U.S. patent application number 14/020685 was filed with the patent office on 2014-01-30 for bone fixation device, tools and methods.
Invention is credited to Robert G. Coleman, Stephen B. Gunther, Kai U. Mazur, Stephen R. McDaniel, Charles L. Nelson, Trung Ho Pham, Herber Saravia.
Application Number | 20140031823 14/020685 |
Document ID | / |
Family ID | 43855424 |
Filed Date | 2014-01-30 |
United States Patent
Application |
20140031823 |
Kind Code |
A1 |
Mazur; Kai U. ; et
al. |
January 30, 2014 |
BONE FIXATION DEVICE, TOOLS AND METHODS
Abstract
A bone fixation device is provided with an elongate body having
a longitudinal axis and having a first state in which at least a
portion of the body is flexible and a second state in which the
body is generally rigid, an actuateable gripper disposed at one or
more locations on the elongated body, a hub located on a proximal
end of the elongated body, and an actuator operably connected to
the gripper(s) to deploy the gripper(s) from a retracted
configuration to an expanded configuration. Methods of repairing a
fracture of a bone are also disclosed. One such method comprises
inserting a bone fixation device into an intramedullary space of
the bone to place at least a portion of an elongate body of the
fixation device in a flexible state on one side of the fracture and
at least a portion of a hub on another side of the fracture, and
operating an actuator to deploy at least one gripper of the
fixation device to engage an inner surface of the intramedullary
space to anchor the fixation device to the bone. Various hub
designs are disclosed that may be used in combination with other
fixation device components.
Inventors: |
Mazur; Kai U.; (Santa Rosa,
CA) ; McDaniel; Stephen R.; (San Francisco, CA)
; Pham; Trung Ho; (Santa Rosa, CA) ; Nelson;
Charles L.; (Santa Rosa, CA) ; Gunther; Stephen
B.; (Keswick, VA) ; Saravia; Herber; (San
Francisco, CA) ; Coleman; Robert G.; (Cordova,
TN) |
Family ID: |
43855424 |
Appl. No.: |
14/020685 |
Filed: |
September 6, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12642648 |
Dec 18, 2009 |
8568413 |
|
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14020685 |
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61138920 |
Dec 18, 2008 |
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Current U.S.
Class: |
606/62 |
Current CPC
Class: |
A61B 17/86 20130101;
A61B 17/7291 20130101; A61B 17/7266 20130101; A61B 17/72 20130101;
A61B 17/7225 20130101; A61B 17/68 20130101; A61B 17/1725 20130101;
A61B 17/7208 20130101 |
Class at
Publication: |
606/62 |
International
Class: |
A61B 17/72 20060101
A61B017/72 |
Claims
1. (canceled)
2. An implantable bone fixation device comprising: an elongate hub
comprising a mesh structure and a tubular portion, wherein the mesh
structure comprises a flexible state and a locked state, wherein
the tubular portion is proximal of the mesh structure, the tubular
portion comprising a wall with an outer surface and an inner
surface, the outer surface with a round cross-sectional shape, the
inner surface with a round cross-sectional shape, wherein the wall
extends along the mesh structure, the mesh structure comprising a
plurality of apertures over at least a portion of the outer
surface, wherein the plurality of apertures are configured to
deform to hold a fastener connected to the hub; and an actuator
operably connected to the elongate hub for changing the mesh
structure from the flexible state to the locked state.
3. The implantable bone fixation device of claim 2, wherein the
flexible state comprises any of the group of bending, stretching,
and deforming a material of the mesh structure.
4. The implantable bone fixation device of claim 2, wherein the
mesh structure takes on a rigid state in the locked state.
5. The implantable bone fixation device of claim 2, wherein the
mesh structure comprises a plurality of diamond shaped
apertures.
6. The implantable bone fixation device of claim 2, wherein at
least one aperture expands upon receipt of said fastener to a
diameter of 2.7 mm.
7. The implantable bone fixation device of claim 2, wherein the
tubular portion is rigid.
8. The implantable bone fixation device of claim 2, wherein the
mesh structure comprises at least two layers, each layer comprising
a plurality of apertures.
9. The implantable bone fixation device of claim 8, wherein at
least a portion of the plurality of apertures in a second layer of
the mesh structure overlap a portion of the plurality of apertures
in a first layer of the mesh structure.
10. The implantable bone fixation device of claim 9, wherein at
least one aperture forms a pilot hole in the elongate hub.
11. An implantable bone fixation device comprising: an elongate
body having a flexible state, a rigid state, and a tubular portion,
the elongate body comprising an outer surface and an inner surface
of a tubular wall, the tubular wall comprising an array of holes
over a portion of the outer surface, each of the holes being
configured to expand upon receipt of a fastener there-through,
wherein the elongate body comprises a mesh structure forming the
array of holes; and an actuator operably connected to the elongate
body for changing the elongate body from the flexible state to the
rigid state, wherein a first position of the actuator places the
elongate body in the flexible state and a second position of the
actuator places the elongate body in the rigid state.
12. The implantable bone fixation device of claim 11, wherein said
holes are longitudinally formed.
13. The implantable bone fixation device of claim 11, wherein at
least one hole is elongated to form a slot.
14. The implantable bone fixation device of claim 11, wherein the
rigid state is a locked state.
15. The implantable bone fixation device of claim 11, wherein the
flexible state comprises any of the group of bending, stretching,
and deforming a material of the elongate body.
16. The implantable bone fixation device of claim 11, wherein the
rigid state comprises limiting any of the group of bending,
stretching, and deforming the material of the elongate body.
17. The implantable bone fixation device of claim 11, wherein the
elongate body comprises at least two layers, each layer comprising
an array of slots, wherein the slots of the layers overlap to form
the array of holes in the elongate body.
18. The implantable bone fixation device of claim 17, wherein each
layer comprises a separately formed mesh structure.
19. The implantable bone fixation device of claim 11, wherein at
least one hole expands upon receipt of said fastener to a diameter
of 2.7 mm.
20. The implantable bone fixation device of claim 11, wherein the
tubular portion is rigid.
Description
INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS
[0001] Any and all applications for which a foreign or domestic
priority claim is identified in the Application Data Sheet as filed
with the present application are hereby incorporated by reference
under 37 CFR 1.57.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to devices, tools and methods
for providing reinforcement of bones. More specifically, the
present invention relates to devices, tools and methods for
providing reconstruction and reinforcement of bones, including
diseased, osteoporotic and fractured bones.
[0003] Bone fractures are a common medical condition both in the
young and old segments of the population. However, with an
increasingly aging population, osteoporosis has become more of a
significant medical concern in part due to the risk of osteoporotic
fractures. Osteoporosis and osteoarthritis are among the most
common conditions to affect the musculoskeletal system, as well as
frequent causes of locomotor pain and disability. Osteoporosis can
occur in both human and animal subjects (e.g. horses). Osteoporosis
(OP) and osteoarthritis (OA) occur in a substantial portion of the
human population over the age of fifty. The National Osteoporosis
Foundation estimates that as many as 44 million Americans are
affected by osteoporosis and low bone mass, leading to fractures in
more than 300,000 people over the age of 65. In 1997 the estimated
cost for osteoporosis related fractures was $13 billion. That
figure increased to $17 billion in 2002 and is projected to
increase to $210-240 billion by 2040. Currently it is expected that
one in two women, and one in four men, over the age of 50 will
suffer an osteoporosis-related fracture. Osteoporosis is the most
important underlying cause of fracture in the elderly. Also, sports
and work-related accidents account for a significant number of bone
fractures seen in emergency rooms among all age groups.
