750 is assembled over the nail-handle connection area.
Following introduction of most of the nail into the bone, the
insertion apparatus is disconnected and removed to allow
introduction of the rest of the nail into the bone.
[0287] FIGS. 24A and 24B are, respectively, assembled and partially
exploded views of some embodiments of another nail installation
device 770. As shown, installation device 770 is similar to
insertion device 750, except that the complementary parts 772 and
774 configured to enclose the connection area between the nail 752
and the handle 754 is generally rectangular rather than
cylindrical. Because of the similarity to device 750, further
description will be omitted in the interest of brevity.
[0288] Reference is now made to FIGS. 25A and 25B, which are
partial cut-away views illustrating a portion of the radiolucent
connector 790, connected to a drill power unit 792 (only partially
shown). In use, the opposite end of connector 790 is attached to a
drill bit (not shown in the figure), optionally at an angle of 90
degrees. Connector 790 includes a flexible cable 794, configured to
transmit the torque and speed from the power unit 792 to the drill
bit. The cable 794 is connected to a coupler 796, which is attached
to a spring 798. This, in turn, is attached at its other end to
additional coupler 800, which is configured for connection to power
unit 792.
[0289] In FIG. 25A, a non-activated configuration of apparatus 790
is illustrated. In this configuration, the two couplers 796 and 800
at the ends of spring 798 do not engage with each other, and thus
even if the power unit 792 is operated, the torque is not
transferred and the drill bit shall not rotate.
[0290] FIG. 25B illustrates the "activated" configuration of the
drilling assembly. Upon holding component 790, the surgeon must
push power unit 792 to engage coupler 800, so that the later
advances, presses against spring 798, and engages with the second
coupler 796. This clutch mechanism helps prevent accidental
operation of the drill.
[0291] In an exemplary embodiment of the invention, the actual
drilling tool is made of material that provides for both suitable
biocompatibility and biomechanical properties (e.g., hardness). In
an exemplary embodiment of the invention, the drilling tool is a
standard drill bit used for intra-operatively drilling of holes in
the bone. Optionally, the drill bit is made of stainless steel.
Optionally, the drill bit is made of high-speed steel or other
materials, such as cobalt steel alloys, which hold their hardness
at higher temperatures and thus may be used to drill hard
materials.
[0292] Other hard materials for constructing the drill tool may be
tungsten carbide and other carbides, and polycrystalline diamond
(PCD). Optionally, the drilling tool may be coated with material
that provides for additional characteristics, such as heat
resistance and/or corrosion resistance and/or hardness. Coating
materials that may be used are, for example, black oxide, titanium
nitride (TiN), titanium aluminum nitride (TiAlN), titanium carbon
nitride (TiCN), diamond powder and zirconium nitride. In another
exemplary embodiment of the invention, instead of a drill bit a
whole saw or other cutting implement may be used. In an exemplary
embodiment of the invention, the drill bit is allowed to be made of
less hard materials as it is used only a small number of times
and/or is used for drilling a composite material.
[0293] FIGS. 26A-26B illustrate embodiments of the invention in
which provision is made for removal of drilling debris. A device
806 according to such embodiments includes a suction tube 808 the
interior 820 of which is configured to be attached to a vacuum
source (not shown) and a drill-receiving portion 810 have a hole
812 through which a drill bit 814 projects to the drilling
site.
[0294] Additionally and/or alternatively, drill 814 may be
cannulated at 816. Optionally, a suction tube (not shown) is
located within cannulation 816. Alternatively, there is no suction
tube, and the suction is performed directly from the cannulation or
using a separate suction tube. Optionally, suction of drilling
products may be performed simultaneously from the drill bit
cannulation (with or without a separate suction tube) and from a
suction tube 808 as illustrated. The suction tube may be made of
various materials, such as, but not limited to, metals and
polymers. In some embodiments, the suction tube is made of a rigid
material. In some embodiments, the suction tube is flexible.
[0295] In an exemplary embodiment of the invention, the drill is
powered by suction and/or air-flow provided in a surgery, e.g.,
from a wall mounted centralized source, and such suction is also
used for suction of debris in addition to or instead of powering
the drill.
