U.S. patent application number 13/055920 was filed with the patent office on 2012-04-19 for fracture fixation systems.
This patent application is currently assigned to SMITH & NEPHEW INC. Invention is credited to David L. Brumfield, Alan William Bull, Graeme Howling, Nicola Macauley, William D. Patterson, James K. Rains, John Rose.
Application Number | 20120095463 13/055920 |
Document ID | / |
Family ID | 39746946 |
Filed Date | 2012-04-19 |
United States Patent
Application |
20120095463 |
Kind Code |
A1 |
Rains; James K. ; et
al. |
April 19, 2012 |
FRACTURE FIXATION SYSTEMS
Abstract
Systems for bone fracture repair are disclosed. One system
includes a biocompatible putty that may be packed about a bone
fracture to provide full loadbearing capabilities within days. The
disclosed putties create an osteoconductive scaffold for bone
regeneration and degrade over time to harmless resorbable
byproducts. Fixation devices for contacting an endosteal wall of an
intramedullary (IM) canal of a fractured bone are also disclosed.
One such fixation device includes a woven elongated structure
fabricated from resorbable polymer filaments. The woven elongated
structure has resilient properties that allow the woven structure
to be radially compressed and delivered to the IM canal using an
insertion tube. When the insertion tube is removed, the woven
structure expands towards its relaxed cross-sectional width to
engage the endosteal wall. The woven elongated structure is
impregnated with a resorbable polymer resin that cures in situ, or
in the IM canal.
Inventors: |
Rains; James K.; (Cordova,
TN) ; Rose; John; (Collierville, TN) ; Bull;
Alan William; (York, GB) ; Macauley; Nicola;
(York, GB) ; Brumfield; David L.; (Collierville,
TN) ; Patterson; William D.; (Southaven, MS) ;
Howling; Graeme; (Leeds, GB) |
Assignee: |
SMITH & NEPHEW INC
|
Family ID: |
39746946 |
Appl. No.: |
13/055920 |
Filed: |
July 24, 2009 |
PCT Filed: |
July 24, 2009 |
PCT NO: |
PCT/US2009/051713 |
371 Date: |
October 24, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61083837 |
Jul 25, 2008 |
|
|
|
61084237 |
Jul 28, 2008 |
|
|
|
61142756 |
Jan 6, 2009 |
|
|
|
Current U.S.
Class: |
606/63 |
Current CPC
Class: |
A61F 2210/0004 20130101;
A61F 2250/001 20130101; A61B 17/68 20130101; A61L 27/46 20130101;
A61B 17/80 20130101; A61F 2/30965 20130101; A61L 2400/06 20130101;
A61L 24/0084 20130101; A61B 17/7258 20130101; A61F 2240/001
20130101; A61F 2/2846 20130101; A61F 2002/30062 20130101; A61F
2310/00179 20130101; A61F 2210/0066 20130101; A61B 17/82 20130101;
A61B 2017/00867 20130101; A61F 2210/0085 20130101; A61L 27/56
20130101; A61B 17/72 20130101; A61B 17/64 20130101; A61L 27/58
20130101; C08L 75/04 20130101 |
Class at
Publication: |
606/63 |
International
Class: |
A61B 17/72 20060101
A61B017/72 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 25, 2008 |
GB |
0813659.0 |
Claims
1. An assembly for placing a fixation device in contact with an
endosteal wall of an intramedullary (IM) canal of a fractured bone,
the assembly comprising: an elongated structure having walls with
interstices and a closed distal end; an insertion tube having an
inner diameter that accommodates the elongated structure; the
elongated structure being compressible to a cross-sectional width
smaller than an inner diameter of the insertion tube so as to fit
within the insertion tube, and being expandable upon release from
the insertion tube to an outer cross-sectional width greater than
an outer diameter of the insertion tube for engaging the endosteal
wall of the IM canal.
2. The assembly of claim 1 further comprising a retention element
that surrounds the elongated structure for retaining resin, the
retention element being selected from the group consisting of a
balloon, bag and sleeve.
3. The assembly of claim 2 wherein the retention element comprises
a resorbable polymer.
4. The assembly of claim 2 wherein the retention element is
porous.
5. The assembly of claim 1, wherein the elongated structure is
woven.
6. The assembly of claim 5 wherein the woven elongated structure is
selected from the group consisting of a braided elongated
structure, a triaxial braided elongated structure, a pair of
braided elongated structures with one smaller inner braided
elongated structure disposed axially within a larger outer braided
elongated structure, a bundle of braided elongated structures, a
bundle of braided elongated structures disposed axially within an
outer braided elongated structure, a braided elongated structure
with a plurality of cavities extending along a length of the
braided elongated structure, and a spacer fabric.
7. The assembly of claim 5 wherein the woven elongated structure
comprises filaments selected from the group consisting of
polyurethanes, poly-alpha-hydroxy acids, polylactides,
polyglycolides, poly-(D,L-lactide-co-glycolide),
polyglycolide-co-trimethylenecarbonate, poly-(L-lactide),
poly-(L-CO-D,L-lactide), poly-(D,L-lactide), polyglactin acid, a
combination, poly-(D-lactide), combinations thereof and copolymers
thereof.
8. The assembly of claim 5 wherein the woven elongated structure
includes degradable metal fiber disposed with the woven
structure.
9. The assembly of claim 1 wherein the elongated structure
accommodates a plurality of loose resorbable fibers for mixing with
resin injected into the woven elongated structure.
10. The assembly of claim 1 wherein the elongated structure
accommodates an elongated structural reinforcing element.
11. The assembly of claim 1 wherein the elongated structure is a
spacer fabric having a top panel, a bottom panel, and vertical
fibers connecting the top and bottom panels.
12. The assembly of claim 11 wherein the vertical fibers are
arranged in spaced apart groups of vertical fibers.
13. The assembly of claim 11 wherein the top and bottom panels
comprise longitudinally extending fibers and transversely extending
fibers, the longitudinally extending fibers being thicker than the
transversely extending fibers.
14. The assembly of claim 13 wherein the vertical fibers are
thicker than the transversely extending fibers.
15. The assembly of claim 11 wherein the top and bottom panels
comprise longitudinally extending fibers and transversely extending
fibers, the longitudinally extending fibers and the vertical fibers
being thicker than the transversely extending fibers.
16. The assembly of claim 1 wherein an injection tube has a
proximal portion in fluid communication with a supply of uncured
injectable resin.
17. A surgical system for repairing a fractured bone, the assembly
comprising: an insertion tube; an elongated structure having a
plurality of interstices, the elongated structure being releasably
compressed within the insertion tube; and a resin disposed on the
elongated structure and wherein upon release from the insertion
tube, the elongated structure expands to make contact with an
endosteal wall of the intramedullary canal.
18. The surgical system of claim 17, comprising an elongated
support that fits between segments of the fractured bone.
19. The surgical system of claim 17, wherein the elongated
structure is woven.
20. The surgical system of claim 17, comprising an injection tube,
wherein the injection tube has a proximal portion in fluid
communication with a supply of uncured injectable resin.
21. The surgical system of claim 17, further comprising a retention
element that surrounds the elongated structure for retaining resin,
the retention element being selected from the group consisting of a
balloon, bag and sleeve.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application Ser. No. 61/142,756, filed on Jan. 6, 2009, U.S.
Provisional Application Ser. No. 61/084,237, filed on Jul. 28,
2008, U.S. Provisional Application Ser. No. 61/083,837, filed on
Jul. 25, 2008, and G.B. Provisional Application Serial No.
0813659.0, filed on Jul. 25, 2008. The disclosure of each
application is incorporated by reference in its entirety.
BACKGROUND
[0002] 1. Technical Field
[0003] This disclosure relates generally to orthopedic implants
and, more particularly, to orthopedic implants adapted for fracture
repair and methods for repairing fractures.
[0004] 2. Description of the Related Art
[0005] A variety of systems and devices are conventionally used to
treat bone fractures in humans or animals. Bone fractures typically
heal naturally as a result of normal growth or regeneration
processes. Treatment of bone fractures generally includes placing
bone fragments into an anatomically correct position and
orientation, referred to as "reduction," and maintaining the
fragments in place until healing naturally occurs, referred to as
"fixation." Accordingly, a primary objective in the treatment of
bone fractures is the fixation or stabilization of the reduced,
fractured bone for the duration of the healing process.
[0006] Conventional systems and devices for treatment of fractures
include external fixation means, such as traction, splints, or
casts, and internal fixation means, such as plates, nails, pegs,
screws, and other fixtures. Internal fixation devices are installed
on or in the fractured bone across the fracture site. For example,
plates, screws, pegs apply compression forces across a fracture
site, thereby aiding in stabilizing a bone fracture across the
fracture site. Intramedullary nails are installed longitudinally
into the intramedullary (IM) canal of a fractured bone across the
fracture site and provide torsional stabilization as well as load
sharing along the central axis of the bone.
[0007] One common problem with internal fixation devices is that
the installation of such devices is generally dependent on the
presence of sufficient amounts of high quality bone tissue in the
vicinity of the fracture. When bone tissue is lost, due to disease,
a pathological condition or for other reasons, it may be difficult
to install internal fixation devices to stabilize the bone
sufficiently for healing. For example, persons with thin or fragile
bones, such as osteoporosis patients, avascular necrosis patients
and patients with metastatic bones, may be particularly prone to
difficulties with fixation and healing of fractures. Unfortunately,
these are the very patients that are most prone to bone fractures.
While external fixation devices and methods are available, external
fixation devices can be cumbersome, uncomfortable, limit or prevent
ambulation and therefore generally fail to satisfy the needs of
such patients.
[0008] Current fixation devices, both internal and external, also
fail to meet the needs of injured soldiers and other trauma
victims. Specifically, approximately thirty percent of all
battlefield trauma cases involve bone fractures, typically due to
high energy events, such as blasts or gunshots. For example, the
combination of comminuted open fractures with large bone loss and
significant soft tissue loss are common battlefield traumas. Such
cases, often referred to as "segmental defects," are very difficult
to treat and typically require multiple surgeries and long
healing/rehabilitation times that can last as long as two years.
Amputations in these cases are common.
[0009] Current treatment techniques include the use of internal and
external fixation with titanium plates, screws, and rods or IM
nails, and the Ilizarov distraction method for bone-lengthening.
However, current techniques suffer from significant deficiencies,
some of which arise from the mechanical property mismatch between
titanium and bone. This mismatch leads to complications including
further fractures, delayed healing, and a high prevalence of
infection. Furthermore, currently available techniques do not
provide the most effective treatment in repairing large segmental
defects, which are generally defined as a defect or missing bone
segment that exceeds 2 cm in length or width. Because many
currently available fixation devices are not fully load-bearing,
the soldier or patient may be effectively incapacitated during the
recovery period.
[0010] Therefore, in light of the above problems, more effective
fixation methods and devices are urgently needed for the treatment
of both common bone fractures as well as bone fractures considered
to be large segmental defects.
SUMMARY OF THE DISCLOSURE
[0011] Various systems for bone fracture repair are disclosed which
are applicable to typical bone fractures without significant bone
loss and bone fractures classified as having large or significant
segmental defects.
[0012] One disclosed system may comprise fracture putty in the form
of a dynamic putty-like material that, when packed in/around a
compound bone fracture, may provide full load-bearing capabilities
within days. The disclosed putties may create an osteoconductive
scaffold for bone regeneration. The disclosed putties may also
degrade over time to harmless resorbable by-products as normal bone
regenerates. The disclosed putties may be curable in situ.
[0013] The disclosed putties may be made from resorbable polymers
which can harden or cure in situ, for example polyurethane,
polypropylene fumarate, polycapralactone, etc.
[0014] The disclosed putties may include a first or primary filler
in the form of biocompatible and osteoconductive particles that can
form a scaffold structure that bridges healthy bone segments. The
first or primary filler, preferably in the form of particles, may
also provide porosity, bone ingrowth surfaces and enhanced
permeability or pore connectivity. One suitable particulate filler
material is hydroxyapatite (HA) although other suitable filler
materials will be apparent to those skilled in the art such as
calcium phosphates, orthophosphates, monocalcium phosphates,
dicalcium phosphates, tricalcium phosphates, whitlockite,
tetracalcium phosphates, amorphous calcium phosphates and
combinations thereof.
[0015] The particles may comprise degradable polymer (e.g. PU, PLA,
PGA, PCL, co-polymers thereof, etc.) or the particles may comprise
degradable polymer containing one or more ceramic fillers. The
first filler particles may be provided in varying sizes.
[0016] In one refinement, the first filler particles have mean
diameters ranging from about 1 .mu.m to about 15 .mu.m. For
example, in one disclosed putty, the first filler has a mean
particle size of about 10 .mu.m.
[0017] In a refinement, the porosity and compressive properties of
the disclosed putties may be manipulated using additional fillers
materials that may be HA or another suitable biocompatible
material. Such refinements include the addition of particles having
mean diameters ranging from about 400 to about 4000 .mu.m. In
certain disclosed putties, the additional filler materials may be
provided in one or more size distributions. For example, additional
filler material is provided in size distributions ranging from
about 400 to about 4200 .mu.m, from about 400 to about 3200 .mu.m,
from about 600 to about 3000 .mu.m, from about 800 to about 2800
.mu.m, from about 400 to about 2200 .mu.m, from about 800 to about
1800 .mu.m, from about 1400 to about 3200 .mu.m, from about 1800 to
about 2800 .mu.m, etc. The ratio of the particle size distributions
can be manipulated depending upon the compression strength required
or the porosity required. For example, large segmental defect
injuries to load bearing bones will necessitate higher compression
strength and possibly reduced porosity. In contrast, large
segmental defect injuries to non-load bearing bones require less
compression strength thereby enabling the surgeon to use the putty
with a higher porosity for shorter healing times.
[0018] In one example, a second filler is added that may have a
mean particle diameter ranging from about 400 to about 1800 .mu.m
and a third filler that may have a mean particle size greater than
the mean particle size of the second filler and ranging from about
1800 to about 4000 .mu.m.
[0019] In a refinement, the resin may be present in an amount
ranging from about 15 to about 40 wt %, the first filler may be
present in an amount ranging from about 10 to about 25 wt %, the
second filler may be present in an amount ranging from about 20 to
about 40 wt %, and the third filler may be present in an amount
ranging from about 15 to about 35 wt %.