[0004] One current treatment of bone fractures includes surgically
resetting the fractured bone. After the surgical procedure, the
fractured area of the body (i.e., where the fractured bone is
located) is often placed in an external cast for an extended period
of time to ensure that the fractured bone heals properly. This can
take several months for the bone to heal and for the patient to
remove the cast before resuming normal activities. In some
instances, an intramedullary (IM) rod or nail is used to align and
stabilize the fracture. In that instance, a metal rod is placed
inside a canal of a bone and fixed in place, typically at both
ends. See, for example, Fixion.TM. IM (Nail), www.disc-o-tech.com.
This approach requires incision, access to the canal, and placement
of the IM nail. The nail can be subsequently removed or left in
place. A conventional IM nail procedure requires a similar, but
possibly larger, opening to the space, a long metallic nail being
placed across the fracture, and either subsequent removal, and or
when the nail is not removed, a long term implant of the IM nail.
The outer diameter of the IM nail must be selected for the minimum
inside diameter of the space. Therefore, portions of the IM nail
may not be in contact with the canal. Further, micro-motion between
the bone and the IM nail may cause pain or necrosis of the bone. In
still other cases, infection can occur. The IM nail may be removed
after the fracture has healed. This requires a subsequent surgery
with all of the complications and risks of a later intrusive
procedure. In general, rigid IM rods or nails are difficult to
insert, can damage the bone and require additional incisions for
cross-screws to attach the rods or nails to the bone.
[0005] Some IM nails are inflatable. See, for example, Meta-Fix IM
Nailing System, www.disc-o-tech.com. Such IM nails require
inflating the rod with very high pressures, endangering the
surrounding bone. Inflatable nails have many of the same drawbacks
as the rigid IM nails described above.
[0006] External fixation is another technique employed to repair
fractures. In this approach, a rod may traverse the fracture site
outside of the epidermis. The rod is attached to the bone with
trans-dermal screws. If external fixation is used, the patient will
have multiple incisions, screws, and trans-dermal infection paths.
Furthermore, the external fixation is cosmetically intrusive,
bulky, and prone to painful inadvertent manipulation by
environmental conditions such as, for example, bumping into objects
and laying on the device. Other concepts relating to bone repair
are disclosed in, for example, U.S. Pat. No. 5,108,404 to Scholten
for Surgical Protocol for Fixation of Bone Using Inflatable Device;
U.S. Pat. No. 4,453,539 to Raftopoulos et al. for Expandable
Intramedullary Nail for the Fixation of Bone Fractures; U.S. Pat.
No. 4,854,312 to Raftopolous for Expanding Nail; U.S. Pat. No.
4,932,969 to Frey et al. for Joint Endoprosthesis; U.S. Pat. No.
5,571,189 to Kuslich for Expandable Fabric Implant for Stabilizing
the Spinal Motion Segment; U.S. Pat. No. 4,522,200 to Stednitz for
Adjustable Rod; U.S. Pat. No. 4,204,531 to Aginsky for Nail with
Expanding Mechanism; U.S. Pat. No. 5,480,400 to Berger for Method
and Device for Internal Fixation of Bone Fractures; U.S. Pat. No.
5,102,413 to Poddar for Inflatable Bone Fixation Device; U.S. Pat.
No. 5,303,718 to Krajicek for Method and Device for the
Osteosynthesis of Bones; U.S. Pat. No. 6,358,283 to Hogfors et al.
for Implantable Device for Lengthening and Correcting Malpositions
of Skeletal Bones; U.S. Pat. No. 6,127,597 to Beyar et al. for
Systems for Percutaneous Bone and Spinal Stabilization, Fixation
and Repair; U.S. Pat. No. 6,527,775 to Warburton for Interlocking
Fixation Device for the Distal Radius; U.S. Patent Publication
US2006/0084998 A1 to Levy et al. for Expandable Orthopedic Device;
and PCT Publication WO 2005/112804 A1 to Myers Surgical Solutions,
LLC for Fracture Fixation and Site Stabilization System. Other
fracture fixation devices, and tools for deploying fracture
fixation devices, have been described in: US Patent Appl. Publ. No.
2006/0254950; U.S. Ser. No. 60/867,011 (filed Nov. 22, 2006); U.S.
Ser. No. 60/866,976 (filed Nov. 22, 2006); and U.S. Ser. No.
60/866,920 (filed Nov. 22, 2006). In view of the foregoing, it
would be desirable to have a device, system and method for
providing effective and minimally invasive bone reinforcement and
fracture fixation to treat fractured or diseased bones, while
improving the ease of insertion, eliminating cross-screw incisions
and minimizing trauma.
SUMMARY OF THE INVENTION
[0007] ASPECTS OF THE INVENTION RELATE TO EMBODIMENTS OF A BONE
FIXATION DEVICE AND TO METHODS FOR USING such a device for
repairing a bone fracture. The bone fixation device may include an
elongate body with a longitudinal axis and having a flexible state
and a rigid state. The device further may include a plurality of
grippers disposed at longitudinally-spaced locations along the
elongated body, a rigid hub connected to the elongated body, and an
actuator that is operably-connected to the grippers to deploy the
grippers from a first shape to an expanded second shape.
[0008] In one embodiment, a bone fixation device is provided with
an elongate body having a longitudinal axis and having a first
state in which at least a portion of the body is flexible and a
second state in which the body is generally rigid, an actuateable
gripper disposed at a distal location on the elongated body, a hub
located on a proximal end of the elongated body, and an actuator
operably connected to the gripper to deploy the gripper from a
retracted configuration to an expanded configuration.
[0009] Methods of repairing a fracture of a bone are also
disclosed. One such method comprises inserting a bone fixation
device into an intramedullary space of the bone to place at least a
portion of an elongate body of the fixation device in a flexible
state on one side of the fracture and at least a portion of a hub
on another side of the fracture, and operating an actuator to
deploy at least one gripper of the fixation device to engage an
inner surface of the intramedullary space to anchor the fixation
device to the bone.
[0010] One embodiment of the present invention provides a low
weight to volume mechanical support for fixation, reinforcement and
reconstruction of bone or other regions of the musculo-skeletal
system in both humans and animals. The method of delivery of the
device is another aspect of the invention. The method of delivery
of the device in accordance with the various embodiments of the
invention reduces the trauma created during surgery, decreasing the
risks associated with infection and thereby decreasing the
recuperation time of the patient. The framework may in one
embodiment include an expandable and contractible structure to
penult re-placement and removal of the reinforcement structure or
framework.
[0011] In accordance with the various embodiments of the present
invention, the mechanical supporting framework or device may be
made from a variety of materials such as metal, composite, plastic
or amorphous materials, which include, but are not limited to,
steel, stainless steel, cobalt chromium plated steel, titanium,
nickel titanium alloy (nitinol), superelastic alloy, and
polymethylmethacrylate (PMMA). The device may also include other
polymeric materials that are biocompatible and provide mechanical
strength, that include polymeric material with ability to carry and
delivery therapeutic agents, that include bioabsorbable properties,
as well as composite materials and composite materials of titanium
and polyetheretherketone (PEEK.TM.), composite materials of
polymers and minerals, composite materials of polymers and glass
fibers, composite materials of metal, polymer, and minerals.
[0012] Within the scope of the present invention, each of the
aforementioned types of device may further be coated with proteins
from synthetic or animal source, or include collagen coated
structures, and radioactive or brachytherapy materials.