[0296] In some embodiments, the suction process is accompanied by
irrigation, for example by sterile saline solution. In such
embodiments, during drilling, saline is delivered through drill bit
cannulation 816, while suction of the drilling material is achieved
using tube 808. Alternatively, irrigation fluid is introduced
through tube 808 and the drilling products are sucked from an inner
tube inside the drill bit cannulation. Optionally, drill bit is not
cannulated, and both tubes (for liquid flushing and for suction)
are positioned outside the drill bit, one over the other.
[0297] Irrigation as described enables cooling of the implant and
surrounding tissue while drilling is being performed, to avoid
damage of tissue and/or devices, as well as debris removal.
[0298] FIG. 26A illustrates another debris removal and irrigation
device 822 according to some embodiments. Here, device 822 includes
a drill 824, which may be cannulated at 826 for irrigation and a
separate tube 828 for suction which may be placed in proximity to
each other during drilling by the surgeon. Alternatively, the
functions of tube 826 and cannulation 826 may be reversed, or both
cannulation 826 and tube 828 may be used for suction.
[0299] Experiments have been conducted to assess the effectiveness
of drilling a bone implant together with evacuation of the drilling
material. During the test, a composite material bone plate, made of
carbon fibers-reinforced PEEK, was drilled using a drill bit, which
was contained within a polymeric tube. The later was attached to
the plate while its other end was connected to a vacuum pump to
allow suction of the drilling products. Upon drilling, the drilling
products were sucked into the tube and removed from the plate and
its surrounding. Following drilling, the plate and the area outside
the tube were inspected. The test results indicated that only an
insignificant amount of residues was detected.
[0300] In some embodiments of the invention, the drill bit is used
to create a perpendicular round hole. Additionally and/or
alternatively, the drill bit creates an oblique hole.
[0301] Materials and/or coating for the drilling tool may be one or
more of those described above.
[0302] In another exemplary embodiment of the invention, the drill
bit is a hole saw.
[0303] The drill bit may be of conventional form, or optionally may
also comprise a tap (thread cutting), to create a thread, at least
at part of the plate screw hole, so that the screws may be locked
to the plate. Alternatively, a separate tap may be used.
Additionally and/or alternatively, while screwing the screw into
the bone through the plate or nail hole, the screw itself serves as
a tap of the plate, and its threaded part is locked to the plate or
nail.
Exemplary Component Fabrication Methods
[0304] In an exemplary method of fabrication, the core and the
sleeve are constructed from pre-impregnated (prepreg) tapes of
carbon fiber-reinforced polymer, preferably thermoplastic polymer
such as PEEK. In some embodiments of the invention, the core is
formed by compression molding. Before molding, the prepreg tapes
are pre cut to the size and shape of the mold cavity, and inserted
into the mold in accurate total weight.
[0305] Where the bone-supporting components are supplied
pre-drilled, the passages are optionally created during the
compression molding process (and not by drilling). Alternatively,
passages are created during the compression molding process and
drilling is used following molding to achieve the final desired
shape and dimensions of the passages).
[0306] The sleeve is then build over the core by spirally winding
tape of the prepreg composite, optionally at a pitch of 45 degrees
relative to the longitudinal axis of the core. When more than one
tape is used to build up the sleeve, the adjacent tapes are
alternatingly spirally wound clockwise and counterclockwise
optionally having a pitch of +/-45 deg relative to the longitudinal
axis of the core.
[0307] The winding tool for the sleeve optionally includes a heater
to heat the tape before the winding, preferably also pre-heating
the core, and a pressing wheel to create consolidation of the
winding tape into the core. In some embodiments, to strengthen the
implant, the process of compression molding is performed under high
pressure. For example, the pressure may be higher than 100 Atm.,
optionally higher than 400 Atm., optionally higher than 700 Atm.,
optionally higher than 1,000 Atm.
[0308] According to some embodiments of the invention, the prepreg
tapes are heated during winding. The heating is optionally provided
by a laser. Alternatively and/or additionally, an Infra Red source
is used for heating the tape during winding. Alternatively and/or
additionally, the tape is heated using hot gas such as air.
[0309] In some embodiments, a composite material bone implant, for
example an intramedullary nail, is produced from a core of
longitudinal tapes of fiber-reinforced polymer, formed by
compression molding, followed by winding of tapes of
fiber-reinforced polymer over the core, together with laser
heating. Use of this technique for the manufacturing of a bone
implant component may eliminate the need of a final compression
molding (i.e., for the core with the helically wound tapes).