[0020] In another refinement, the first filler may have a mean
particle diameter ranging from about 8 to about 12 .mu.m, the
second filler may have a mean particle diameter ranging from about
800 to about 1800 .mu.m and the third filler may have a mean
particle diameter ranging from greater than 1800 to about 2800
.mu.m. In a further refinement of this concept, the resin may be
present in an amount ranging from about 20 to about 30 wt %, the
first filler in an amount ranging from about 10 to about 20 wt %,
the second filler in an amount ranging from about 25 to about 35 wt
%, the third filler in an amount ranging from about 20 to about 30
wt %.
[0021] In another refinement, the first filler is present in a
first amount, the second filler is present in a second amount and
the third filler is present in a third amount. A ratio of the
second to third amounts may range from about 1:1 to about 1.5:1. In
another refinement, a ratio of the second and third amounts
combined to the first amount may range from about 3.5:1 to about
4.5:1
[0022] The disclosed putties may also include an additional
porogen. In one refinement, the porogen is mannitol but other
biocompatible porogens will be apparent to those skilled in the art
such as crystalline materials in the form of salts, sugars,
etc.
[0023] Another disclosed moldable material for orthopedic
implantation and reconstruction comprises a resorbable polymer
resin present an amount ranging from about 20 to about 60 wt %, a
first filler having a first mean particle diameter ranging from
about 1 to about 15 .mu.m and present in an amount ranging from
about 10 to about 30 wt %, and mannitol as a porogen and present in
an amount ranging from about 30 to about 50 wt %.
[0024] The disclosed putties may also include a blowing agent. In
one refinement, the blowing agent is water but other biocompatible
blowing agents will be apparent to those skilled in the art.
[0025] Fixation devices for contacting an endosteal wall of an
intramedullary (IM) canal of a fractured bone are also disclosed.
One such fixation device comprises a woven elongated structure
fabricated from a resorbable polymer filaments. The woven elongated
structure may have a relaxed cross-sectional width and a compressed
cross-sectional width. The relaxed cross-sectional width may be at
least about 50% larger than the compressed cross-sectional width.
This resilient property allows the woven structure to be radially
compressed, placed in an insertion tube and delivered to the IM
canal using the insertion tube. When the insertion tube is removed,
the woven structure expands towards its relaxed cross-sectional
width to engage the endosteal wall. The woven elongated structure
may have a closed distal end. The woven elongated structure is
coated with a resorbable polymer resin that cures in situ, or in
the IM canal. The combination of the woven elongated structure and
the cured resin provides a strong internal fixation device.
[0026] In a refinement, the woven elongated structure is selected
from the group consisting of a braided elongated structure, a
triaxial braided elongated structure, a pair of braided elongated
structures with one smaller inner braided elongated structure
disposed axially within a larger outer braided elongated structure,
a bundle of braided elongated structures, a bundle of braided
elongated structures disposed axially within an outer braided
elongated structure, a braided elongated structure with a plurality
of cavities extending along a length of the braided elongated
structure, and an elongated structure fabricated from the spacer
fabric that may be rolled or folded.
[0027] For embodiments that employee a triaxial braided elongated
structure, the longitudinal fibers may be single or individual
fibers, longitudinal fiber bundles or yarns, or the longitudinal
fibers may be crimped.
[0028] In a refinement, the device may include a retention
structure that substantially encloses the woven elongated structure
for inhibiting the migration of injected resin out through the
woven elongated structure and possibly of the IM canal. The
retention structure may be selected from the group consisting of a
balloon, a bag, a sheath or other suitable enclosure. The retention
element may be fabricated from a resorbable material, such as a
resorbable polymer. In such a refinement, the woven elongated
structure may be filled with resin.
[0029] In another refinement, the resin may include particulate
filler material as described above. In another refinement, the
resin further comprises reinforcing resorbable fibers. In another
refinement, the woven elongated structure accommodates an elongated
structural reinforcing element.
[0030] In a refinement, the woven elongated structure may comprise
filaments selected from the group consisting of polyurethanes,
poly-alpha-hydroxy acids, polylactides, polyglycolides,
poly-(D,L-lactide-co-glycolide),
polyglycolide-co-trimethylenecarbonate, poly-(L-lactide),
poly-(L-CO-D,L-lactide), poly-(D,L-lactide), polyglactin acid, a
combination, poly-(D-lactide), combinations thereof and copolymers
thereof.
[0031] In another refinement, the woven elongated structure
accommodates a plurality of loose resorbable fibers for mixing with
resin injected into the woven elongated structure.
[0032] An assembly for placing a fixation device in contact with an
endosteal wall of an intramedullary (IM) canal of a fractured bone
is also disclosed. One disclosed assembly comprises an insertion
tube that accommodates a woven elongated structure as described
above. The woven elongated structure may have a closed distal end
and is in compressible to a cross-section smaller than an inner
diameter of the injection tube but expandable to relaxed
cross-section greater than an inner diameter of the injection tube
for engaging the endosteal wall of the IM canal. The woven
elongated structure accommodates a distal end of an injection tube
for delivering resin to the woven elongated structure.
[0033] The woven elongated structure may take the form of any of
the alternatives described above, may include a retention element,
one or more reinforcing elements and/or a plurality of loose
reinforcing fibers. Further, the use of an insertion tube enables
the option of providing a woven elongated structure that is
pre-wetted with uncured resin which cures in situ using the
assembly described above. In another refinement, the resin is
light-curable and can be cured in situ by passing a light emitting
device axially through the woven elongated structure after it is
placed in the IM canal.
[0034] Use of any of the internal fixation devices or systems
disclosed herein may be combined with one or more external fixation
systems, as will be apparent to those skilled in the art.
[0035] The disclosed fixation systems and methods may yield one or
more of the following benefits: (1) the patient may be more rapidly
restored to ambulatory function while healing naturally occurs; (2)
a single procedure may be employed that significantly simplifies
orthopedic surgery; (3) fewer secondary fractures may result from
use of the disclosed systems and methods thereby promoting normal
healing and fewer infections; (4) reduction in
recovery/rehabilitation time; (5) potential treatment for severe
bone loss; (6) potential treatment for joint fractures; (7)
reduction in the number of amputations; (8) the fixation systems
are wholly or at least partly resorbable thereby avoiding the need
for a secondary procedure to remove the fixation device after the
bone has healed.
[0036] There is provided a fixation device for contacting an
endosteal wall of an intramedullary (IM) canal of a fractured bone,
the device comprising: a woven elongated structure fabricated from
resorbable polymer filaments, the woven elongated structure having
a relaxed cross-sectional width and a compressed cross-sectional
width, the relaxed cross-sectional width being at least about 50%
larger than the compressed cross-sectional width, the woven
structure expanding towards its relaxed cross-sectional width to
engage the endosteal wall when not radially compressed to its
compressed cross-sectional width, the woven elongated structure
comprising a closed distal end, the woven elongated structure being
coated with a resorbable polymer resin.
[0037] In some embodiments, the woven elongated structure is
selected from the group consisting of a braided elongated
structure, a triaxial braided elongated structure, a pair of
braided elongated structures with one smaller inner braided
elongated structure disposed axially within a larger outer braided
elongated structure, a bundle of braided elongated structures, a
bundle of braided elongated structures disposed axially within an
outer braided elongated structure, a braided elongated structure
with a plurality of cavities extending along a length of the
braided elongated structure, and an elongated structure fabricated
from the spacer fabric.
[0038] In some embodiments, the fixation device further includes a
retention structure that substantially encloses the woven elongated
structure, the retention structure being selected from the group
consisting of a balloon, a bag, and a sleeve.
[0039] In some embodiments, the woven elongated structure is
impregnated with resin.
[0040] In some embodiments, the woven elongated structure is a
braided elongated structure and the compressed cross-sectional
width is a locked-out diameter.
[0041] In some embodiments, the braid angle .theta. ranges from
about 5 degrees to about 22 degrees.
[0042] In some embodiments, the resin further comprises reinforcing
resorbable fibers.
[0043] In some embodiments, the woven elongated structure
accommodates an elongated structural reinforcing element.
[0044] In some embodiments, the woven elongated structure
accommodates a plurality of loose resorbable fibers for mixing with
resin injected into the woven elongated structure.
[0045] In some embodiments, the woven elongated structure is
fabricated from spacer fabric comprising a top panel, a bottom
panel, and vertical fibers connecting the top and bottom
panels.
[0046] In some embodiments, the vertical fibers are arranged in
spaced apart groups of vertical fibers.
[0047] In some embodiments, the top and bottom panels comprise
longitudinally extending fibers and transversely extending fibers,
the longitudinally extending fibers being thicker than the
transversely extending fibers.
[0048] In some embodiments, the vertical fibers are thicker than
the transversely extending fibers.
[0049] In some embodiments, the top and bottom panels comprise
longitudinally extending fibers and transversely extending fibers,
the longitudinally extending fibers and the vertical fibers being
thicker than the transversely extending fibers.
[0050] There is also provided an assembly for placing a fixation
device in contact with an endosteal wall of an intramedullary (IM)
canal of a fractured bone, the assembly comprising: an insertion
tube that accommodates a woven elongated structure; the woven
elongated structure for receiving resin, the woven elongated
structure having a closed distal end, the woven elongated structure
being compressible to a cross-sectional width smaller than an inner
diameter of the injection tube, the woven elongated structure
having a relaxed outer cross-sectional width greater than an outer
diameter of the injection tube for engaging the endosteal wall of
the IM canal, the woven elongated structure accommodating a distal
end of an injection tube; injection tube further comprising a
proximal end in communication with a supply of uncured injectable
resin for delivering resin to the woven elongated structure.
[0051] In some embodiments, the assembly further includes a
retention element that surrounds the woven elongated structure for
retaining resin, the retention element being selected from the
group consisting of a balloon, bag and sleeve.
[0052] In some embodiments, the retention element is fabricated
from a resorbable polymer.
[0053] In some embodiments, the woven elongated structure is
selected from the group consisting of a braided elongated
structure, a triaxial braided elongated structure, a pair of
braided elongated structures with one smaller inner braided
elongated structure disposed axially within a larger outer braided
elongated structure, a bundle of braided elongated structures, a
bundle of braided elongated structures disposed axially within an
outer braided elongated structure, a braided elongated structure
with a plurality of cavities extending along a length of the
braided elongated structure, and an elongated structure fabricated
from the spacer fabric.
[0054] In some embodiments, the woven elongated structure comprises
filaments selected from the group consisting of polyurethanes,
poly-alpha-hydroxy acids, polylactides, polyglycolides,
poly-(D,L-lactide-co-glycolide),
polyglycolide-co-trimethylenecarbonate, poly-(L-lactide),
poly-(L-CO-D,L-lactide), poly-(D,L-lactide), polyglactin acid, a
combination, poly-(D-lactide), combinations thereof and copolymers
thereof.
[0055] In some embodiments, the woven elongated structure
accommodates a plurality of loose resorbable fibers for mixing with
resin injected into the woven elongated structure.
[0056] In some embodiments, the woven elongated structure
accommodates an elongated structural reinforcing element.
[0057] In some embodiments, the woven elongated structure is
fabricated from spacer fabric comprising a top panel, a bottom
panel, and vertical fibers connecting the top and bottom
panels.
[0058] In some embodiments, the vertical fibers are arranged in
spaced apart groups of vertical fibers.
[0059] In some embodiments, the top and bottom panels comprise
longitudinally extending fibers and transversely extending fibers,
the longitudinally extending fibers being thicker than the
transversely extending fibers.
[0060] In some embodiments, the vertical fibers are thicker than
the transversely extending fibers.
[0061] In some embodiments, the top and bottom panels comprise
longitudinally extending fibers and transversely extending fibers,
the longitudinally extending fibers and the vertical fibers being
thicker than the transversely extending fibers.
[0062] There is provided an assembly for placing a fixation device
in contact with an endosteal wall of an intramedullary (IM) canal
of a fractured bone, the assembly comprising: an insertion tube
that accommodates a woven elongated structure; the woven elongated
structure being pre-wetted with uncured resin, the woven elongated
structure having a closed distal end, the woven elongated structure
being compressible to a cross-sectional width smaller than an inner
diameter of the injection tube, the woven elongated structure
having a relaxed outer cross-sectional width greater than an outer
diameter of the injection tube for engagement with the endosteal
wall of the IM canal, the woven elongated structure accommodating a
distal end of an injection tube.
[0063] In some embodiments, the assembly further includes a
retention element that surrounds the woven elongated structure for
retaining resin, the retention element being selected from the
group consisting of a balloon, bag and sleeve.
[0064] In some embodiments, the woven elongated structure is
selected from the group consisting of a braided elongated
structure, a triaxial braided elongated structure, a pair of
braided elongated structures with one smaller inner braided
elongated structure disposed axially within a larger outer braided
elongated structure, a bundle of braided elongated structures, a
bundle of braided elongated structures disposed axially within an
outer braided elongated structure, a braided elongated structure
with a plurality of cavities extending along a length of the
braided elongated structure, and an elongated structure fabricated
from the spacer fabric.
[0065] In some embodiments, the woven elongated structure comprises
filaments selected from the group consisting of polyurethanes,
poly-alpha-hydroxy acids, polylactides, polyglycolides,
poly-(D,L-lactide-co-glycolide),
polyglycolide-co-trimethylenecarbonate, poly-(L-lactide),
poly-(L-CO-D,L-lactide), poly-(D,L-lactide), polyglactin acid, a
combination, poly-(D-lactide), combinations thereof and copolymers
thereof.
[0066] There is further provided a kit for repairing a fracture
bone, the kit comprising: a resorbable resin; a catalyst; a
fixation device comprising a woven elongated structure fabricated
from resorbable polymer filaments, the woven elongated structure
having a relaxed cross-sectional width and a compressed
cross-sectional width, the relaxed cross-sectional width being at
least about 50% larger than the compressed cross-sectional width,
the woven structure expanding towards its relaxed cross-sectional
width to engage the endosteal wall when not radially compressed to
its compressed cross-sectional width; an injection tube comprising
a distal end disposed axially within the fixation device; the
fixation device and distal end of the injection tube being
accommodated in a balloon; the balloon, fixation device and distal
end of the injection tube being accommodated in an insertion
tube.
[0067] In some embodiments, the woven elongated structure is
selected from the group consisting of a braided elongated
structure, a triaxial braided elongated structure, a pair of
braided elongated structures with one smaller inner braided
elongated structure disposed axially within a larger outer braided
elongated structure, a bundle of braided elongated structures, a
bundle of braided elongated structures disposed axially within an
outer braided elongated structure, a braided elongated structure
with a plurality of cavities extending along a length of the
braided elongated structure, and an elongated structure fabricated
from the spacer fabric.
[0068] In some embodiments, the woven elongated structure is a
braided elongated structure and the compressed cross-sectional
width is a locked-out diameter.