Furthermore, the construction of the supporting framework or device
may include radio-opaque markers or components that assist in their
location during and after placement in the bone or other region of
the musculo-skeletal systems.
[0013] Further, the reinforcement device may, in one embodiment, be
osteo incorporating, such that the reinforcement device may be
integrated into the bone.
[0014] In still another embodiment of the invention, a method of
repairing a bone fracture is disclosed that comprises: accessing a
fracture along a length of a bone through a bony protuberance at an
access point at an end of a bone; advancing a bone fixation device
into a space through the access point at the end of the bone;
bending a portion of the bone fixation device along its length to
traverse the fracture; and locking the bone fixation device into
place within the space of the bone. The method can also include the
step of advancing an obturator through the bony protuberance and
across the fracture prior to advancing the bone fixation device
into the space. In yet another embodiment of the method, the step
of anchoring the bone fixation device within the space can be
included.
[0015] An aspect of the invention discloses a removable bone
fixation device that uses a single port of insertion and has a
single-end of remote actuation wherein a bone fixation device
stabilizes bone after it has traversed the fracture. The bone
fixation device is adapted to provide a single end in one area or
location where the device initiates interaction with bone. The
device can be deployed such that the device interacts with bone.
Single portal insertion and single-end remote actuation enables the
surgeon to insert and deploy the device, deactivate and remove the
device, reduce bone fractures, displace or compress the bone, and
lock the device in place. In addition, the single-end actuation
enables the device to grip bone, compresses the rigidizable
flexible body, permits axial, torsional and angular adjustments to
its position during surgery, and releases the device from the bone
during its removal procedure. A removable extractor can be provided
in some embodiments of the device to enable the device to be placed
and extracted by deployment and remote actuation from a single end.
The device of the invention can be adapted and configured to
provide at least one rigidizable flexible body or sleeve. Further
the body can be configured to be flexible in all angles and
directions. The flexibility provided is in selective planes and
angles in the Cartesian, polar, or cylindrical coordinate systems.
Further, in some embodiments, the body is configured to have a
remote actuation at a single end. Additionally, the body can be
configured to have apertures, windings, etc. The device may be
configured to function with non-flexible bodies for use in bones
that have a substantially straight segment or curved segments with
a constant radius of curvature. Another aspect of the invention
includes a bone fixation device in that has mechanical geometry
that interacts with bone by a change in the size of at least one
dimension of a Cartesian, polar, or spherical coordinate system.
Further, in some embodiments, bioabsorbable materials can be used
in conjunction with the devices, for example by providing specific
subcomponents of the device configured from bioabsorbable
materials. A sleeve can be provided in some embodiments where the
sleeve is removable, has deployment, remote actuation, and a single
end. Where a sleeve is employed, the sleeve can be adapted to
provide a deployable interdigitation process or to provide an
aperture along its length through which the deployable
interdigitation process is adapted to engage bone. In some
embodiments, the deployable interdigitation process is further
adapted to engage bone when actuated by the sleeve. In some
embodiments, the bone fixation device further comprises a
cantilever adapted to retain the deployable bone fixation device
within the space. The sleeve can further be adapted to be expanded
and collapsed within the space by a user. One end of the device can
be configured to provide a blunt obturator surface adapted to
advance into the bone. A guiding tip may also be provided that
facilitates guiding the device through the bone. Further, the
deployable bone fixation device can be adapted to receive external
stimulation to provide therapy to the bone. The device can further
be adapted to provide an integral stimulator which provides therapy
to the bone. In still other embodiments, the device can be adapted
to receive deliver therapeutic stimulation to the bone.
[0016] The devices disclosed herein may be employed in various
regions of the body, including: cranial, thoracic, lower
extremities and upper extremities. Additionally, the devices are
suitable for a variety of breaks including, metaphyseal and
diaphyseal.
[0017] The fracture fixation devices of various embodiments of the
invention are adapted to be inserted through an opening of a
fractured bone, such as the radius (e.g., through a bony
protuberance on a distal or proximal end or through the midshaft)
into the intramedullary canal of the bone. In some embodiments, the
fixation device has two main components, one configured component
for being disposed on the side of the fracture closest to the
opening and one component configured for being disposed on the
other side of the fracture from the opening so that the fixation
device traverses the fracture.
[0018] The device components cooperate to align, fix and/or reduce
the fracture so as to promote healing. The device may be removed
from the bone after insertion (e.g., after the fracture has healed
or for other reasons), or it may be left in the bone for an
extended period of time or permanently.
[0019] In some embodiments, the fracture fixation device has one or
more actuatable anchors or grippers on its proximal and/or distal
ends. These anchors may be used to hold the fixation device to the
bone while the bone heals.
[0020] In some embodiments, to aid in insertion into the
intramedullary canal, at least one component of the fracture
fixation device has a substantially flexible state and a
substantially rigid state. Once in place, deployment of the device
also causes the components to change from the flexible state to a
rigid state to aid in proper fixation of the fracture. At least one
of the components may be substantially rigid or semi-flexible. At
least one component may provide a bone screw attachment site for
the fixation device.
[0021] Embodiments of the invention also provide deployment tools
with a tool guide for precise alignment of one or more bone screws
with the fracture fixation device. These embodiments also provide
bone screw orientation flexibility so that the clinician can select
an orientation for the bone screw(s) that will engage the fixation
device as well as any desired bone fragments or other bone or
tissue locations.
[0022] These and other features and advantages of the present
invention will be understood upon consideration of the following
detailed description of the invention and the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] THE novel features of the invention are set forth with
particularity in the appended claims. A better understanding of the
features and advantages of the present invention will be obtained
by reference to the following detailed description that sets forth
illustrative embodiments, in which the principles of the invention
are utilized, and the accompanying drawings of which:
[0024] FIG. 1 is a perspective view of an embodiment of a bone
fixation device implanted in a bone according to the invention.
[0025] FIG. 2 is another perspective view of the implanted device
of FIG. 1.
[0026] FIG. 3 is a longitudinal cross-section view of the bone
fixation device of FIG. 1 in a non-deployed state.
[0027] FIG. 4 is a plan view of a combination deployment tool that
may be used with the bone fixation device of FIG. 1.
[0028] FIG. 5 is a cross-section view of the tool and device shown
in FIG. 4.
[0029] FIG. 6 is a perspective view of the tool and device shown in
FIG. 4.
[0030] FIG. 7 is a cross-section view of the implanted device of
FIG. 1.
[0031] FIG. 8 is a perspective view of an alternative embodiment of
the implanted device of FIG. 1.
[0032] FIG. 9 is a perspective view of another alternative
embodiment of the implanted device of FIG. 1.
[0033] FIG. 10A is a perspective view of another embodiment of a
bone fixation device shown deployed in a fractured clavicle.
[0034] FIG. 10B is perspective view of the device shown in FIG. 10A
shown in a deployed state.
[0035] FIG. 10C is a side elevation view of the device shown in
FIG. 10A shown in a retracted or undeployed state.
[0036] FIG. 10D is a side elevation view of the device shown in
FIG. 10A shown in a deployed state.
[0037] FIG. 10E is a cross-sectional view of the device shown in
FIG. 10A shown in a retracted or undeployed state.
[0038] FIG. 10F is a cross-sectional view of the device shown in
FIG. 10A shown in a deployed state.
[0039] FIG. 10G is a perspective view of a gripper of the device
shown in FIG. 10A shown in a retracted or undeployed state.