[0310] According to some embodiments of the invention, the process
of manufacturing a composite material bone implant also comprises
the step of slightly expanding the winding, for example, using heat
and internal pressure. In an exemplary embodiment of the invention,
an intramedullary nail is produced in compression molding followed
by tape winding, and then a rod is axially pushed into the heated
mold, to slightly push outwardly the core and the winding.
[0311] According to some embodiments of the invention, production
of a composite material bone implant involves separate compression
molding for two or more portions of the implant, where portions are
later connected, to form the core of the implant. Intramedullary
nails often include a cannulation of about 2-3.5 mm diameter along
their longitudinal axis, to enable introduction of the nail into
the bone over a guide wire. In addition, many of the nails include
a few degrees bent or a radius, to comply with the anatomy of the
bone.
[0312] Production of a bent and cannulated nail in standard
compression molding is possible but generally considered
technically difficult. In an exemplary embodiment of the invention,
in order to achieve proper production of such a nail, two moulds
are used, each for a half of the nail that comprises "half
cannulation". Following the production of the two halves, they can
be molded together with mandrel inside, to get hollow core, or
alternatively winding is performed around the attached two halves
(e.g., tapes are helically wound at .+-.45 degrees), and the entire
construct is then compressed, with a wire in the mold designed to
keep the cannulation along the nail axis.
[0313] Optionally, to shorten the time required for the winding
process and to reduce costs, winding over the longitudinal core is
performed so that one or more tape is placed over another tape, and
each tape is tensioned separately during winding.
[0314] For screws such as 250 in FIG. 10A that include an outer
layer 252 of a hard material, this may be applied as a coating or
by winding metal tape over the screw, optionally by using bending
wheels. Alternatively the tape may be wound over a screw mandrel,
unscrewed from the mandrel, and then screwed over the composite
screw.
Exemplary Methods of Use
[0315] FIG. 28 shows in flow-chart form, an example of how methods
according to some embodiments of the invention may be
performed.
[0316] At 900, after appropriate preparation, a radiolucent (X-ray
transparent) bone-supporting component, for example, a bone plate
as described above, formed of a fiber-reinforced polymer matrix
composite is positioned in proximity to the fracture site so it
overlies the fractured area. At 902, the bone plate (optionally,
the head) is optionally anchored using at least one fixation
component, for example, a bone screw or peg. Optionally, the
targeting guide described herein is used for this.
[0317] At 904, taking advantage of the radiolucency of the bone
plate, the surgeon optionally reduces the fracture by positioning
the bone fragments optimally for good healing.
[0318] At 906, for example, in embodiments in which a drill sleeve
is not used, the surgeon optionally drills through the pre-drilled
holes or built-in drilling guides in the bone plate to accommodate
a desired number of bone pegs or screws.
[0319] The method then proceeds to 914 where the pegs or screws are
installed, for example, using a screw guide as in FIG. 21, to
provide final fixation.
[0320] In embodiments in which a drill guide and/or other
accessories for example as described in connection with FIGS. 18-21
are optionally used, the method proceeds from 904 to 908, where the
radiolucent drill guide and accessories are positioned and
optionally attached to the bone plate. At 910, the drill is
oriented and positioned by the surgeon as required, for example, by
inspecting the fractured area visually or under X-ray through the
bone plate and the drill guide. This is again made possible by the
radiolucency of the bone plate and the drilling accessories formed,
and helps assure that the fixation components are optimally
oriented for best support.
[0321] At 912, with the drill guide and accessories properly
oriented, holes are drilled in the bone. At 914, the fixation
components are installed, optionally using the screw guide.
[0322] In embodiments in which the bores in the bone plate are
blind, both the bone supporting component and the bone may be
drilled at 912. Optionally, during the drilling, debris disposal is
provided.
[0323] Finally, optionally, at 916, the drill guide and other
accessories are discarded after a single use.
Exemplary Dental Implants
[0324] Some embodiments of the invention pertain to dental implants
formed of a composite material, according to embodiments already
described for other bone implants. Optionally, the dental implant
is composed of a single component forming a crown or cap, a screw
that goes into the bone, and an abutment intermediate the crown and
the screw. Optionally, it comprises more than one component.