[0069] In some embodiments, the braid angle .theta. ranges from
about 5 degrees to about 22 degrees.
[0070] In some embodiments, the resin further comprises reinforcing
resorbable fibers.
[0071] In some embodiments, the woven elongated structure
accommodates an elongated structural reinforcing element.
[0072] In some embodiments, the woven elongated structure
accommodates a plurality of loose resorbable fibers for mixing with
resin injected into the woven elongated structure through the
injection tube.
[0073] Other advantages and features will be apparent from the
following detailed description when read in conjunction with the
attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0074] For a more complete understanding of the disclosed systems
and methods, reference should be made to the embodiments
illustrated in greater detail in the accompanying drawings,
wherein:
[0075] FIG. 1 is a cross-sectional view of a fracture with a
disclosed internal fixation system for fracture repair.
[0076] FIG. 2 is a cross-sectional view of a fracture with another
disclosed internal fixation system.
[0077] FIG. 3 is a cross-sectional view of a fracture with another
disclosed internal fixation system.
[0078] FIG. 4 is a cross-sectional view of a fracture with another
disclosed internal fixation system.
[0079] FIG. 5 is a cross-sectional view of a fracture with another
disclosed internal fixation system.
[0080] FIG. 6 is a perspective view of the collar used in the
system of FIG. 5.
[0081] FIG. 7 is a cross-sectional view of a fracture with another
disclosed internal fixation system.
[0082] FIG. 8 is an end view of the connector used in the internal
fixation system of FIG. 7.
[0083] FIG. 9 is a cross-sectional view of a fracture with another
disclosed internal fixation system.
[0084] FIG. 10 is a cross-sectional view of a fracture with another
disclosed internal fixation system.
[0085] FIG. 10A is a cross-sectional view of a fracture with
another disclosed internal fixation system.
[0086] FIG. 11 is a cross-sectional view of a fracture with another
disclosed internal fixation system.
[0087] FIG. 12 is a cross-sectional view of a fracture with another
disclosed system.
[0088] FIG. 13 is a cross-sectional view of a fracture with another
disclosed system.
[0089] FIG. 14 is a perspective view of an inner ring of the system
illustrated in
[0090] FIG. 13.
[0091] FIG. 15 is a top view of an alternative ring for the system
of FIG. 13.
[0092] FIG. 16 is a cross-sectional view of a fracture with yet
another disclosed system.
[0093] FIG. 17 is a plan of view an alternative support for the
system shown in FIG. 16.
[0094] FIG. 18 is a plan view of other alternative support for the
system of FIG. 16.
[0095] FIG. 19 is a cross-sectional view of a fracture with another
disclosed system.
[0096] FIG. 20 is a cross-sectional view of a fracture with another
disclosed system.
[0097] FIG. 21 is a cross-sectional view of a fracture with another
disclosed system.
[0098] FIG. 22 schematically illustrates an external fixator
attached to a bone.
[0099] FIG. 23 schematically illustrates the external fixator of
FIG. 22 attached to a bone with a segmental defect and a disclosed
internal fixation system for fracture repair.
[0100] FIG. 24 is a schematic cross-section of a fractured bone
with another disclosed internal fixation system.
[0101] FIG. 25 is a perspective view of a bone used for mechanical
testing.
[0102] FIG. 26 is a perspective view of a mechanical testing device
with the bone of FIG. 26.
[0103] FIG. 27 graphically illustrates exemplary results of a
mechanical test.
[0104] FIG. 28 schematically illustrates an internal fixation or
system for use with an intramedullary nail.
[0105] FIG. 29 schematically illustrates an internal fixation
system for use with a bone plate.
[0106] FIG. 30 schematically illustrates an internal fixation
system utilizing one or more putties disclosed herein.
[0107] FIG. 31 is a partial and enlarged view of a disclosed
elongated and reinforcing braid structure used with a biocompatible
resin and, optionally, one or more of a balloon, a bag, a sleeve,
chopped fibers, additional braid structures and/or an additional
reinforcing pin or tube as illustrated below.
[0108] FIG. 32 is a partial and enlarged view of a disclosed
reinforcing spacer fabric that may be used with a biocompatible
resin and, optionally, one or more of a balloon, a bag, a sleeve,
chopped fibers, additional woven elongated structures and an
additional reinforcing pin or tube as illustrated below.
[0109] FIG. 32A is a partial and enlarged view of another disclosed
reinforcing spacer fabric similar to FIG. 32, with thicker
longitudinal fibers or fiber bundles and spacings between groups of
vertical fibers.
[0110] FIG. 33 is a photograph illustrating a topological texture
induced in a braid surface as a result of argon etching.
[0111] FIG. 34 is an end view of an elongated braided structure
with a plurality of longitudinal reinforcing fiber bundles.
[0112] FIG. 35 graphically illustrates the effect of a number of
longitudinal fibers filaments in longitudinal fiber bundles on
loadbearing properties of elongated braid structures equipped with
longitudinal fiber bundles.
[0113] FIG. 36 is a side to sectional view of an insertion assembly
for placing a disclosed reinforcing device in an IM canal amount
wherein the reinforcing device comprises a braid or spacer fabric
as illustrated in FIGS. 31-32A respectively.
[0114] FIG. 37 is an insertion tube for use with the insertion
assembly of FIG. 36.
[0115] FIG. 38 is a schematic sectional view of a fractured bone,
IM canal and insertion port that has been previously drilled
through the outer cortical and endosteal wall structures of the
fractured bone.
[0116] FIG. 39 is a schematic sectional view of the bone
illustrated in FIG. 38 with the insertion tube of FIG. 37 disposed
therein.
[0117] FIG. 40 is a schematic sectional view of the assembly,
insertion tube and bone of FIGS. 36-39, particularly illustrating
the insertion of the assembly through the insertion tube.
[0118] FIG. 41 is a schematic sectional view of the assembly,
insertion tube and bone of FIGS. 36-40, particularly illustrating
the placement of the assembly across the fracture site.
[0119] FIG. 42 is a schematic sectional view of the assembly and
bone of FIGS. 36 and 38-41, after the insertion tube of FIG. 37 has
been removed and the braid or spacer fabric has been allowed to
expand.
[0120] FIG. 43 is a schematic sectional view of the assembly and
bone of FIGS. 36 and 38-42, particularly illustrating the injection
of resin into the braid or spacer fabric and optional balloon, bag
or sleeve.
[0121] FIG. 44 is a schematic and sectional view of a braid or
spacer fabric, optional balloon, bag or sleeve, and resin disposed
across a fracture site, whereby if an optional balloon, bag or
sleeve is utilized, excess balloon, bag or sleeve material is cut
at the insertion port through the cortical wall.
[0122] FIG. 45 is a sectional view of one disclosed assembly for
use with the procedure illustrated in FIGS. 38-44.
[0123] FIG. 46 is a sectional view of another disclosed assembly
for use with the procedure illustrated in FIGS. 38-44.
[0124] FIG. 47 is a sectional view of yet another disclosed
assembly for use with the procedure illustrated in FIGS. 38-44.
[0125] FIG. 48 is a sectional view of another disclosed assembly
for use with the procedure illustrated in FIGS. 38-44.
[0126] FIG. 49 is an end view of a dual braid system with a smaller
elongated braid disposed axially within a larger elongated
braid.
[0127] FIG. 50 is an end view illustrating the use of a bundle of
elongated braids, in this example, five braids.
[0128] FIG. 51 is an end view illustrating the use of a bundle of
elongated braids disposed axially within a larger elongated
braid.
[0129] FIG. 52 is an end view of a braid with four separate
cavities that extend axially along the braid.
[0130] FIG. 53 illustrates the braid with three cavities that
extend axially along the braid.
[0131] FIG. 54 illustrates a braid with six peripheral cavities and
a central axial cavity that extend along the braid.
[0132] It should be understood that the drawings are not
necessarily to scale and that the disclosed embodiments are
sometimes illustrated diagrammatically and in partial views. In
certain instances, details which are not necessary for an
understanding of the disclosed systems and methods or which render
other details difficult to perceive may have been omitted. It
should be understood, of course, that this disclosure is not
limited to the particular embodiments illustrated herein.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0133] The disclosed systems and methods are also advantageously
used in treatment of bone fractures associated with disease,
pathological conditions or injury.
[0134] Treatment of Bone Fractures
[0135] Healing of bone fractures generally occurs, at least to some
degree, naturally in humans or animals as a result of formation of
new bone tissue in a fractured bone. New bone formation, which is
sometimes termed "ossification" or bone "in-growth," naturally
occurs due to the activity of bone cells, such as osteoblasts and
osteoclasts and eventually results in closing of a fracture site
with newly formed tissue. In order for the bone tissue to grow such
that a fractured bone heals into its pre-fracture form and restores
its function, the bone pieces or fragments have to be located in
their appropriate natural physical position and orientation, a
process referred to as "reduction." Further, the bone fragments
must be maintained in said position and orientation for the
duration of the healing, referred to as "fixation." Treatment of
fractures is generally aimed at providing the best conditions for a
bone to heal and preventing movement of a bone or its fragments in
order to prevent or lessen damage to bone, cartilage or soft
tissues. Systems disclosed herein are designed to assist in both
reduction and fixation and enhance bone in-growth across a fracture
site by providing biocompatible materials that form a scaffold
across a fracture site.
[0136] Resorbable Materials
[0137] Disclosed methods or devices may comprise or utilize one or
more resorbable, bioerodible, or degradable material for fixation
devices. Upon installation of a fixation device comprising such
material, gradual resorption of the material takes place, thereby
making space available for bone ingrowth, which can be advantageous
over the use of non-resorbable metal materials for fixation
devices. The term "biodegradable" may be used interchangeably with
the terms "bioabsorbable", "bioresorbable", "resorbable",
"degradable", "erodible", or "bioerodible", and these terms are
used to characterize materials that gradually disintegrate after
implantation into a human or an animal.
[0138] Biodegradable materials used may be beneficial for promotion
of tissue formation, with properties such as porosity and
degradation chosen to encourage tissue growth and vascularization,
if appropriate, within the material. Degradation rate may be
coupled to the rate of bone tissue formation so that neither the
load-bearing capabilities of the tissue, nor tissue regeneration
are compromised. Accordingly, degradation rate of biodegradable
materials may be timed to ensure adequate time for growth of bone
tissue into a void, space, or cavity between a bone and a joint
implant. The resorbable material may be at least partially resorbed
over a predetermined period of time. The degradation time may be
chosen depending on a particular application and can range from a
few weeks to a few years or more. As with all implanted materials,
biodegradable materials may be sterilizable to prevent infection.
Sterilization may or may not substantially interfere with the
bioactivity of the material, alter its chemical composition or
affect its biocompatibility or degradation properties.
[0139] The resorbable materials may include, but are not limited
to, polymeric materials, such as polyurethane, poly-alpha-hydroxy
acids, polylactide and polyglycolide, including their copolymers,
poly-(D,L-lactide-co-glycolide) and
polyglycolide-co-trimethylenecarbonate; stereopolymers, such as
poly-(L-lactide) or poly-Lactic acid (PLA), poly-(L-CO-D,L-lactide)
and poly-(D,L-lactide), polyglactin acid (PGA), a combination
thereof (PLA/PGA) or any derivative, combination, composite, or
variation thereof, poly-(D,L-lactide-co-glycolide) (PDLLA-co-PGA),
poly-(L-lactide) (PLLA), poly-(D-lactide) (PDLA),
polyglycolide-co-trimethylenecarbonate, (PGA-co-TMC),
poly-(L-CO-D,L-lactide), poly-(D,L-lactide), (PDLLA). The use of
slow degrading and highly crystalline polymers, such as
poly-(L-lactide) and poly(L-CO-D,L-lactide) stereocopolymers with a
low D,L amount, amorphous polymers, such as poly-(L-CO-D,L-lactide)
stereocopolymers with a high D,L amount of poly-(D,L-lactide), or
fast-degrading copolymers, such as poly-(D,L-lactide-co-glycolide)
or polyglycolide-co-trimethylenecarbonate, is envisioned and falls
within the scope of this disclosure. The use of injectable or
crosslinkable polymers, including, but not limited to,
photopolymerizable and chemically polymerizable polymers and
polymers that harden in situ, is also encompassed by this
disclosure, including but not limited to the use of polymers of
sebacic acid (SA), alone, or copolymers of SA and 1,3-bis
(p-carboxyphenoxy) propane (CPP), or 1,6-bis (p-carboxyphenoxy)
hexane (CPH), or poly(propylene fumarate) (PPF). Resorbable
materials are not limited to the foregoing and may also include any
fully or partially degradable or erodible in a body chemical
composition, including but not limited to carbohydrates and
derivatives thereof, such as such as cellulose or hyaluronic acid.
A modification of polymeric materials to adjust their structural,
mechanical or chemical properties, or facilitate biological
responses in tissues is envisioned and falls within the scope of
this disclosure. The resorbable material may include a two phase
polymer system wherein one phase degrades faster than another to
allow for adequate strength and bone in-growth. The system may be a
non-miscible blend. An example of the two phase polymer system is
PDLA in combination with polyurethane.
[0140] Hardenable Void Fillers--Putties and Resins
[0141] Disclosed methods or devices may comprise or utilize one or
more of hardenable resins that are biocompatible and at least
partially resorbable. A term "hardenable" as used herein means that
the material is able to change consistency, harden, stiffen,
crosslink, cure and become firm, stable, or settled. Both putties
and resins may be injectable before they cure. The disclosed
putties generally include resin, with additional filler materials
to make the putty more viscous and moldable. The disclosed putties
are used alone or in combination with additional fixation devices
for the repair of segmental defects. In contrast, disclosed resins
are primarily used in the IM canal in combination with one or more
reinforcing and/or containment devices.
[0142] Certain disclosed polyurethane resins are two component
material available from PolyNovo Biomaterials Pty. Ltd. of
Australia (http://www.polynovo.com/). One particularly suitable
polyurethane resin is made from a hydroxyl functional material
(R--OH) that is reacted with a polyisocyanate (R--NCO). The setting
time of the resin is controlled through the addition of one or more
catalysts to the reaction mixture. The isocyanate may be
ethyl-lysine diisocyanate (ELDI) and the hydroxyl may be
pentaerythritol. The polyurethane may include an ester bond, which
allows for hydrolyzed degradation to take place.
[0143] The PolyNovo polyurethane resins and alternative resins are
described in the following U.S. Patent Application Publications and
PCT Application: (1) 2005/0197422; (2) 2005/0238683; (3)
2006/0051394; and WO 2009/043099, each of which is herein
incorporated by reference.