[0040] FIG. 10H is a side elevation view of a gripper and actuator
of the device shown in FIG. 10A shown in a retracted or undeployed
state.
[0041] FIG. 10I is a perspective view of a gripper and actuator of
the device shown in FIG. 10A shown in a deployed state.
[0042] FIG. 11A is perspective view of another embodiment of a bone
fixation device shown in a retracted or undeployed state.
[0043] FIG. 11B is perspective view of the device shown in FIG. 11A
shown in a deployed state.
[0044] FIG. 11C is a cross-sectional view of the device shown in
FIG. 11A shown in a retracted or undeployed state.
[0045] FIG. 11D is a cross-sectional view of the device shown in
FIG. 11A shown in a deployed state.
[0046] FIG. 12A shows an isometric side view of an exemplary
embodiment of a bone fixation device hub.
[0047] FIG. 12B shows a side view of the bone fixation device of
FIG. 12A.
[0048] FIG. 12C shows a front view of the bone fixation device of
FIG. 12A.
[0049] FIG. 12D shows back view of the bone fixation device of FIG.
12A.
[0050] FIG. 12E shows an isometric front view of the bone fixation
device of FIG. 12A.
[0051] FIG. 12F shows a plan view of a surface on the bone fixation
device of FIG. 12A.
[0052] FIG. 12G shows an isometric side view of the bone fixation
device of FIG. 12A implanted in a bone.
[0053] FIG. 12H shows an isometric elevated view of the bone
fixation device of FIG. 12A implanted in a bone.
[0054] FIG. 12I shows an isometric view of the bone fixation device
of FIG. 12A implanted in a bone.
[0055] FIG. 13A shows an isometric side view of an another
exemplary embodiment of a bone fixation device hub.
[0056] FIG. 13B shows a side view of the bone fixation device of
FIG. 13A.
[0057] FIG. 13C shows a front view of the bone fixation device of
FIG. 13A.
[0058] FIG. 13D shows a back view of the bone fixation device of
FIG. 13A.
[0059] FIG. 13E shows an isometric view of the bone fixation device
of FIG. 13A.
[0060] FIG. 14A shows an isometric side view of another exemplary
embodiment of a bone fixation device hub.
[0061] FIG. 14B shows a side view of the bone fixation device of
FIG. 14A.
[0062] FIG. 14C shows a front view of the bone fixation device of
FIG. 14A.
[0063] FIG. 14D shows a back side view of the bone fixation device
of FIG. 14A.
[0064] FIG. 14E shows an isometric side view of the bone fixation
device of FIG. 14A.
[0065] FIG. 14F shows a close up view of a optional portion of the
bone fixation device of FIG. 14A.
[0066] FIG. 15A shows an isometric side view of another exemplary
embodiment of a bone fixation device hub.
[0067] FIG. 15B shows a side view of the bone fixation device of
FIG. 15A.
[0068] FIG. 15C shows a front view of the bone fixation device of
FIG. 15A.
[0069] FIG. 15D shows a back view of the bone fixation device of
FIG. 15A.
[0070] FIG. 16A shows an isometric side view of another exemplary
embodiment of a bone fixation device hub.
[0071] FIG. 16B shows an isometric front view of the bone fixation
device of FIG. 16A.
[0072] FIG. 16C shows an isometric top view of the bone fixation
device of FIG. 16A.
[0073] FIG. 16D shows a front view of the bone fixation device of
FIG. 16A.
[0074] FIG. 16E shows an optional screw for use with the bone
fixation device of FIG. 16A.
[0075] FIG. 17A shows an isometric side view of another exemplary
embodiment of a bone fixation device hub.
[0076] FIG. 17B shows a side view of the bone fixation device of
FIG. 17A.
[0077] FIG. 17C shows a close up side view of the bone fixation
device of FIG. 17A.
[0078] FIG. 18A shows an isometric side view of another exemplary
embodiment of a bone fixation device hub.
[0079] FIG. 18B shows a side view of the bone fixation device of
FIG. 18A.
[0080] FIG. 19A shows an isometric side view of another exemplary
embodiment of a bone fixation device hub.
[0081] FIG. 19B shows a side view of the bone fixation device hub
of FIG. 19A.
[0082] FIG. 20A shows an isometric side view of another exemplary
embodiment of a bone fixation device hub.
[0083] FIG. 20B shows an exploded side view of the bone fixation
device of FIG. 20A.
DETAILED DESCRIPTION OF INVENTION
[0084] By way of background and to provide context for the
invention, it may be useful to understand that bone is often
described as a specialized connective tissue that serves three
major functions anatomically. First, bone provides a mechanical
function by providing structure and muscular attachment for
movement. Second, bone provides a metabolic function by providing a
reserve for calcium and phosphate. Finally, bone provides a
protective function by enclosing bone marrow and vital organs.
Bones can be categorized as long bones (e.g. radius, femur, tibia
and humerus) and flat bones (e.g. skull, scapula and mandible).
Each bone type has a different embryological template. Further each
bone type contains cortical and trabecular bone in varying
proportions. The devices of this invention can be adapted for use
in any of the bones of the body as will be appreciated by those
skilled in the art.
[0085] Cortical bone (compact) forms the shaft, or diaphysis, of
long bones and the outer shell of flat bones. The cortical bone
provides the main mechanical and protective function. The
trabecular bone (cancellous) is found at the end of the long bones,
or the epiphysis, and inside the cortex of flat bones. The
trabecular bone consists of a network of interconnecting trabecular
plates and rods and is the major site of bone remodeling and
resorption for mineral homeostasis. During development, the zone of
growth between the epiphysis and diaphysis is the metaphysis.
Finally, woven bone, which lacks the organized structure of
cortical or cancellous bone, is the first bone laid down during
fracture repair. Once a bone is fractured, the bone segments are
positioned in proximity to each other in a manner that enables
woven bone to be laid down on the surface of the fracture. This
description of anatomy and physiology is provided in order to
facilitate an understanding of the invention. Persons of skill in
the art will also appreciate that the scope and nature of the
invention is not limited by the anatomy discussion provided.
Further, it will be appreciated there can be variations in
anatomical characteristics of an individual patient, as a result of
a variety of factors, which are not described herein. Further, it
will be appreciated there can be variations in anatomical
characteristics between bones which are not described herein.
[0086] FIGS. 1 and 2 are perspective views of an embodiment of a
bone fixation device 100 having a proximal end 102 (nearest the
surgeon) and a distal end 104 (further from surgeon) and positioned
within the bone space of a patient according to the invention. In
this example, device 100 is shown implanted in the upper (or
proximal) end of an ulna 106. The proximal end and distal end, as
used in this context, refers to the position of an end of the
device relative to the remainder of the device or the opposing end
as it appears in the drawing. The proximal end can be used to refer
to the end manipulated by the user or physician. The distal end can
be used to refer to the end of the device that is inserted and
advanced within the bone and is furthest away from the physician.
As will be appreciated by those skilled in the art, the use of
proximal and distal could change in another context, e.g. the
anatomical context in which proximal and distal use the patient as
reference, or where the entry point is distal from the surgeon.
[0087] When implanted within a patient, the device can be held in
place with suitable fasteners such as wire, screws, nails, bolts,
nuts and/or washers. The device 100 is used for fixation of
fractures of the proximal or distal end of long bones such as
intracapsular, intertrochanteric, intercervical, supracondular, or
condular fractures of the femur; for fusion of a joint; or for
surgical procedures that involve cutting a bone. The devices 100
may be implanted or attached through the skin so that a pulling
force (traction may be applied to the skeletal system).