Optionally, the abutment and the bone screw are one composite
material component. Optionally, the different components are made
of more than one material, including of a non-composite
material.
[0325] In some embodiments, the implant is configured so that its
strength and elasticity are compatible with the loads exerting on
the tooth and/or bone. In an embodiment, the composite material
dental implant is coated, for example with material that improves
the ability of the implant to integrate in the bone and enhances
bone ingrowth. Such coating may be, for example, porous titanium or
hydroxyapatite (HA). In an embodiment, the coating is added using a
vacuum plasma spray (VPS) technique. In an exemplary embodiment of
the invention, the thickness of the coating is in the range of
50-70 .mu.m.
[0326] In some embodiments, a coating is added following implant
surface treating, for instance grid blast or bombardment of argon
ionized ions. Optionally, particles of the coating material (e.g.,
titanium) are inserted into the implant surface prior to performing
the coating itself, in order to improve the adhesion of the coating
to implant surface. In an embodiment, the composite material bone
implant is heated and the particles are forced/introduced so that
they penetrate into the implant outer layer. In an embodiment,
particles of coating material are not limited to the outer layer of
the implant, but rather are incorporated into the entire implant,
optionally during the production of the implant construct.
[0327] In some embodiments, the area of the dental implant that
contacts soft tissue comprises smooth surface, in order to prevent
infection at the region of the implant. Optionally, the smooth
surface does not comprise the coating. Alternatively, the smooth
surface comprises smooth, non-porous, coating.
[0328] It is expected that during the life of a patent maturing
from this application many relevant ultrasound transducers will be
developed and the scope of the term transducer is intended to
include all such new technologies a priori.
[0329] As used herein the term "about" refers to .+-.10%.
[0330] The terms "comprises", "comprising", "includes",
"including", "having" and their conjugates mean "including but not
limited to".
[0331] The term "consisting of" means "including and limited
to".
[0332] The term "consisting essentially of" means that the
composition, method or structure may include additional
ingredients, steps and/or parts, but only if the additional
ingredients, steps and/or parts do not materially alter the basic
and novel characteristics of the claimed composition, method or
structure.
[0333] As used herein, the singular form "a", "an" and "the"
include plural references unless the context clearly dictates
otherwise. For example, the term "a compound" or "at least one
compound" may include a plurality of compounds, including mixtures
thereof.
[0334] Throughout this application, various embodiments of this
invention may be presented in a range format. It should be
understood that the description in range format is merely for
convenience and brevity and should not be construed as an
inflexible limitation on the scope of the invention. Accordingly,
the description of a range should be considered to have
specifically disclosed all the possible subranges as well as
individual numerical values within that range. For example,
description of a range such as from 1 to 6 should be considered to
have specifically disclosed subranges such as from 1 to 3, from 1
to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as
well as individual numbers within that range, for example, 1, 2, 3,
4, 5, and 6. This applies regardless of the breadth of the
range.
[0335] Whenever a numerical range is indicated herein, it is meant
to include any cited numeral (fractional or integral) within the
indicated range. The phrases "ranging/ranges between" a first
indicate number and a second indicate number and "ranging/ranges
from" a first indicate number "to" a second indicate number are
used herein interchangeably and are meant to include the first and
second indicated numbers and all the fractional and integral
numerals therebetween.
[0336] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention, which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable subcombination
or as suitable in any other described embodiment of the invention.
Certain features described in the context of various embodiments
are not to be considered essential features of those embodiments,
unless the embodiment is inoperative without those elements.
[0337] Although the invention has been described in conjunction
with specific embodiments thereof, it is evident that many
alternatives, modifications and variations will be apparent to
those skilled in the art. Accordingly, it is intended to embrace
all such alternatives, modifications and variations that fall
within the spirit and broad scope of the appended claims.
[0338] All publications, patents and patent applications mentioned
in this specification are herein incorporated in their entirety by
reference into the specification, to the same extent as if each
individual publication, patent or patent application was
specifically and individually indicated to be incorporated herein
by reference. In addition, citation or identification of any
reference in this application shall not be construed as an
admission that such reference is available as prior art to the
present invention. To the extent that section headings are used,
they should not be construed as necessarily limiting.
* * * * *