[0144] With the addition of fillers, the polyurethane resin can
form a putty which is moldable by hand. Other additives such as
porogens and blowing agents are used to create porosity.
[0145] In addition to polyurethanes, the disclosed putties and
resins, the disclosed putties may be made from resorbable polymers
which can harden or cure in situ, for example polyurethane,
polypropylene fumarate, polycapralactone, etc.
[0146] Alternatively, the resin, or putty made therefrom, may be an
injectable and/or moldable, biocompatible calcium phosphate
material that sets in situ, such as NORIAN.RTM. (Norian Corporation
of 1302 Wrights Lane East, West Chester, Pa., USA).
[0147] The resin may also comprise a biocompatible epoxy resin. The
most common commercially available epoxy resin is Diglycidyl Ether
of Bisphenol-A (DGEBA) which is the reaction product of Bisphenol A
and Epichlorohydrin.
[0148] The resins and putties made from the resins may be
customized. In particular, properties of a putty or resin are
designed, selected or modified so that the material possesses
properties suitable or desirable for stabilization of a fracture
when injected into the bone cavity. Examples of some of the
material's properties that can be customized include, but are not
limited to: porosity, pore connectivity, permeability, compression
strength, Young's modulus, bending modulus, shear modulus,
torsional modulus, yield strength, ultimate strength, or Poisson's
ratio. A putty or resin may be further stabilized to contain a
radio opaque material for x-ray visualization in order to assess or
improve positioning intra-operatively, and monitor an implant
during follow up visits.
[0149] The resin may comprise a suitable degradable ceramic cement
such comprising any one or more of, brushite, calcium sulphate and
calcium phosphate.
[0150] The resins may comprise degradable glass ionomers. These
resins can be produced by combining acid functionalized polymers
with ion leaching glasses such as a degradable polyacrylic
acid-co-caprolatone copolymers or a polyamino acid combined with
degradable glasses which liberate divalent and trivalent ionic
species such as calcium, magnium, zinc, aluminium, iron, copper
etc.
[0151] Degradable polymeric based cements may also comprise
unsaturated low molecular weight polymers, such as fumerates or
branched or telechelic macromers based on degradable polyester,
polyamide, polyurethane, polycarbonate, etc. One example is low
molecular weight polylactide-glycolide containing unsaturated
acrylate groups which can be activated in situ by the addition of a
chemical activating agent (e.g., a peroxide or azo compound) and/or
the addition of energy (e.g., electromagnetic (light), heat,
ultrasound, etc.).
[0152] Exemplary Putties
[0153] Hydroxyapatite (HA) is an ideal filler for use with a
polymer resin to form a moldable putty because of its low cost,
radiopaque properties and osteoconductive properties. Although the
examples below include HA (hydroxyapatite) as the fillers, those
having ordinary skill in the art would understand that other forms
of calcium phosphate may be used. As examples, other apatites,
calcium phosphates, orthophosphates, monocalcium phosphates,
dicalcium phosphates, tricalcium phosphates, whitlockite,
tetracalcium phosphates, amorphous calcium phosphates may be
substituted for HA. The filler particles may also be composites,
e.g., particles of polymer and calcium phosphate materials such as
HA.
[0154] In the examples that follow, a porous and hand moldable
putty is provided from a polyurethane resin and an HA filler.
However, resins other than polyurethane may be employed as
discussed above. The putties form a porous scaffold across a
fracture site that cures in situ at body temperatures. By varying
the amount of filler and optionally utilizing one or more porogens
and/or blowing agents, the properties of the putty can be
customized to a particular application or injury.
[0155] The particle size range of HA can range from about 5 .mu.m
to about 4000 .mu.m. However, in the examples that follow, the HA
was sieved to particle sizes from about 10 .mu.m to about 2800
.mu.m. The HA content of the resulting putties ranged from about 15
wt % to about 80 wt %. Using different particle sizes and amounts
of HA, or various size distributions of HA, it was found that the
porosity and compressive properties of the putties can be
manipulated for the injury being treated.
[0156] For example, increasing the amount of the 10 .mu.m particle
size HA (i.e., the "first" filler) will increase the compressive
strength of the putty and will eventually lower the porosity of the
putty. To provide a balance between compressive strength and
porosity, a combination of small particle or 10 .mu.m particle HA
and large particle or 800- and 2800 .mu.m HA (i.e., as "second" and
possibly "third" fillers) may be utilized.
[0157] Other samples use a blowing agent as well as HA filler in
the formulation. A blowing agent will aid in the creation of open
cell porosity by rapidly off gassing in the resin to form bubbles.
The blowing agent used was H.sub.2O, which off gasses carbon
dioxide. However, other blowing agents will be apparent to those
skilled in the art. This and the combination of adhesive particles
also yield hand moldable putty that is porous.
[0158] Lastly, 10 .mu.m size HA was used as filler with a porogen
in the form of mannitol, from SPI Pharma Inc. of Wilmington Del.
(http://www.spipharma.com/). The mannitol not only acts as a
porogen but also appears to reinforce the compressive strength of
the putty until it degrades leaving void spaces in the putty. The
mannitol porogen used has a sieve size ranging from about 170 .mu.m
to 1900 .mu.m. These voids are connected resulting in open celled
porosity because of the contact between the mannitol particles.
[0159] The addition of porogens and the employment of particle size
manipulation can provide homogenous porosity values. Fast
dissolving porogens include, but are not limited to mannitol,
calcium sulfate and other salts and sugars. In contrast, a discrete
amount of putty or resin may be mixed with loose particles of a
solid material, such as calcium phosphates, in order to stick the
loose particles together but not fill all the spaces between them,
which results in a porous putty. The solid particles may be of the
same material, such as fast or slow resorbing materials or may
include biologically active or non-active materials.
[0160] Once the resin is mixed, the HA particles, optional mannitol
and optional water are added and blended with the resin mixture at
room temperature. The resin will typically cure or set at body
temperature.
TABLE-US-00001 TABLE 1 Weight Percent Formulation of Samples 0.8
mm- Ratio of 170 .mu.m- 10 .mu.m 2.8 mm 0.8-1.8/ 1.9 mm HA HA
1.8-2.8 mannitol H.sub.2O parti- parti- mm HA particles (blowing
Sample Resin cles cles parti- (porogen) agent) No. (wt %) (wt %)
(wt %) cles (wt %) (wt %) I 29.4 0 70.6 13:11 0 0 II 25.0 15 60.0
13:11 0 0 III 23.3 14 62.8 16:11 0 0 IV 45.5 54.5 0 n/a 0 0 V 24.7
14.8 59.3 13:11 0 1.2 VI 43.5 17.4 0 n/a 39.1 0
TABLE-US-00002 TABLE 2 Mechanical Results Sample Compression
Porosity Connectivity No. (MPa; Mean) (%) (%) I 12 34.3 99 II 12 15
95 III 6 31 99 IV 20 24 97 V 3 33 99 VI 19 n/a n/a
[0161] As shown above, Samples I-VI provided various values for
compressive strength, which were generated using an aqueous
compression test method. The method includes conditioning the
sample for 24 hours in a phosphate buffered saline (PBS) solution
at 37.degree. C. (body temperature) before compression testing. The
samples were dimensioned by casting the samples in a PTFE split
mold (a right cylinder with the length at twice the diameter (24
mm.times.12 mm)) for 15 minutes at room temperature, in accordance
with ASTM D695. Next, the samples were removed from the mold and
conditioned at 37.degree. C. for two hours then placed in the PBS
solution.
[0162] After being conditioned for 24 hours in solution, the
samples were tested using the MTS 150 screw machine. The test speed
of the screw machine was at 1 mm/min, which is in compliance with
ASTM D695. A 5 KN load cell was used to measure stress. Most of the
compression test samples were greater than or equal to cancellous
bone, which is about 10 MPa according to McCalden et al., JBJS,
1997, vol. 79, pp. 421-427. Three repetitive tests were conducted
in the results averaged and listed in Table 2.
[0163] Samples I-VI were also tested for porosity and pore
connectivity using a .mu.CT machine. By using this machine, cross
sectional images can be taken to measure cell formation. See Table
2 for porosity results.
[0164] Unlike other resorbable resins, the above samples exhibit a
porosity that is created by using varying filler particles of
varying sizes, porogens and/or blowing agent. Also the samples
remained moldable by hand with the properties of being drillable
and radiopaque after cure.
[0165] The disclosed putties may include one or more antibiotics,
one or more antimicrobials for fighting infection. The disclosed
putties may also include osteoconductive additive such as one or
more bone morphogenetic proteins (BMPs). The resin of the disclosed
putties may include components that are not degradable or
resorbable such as reinforcing fibers. The disclosed resins may
also be ultraviolet (UV) light curable or cross-link curable. In
addition to polyurethane, other in situ hardening or curing
materials can be used, e.g., polypropylene fumerate.
[0166] By using various amounts and particle sizes of filler, e.g.,
HA, drillable, moldable and osteoconductive putties are disclosed
that can be remodeled by bone. The different size filler particles
along with varying amounts of filler also result in improved
compressive strength. The disclosed putties provide the surgeon
more control of the pore size. The disclosed putties may be hand
deliverable by the surgeon and do not require special injection
devices.
[0167] The putty may incorporate a calcium phosphate mixture formed
by first soaking conventional hydroxyapatite (HA) powder (such as a
commercially available HA powder having an average particle size of
about 45 to about 125 .mu.m) in a silver nitrate-containing and/or
silver fluoride-containing aqueous or organic solution for a period
of time. The aqueous or organic solution may comprise both silver
fluoride and silver nitrate. Beta tricalcium phosphate may be
substituted for HA or HA may be combined with beta tricalcium
phosphate. The calcium phosphate mixture includes about 0.1 percent
to about ten percent by weight of silver. The calcium phosphate
mixture may include about 0.5 percent to about three percent by
weight of silver. One or more of carbonate, fluoride, silicon,
magnesium, strontium, vanadium, lithium, copper, and zinc may be
added to the calcium phosphate mixture.
[0168] The disclosed fracture putties may be curable in vivo and
may be designed to closely match the mechanical (stress/strain--in
tension, compression, bending, and torsion) and structural
properties of natural bone. In general, the disclosed fracture
putties provide initial fracture fixation, followed by full
load-bearing capability for patient ambulation and create an
optimal mechanical environment in the form of a scaffold structure
which promotes natural bone regrowth or ingrowth, including within
large gaps between bone segments. The disclosed fracture putties
may be intrinsically non-toxic and non-antigenic, and may degrade
into harmless resorbable by-products, and/or be resorbed by
osteoclasts, the body's bone-dissolving cells, as bone regenerates,
thereby transferring load-bearing to bone over time. The disclosed
fracture putties may be compatible with, and infusible by, existing
osteoinductive bone pastes, bone morphogenetic proteins, growth
factors, antibiotics, antimicrobials, non-degradable components,
ultraviolet (UV) curable cross linkers, etc.
[0169] In general, the procedure for fracture treatment using a
disclosed putty includes the following steps: (1) reduce fracture;
(2) make an entry point, which may be collinear with the axis of
the bone or oblique to the axis of the bone; and (3) apply putty in
the IM canal across the fracture to achieve adequate fixation on
either side of the fracture. The procedure may also include
preparing the canal. This may be accomplished with a standard
reamer or a reamer with an expandable cutting head. The procedure
may include inserting an additional device into the intramedullary
canal and/or across the fracture as described in FIGS. 1-3, 5, 7,
9-13, 16, 19-21, 23-24 and 28-30.
[0170] The putty or resin may contain a reinforcing element, such
as fibers or a particulate. Fibrous reinforcing materials include,
but are not limited to, ceramic fibers or whiskers, polymeric
fibers and metal fibers, for example, fibers made from magnesium
and its alloys are degradable. Polymer materials may include, but
are not limited to, homopolymers and co-polymers of PET, PP, PE,
Nylon, PEEK, PLA, and PGA. Particulate reinforcing material may be
in the shape of plates or rods. Examples include clays, micas,
alumina, hydroxyapatite, calcium carbonate, calcium phosphates, and
zirconia.
[0171] Some of the disclosed putties have a strength of at least
200 MPa, while others have a strength of at least 500 MPa.
[0172] It is particularly advantageous if the void filler bonds to
the exposed bone within the defect. The void filler may also
comprise an allogenic or autologous bone graft material. The void
filler may also comprise a particulate or granular bone substitute
material such as JAX.TM. (Smith & Nephew, Inc). Depending on
the type of void filler used, additional strength properties may be
conferred up the system.
[0173] Alternatively, one or more rods, pins or tubes of a stiff
material may be placed into the intramedullary canal, which are
then anchored in place by injection or insertion of the putty or
resin. Examples of the stiff materials include metals, ceramics and
polymers. With polymers the stiffness could be enhanced by
preparing orientated rods, such as by die drawing. Another example
is the use of composite materials for the rods, such as a
PEEK/carbon fiber composite or degradable PLLA fiber
composites.
[0174] Further, as noted below, a braided, woven or knitted sleeve
may be placed into the intramedullary canal and impregnated with
the putty or resin. The sleeve may be made from a resorbable or
non-resorbable material. The sleeve may include a radio-opaque
marker. The sleeve may be compressed radially or stretched axially
via instrumentation for insertion, such that when inserted and
released, it can expand to conform to the dimensions of the
intramedullary canal. The sleeve may be made from resorbable
fibers, such as PDLA.
[0175] Also, as noted below, a bag or balloon may be used to fill
the intramedullary canal and filled with the putty or resin. When
the device is pressurized and expands it engages into the endosteal
wall to fixate the device via friction. An adhesive may be applied
to the outer surface of the bag so that it will adhere to the
endosteal wall after placement, thereby enhancing fixation. The
bag/balloon device may have some porosity to allow the putty or
resin to perfuse/leach to enable it to adhere to the endo steal
wall. There may be a section in the central region of the
bag/balloon that contains no porosity to prevent leakage of the
putty or resin into the fracture gap. The bag or balloon may
alternatively have reinforcing ribs or rods attached to either its
inner or outer surface.
[0176] A bag or balloon may also be used to fill the intramedullary
canal and filled with a pressurized liquid and then sealed. This
has the advantage that the liquid can be removed at a later date to
facilitate removal of the device. Alternatively, the liquid may
reversibly solidify, such as polycaprolactone or a
thermo-reversable gel.