[0088] In the embodiment shown in FIG. 1, the design of the
metaphyseal fixation device 100 depicted is adapted to provide a
bone engaging mechanism or gripper 108 adapted to engage target
bone of a patient from the inside of the bone. As configured for
this anatomical application, the device is designed to facilitate
bone healing when placed in the intramedullary space within a post
fractured bone. This device 100 has a gripper 108 positioned
distally and shown deployed radially outward against the wall of
the intramedullary cavity. On entry into the cavity, gripper 108 is
flat and retracted (FIG. 3). Upon deployment, gripper 108 pivots
radially outward and grips the diaphyseal bone from the inside of
the bone. One or more screws 110 placed through apertures through
the hub 112 lock the device 100 to the metaphyseal bone. Hence, the
metaphysis and the diaphysis are joined. A flexible-to-rigid body
portion 114 may also be provided, and in this embodiment is
positioned between gripper 108 and hub 112. It may be provided with
wavy spiral cuts 116 for that purpose, as will be described in more
detail below.
[0089] FIG. 3 shows a longitudinal cross-section of device 100 in a
non-deployed configuration. In this embodiment, gripper 108
includes two pairs of opposing bendable gripping members 118. Two
of the bendable gripping members 118 are shown in FIG. 3, while the
other two (not shown in FIG. 3) are located at the same axial
location but offset by 90 degrees. Each bendable gripping member
118 has a thinned portion 120 that permits bending as the opposite
distal end 122 of member 118 is urged radially outward, such that
member 118 pivots about thinned portion 120. When extended, distal
ends 122 of bendable members 118 contact the inside of the bone to
anchor the distal portion of device 100 to the bone. In alternative
embodiments (not shown), the gripper may comprise 1, 2, 3, 4, 5, 6
or more bendable members similar to members 118 shown.
[0090] During actuation, bendable members 118 of gripper 108 are
urged radially outward by a ramped surface on actuator head 124.
Actuator head 124 is formed on the distal end of actuator 126. The
proximal end of actuator 126 is threaded to engage a threaded bore
of drive member 128. The proximal end of drive member 128 is
provided with a keyed socket 130 for receiving the tip of a rotary
driver tool 132 (shown in FIG. 5) through the proximal bore of
device 100. As rotary driver tool 132 turns drive member 128,
actuator 126 is drawn in a proximal direction to outwardly actuate
gripper members 118.
[0091] A hemispherical tip cover 134 may be provided at the distal
end of the device as shown to act as a blunt obturator. This
arrangement facilitates penetration of bone (e.g. an intramedullary
space) by device 100 while keeping the tip of device 100 from
digging into bone during insertion.
[0092] As previously mentioned, device 100 may include one or more
flexible-to-rigid body portions 114. This feature is flexible upon
entry into bone and rigid upon application of compressive axial
force provided by tensioning actuator 126. Various embodiments of a
flexible-to-rigid portion may be used, including dual helical
springs whose inner and outer tubular components coil in opposite
directions, a chain of ball bearings with flats or roughened
surfaces, a chain of cylinders with flats, features, cones,
spherical or pointed interdigitating surfaces, wavy-helical cut
tubes, two helical cut tubes in opposite directions, linear wires
with interdigitating coils, and bellows-like structures.
[0093] The design of the flexible-to-rigid tubular body portion 114
allows a single-piece design to maximize the transformation of the
same body from a very flexible member that minimizes strength in
bending to a rigid body that maximizes strength in bending and
torsion. The flexible member transforms to a rigid member when
compressive forces are applied in the axial direction at each end,
such as by an actuator similar to 126. The body portion 114 is
made, for example, by a near-helical cut 116 on a tubular member at
an angle of incidence to the axis somewhere between 0 and 180
degrees from the longitudinal axis of the tubular body portion 114.
The near-helical cut or wavy-helical cut may be formed by the
superposition of a helical curve added to a cyclic curve that
produces waves of frequencies equal or greater than zero per turn
around the circumference and with cyclic amplitude greater than
zero. The waves of one segment nest with those on either side of
it, thus increasing the torque, bending strength and stiffness of
the tubular body when subjective to compressive forces. The tapered
surfaces formed by the incident angle allow each turn to overlap or
interdigitate with the segment on either side of it, thus
increasing the bending strength when the body is in compression.
Additionally, the cuts can be altered in depth and distance between
the cuts on the longitudinal axis along the length of body portion
114 to variably alter the flexible-to-rigid characteristics of the
tubular body along its length.
[0094] The cuts 116 in body portion 114 allow an otherwise rigid
member to increase its flexibility to a large degree during
deployment. The tubular member can have constant or varying
internal and external diameters. This design reduces the number of
parts of the flexible-to-rigid body portion of the device and
allows insertion and extraction of the device through a curved
entry port in the bone while maximizing its rigidity once inserted.
Application and removal of compressive forces provided by a
parallel member such as wire(s), tension ribbons, a sheath, wound
flexible cable, or actuator 126 as shown will transform the body
from flexible to rigid and vice versa.
[0095] In operation, as actuator 126 is tightened, gripper members
118 are extended radially outwardly. Once the distal ends of
gripper members 118 contact bone and stop moving outward, continued
rotation of actuator 126 draws the proximal end 102 and the distal
end 104 of device 100 closer together until cuts 116 are
substantially closed. As this happens, body portion 114 changes
from being flexible to rigid to better secure the bone fracture(s),
as will be further described below. Rotating drive member 128 in
the opposite direction causes body portion 114 to change from a
rigid to a flexible state, such as for removing device 100 if
needed in the initial procedure or during a subsequent procedure
after the bone fracture(s) have partially or completely healed.
Body portion 114 may be provided with a solid longitudinal portion
136 (as best seen in FIGS. 3 and 9) such that cuts 116 are a series
of individual cuts each traversing less than 360 degrees in
circumference, rather than a single, continuous helical cut. This
solid portion 136 can aid in removal of device 100 by keeping body
portion 114 from extending axially like a spring.
[0096] FIG. 4 illustrates a combination tool 138 useful for
inserting device 100, actuating gripper 108, compressing
flexible-to-rigid body portion 114, approximating the fracture in
bone 106, aligning anchor screw(s) 110, and removing device 100, if
desired. In this exemplary embodiment, tool 138 includes an
L-shaped body 140 that mounts the other components of the tool and
also serves as a handle. The main components of tool 138 are a
device attachment portion 142, a rotary driver 132, an
approximating driver 144, and a screw alignment portion 146.
[0097] FIG. 5 shows a cross-section of the tool 138 and device 100
illustrated in FIG. 4. As shown, device attachment portion 142
includes a knob 148 rigidly coupled to a tube 150 which is
rotatably mounted within sleeve 152. Sleeve 152 in turn is fixedly
mounted to tool body 140. The distal end of tube 150 is provided
with external threads for engaging the internal threads on the
proximal end of device 100. As best seen in FIG. 4, both the distal
end of sleeve 152 and the proximal end of device 100 may be
provided with semicircular steps that inter-engage to prevent
device 100 from rotating with respect to sleeve 152. With this
arrangement, device 100 can be prevented from rotating when it is
secured to tool 138 by tube 150 of device attachment portion 142.
The mating semicircular steps also serve to position device 100 in
a particular axial and angular orientation with respect to tool 138
for aligning screws with screw holes, as will be later
described.
[0098] Rotary driver 132 may be used to actuate gripper 108 and
compress flexible-to-rigid body portion 114 after device 100 is
inserted into bone 106. Driver 132 may also be used to allow body
portion 114 to decompress and gripper 108 to retract if removal of
device 100 from bone 106 is desired. In the embodiment shown,
driver 132 includes knob 154, torsion spring 156, hub 158, bushing
160 and shaft 162. The distal end of shaft 162 is provided with a
mating tip 164, such as one having a hex-key shape, for engaging
with keyed socket 130 of device 100 (best seen in FIG. 3), such
that turning driver shaft 162 turns drive member 128 and axially
actuates actuator 126, as described above.
[0099] The proximal end of shaft 162 may be fitted with a bushing
160, such as with a press-fit. Hub 158 may be secured over bushing
160, such as with a pin through bushing 160 and shaft 162. In this
embodiment, knob 154 is rotatably mounted over hub 158 and bushing
160 such that knob 154 can rotate independently from shaft 162. A
torsion spring 156 may be used to couple knob 154 to hub 158 as
shown to create a torque limiting and/or torque measuring driver.
With this indirect coupling arrangement, as knob 154 is rotated
about shaft 162, spring 156 urges hub 158 and shaft 162 to rotate
in the same direction. Rotational resistance applied by device 100
to shaft tip 164 will increase in this embodiment as gripper 108
engages bone 106, and flexible-to-rigid body portion 114
compresses. As more torque is applied to knob 154, it will advance
rotationally with respect to hub 158 as torsion spring 156
undergoes more stress. Markings may be provided on knob 154 and hub
158 to indicate the torque being applied. In this manner, a surgeon
can use driver 132 to apply torque to device 100 in a predetermined
range. This can help ensure that gripper 108 is adequately set in
bone 106, body portion 114 is sufficiently compressed, and
excessive torque is not being applied that might damage device 100,
bone 106 or cause slippage therebetween. A slip clutch or other
mechanism may be provided to allow the applied torque to be limited
or indicated. For example, driver 132 may be configured to "click"
into or out of a detent position when a desired torque is reached,
thus allowing the surgeon to apply a desired torque without needing
to observe any indicia on the driver. In alternative embodiments,
the driver knob may be selectably or permanently coupled to shaft
162 directly.
[0100] After device 100 is inserted in bone 106 and deployed with
tool 138 as described above, the approximating driver portion 144
of tool 138 may be used to compress one or more fractures in bone
106. Approximating driver 144 includes knob 166 located on sleeve
152. Knob 166 may be knurled on an outer circumference, and have
threads on at least a portion of its axial bore. The internal
threads of knob 166 engage with mating external threads on sleeve
152 such that when knob 166 is rotated it advances axially with
respect to sleeve 152. When device 100 is anchored in bone 106,
sleeve 152 is prevented from moving away from the bone.
Accordingly, as knob 166 is advanced axially toward bone 106, it
serves to approximate bone fractures located between gripper 108
and knob 166. Suitable thread pitch and knob circumference may be
selected to allow a surgeon to supply a desired approximating force
to bone 106 by using a reasonable rotation force on knob 166. In
alternative embodiments (not shown), a torque indicating and/or
torque limiting mechanism as described above may be incorporated
into approximating driver 144.
[0101] As previously indicated, tool 138 may also include a screw
alignment portion 146. In the embodiment depicted in the figures,
alignment portion 146 includes a removable alignment tube 168 and
two bores 170 and 172 through tool body 140. In alternative
embodiments (not shown), a single bore or more than two bores may
be used, with or without the use of separate alignment tube(s).
[0102] In operation, alignment tube 168 is first received in bore
170 as shown. In this position, tube 168 is in axial alignment with
angled hole 174 at the distal end 102 of device 100. As described
above, the mating semicircular steps of device 100 and sleeve 152
position angled hole 174 in its desired orientation. With this
arrangement, a drill bit, screw driver, screw and/or other
fastening device or tool may be inserted through the bore of tube
168 such that the device(s) are properly aligned with hole 174. The
outward end of alignment tube 168 may also serve as a depth guide
to stop a drill bit, screw and/or other fastener from penetrating
bone 106 beyond a predetermined depth.
[0103] Alignment tube 168 may be withdrawn from bore 170 as shown,
and inserted in bore 172. In this position, tube 168 aligns with
hole 176 of device 100. As described above, a drill bit, screw
driver, screw and/or other fastening device may be inserted through
the bore of tube 168 such that the device(s) are properly aligned
with hole 176.
[0104] FIG. 6 shows alignment tube 168 of tool 138 aligning screw
110 with angled hole 174 at the distal end of device 100, as
described above.
[0105] FIG. 7 shows a first screw 110 received through angled hole
174 and a second screw 110 received through hole 176 in device 100
and into bone 106. Screws 110 may be installed manually or with the
aid of tool 138 as described above. The heads of screws 110 may be
configured to be self-countersinking such that they remain
substantially beneath the outer surface of the bone when installed,
as shown, so as to not interfere with adjacent tissue. In this
embodiment, the proximal end 102 of device 100 is secured to bone
106 with two screws 110, and the distal end 104 is secured by
gripper 108. In this manner, any bone fractures located between the
proximal screw 110 and distal gripper 108 may be approximated and
rigidly held together by device 100. In alternative embodiments
(not shown), more than one gripper may be used, or only screws or
other fasteners without grippers may be used to secure device 100
within bone 106. For example, the device shown in FIG. 1 could be
configured with a second gripper located between screw 110 and the
middle of the device if the fracture is located more at the
mid-shaft of the bone. Similarly, more than two screws or other
fasteners may be used, or only grippers without fasteners may be
used. In various embodiments, holes such as 174 and 176 as shown
and described above can be preformed in the implantable device. In
other embodiments, some or all of the holes can be drilled or
otherwise formed in situ after the device is implanted in the
bone.
[0106] Once device 100 is secured within bone 106, combination tool
138 may be removed by turning knob 148 to disengage threads of tube
150 from threads within the proximal end 102 of device 100. An end
plug 178 may be threaded into the proximal end 102 of device 100 to
preventing growth of tissue into implanted device 100. Device 100
may be left in bone 106 permanently, or it may be removed by
performing the above described steps in reverse. In particular,
plug 178 is removed, tool 138 is attached, screws 110 are removed,
gripper 108 is retracted, and device 100 is pulled out using tool
138.
[0107] FIGS. 8 and 9 show alternative embodiments similar to device
100 described above. Device 100' shown in FIG. 8 is essentially
identical to device 100 described above but is shorter in length
and utilizes a single anchor screw 110 at its proximal end 102.
Device 100'' shown in FIG. 9 is similar to device 100', but is
shorter still. In various embodiments, the devices may be
configured to have a nominal diameter of 3 mm, 4 mm, 5 mm or 6 mm.
It is envisioned that all three device designs 100, 100' and 100''
may each be provided in all three diameters such that the chosen
device is best suited for the particular fracture(s) and anatomy in
which it is implanted.
[0108] In accordance with the various embodiments of the present
invention, the device may be made from a variety of materials such
as metal, composite, plastic or amorphous materials, which include,
but are not limited to, steel, stainless steel, cobalt chromium
plated steel, titanium, nickel titanium alloy (nitinol),
superelastic alloy, and polymethylmethacrylate (PMMA). The device
may also include other polymeric materials that are biocompatible
and provide mechanical strength, that include polymeric material
with ability to carry and delivery therapeutic agents, that include
bioabsorbable properties, as well as composite materials and
composite materials of titanium and polyetheretherketone
(PEEK.TM.), composite materials of polymers and minerals, composite
materials of polymers and glass fibers, composite materials of
metal, polymer, and minerals.