[0177] FIGS. 1-29
[0178] Referring to the accompanying drawings in which like
reference numbers indicate like elements, FIG. 1 illustrates a bone
100 with fracture 102 and a system 10 for fracture repair. The
system 10 includes a hardenable putty 12 and a fixator 14 inserted
into the intramedullary canal. The putty 12 may be made of a
polyurethane material having embedded ceramic particles, chopped
fibers and/or HA particles. Further, in FIG. 1, the fixator 14 may
be a braided sleeve made from poly-L-lactide (PLLA) fibers and
impregnated with polyurethane resin. The sleeve may be impregnated
in vivo. The fixator 14 may also include axial channels or a
cannulation.
[0179] In FIG. 1, the fixator 14 is illustrated as engaging the
endosteal or cortical wall of the bone 100. Alternatively, the
fixator 14 may be sized to allow for blood flow between the
endosteal wall and the fixator 14. The fixator 14 may be pinned or
fastened on each side of the fracture 102 to connect the bone
segments. For example, resorbable screws may be used to fasten the
fixator 14 to the bone 100.
[0180] In another embodiment, the putty 12 is replaced by a
resorbable metal spacer formed as a monolith with a central axial
bore that accommodates the fixator 14. Additional resin or putty
may be used to fill any cracks or voids.
[0181] FIG. 2 illustrates the bone 100 having the fracture 102 and
a system 110 for fracture repair. The system 110 includes a
resorbable and hardenable putty 112, a fixator 114, and a
hardenable tube 116. In FIG. 2, the fixator 114 may be a braided
sleeve (see also FIG. 31) made from PLLA fibers or a spacer fabric
(see also FIGS. 32 and 32A) made from PLLA and impregnated with the
resorbable and hardenable putty 112, or a hardenable and resorbable
polyurethane resin. The sleeve may be impregnated in vivo. The tube
116 may be made from a shape memory material, such as a shape
memory polymer. The tube 116 may be constructed and arranged such
that the tube 116 has a first size before implantation but changes
to achieve a second size after implantation based upon the shape
memory effect. Alternatively, the fixator 114 may include axial
channels or a cannulation.
[0182] FIG. 3 illustrates the bone 100 having the fracture 102 and
a system 210 for fracture repair. The system 210 includes a
resorbable putty 212, a fixator 214, and a wrapping 216. Wrapping
216 is made from a mesh material impregnated with a putty or resin,
such as polyurethane resin. The wrapping 216 may be impregnated in
vivo. The fixator 214 is made from a resorbable material, such as a
shape memory polymer. The fixator 214 may include axial channels or
a cannulation.
[0183] In FIG. 3, the fixator 214 may comprise a degradable
scaffold section 214a disposed between degradable internal splint
sections 214b. The degradable scaffold 214a may be more porous and
may be provided in the forms of injectable gels, resins, or
preformed structures. The wrapping 216 may be in the form of a
degradable tissue guided scaffold and optional incorporation of an
active material such as an antibiotic, steroid, etc. The internal
splint sections 214b may be made of resorbable fibers impregnated
with an in-situ settable resin. The tissue guided (TGS) scaffold
216 may be placed round the defect direct cell growth and to act as
a retaining mechanism for soft gels, resins, loose particulates or
cements. The TGS 216 may be porous to encourage tissue ingrowth. In
one embodiment, the TGS 216 is a body temperature activated shape
memory split tube which activates and tightens around the bone 100.
The TSG 216 may have pores in the range of about 35 .mu.m to trap
macrophages which then cause cells to liberate cell signaling
molecules and resulting tissue repair. The gel, putty or paste 212
can be composed of gelling materials such as PLAGA granules,
hylaronic acid, light curable materials such as polylactide-based
macromers, collogen, gelatin, chitosan sponge, calcium sulphate, in
situ setting ceramic cement, etc.
[0184] FIG. 4 illustrates the bone 100 having the fracture 102 and
a system 310. The system 310 includes a hardenable putty 312 and a
plurality of ceramic channels or chopped fibers 318. The hardenable
putty 312 may be polyurethane resin and HA particles or another
suitable filler. If the fracture 102 is sufficiently small, the
putty or resin 312 may be merely polyurethane resin. As examples,
if channels 318 are employed, the channels 318 may be tubes,
plates, or cones. The putty 312 and the ceramic channels or chopped
fibers 318 may be mixed together and placed in the fracture 102.
For example, the putty 312 and the chopped fibers or ceramic
channels 318 may be shaped into a cylinder. Once the putty cylinder
312 is placed in the fracture 102, the fracture 102 and adjacent
area may be wrapped to add strength and hold the putty 312 in
place. As examples, the fracture 102 may be wrapped with a
resorbable material, a putty or resin, a woven resorbable material,
or a woven material impregnated with a foam or non-foam putty or
resin.
[0185] FIGS. 5-6 illustrate the bone 100 having the fracture 102
and a system 410. The system 410 may include a balloon 412, a
collar pair 414, and at least one band 416. The balloon 412, the
collar pair 414, and at least one band 416 all may be made from a
resorbable material. The balloon 412 expands in multiple
directions. Thus, in FIG. 5, the balloon 412 expands into the
intramedullary canal and into the segmental defect. Portions of the
balloon 412 may include a gripper 420 for gripping the endosteal
wall or other portions of bone. The balloon 412 may be filled with
a putty or resin, such as a polyurethane resin. As best seen in
FIG. 6, the collar pair 414 may include structural ribs 418. The
balloon 412 may include axial channels or a cannulation to allow
for blood flow.
[0186] Alternatively, the balloon 412 may be replaced with putty or
resin, and the collars 414 replaced with tubular structures that
are held in place by the bands or clamps 416.
[0187] FIG. 7 illustrates the bone 100 having the fracture 102 and
a system 500 for fracture repair. The system 500 includes a collar
510 and a fixator 512. The collar 510 is made from a porous shape
memory material. The fixator 512 may be a pre-formed part and may
be impregnated with a putty or resin such as a polyurethane resin.
As best seen in FIG. 8, the collar 510 is generally cylindrical and
includes peripheral passages 514, a second face 516, and tabs 518.
The passages 514 may be cylindrical and allow for bone in-growth.
The tabs 518 engage the bone surface to substantially prevent
rotation of the bone segments. The fixator 512 may also include
axial channels or a cannulation.
[0188] FIG. 9 illustrates the bone 100 having the fracture 102 and
a system 600 for fracture repair. The system 600 includes a first
putty or resin 610, a second putty 612, and a third putty 614. The
first, second and third putties 610, 612, 614 may be hardenable
and/or resorbable and the porosity and compressive strength may be
varied as disclosed above, depending upon the particular injury and
patient condition.
[0189] FIG. 10 illustrates the bone 100 having the fracture 102 and
a system 700 for fracture repair. The system 700 includes a fitting
710. The fitting 710 may be T-shaped or Y-shaped. The fitting 710
may be formed of a single component or from two members spliced
together. The fitting 710 may be filled with a putty or resin. The
fitting 710 may be made of a braided material. A resorbable putty
712 may be packed around the fitting 710. The resorbable putty 712
may be porous. After the fitting 710 is placed into the
intramedullary canal, a portion of the fitting 710 may be snipped
or broken off. The fitting 710 may be made of a resorbable
material. FIG. 10A illustrates another fitting 710a with
arrow-shaped or barbed ends 710b. The ends 710b may be threaded.
The fitting 710a may be made of a resorbable material.
[0190] FIG. 11 illustrates the bone 100 having the fracture 102 and
a system 800 for fracture repair. The system 800 includes a
reinforced resin or putty 810 for mechanical strength and a
hardenable and resorbable putty 812. The putty 812 may be porous
for bone ingrowth. The dimensions "d" and "1" may be controlled
depending upon the size of the fracture site. The reinforced putty
or resin 810 may include axial channels or a cannulation.
[0191] FIG. 12 illustrates the bone 100 having the fracture 102 and
a system 900 for fracture repair. The system 900 includes a fixator
910 made of a resin and a braided mesh wrap 912 impregnated with
the resin. The resin may be applied as a foam. The braided mesh may
provide a porous scaffold. The fixator 910 may include axial
channels or a cannulation.
[0192] In any of the above-examples, the endo steal surface of the
intramedullary canal may be rifled or spirally cut to improve
torsional strength. In any of the above examples, the system may
include a guided tissue regeneration membrane. The guided tissue
regeneration membrane may be placed between soft tissue and the
fracture repair device. As examples, the membrane may be placed
between soft tissue and the putty or resin, between the soft tissue
and the resorbable material, between the soft tissue and the wrap,
between the fixator and the soft tissue, or the membrane may be
used in place of the wrap. The membrane prevents soft tissue from
growing into the fracture repair device but does allow for bone
in-growth. As an example, guided tissue regeneration membrane may
be BIO-GIDE.RTM. Resorbable Bilayer Membrane. BIO-GIDE is a
registered trademark of Osteomedical Ltd. of Parliament Street
14-16, Dublin, Ireland. The guided tissue regeneration membrane may
be coated with silver or silver salt for antimicrobial
purposes.
[0193] FIG. 13 illustrates another system 1100 for fracture repair.
The system 1100 includes a fixator 1110, an optional support 1112
(see also FIG. 14), optional sutures 1112a and optional rod-like
supports 1112b. The fixator 1110 may be made of a solid material, a
porous material, a braided material, or some combination thereof.
In one embodiment, the fixator 1110 is a press-fit rod made from
resilient plastic. The system 1100 may also include a hardenable
and resorbable putty 1114. The optional support 1112 may be
generally cylindrical, oval, C-shaped or U-shaped. The support 1112
may be made from a porous material, a high strength resorbable
material, or magnesium. The support 1112 may be made from a shape
memory foam. The support 1112 may be placed within the fracture gap
or segmental defect to provide structural support between the bone
ends. Several supports 1112 of different sizes and/or length may be
contained within a kit, and a health care provider may select the
appropriate size and/or length for the particular fracture gap or
segmental defect from the kit. Another option is to use rod-like
supports 1112b.
[0194] Still referring to FIG. 13, the fixator 1110 is typically
placed in the intramedullary canal as shown. The fixator 1110 may
be impregnated with a resin, such as a polyurethane resin or one of
the alternatives described above. The support 1112 then may be
placed between the bone segments and around the fixator 1110. In
some embodiments, the putty or resin 1114 may be packed around the
support 1112. In other embodiments, no supports 1112, 1112b are
utilized and the putty or resin is packed around fixator 1110. In
still other embodiments, resorbable sutures 1112a may be wrapped
around the exterior of the bone to minimize rotation of the bone
segments. The sutures 1112a may be employed with or without
supports 1112, 1112b.
[0195] FIG. 14 illustrates the support 1112 of the system 1100 of
FIG. 13. Typically, the support 1112 is C-shaped and includes
protrusions 1116 along its inner wall. The protrusions 1116 may be
used to frictionally or mechanically engage the fixator 1110.
Alternatively, the protrusions may be used to provide a space
between the support 1112 and the fixator 1110. The protrusions 1116
may be randomly placed or placed in a pattern and may be omitted
entirely. If used, the protrusions 1116 may have any shape. As
examples, the protrusions 1116 may be cylindrical, square,
triangular, or conical. In FIG. 14, the protrusions 1116 are
cylindrical. The protrusions 1116 may have any length. For example,
each protrusion 1116 may have a length in the range from about 0.1
mm to about 5 mm, and more preferably from about 0.5 mm to about 3
mm. In the depicted embodiment, each protrusion has a length of
about 1.5 mm.
[0196] FIG. 15 illustrates an alternative to the support 1112 of
FIGS. 13-14. In FIG. 15, the support 1112 has exterior spaces or
gaps 1111 and radial protrusions 1113. The spaces 1111 may receive
the putty or resin 1114.
[0197] FIG. 16 illustrates another system for fracture repair 1200.
The system 1200 includes a fixator 1210 and a plurality of supports
1212. The fixator 1210 may be made of a solid material, a porous
material, a braided material, or some combination thereof. The
supports 1212 may be spaced about the fracture gap or segmental
defect. Any number of supports 1212 may be used. As an example,
from about two to about eight supports 1212 may be used within the
fracture gap or segmental defect. In FIG. 16, three supports 1212
are used (one of the supports is hidden by the fixator), each being
about 120 degrees apart. The supports 1212 may be made from a
porous material, a high strength resorbable material, such as a
magnesium alloy. The supports 1212 may be made from a shape memory
foam. The supports 1212 may be placed within the fracture gap or
segmental defect to provide structural support between the bone
ends. Several supports 1212 of different thickness and/or length
may be contained within a kit, and a health care provider may
select the appropriate thickness and/or length for the particular
fracture gap or segmental defect from the kit. The system 1200 of
FIG. 16 may also include a putty or resin (not shown) placed
in-between and around the supports 1212.
[0198] In one method, the fixator 1210 is placed in the IM canal.
The fixator 1210 may then be impregnated resin. The supports 1212
then may be placed between the bone segments and around the fixator
1210. One of the disclosed putties may be packed around the support
1212.
[0199] FIGS. 17 and 18 illustrate alternatives to the supports 1212
illustrated in FIG. 16. In FIG. 17, the support 1212' is H-shaped.
In FIG. 18, the support 1212'' is I-shaped.
[0200] FIG. 19 illustrates another system 1300 for fracture repair.
The system 1300 includes a fixator 1310. The fixator 1310 may be
made of a solid material, a porous material, a braided material, or
some combination thereof. As shown in FIG. 19, the fixator 1310 has
intramedullary canal portion and a support portion 1312. The
fixator 1310 may be unitary or integrally formed. The system 1300
may also include a disclosed putty 1314. The support portion 1312
may be generally cylindrical, oval, square, hexagonal, or some
other shape. As also shown in FIG. 19, the support portion 1312
extends radially beyond the intramedullary canal to provide support
to the bone segments. The support portion 1312 may be made from the
same material as the fixator 1310 or a different material. As
examples, the support portion 1312 may be made from a porous
material, a high strength resorbable material, magnesium, or a
shape memory material. Several fixators 1310 with support portions
1312 of different sizes and/or length may be contained within a
kit, and a health care provider may select the appropriate size
and/or length for the particular fracture gap or segmental defect
from the kit.
[0201] Still referring to FIG. 19, in one disclosed method, the
fixator 1310 is placed in the intramedullary canal and fixator 1310
is impregnated with resin. The putty 1314 may then be packed around
the support portion 1312.
[0202] FIG. 20 illustrates yet another system 1400 for fracture
repair. The system 1400 includes a fixator 1410 and at least two
supports 1412. The fixator 1410 may be made of a solid material, a
porous material, a braided material, or some combination thereof.
In the depicted embodiment, there are two supports 1412, each one
placed adjacent a bone segment. The system 1400 may also include a
putty or resin 1414. The supports 1412 may be generally
cylindrical, oval, C-shaped or U-shaped. As examples, the supports
1412 may be made from a metal, a non-resorbable material, a porous
material, a high strength resorbable material, magnesium, or a
shape memory material. The support 1412 may be placed within the
fracture gap or segmental defect to provide structural support
between the bone ends. The supports 1412 may be adapted to
frictionally or mechanically engage the fixator 1410. The supports
1412 may be fastened to the fixator 1410 through the use of a
fastener (not shown).
[0203] The supports 1412 may also include protrusions (not shown)
along the fixator contacting surface, similar to the support 1112
of the FIG. 14. The supports 1412 of FIG. 20 may be arranged with a
space in-between or stacked upon one another to substantially fill
the fracture gap or segmental defect. While in FIG. 20 the supports
1412 appear parallel to one another, those having ordinary skill in
the art would understand that the supports 1412 are more likely to
be angled relative to one another with the particular angle
dependent upon the size and shape of the particular fracture gap or
segmental defect. Several supports 1412 of different size and/or
thickness may be contained within a kit, and a health care provider
may select the appropriate size and/or thickness for the particular
fracture gap or segmental defect from the kit.
[0204] Still referring to FIG. 20, in one disclosed method, the
fixator 1410 is placed in the IM canal. The fixator 1410 is
impregnated with the putty or resin. The supports 1412 then may be
placed between the bone segments and around the fixator 1410. The
putty 1414 may be packed around the support 1412.
[0205] FIG. 21 illustrates another system 1500 for fracture repair.
The system 1500 includes a fixator 1510 and at least two pin
supports 1512. The fixator 1510 may be made of a solid material, a
porous material, a braided material, or some combination thereof.
As shown in FIG. 21, two pin supports 1512 are employed, each one
placed adjacent a bone segment. However, those having ordinary
skill in the art would understand that any number of pin supports
1512 may be used. The system 1500 may also include a putty or resin
1514. The pin supports 1512 may be generally cylindrical, square,
hexagonal, or triangular. The pin supports 1512 may be provided in
the shape of a fastener, such as a screw. As examples, the supports
1512 may be made from a metal, a non-resorbable material, a porous
material, a high strength resorbable material, magnesium, or a
shape memory material. The supports 1512 may be placed partially
into or entirely through the fixator 1510. In one embodiment, four
pin supports 1512 are employed in the form of two substantially
diametrically opposed pairs, each pin support 1512 extending only
partially into the fixator. While in FIG. 21, the pin supports 1512
appear parallel to one another, those having ordinary skill in the
art would understand that the pin supports 1512 are more likely to
be angled relative to one another with the particular angle
dependent upon the size and shape of the particular fracture gap or
segmental defect. Several supports 1512 of different thickness
and/or length may be contained within a kit, and a health care
provider may select the appropriate thickness and/or length for the
particular fracture gap or segmental defect from the kit.
[0206] In one disclosed method, the fixator 1510 is placed in the
intramedullary canal. The fixator 1510 may then impregnated with a
resin. The supports 1512 may then be placed between the bone
segments and through the fixator 1510. The putty 1514 may then be
packed around the supports 1512.
[0207] FIGS. 22-27 illustrate the use of the system for fracture
repair. Although the system is illustrated in use on a sheep femur,
the system is applicable to any mammalian bone. Referring now to
FIG. 22, the bone 100 is first reamed. The intramedullary canal is
reamed up to about 11.5 mm using a reaming tool. As best seen in
FIG. 23, an external fixation device 1000 is then used to fixate
the bone (to preserve bone alignment) while a segmental defect 1010
of about 25 mm is made in generally the mid-diaphyseal region using
a hack saw. The segmental section 1010 of bone 100 is then removed
and all remaining marrow and fat is removed from the intramedullary
canal using cotton swabs (not shown). A braided sleeve or tube of
space or material 1012 is then inserted into the intramedullary
canal until the canal is completely filled and the segmental defect
1010 is bridged.
[0208] The sleeve 1012 may be a braid of PLLA fibers having an
outside diameter of about 7 mm, and the sleeve 1012 may be
previously heat-set to expand the sleeve to about 12 mm when
deployed. The term "heat-set" refers to a process that sets the
braid to a new diameter via a thermal treatment. What is
significant is that the braid has a first diameter (in this case 12
mm) and recovers to the first diameter after stretching to achieve
a second diameter (in this case 7 mm).
[0209] Referring now to FIG. 24, a small section of resorbable mesh
1016 is then impregnated with a foaming formulation of polyurethane
material and wrapped around the segmental defect section 1010 of
the bone 100. The bone 100 is then placed in an oven at 37 degrees
C. for approximately two hours to allow the polyurethane foam to
fully set. The bone 100 is then removed from the oven and allowed
to sit for about 8 to about 16 hours.
[0210] In about twenty-four hours, an injectable, non-foaming
formulation of polyurethane material is injected into the braided
sleeve 1012 in the bone's intramedullary canal. The braided sleeve
1012 may include axial channels or a cannulation to allow for blood
flow. The polyurethane resin is filled to the top of the bone 100,
and small leaks at the segmental defect section 1010 may be closed
off to prevent loss of resin material. The bone 100 may be allowed
to set for about 1 to about 4 days, e.g., for about two days, to
allow full curing prior to potting for subsequent mechanical
testing. Potting involves using a two-part PMMA dental bone cement
mixed in a ratio of two-parts powder to one-part liquid. After
potting, the bone 100 is allowed to sit for about 8 to about 16
hours.
[0211] As best seen in FIGS. 25-26, mechanical testing employs a
bearing roller plate fixture 1020 that allows loading of a femoral
head of the bone 100. The fixture is set up such that only the
femoral head is in contact with the fixture during displacement of
a crosshead 1022. A simple compression method is used with a strain
endpoint of 100%. Load is applied at a speed of about 5 mm/min.
until failure of the construct.
[0212] FIG. 27 illustrates one example of the results of mechanical
testing. In the graph shown in FIG. 27, the maximum load achieved
is approximately 30-50% of normal weight bearing. During testing,
failure appears to be in bending only and not achieved by torque
failure. The shape of the intramedullary canal when filled with the
polyurethane-impregnated braided sleeve 1012 may prevent rotation
of the relative bone segments. The failure appears to be ductile,
which is significant as it avoids a catastrophic failure. Ductile
failure is preferred because if a device is overloaded, it will
bend rather than shatter.
[0213] Any of embodiments disclosed herein may be used to augment
external or other internal fixation devices. FIG. 23 illustrates an
external fixator augmented with the system 1010; FIGS. 28 and 29
illustrate two more examples of augmentation.
[0214] FIG. 28 schematically illustrates a fracture repair system
for use with an intramedullary nail 1610. The system 1600 may
includes an optional fixator 1630 or simply be packed with void
filler 1650 in the form of resin or putty. If used, the fixator
1630 may be fabricated from a braided sleeve but other materials
could equally be used. The system 1600 may also include a support
1640 and/or a putty or resin 1650. The intramedullary nail 1610 may
be placed in the intramedullary canal and held in place with one or
more fasteners 1620, which may be screws. The intramedullary nail
1610 may be made of any biocompatible material, including, but not
limited to, stainless steel, titanium, and carbon-reinforced PEEK.
The system 1600 may be used with the intramedullary nail 1610 to
augment fixation.
[0215] FIG. 29 schematically illustrates a fracture repair system
for use with an external fixator such as a bone plate 1710. See
also the external fixator 1000 of FIG. 23. The system 1700 includes
may include an internal fixator 1730. The system 1700 may also
include a support 1740 and/or a putty or resin 1750. The bone plate
1710 may be placed on the bone and held in place with one or more
fasteners 1740. The bone plate 1710 may be made of any
biocompatible material, including, but not limited to, stainless
steel, titanium, and carbon-reinforced PEEK. The system 1700 may be
used with the bone plate 1710 to augment fixation.
[0216] In other embodiments, the fracture repair system may use an
external fixator to augment the internal support and putty/resin
combination. Typical external fixators include Ilizarov frames,
hexapod frames, and bar frames.
[0217] FIGS. 30-54
[0218] Additional embodiments that make use of the polyurethane
resins and polyurethane-based putties disclosed above in
combination with braided sleeves, spacer fabrics, balloons, bags,
sleeves, chopped fibers and additional structural reinforcing
elements, will be discussed below in connection with FIGS.
30-48.
[0219] Turning to FIG. 30, a bone 100 is shown with a fracture 102.
It will be assumed that the fracture 102 is greater than 2 cm wide
and is therefore considered to be a large segmental defect. After
cavities 1801 are formed in the two bone segments, the cavities
1801 and IM canal may be packed with a putty 1802 with a high
degree of strength upon curing. Because bone ingrowth in the IM
canal is not important and structural integrity during the healing
process is paramount, the putty 1802 may comprise a polyurethane
resin with a relatively high 10 .mu.m HA particle content and
relatively low porosity such as sample IV of Tables 1 and 2
above.
[0220] After the first putty 1802 is in place, a second putty 1803
may be molded in the annular area of cortical bone loss. Because
cortical bone ingrowth is paramount for the annular area in which
the second putty 1803 is placed, the second putty 1803 should be
porous upon curing like samples II, III or VI. Obviously, the exact
formulas for the putties 1802, 1803 may be varied as will be
apparent to those skilled in the art. Further, the putties 1802 and
1803 may be combined with any one or more of the supporting
structural elements described above in connection with FIGS. 1-29
or below in connection with FIGS. 31-45.
[0221] Turning to FIG. 31, an exemplary braided structure 1805 is
disclosed. The braided structure 1805 includes a plurality of
bundles 1806 with each bundle including a plurality of filaments
1807. The braided structure 1805 is also characterized by the braid
angle .theta., which is the angle between the bundles 1806 and the
long axis 1808 of the braided structure 1805. The braid diameter,
or the diameter of the finished braided elongated structure 1805
after heat setting and in a relaxed state, is also a relevant
physical property. The "locked-out" diameter of a braided elongated
structure 1805 is also a relevant physical property. The locked-out
diameter of a braided elongated structure 1805 is defined as the
diameter of the braided structure 1805 when the structure 1805 is
fully stretched along its long axis 1808. The locked-out diameter
of a braided structure 1805 is related to the number of braiding
heads used to weave the elongated braided structure 1805, the
number of filaments 1807 in each bundle 1806 and the braiding angle
.theta.. If the number of braiding heads and the number of
filaments 1807 in each bundle 1806 is constant, the diameter of the
locked-out braid 1805 will decrease as the braiding angle .theta.
decreases. As the ratio of the braid diameter (after heat setting,
relaxed state) to the locked-out diameter increases, the braid
becomes more open in the relaxed state, i.e. the openings between
the bundles increase in size and the elongated braided structure
1805 filled with resin is more prone to leakage between the bundles
1806.
[0222] Effect of Braiding Parameters on Braid Performance in
Fracture Fixation Device
[0223] A range of biaxial braids were produced from PLLA
monofilaments, 100 .mu.m in diameter. Properties of the elongated
braided structures are summarized in Table 3 below.
TABLE-US-00003 TABLE 3 Braid Properties Dia- Dia- meter meter of of
man- Locked- mandrel drel Braid out braid used length Fila- braid
manu- for (mm) Braid Braid- ments dia- factured heat (locked- Braid
ref ing per meter on setting out angle no. heads bundle (mm) (mm)
(mm) state) .theta. (.degree.) 66/01 16 32 4.43 6.25 6.25 22.8 11
66/02 16 32 4.36 6.25 6.25 31.2 8 66/03 16 32 4.51 6.25 6.25 26.0
9.8 67/01 16 19 3.60 6.25 6.25 9.6 20.6 67/02 16 19 3.43 6.25 6.25
20.0 9.7 67/03 16 19 3.54 6.25 6.25 34.8 5.8 68/01 16 27 4.41 6.25
6.25 11.2 21.5 68/02 16 27 4.35 6.25 6.25 22.5 10.9 68/03 16 27
4.18 6.25 6.25 31.5 7.6
[0224] The elongated braided structures were produced in sleeve
format on a 16-head machine (Pickmaster, JB Hyde & Co). Each
head was threaded up with 100 .mu.m PLLA filament ends. The fiber
bundles (or yarns) were twisted at a rate of 20 turns per meter to
help maintain their integrity. The bundles were then braided over a
fixed diameter mandrel using a bias weave. In this configuration,
the continuous yarns crossed over and under each other to form a
continuous spiral pattern with eight bundles traveling in one
direction and the remaining eight bundles in an opposite
direction.
[0225] A series of braids were produced with varying braid length,
defined as the length of braid per 360 degrees revolution of each
yarn around the braid. The braid length was measured in a
locked-out state (i.e., fully stretched in the axial directions) as
the braid came off the machine. The woven sleeves were heat-set
over the same diameter mandrel by immersion in hot water at 90
degrees C. for about 10 seconds.
[0226] The elongated braided structures were then tested for
bending strength by placing the elongated braided structures in a
PTFE oven with a cylindrical cavity 7 mm in diameter and 100 mm
long. The 100 mm length of braid was inserted into the cavity,
which was then filled with a degradable polyurethane resin
(PolyNovo Pty. Ltd.) and allowed to cure at 37 degrees C. for 72
hours. The samples were removed from the oven and left to cure at
37 degrees C. for another 24 hours. The samples were then removed
from the oven and tested in 3 point bend with a support span of 70
mm and a cross head speed of 3.4 mm/min. The flexural modulus from
the test for the different braids is shown in the table below.
TABLE-US-00004 TABLE 4 Effect of Braid Length and Angle on Flexural
Modulus Braid Flexural Braid ref. length Braid angle modulus/ no.
(mm) .theta. (.degree.) (GPa) 66/01 22.8 11 2.63 66/02 31.2 8 2.81
66/03 26.0 9.8 2.97 67/01 9.6 20.6 2.19 67/02 20.0 9.7 2.24 67/03
34.8 5.8 2.49 68/01 11.2 21.5 2.26 68/02 22.5 10.9 2.37 68/03 31.5
7.6 2.72
[0227] From Table 4, it can be observed that as the braid length
increases, the flexural modulus increases. This behavior was
attributed to higher braid lengths resulting in reduced braid
angles .theta., i.e., the angle between the direction of the fibers
in a bundle and the longitudinal axis of the braid. The resulting
improved alignment between the fibers and the braid results in a
greater proportion of the fibers' properties contributing to the
overall strength of the composite material. However, it is also
observed that, as the braid length increases, the springiness or
recovery force of the elongated braided structures decreases, which
is undesirable. Further, the elongated braided structures with
longer braid lengths were also observed to larger interstices in
the relaxed state and were therefore more prone to allowing leakage
of the resin through the walls of the elongated braided structures.