[0109] Within the scope of the present invention, each of the
aforementioned types of device may further be coated with proteins
from synthetic or animal source, or include collagen coated
structures, and radioactive or brachytherapy materials.
Furthermore, the construction of the supporting framework or device
may include radio-opaque markers or components that assist in their
location during and after placement in the bone or other region of
the musculo-skeletal systems.
[0110] Further, the reinforcement device may, in one embodiment, be
osteo incorporating, such that the reinforcement device may be
integrated into the bone. In a further embodiment, there is
provided a low weight to volume device deployed in conjunction with
other suitable materials to form a composite structure in-situ.
Examples of such suitable materials may include, but are not
limited to, bone cement, high density polyethylene, Kapton.RTM.,
polyetheretherketone (PEEK.TM.), and other engineering
polymers.
[0111] Once deployed, the device may be electrically, thermally, or
mechanically passive or active at the deployed site within the
body. Thus, for example, where the device includes nitinol, the
shape of the device may be dynamically modified using thermal,
electrical or mechanical manipulation. For example, the nitinol
device may be expanded or contracted once deployed, to move the
bone or other region of the musculo-skeletal system or area of the
anatomy by using one or more of thermal, electrical or mechanical
approaches.
[0112] It is contemplated that the inventive implantable device,
tools and methods may be used in many locations within the body.
Where the proximal end of a device in the anatomical context is the
end closest to the body midline and the distal end in the
anatomical context is the end further from the body midline, for
example, on the humerus, at the head of the humerus (located
proximal, or nearest the midline of the body) or at the lateral or
medial epicondyle (located distal, or furthest away from the
midline); on the radius, at the head of the radius (proximal) or
the radial styloid process (distal); on the ulna, at the head of
the ulna (proximal) or the ulnar styloid process (distal); for the
femur, at the greater trochanter (proximal) or the lateral
epicondyle or medial epicondyle (distal); for the tibia, at the
medial condyle (proximal) or the medial malleolus (distal); for the
fibula, at the neck of the fibula (proximal) or the lateral
malleoulus (distal); the ribs; the clavicle; the phalanges; the
bones of the metacarpus; the bones of the carpus; the bones of
themetatarsus; the bones of the tarsus; the sternum and other
bones, the device may be adapted and configured with adequate
internal dimension to accommodate mechanical fixation of the target
bone and to fit within the anatomical constraints. As will be
appreciated by those skilled in the art, access locations other
than the ones described herein may also be suitable depending upon
the location and nature of the fracture and the repair to be
achieved. Additionally, the devices taught herein are not limited
to use on the long bones listed above, but can also be used in
other areas of the body as well, without departing from the scope
of the invention. It is within the scope of the invention to adapt
the device for use in flat bones as well as long bones.
[0113] FIGS. 10A-10I show another embodiment of a bone fixation
device constructed according to aspects of the invention. FIG. 10A
is a perspective view showing the exemplary device 200 deployed in
a fractured clavicle 202. Device 200 is similar to device 100
described above and shown in FIGS. 1-7, but has a gripper 204
located near its proximal end, another gripper 206 located at a
more distal location, and a flexible-to-rigid body portion 208
located near the distal end of the device. A bone screw 210 and
gripper 204 are configured to secure device 200 inside bone 202 on
the proximal side of fracture 212, while gripper 206 and
flexible-to-rigid body portion 208 are configured to secure device
200 on the distal side of fracture 212. In other respects,
construction and operation of device 200 is much like that of
device 100 described above.
[0114] In this exemplary embodiment, each of the two grippers 204
and 206 has four outwardly expanding arms 214. These arms are
spaced at 90 degree intervals around the circumference of the
device body. The arms 214 of gripper 204 may be offset by 45
degrees from arms 214 of gripper 206 as shown in the figures to
distribute the forces applied by grippers 204 and 206 on the bone
202. As shown in FIGS. 10E and 10F, a single actuator 216 may be
used to deploy both grippers 204 and 206. Actuator 216 may also be
used to axially compress flexible-to-rigid body portion 208 to make
it substantially rigid. At least a portion of actuator 216 may be
flexible to allow flexible-to-rigid body portion 208 to assume a
curved shape, as best seen in FIGS. 10A and 10B. Alternatively, it
may be desirable in some embodiments to have flexible-to-rigid body
portion 208 maintain a straight or a curved configuration
regardless of whether it is in a flexible or rigid state. In these
embodiments, the actuator may be rigid and faulted with the desired
straight and/or curved shape to match the flexible-to-rigid body
portion. In some embodiments, it may also be desirable to design at
least a portion of the actuator with a high degree of axial
elasticity to allow the actuator to continue to expand some
gripper(s) and/or compress some flexible-to-rigid body portion(s)
after other gripper(s) and/or flexible-to-rigid body portion(s)
have already been fully deployed.
[0115] Referring to FIGS. 10G-10I, further details of an exemplary
gripper 204 are shown. FIGS. 10G and 10H show gripper 204 with
bendable arms 214 in a retracted state. As cam 218 of actuator 216
is driven axially into the distal ramped ends of arms 214, arms 214
bend at thinned portions 220 to move radially outward toward the
deployed position shown in FIG. 10I. Notches 222 may be provided in
the distal ends of arms 214 as shown to allow arms 214 to better
grip interior bone surfaces. Without departing from the scope of
the invention, one, two, three, or more bendable arms may be
used.
[0116] Referring to FIGS. 11A-11D, another embodiment of a bone
fixation device is shown. Device 300 includes a curved hub 302,
proximal gripper 304, flexible-to-rigid body portion 306, and
distal gripper 308. Distal gripper 308 is similar in construction
and operation to grippers 204 and 206 described above. Proximal
gripper 304 is provided with three pairs of scissor arms 310. Each
pair of arms 310 is pivotably interconnected at a mid-portion by a
pin. Each arm is pivotably connected with a pin to either proximal
end piece 312 or distal end piece 314. When end pieces 312 and 314
are moved closer together, arms 310 pivot radially outward from an
axially aligned retracted position, as shown in FIGS. 11A and 11C,
to a deployed position, as shown in FIGS. 11B and 11D. In the
deployed position, the distal ends of the six arms 310 engage an
inner surface of a bone as previously described.
[0117] In operation, device 300, with grippers 304 and 308 in a
retracted state, may be inserted into the intramedullary space
within a bone, such as the radius. Device 300 may be inserted
through a curved opening formed in the bone, such as an opening
formed through a bony protuberance on a distal or proximal end or
through the midshaft of the bone. Curved hub 302 may be configured
with the same geometry of the curved opening in the bone, and when
the flexible-to-rigid body portion 306 is in its flexible state, it
can assume this same geometry. Once device 300 is in place inside
the bone, actuator 315 (shown in FIGS. 11C and 11D) may be actuated
from the proximal end of device 300 by turning drive member 317 in
a manner similar to that previously described. Longitudinal
movement of actuator 315 toward the proximal end of device 300
causes flexible-to-rigid body portion 306 to foreshorten and assume
its rigid state, and causes grippers 304 and 308 to outwardly
deploy against the bone. Bone screws may be inserted through holes
316 shown in curved hub 302 to secure the proximal end of device
300 to the bone. Further details of the construction and operation
of a device similar to device 300 may be found in co-pending U.S.
application Ser. No. 11/944,366 filed Nov. 21, 2007 and entitled
Fracture Fixation Device, Tools and Methods.