Both of these observations appear to indicate that (1) elongated
braid structures with high braid lengths have lower recovery forces
and are therefore less likely to self expand and conform to the
endosteal wall that (2) such elongated braid structures will allow
significant leakage of resin past the braid and may therefore may
need a retention means for inhibiting migration of resin such as a
balloon, bag or sleeve as discussed below in connection with FIGS.
36-48.
[0228] Braids with increased numbers of filaments in each bundle
were found to be harder to compress and would require a larger
entry hole into the bone. Alternatively, as the braid length
increases, the braid becomes easier to compress. As a result,
elongated braid structures with braid angles .theta. greater than
about 8 degrees are suitable for most fracture fixation
applications. Ideally the braid angle .theta. ranges from about 8
degrees to about 20 degrees, more preferably from about 8 degrees
to about 12 degrees.
[0229] Surface Treatment of Braids of Braid/Polyurethane Resin
Composite Structures
[0230] Surface treatments of braids were conducted to determine the
effect on the properties of the composite structure (i.e., braid
and resin). Sections of the braid number 66/03 were treated as
follows with the results being tabulated in Table 5. A control
braid washed in isoproponal for a minimum of 2 hrs and air dried.
For the air plasma treatment, the braid treated with air plasma for
5 minutes at a pressure of 1.2.times.10.sup.-1 bar, at a reflected
power of 5 W. For the extended argon plasma treatment, the braid
was exposed for 20 minutes in a 60 degrees C. chamber temperature,
2.times.10.sup.-1 pressure and a reflected power of 20 W. For the
NaOH etch, the braid was immersed in 4 M NaOH solution for 2 hours
and then air dried. For the allyl alcohol plasma, the braid was
treated at a pressure of 200 mtorr allyl alcohol and a reflected
power of 20 W with a treatment cycle comprising 2 minutes of
continuous wave plasma followed by 15 minutes of pulsed plasma with
a duty cycle of 1 ms (on)/5 ms (on & off). The flexural
properties of the composites made from the above surface-treated
braids are given in the Table 5 below. The polyurethane resin
contained 20 wt % HA with an average particle size below 10 um
(Plasma Biotal, UK) as a filler.
TABLE-US-00005 TABLE 5 Effects of Surface Treatment on Elongated
Braid Structures Flexural Flexural modulus/ Braid treatment
strength/(MPa) (GPa) Control - no treatment 97.8 2.97 Air Plasma
105.3 2.93 Argon Plasma 116.4 3.13 NaOH etch (4M solution) 104.0
2.89 Allyl Alcohol plasma 118.7 3.20
[0231] As shown in SEM image of FIG. 33, the argon plasma treatment
creates a micro-texture on the surface of the PLLA fibers. Without
being bound to any particular theory, it is believed that the
microtexture shown in FIG. 33 will improve the mechanical
interlocking between the fibers in the braid and the cured
polyurethane resin and hence improve the mechanical properties of
the final composite structure which comprises an elongated braid
saturated with polyurethane or another suitable resin, which has
been cured.
[0232] Braids with Longitudinal Fibers
[0233] The mechanical performance of the elongated braided
structures can be further improved by the incorporation of
longitudinal fibers. Specifically, the cross-sectional view of FIG.
34 shows an elongated braid 1815 with braid bundles 1807 and the
longitudinal fiber bundles 1816. The additional longitudinal fibers
1816 are aligned with the axis 1808 of the braid 1815 and
significantly improve the bending strength of the final composite
material, which is the primary loading condition imposed on
fracture fixation devices. Such braids 1815 are also referred to as
triaxial braids.
[0234] For example, triaxial braids 1815 were made which had an
approximate relaxed external diameter of 3 mm. The elongated
braided structures 1815 were manufactured to a nominal external
diameter of 3 mm with eight bundles 1816 of longitudinal fibers per
braid. Triaxial braids 1850 with bundles 1860 of longitudinal
fibers of two, five and eight fibers were made and tested.
[0235] Testing was done by inserting the elongated braided
structures into a plastic rod of 70 mm length, with a cut half way
to simulate a fracture. As an example, the plastic rod could be
made of Delrin.RTM.. Delrin.RTM. is a registered trademark of E. I.
Du Pont De Nemours and Company of Wilmington, Del. The rod has an
internal channel through the section with a 3 mm diameter. After
placement of the braid, a polyurethane resin was used to fill the
canal and left to cure at 37 degrees C. The samples were then
tested using a cantilever test method. One side of the plastic rod
was firmly clamped, and the plastic rod on the opposite side of the
simulated fracture was loaded at a distance of 25 mm from the
fracture at a rate of 10 mm/min. A chamfer at an angle of 45
degrees C. was cut on the lower side of the plastic rod each side
of the fracture to prevent the two pieces of plastic impinging on
each other during the test.
[0236] The corresponding moment v. extension curves 1820, 1821,
1822 for the two longitudinal filaments per bundle 1816 sample,
five longitudinal filaments per bundle 1816 sample and eight
longitudinal filaments per bundle 1816 sample respectively are
graphically presented in FIG. 35. It can be seen that as the number
of longitudinal fibers increases from two longitudinal filaments
per longitudinal bundle 1816 (see the plot line 1820) to eight
longitudinal filaments per longitudinal filament bundle 1816 (see
the plot line 1822), the load required (y-axis) to deform the
sample to a given extension (x-axis) increases.
[0237] Alternatively, the ability of triaxial braids 1815 to be
compressed and return to the heat-set diameter can be improved by
using crimped fibers as the longitudinal reinforcement. Crimped
longitudinal fibers can be used individually, i.e., as a single
fiber, or can be combined into bundles like those shown at 1816 in
FIG. 34.
[0238] Further, the braids for the fracture fixation devices may be
made from braids or cords. For example, PLLA filaments (.about.100
.mu.m diameter) could be braided into a cord to produce a cord with
a 2 mm diameter. These cords could then be braided into a biaxial
or triaxial braided sleeve suitable for bones with large IM canals.
The advantage braided cord or braided braid designs is excellent
recovery properties. In contrast, large braids made from PLLA
filaments alone may not have sufficient recovery properties.
[0239] Shaped Tip to Facilitate Insertion of the Elongated Braid or
Spacer Fabric
[0240] Turning to FIGS. 36 and 38, a shaped, tapered or pointed
distal end 1830 of the elongated braided structure 1805 improves
the ease in which a braid 1805 can be inserted into a bone 100
through a narrow injection opening or port 1831 or the ease in
which a braid 1805 and assembly 1835 can be inserted through the
opening 1831. The assembly 1835 shown in FIG. 36 may include a
balloon 1836 (or alternatively, bag or sleeve), an injection tube
1837, chopped fibers (not shown) and structural reinforcing
elements (also not shown). Ideally, the end 1830 of the elongated
braided structure 1805 is shaped into a point as shown in FIG. 36.
The pointed end 1830 can be formed by melting the end of the
elongated braided structure 1805 (or spacer fabric structure 1810)
in a conical mold (not shown) to produce a pointed tip 1830. If the
elongated braided structure 1805 is to be used in a segmental
defect (FIG. 30) then a pointed end 1830 can be formed at both ends
of the elongated braided structure 1805 to improve the insertion
into the bone IM cavity of each piece of bone. Other shapes for the
tip 1830, where the cross-sectional area of the tip 1830 is less
than the cross-sectional area of the elongated braided structure
1805 will also improve the insertion ability. Examples include a
rounded tip, a flat ribbon like tip with rounded or sharp point, or
a curved tip to aid in non-axial entries. Other tip designs are too
numerous to mention here as will be apparent to those skilled in
the art.
[0241] It is also possible to include a radiopaque material or
marker into the shaped tip 1830 to allow visualization of the
distal end 1830 of the elongated braided structure 1805 during
insertion. This would allow the surgeon to ensure the elongated
braided structure 1805 is inserted past the fracture site 102 to an
optimal position before the resin in inserted and allowed to cure.
For example the shaped tip 1830 could be made by melting some PLLA
(or other degradable polymer) containing a radiopaque filler (e.g.,
hydroxyapatite) around the end 1830 of the elongated braided
structure 1805 during the shaping operation.
[0242] Ideal Filler Level for Resin
[0243] To allow the samples to be radiopaque, about 20 wt %
hydroxyapatite (HA) was mixed with the polyurethane resin. A range
of particle sizes were investigated, particle size analysis data is
given in the table below. Particle characterization was carried out
using a Beckman Coulter LS 13 320 Series Laser Diffraction Size
Analyzer with Tornado Dry Powder System. All HA was oven dried,
sintered and milled to form angular shaped particles (no spray
dried) and supplied by Plasma Biotal, UK.
TABLE-US-00006 TABLE 6 Effect of HA Mean Particle Variation on
Braid/Resin Composite Structures HA Mean (.mu.m) d.sub.10 d.sub.50
d.sub.90 Powder 1 9.982 6.128 11.55 16.74 Powder 2 107.5 68.78
135.5 192.5 Powder 3 281.3 167.3 316.1 524.8
Mean is the volume mean diameter, d.sub.10 is the diameter size
wherein 10% of the sample has a smaller diameter; d.sub.50 is the
diameter size wherein 50% of the sample has a smaller diameter; and
d.sub.90 is the diameter size wherein 90% of the sample has a
smaller diameter.
[0244] It was found that if the HA particles were too large then
they settled under gravity in the resin before it cured. To best
accommodate the viscosity of the polyurethane resin, a powder with
an average size of around 10 .mu.m was found to be ideal. To
determine the ideal filler level, a series of samples were made
with Powder 1 (Table 6) at different filler levels as shown in
Table 7. Braid ref. no. 67/02 (Table 4) was used for each sample.
The samples were made by placing the elongated braided structures
in a PTFE mold with a cylindrical cavity 7 mm in diameter and 100
mm long. The 100 mm length of braid was inserted into the cavity,
which was then filled with a degradable polyurethane resin
(PolyNovo Pty Ltd) containing the fillers and allowed to cure in an
oven at 37 degrees C. for 72 hours. The samples were then removed
from the mold and left in the oven to cure at 37 degrees C. for a
further 24 hours. The samples were then removed from the oven and
tested for mechanical strength in three-point bend with a support
span of 70 mm and a cross head speed of 3.4 mm/min. The flexural
modulus from the test for the different braids is shown in the
Table 7.
TABLE-US-00007 TABLE 7 Effect of HA Content on Braid/Resin
Composite Structures Filler Level Peak Flex Flex Modulus Strain to
Failure (% w/w) Strength (MPa) (GPa) (%) 20 65.6 2.3 No failure
observed to 21% strain 25 57.5 2.2 No failure observed to 21%
strain 30 64.9 2.6 12.6 35 69.4 3.1 9.5 40 63.8 3.5 5.5
[0245] It can be seen that, as the wt % of fillers increases, in
general, the flexural modulus of the samples increases and that the
strain to failure decreases. Based on the results obtained for
mechanical properties and radiopacity, a HA filler with a particle
size of around 10 .mu.m and at a level between 20 and 35 wt % is
satisfactory, with a level of 30 wt % being more satisfactory.
Higher or lower HA levels would be acceptable, depending on the
application.
[0246] As illustrated in connection with FIGS. 36-48, the elongated
braided structures 1805 or spacer fabric could also be contained in
a balloon 1836, bag or sleeve. Balloons 1836, bags or sleeves may
eliminate or reduce resin leakage past the elongated braided
structure 1805 or spacer fabric and into the fracture site, also
known as extravasation. Use of crimped fibers as longitudinal
components in a triaxial braid 1815 (FIG. 34) may also provide
improved performance. Use of braids 1805 made more bundles and
fibers produce braids 1805 with a tighter weave thereby reducing
leakage of resin through the elongated braided structure 1805.
[0247] As shown below, a braided elongated structure 1805 may be
used to provide reinforcement for an in situ curable intramedullary
fixation device. The elongated braided structure 1805 may be
inserted into the IM canal of the bone 100, followed by an in situ
curable resin, e.g. polyurethane resin, which will penetrate the
elongated braided structure 1805 and harden. After the resin has
cured, the combination of the resin and braid 1805 forms a fiber
reinforced composite structure.
[0248] Similar to a braided elongated structure 1805, a structure
made from spacer fabric structures 1810, 1810a as shown in FIGS.
32-32A may be employed. The spacer fabric structures 1810, 1810a
also readily absorb resin and form a fiber reinforced composite
material similar to the braided structure 1805 of FIG. 31. Once
formed as an elongated roll, fold or elongated structure, the
spacer fabric structures 1810, 1810a can be compressed and
subsequently expand to the generally cylindrical, but irregular
shape of an IM canal. For example, the spacer fabric structures
1810, 1810a that have a relaxed cross-sectional width of about 8 mm
can be compressed to fit inside an insertion tube with an inner
diameter of about 3.9 mm, leaving room for an axial injection tube
having an OD of about 2 mm.
[0249] In FIGS. 32-32A, the spacer fabrics 1810, 1810a include top
and bottom panels 1814a-1814b and 1814c-1814d respectively. In FIG.
32 the middle section 1813 includes an essentially uniform
distribution of fibers extending between the top and bottom panels
1814a, 1814b. In FIG. 32A, groups of vertical fibers 1813a are
spaced apart. As one example, for a piece of spacer fabric 1810a
that is about 14 mm wide and about 8 mm thick, the groups of fibers
1813a may have widths of about 3 mm with spacings of about 2 mm
between groups 1813a. Of course, these dimensions can vary greatly
and will depend on the width, thickness and desired compressibility
and expandability properties of the spacer fabric.
[0250] In FIG. 32A, the spacer fabric 1810a includes longitudinal
fibers 1811 or longitudinal fiber bundles having diameters greater
than the transverse fibers 1812. For a spacer fabric 1810a that is
about 14 mm wide, 8 mm thick, the longitudinal fibers 1811 may have
diameters of about 100 .mu.m while the transverse fibers 1812 may
have smaller diameters, for example about 20 .mu.m. Multiple
longitudinal fiber bundles or yarns may be used instead of single
longitudinal fibers 1811. The vertical fibers 1813a may also have
larger diameters of about 100 .mu.m. One disclosed spacer fabric is
fabricated from PLLA but other resorbable polymer fibers discussed
above may be used as will be apparent to those skilled in the
art.
[0251] Methods and instruments for introducing fixation devices in
the IM canal of a fractured bone are illustrated in FIGS. 36-48.
Turning first to FIG. 36, an insertion assembly 1835 comprises an
injection tube 1837 with a proximal end 1838 connected to an
injection port 1839. The injection tube 1837 also includes a distal
end 1840 disposed axially within the elongated braided structure
1805 (or spacer fabric structure 1810). In the embodiment shown in
FIG. 36, the elongated braided structure 1805 is contained within a
balloon 1836 which may also be a bag, sleeve or other suitable
retention element. The injection tube 1837 passes through a
hemostasis valve 1841 that includes a filter side port 1842 which
contains fluid but allows air or gases to release, and a port 1843
through which the injection tube 1837 passes. An insertion tube or
catheter 1850 is shown in FIG. 37 with a flared proximal end 1851
and a narrow distal or insertion end 1852.
[0252] Turning to FIG. 38, an injection port 1831 is formed in the
cortical wall of the fractured bone 100 by drilling or other means
and the IM canal is reamed or otherwise prepared using methods
known to those skilled in the art. In FIG. 39, the insertion tube
1850 is inserted through the port 1831 so that its distal end 1852
extends past the fracture 102. As shown in FIG. 40, the assembly
1835 is inserted through the proximal end 1851 of the insertion
tube 1850. As shown in FIG. 41, the assembly 1835 is pushed
downward through the insertion tube 1850 until the elongated
braided structure 1805 straddles either side of the fracture
102.
[0253] Once the position shown in FIG. 41 is reached, the insertion
tube 1850 can be withdrawn through the opening as indicated in FIG.
42. As shown in FIG. 43, the elongated braided structure 1805 and
balloon 1836 can be filled with resin using the injector 1860.
During the injection process illustrated in FIG. 43, the injection
tube 1837 can be retracted proximally from the position shown in
FIG. 42 to the position shown in FIG. 43 and further proximally
until the tube 1837 is withdrawn entirely from the balloon 1836 and
hemostasis valve with side port 1841 as illustrated in FIG. 44.
Further, as shown in FIG. 44, the proximal end 1861 of the balloon
1836 may be trimmed at the injection port 1831. The trimming
process may be performed before or during the setting of the resin.
The balloon 1836 and braid 1805 may be fabricated from resorbable
materials.
[0254] As illustrated in FIGS. 45-54, the components of the
assembly 1835 can be varied. For example, the balloon 1836 may be
replaced with the bag or sleeve or other suitable enclosure for
retaining resin in the IM canal. The elongated braided structure
1805 may be replaced with a triaxial braid 1815, a spacer fabric
structure 1810, or one of the structures shown in FIGS. 49-54. The
balloon 1836, bag or sleeve may be eliminated entirely if the
combination of the braid or spacer fabric and resin provides the
desired amount of resin retention. Chopped fibers may also be
inserted into either the balloon 1836 (or bag or sleeve), braid
1805 or spacer fabric to strengthen the resin and/or the composite
structure. If chopped fibers are utilized, an elongated braid or
spacer fabric may not be necessary and a balloon, bag or sleeve
structure containing a suitable amount of fibers can be inserted
into the IM canal and filled with resin. Reinforcing elements in
the form of pins or tubes may also be employed. If a reinforcing
element is utilized, a braided sleeve or spacer fabric may be
utilized, pre-wetted with resin, the excess resin removed and the
braid or spacer fabric inserted into the IM canal using the
reinforcing element. In such an embodiment, the resin may be light
curable and a light pipe or light device may be inserted downward
through the braid or spacer fabric for curing the resin as shown in
FIG. 48 and discussed below.
[0255] FIGS. 45-48 are cross-sectional views of various insertion
assemblies 1835a-1835d. These cross-sectional views are not the
scale and are intended to describe the various combination of
elements for insertion assemblies that are encompassed by this
disclosure.
[0256] FIG. 45 is a cross-sectional view of an assembly 1835a that
comprises an insertion tube 1850, a balloon 1836 (or bag or sleeve)
and an elongated braid 1805 (or triaxial braid 1815 or spacer
fabric structure 1810). The elongated braided structure 1805 is
filled with resin 1870 using an injection tube 1837 (not shown in
FIG. 45). Optionally, the elongated braided structure 1805 may have
been partially filled or charged with chopped fibers 1871 for added
strength to the composite structure once the resin 1870 has cured.
It is anticipated that the elongated braided structure 1805 may be
chosen so as to prevent migration of resin 1870 to the annular area
1872 between the elongated braided structure 1805 and the balloon
1836. If this is the case, the balloon 1836 (or bag or sleeve) may
not be necessary. If substantial migration occurs to the area 1872,
a retention means such as a balloon 1836 or bag or sleeve may be
desirable to prevent resin migration to other parts of the
patient's body. The elongated braid 1805 and balloon 1836 are sized
to expand and engage the endosteal wall of the IM canal. The
expansion may be natural for the elongated braided structure 1805
as it expands to its relaxed state or the expansion may be prompted
or caused by the injection with the resin 1870.
[0257] On the other hand, turning to FIG. 46, a braid, bag or
sleeve is not utilized. In the assembly 1835b includes an insertion
tube 1850 a balloon 1836 (or bag or sleeve) and an injection tube
1837 (not shown). In the assembly 1835b, the balloon 1836 is
optionally charged with chopped fibers 1871. The balloon 1836 will
then be injected with resin 1870 (not shown in FIG. 46) to form a
composite structure of resin 1870, fibers 1871 and the balloon 1836
in the IM canal. The balloon 1836 (or bag or sleeve) is preferably
fabricated from resorbable material. As noted above, a braid 1805
can be used that is pre-charged with chopped fibers 1871 prior to
injection with resin 1870. Upon injection with resin 1870, the
balloon 1836 will engage the endosteal wall of the IM canal.
[0258] Turning to FIG. 47, the assembly 1835c includes an insertion
tube 1850, a balloon 1836 and braid 1805 and a structural
stiffening member 1875. While only a single stiffening member 1875
is shown, a plurality of stiffening members 1875 may be utilized.
Further, while a tubular stiffening member 1875 is illustrated, the
stiffening member may be a pin or rod as well. Other shapes for
stiffening members 1875 will be apparent to those skilled in the
art. Resin may be injected through the axial opening 1876 in the
stiffening member 1875 or through the annular area 1877 between the
elongated braided structure 1805 and stiffening member 1875 using
an injection tube 1837 (not shown in FIG. 47). Again, the balloon
1836 (or bag or sleeve) may not be necessary, depending upon the
structure of the elongated braided structure 1805 and its ability
to retain and prevent migration of resin. Alternatively, the
elongated braided structure 1805 (or spacer fabric structure 1810)
may be eliminated in favor of the balloon 1836, bag or sleeve.
Again, the elongated braid 1805 or spacer fabric structure 1810 and
balloon 1836, if utilized, are sized so as to expand engage the
endosteal wall of the IM canal.
[0259] Turning to FIG. 48, the assembly 1835d includes an insertion
tube 1850 and a braid 1805 that has been pre-wetted with uncured
resin 1870a. A light pipe or light emitting device 1880 is shown
passing through the axial center of the pre-wetted braid 1805. The
elongated braided structure 1805 may be wetted with resin 1870a
outside of the tube 1850 and the resin 1870a may be a light-curable
resin. In this embodiment, an outer balloon 1836 or retention means
may not be required. Once the insertion tube 1850 is removed, the
elongated braided structure 1805 is allowed to expand and engage
the endosteal wall of the IM canal before the resin is cured with
the light-emitting device 1880.
[0260] In addition to a single elongated braid 1805, for added
structural strength, a plurality of braids or braids with multiple
cavities that extend along the length of the braid and may be
employed as illustrated in FIGS. 49-54. FIG. 49 illustrates the use
of a smaller elongated braid 1805a disposed axially within a larger
braid 1805b. FIG. 50 illustrates a plurality of smaller braids
1805c used as a bundle 1890. FIG. 51 illustrates the use of a
bundle 1890 as shown in FIG. 50 disposed within a larger outer
braid 1805b. The multiple braid systems of FIGS. 49-50 provide
additional braided surface areas that become embedded or filled
with resin 1870. When the resin is cured, the structures shown in
FIGS. 49-51 will typically be stronger than single braid
systems.
[0261] In contrast, the elongated braided structures may include
multiple cavities as illustrated in FIGS. 52-54. In FIG. 52, the
elongated braided structure 1805d includes a pair of perpendicular
wall structures 1891, 1892 to create for cavities 1893 that extend
along the length of the elongated braided structure 1805d. In FIG.
53, the elongated braided structure 1805e includes three walls 1894
to create three cavities 1893. In FIG. 54, the braid structure
1805f includes an outer elongated braid 1805g, an inner elongated
braid 1805h, and a plurality of radial wall structures 1895 that
define a plurality of peripheral cavities 1893b that extend along
the length of the braid structure 1805f. The wall structures
1891-1895 become filled or embedded with resin 1870 to add strength
to the overall braid structures 1805d-1805f.
[0262] In summary, a vast number of possibilities for the insertion
assembly 1835, 1835a-1835d is possible. Elongated braided
structures 1805 or triaxial braided elongated structures 1815 may
be used alone with resin 1870 or in combination with a retention
means such as a balloon 1836, bag or sleeve. Spacer fabric
structures 1810 may be used alone with resin or in combination with
a retention means such as a balloon 1836, bag or sleeve. Chopped
fibers 1871 may be added to the resin in any of the above
embodiments or added to the elongated braided structure 1805 or
spacer fabric structure 1810 prior to insertion and prior to
injection with resin 1870. A balloon 1836, bag or sleeve may be
charged with chopped fibers and used with or without an elongated
braid 1805, triaxial braid 1815, or spacer fabric structure 1810,
1810a. Resorbable reinforcing elements such as pins or tubes 1875
may be combined with any of the above embodiments. Elongated braid
structures 1805, elongated triaxial braided structures 1815 and
spacer fabric structures 1810 may also be pre-wetted with resin
prior to insertion and then cured in situ after radial expansion to
the endosteal wall. The reinforcing element may be used to insert
the pre-wetted braid 1805, 1815 or the spacer fabric structure
1810. In addition to single braid systems illustrated in FIGS.
36-48, multiple braid systems or braids with multiple cavities may
be utilized as illustrated in FIGS. 49-54 to provide additional
braided surface areas that can be embedded with cured resin for
added strength. Any of the braided structures illustrated in FIGS.
49-54 may be triaxial, or braided structures with longitudinal
fibers or longitudinal fiber bundles disposed therein.
[0263] An elongated braid 1805, 1815 or spacer fabric structure
1810 is manufactured as described above. The distal end 1830 of the
elongated braided structure 1805 may be tapered or shaped as
described above. In any event, the ends of the elongated braided
structure 1805, 1815 or the spacer fabric structure 1810 should be
melted to eliminate fraying. In one example, the flexible insertion
tube 1850 has an OD of about 4.2 mm and the elongated braid 1805
has a relaxed OD of about 8 mm. The elongated braided structure
1805 is placed over the flexible injection tube 1837 which, at its
distal end, has an OD of about 2 mm. The injection tube 1837 is
used to push the elongated braided structure 1805 into the
insertion tube 1850 or, if a balloon 1836, bag or sleeve is
employed, the injection tube 1837 is used to push the elongated
braided structure 1805 into the balloon 1836 and then the injection
tube 1837, braid 1805, and balloon 1836 are then inserted into the
flexible insertion tube 1850. The distal end of the balloon 1836 is
closed and the proximal end of the balloon 1836 may include a valve
such as a hemostatic valve to provide a seal around the injection
tube 1837.
[0264] Surgical kits of various forms may also be provided for use
by physicians. For example, a surgical kit may include a woven
elongated structure 1805, which accommodates a distal end of an
injection tube 1837, and which is disposed within a balloon 1836.
The balloon 1836, elongated woven structure 1805 and injection tube
1837 may be disposed within an insertion tube or catheter 1850. A
valve 1841 may are may not be connected to the balloon 1836 and
injection tube 1837. A syringe or other resin 1870 delivery device
may also be included for delivering resin 1870 to the woven
elongated structure 1805 and to the interior of the balloon 1836.
The resin 1870 may also be provided in a kit form which includes an
appropriate catalyst and filler, if necessary. Reinforcing elements
1875 or fibers 1871 may also be included and may be positioned
inside the woven elongated structure 1805.
[0265] Surgical Procedures
[0266] Various surgical procedures may be employed to utilize the
assemblies 1835-1835d. First, an incision is made in an entry
portal 1831 is drilled into the fractured bone at an appropriate
spacing from the fracture 102. The two-part polyurethane resin is
mixed. The selected assembly 1835-1835d is then inserted into the
IM canal. The insertion tube 1850 is withdrawn. The resin is
injected through the injection tube 1837 thereby filling the
elongated braided structure 1805 (or braid 1815 or spacer fabric
structure 1810) and balloon 1836 (or bag or sleeve) with resin
1870. The injection tube 1837 is withdrawn and the proximal end of
the balloon 1836 is trimmed at the portal site 1831. The incision
is then closed. The elongated braided structure 1805 and/or balloon
1836 may be pre-charged with chopped fibers 1871 as described
above. A balloon 1836 (or bag or sleeve) may be utilized without a
braid 1805 and vice versa as discussed above.
[0267] If a pre-wetted braid 1805 is utilized, an incision and
entry portal 1831 is made. The resin 1870 is mixed and injected
into a container. The elongated braid 1805, triaxial elongated
braid 1815 or spacer fabric structure 1810 is soaked in the resin
and then inserted into the IM canal using an insertion tube 1850
and injection tube 1837 as a pusher. The insertion tube 1850 is
withdrawn. If the resin is to be cured by body temperature, the
injection tube 1837 can be withdrawn. If light is needed to cure
the resin 1870, a light pipe or other light emitting device is
inserted down through the wetted braid 1805, 1815 or spacer fabric
structure 1810. The light is passed through the wetted fabric and
then withdrawn. The wound is then closed. A pre-wetted braid 1805,
1815 or spacer fabric structure 1810 can also be practiced with a
balloon 1836, bag or sleeve, with or without light-curable
resin.
[0268] The structures and methods disclosed herein may be used
independently for bone treatment or fracture repair. Alternatively,
the structures and methods disclosed herein may be used in
conjunction with external or internal devices. The structures and
methods disclosed herein also may be used in an osteotomy.
[0269] While only certain embodiments have been set forth,
alternatives and modifications will be apparent from the above
description to those skilled in the art. These and other
alternatives are considered equivalents and within the spirit and
scope of this disclosure and the appended claims.
* * * * *
References