[0118] Device 300 is an example of an embodiment utilizing mixed
gripper types. In other words, this device uses one scissors-arm
tripod gripper 304 and one bendable-arm gripper 308. Other
embodiments of the invention (not shown) use various combinations
of gripper(s) and/or flexible-to-rigid body portion(s). Further
exemplary gripper embodiments are described in detail in co-pending
U.S. application Ser. No. 61/100,652 filed Sep. 26, 2008 and
entitled Fracture Fixation Device, Tools and Methods. It is
envisioned that virtually any combination of zero, one, two, or
more grippers may be used in combination with zero, one, two or
more flexible-to-rigid body portions to form a device adapted to a
particular bone anatomy, fracture, disease state or fixation
purpose. The grippers and/or flexible-to-rigid body portions may
each be of identical or different construction, and may be placed
together or at other locations along the device. Further, a
straight, curved, flexible, rigid, or no hub at all may be used
with the above combinations. Additionally, screws, K-wires, sutures
or no additional fixation may be used with these various devices.
The devices may be specially designed and constructed for a
particular purpose or range of purposes. According to aspects of
the invention, the components may also be designed to be
interchangeable and/or produced in various sizes so that surgical
kits may be provided. Such kits would allow surgical teams to
select from a variety of components to build devices themselves,
each suited to a particular patient's unique situation.
[0119] Referring to FIGS. 12A through 20B, further examples of the
hubs discussed above are shown and will now be described.
[0120] FIGS. 12A-12F show details of a curved hub 400 similar to
hub 302 illustrated in FIGS. 11A-11D. In this embodiment, hub 400
has an internally threaded portion at its proximal end 402 for
engaging with an insertion and removal tool as described above.
(The proximal end is referenced as the end closest to the surgeon.)
The proximal end 402 may also have a keyed feature for mating with
the tool for maintaining a desired orientation of hub 400 relative
to the tool. Hub 400 may also be provided with a counterbore at its
distal end 404 for coupling to a gripper or flexible-to-rigid body
portion, such as by press fit and/or welding.
[0121] Exemplary hub 400 includes three holes 406, 408 and 410
through the wall thickness on its concave side, as best seen in
FIG. 12C. Similarly, hub 400 includes four holes 412, 414, 416, and
418 through the wall thickness on its convex side, as best seen in
FIG. 12D. At least a portion of all seven holes may be seen in FIG.
12F. Holes 406 and 412 on opposite sides of hub 400 are aligned to
allow a bone screw to be inserted through the two holes across the
hub to secure hub 400 to the bone and/or to secure bone fragment(s)
with the screw. Similarly, holes 408 and 414 are aligned to receive
a second bone screw, and holes 410 and 416 are aligned to receive a
third bone screw. A fourth screw may be inserted through the open
proximal end 402 of hub 400 and out through hole 418. Each screw
may be passed first through cortical bone, then cancellous bone,
then through the two holes of hub 400, through more cancellous bone
and possibly into more cortical bone on the opposite side of the
bone from where the screw entered.
[0122] In this embodiment, the holes of hub 400 have a diameter of
2.4 mm. In other embodiments, the holes have a diameter of 2.7 mm.
In still other embodiments, the holes may have larger or smaller
diameters. The holes may be threaded during the fabrication of hub
400, or threads may be formed in vivo. Various fixtures, jigs,
tools and methods may be used to align the screws with the holes,
such as a tool similar to tool 138 shown in FIGS. 4-6 and described
above. Further examples of positioning aids are provided in
copending U.S. application Ser. No. 11/944,366 filed Nov. 21, 2007
and entitled Fracture Fixation Device, Tools and Methods. The heads
of the screws may be countersunk into the bone as described in
copending U.S. application Ser. No. 61/117,901 filed Nov. 25, 2008
and entitled Bone Fracture Fixation Screws, Systems and Methods of
Use.
[0123] FIGS. 12G-12I illustrate an example how bone screws 420,
422, 424 may be inserted through hub 400' (which is similar to hub
400) as described above to secure the comminuted fracture depicted
at the distal end of a radius bone 425. One, two, three, four, or
more screws may be used depending on the anatomy and fracture
condition of each particular case. It should be noted that in this
particular embodiment, either screw 422 or 424 may be placed
through hub 400', but not both at the same time, as their paths
intersect inside hub 400'. It can be seen that screws 422 and 424
extend across fracture 426 into bone fragment 428. Accordingly,
either screw 422 or 424 may be used to approximate fracture 426
when the screw is tightened.
[0124] FIGS. 13A-13E show another exemplary embodiment of a bone
fixation device hub 450. Hub 450 is of similar construction to hub
400 described above and includes proximal end 452 and distal end
454. As best seen in FIG. 13C, hub 450 includes four holes 456,
458, 460, and 462 through the wall thickness on its concave side.
Holes 456 and 458 are located the same longitudinal distance from
distal end 454, but are symmetrically located on opposite sides of
a central longitudinal plane. As can be seen, holes 456 and 458
actually overlap to form a single, figure-eight shaped hole. Holes
460 and 462 are also located the same longitudinal distance from
proximal end 452, and are symmetrically located on opposite sides
of a central longitudinal plane.
[0125] As best seen in FIG. 13D, hub 450 also includes six holes
464, 466, 468, 470, 472, and 474 through the wall thickness on its
convex side. Holes 464 and 466 are located the same longitudinal
distance from distal end 454, but are symmetrically located on
opposite sides of a central longitudinal plane. Holes 464 and 466
also overlap to form a single, figure-eight shaped hole, similar to
holes 456 and 458 described above. Holes 468 and 470 are also
located the same longitudinal distance from proximal end 452, and
are symmetrically located on opposite sides of a central
longitudinal plane. Similarly, holes 472 and 474 are also located
the same longitudinal distance from proximal end 452, and are
symmetrically located on opposite sides of a central longitudinal
plane.
[0126] Holes 456 and 464 on diagonally opposite sides of hub 450
are aligned to allow a bone screw to be inserted through the two
holes across the hub, passing through a centerline of hub 450.
Similarly, holes 458 and 466 on diagonally opposite sides of hub
450 are aligned to allow a bone screw to be inserted through the
two holes across the hub, passing through a centerline of hub 450.
Since both of these two screw paths cross the centerline at the
same location forming an X-pattern, only one screw may be placed
through these two pairs of holes 456/464 and 458/466 in any
particular procedure.
[0127] In a similar manner, holes 460 and 468 on diagonally
opposite sides of hub 450 are aligned to allow a bone screw to be
inserted through the two holes across the hub, passing through a
centerline of hub 450. Holes 462 and 470 on diagonally opposite
sides of hub 450 are also aligned to allow a bone screw to be
inserted through the two holes across the hub, passing through a
centerline of hub 450. Since both of these two screw paths cross
the centerline at the same location forming an X-pattern, only one
screw may be placed through these two pairs of holes 460/468 and
462/470 in any particular procedure.
[0128] A third screw may be inserted through the open proximal end
452 of hub 450 and out through either hole 472 or hole 474. Since
these two screw paths also overlap, only one screw may be placed
though them at a time.
[0129] As can be appreciated from FIGS. 13A-13E and the description
above, exemplary hub 450 is symmetrical about a central plane.
Since hub 450 may receive up to three screws, each in one of two
positions, there are a total of eight screw patterns that may be
used with hub 450, depending on the situation. Additionally, only
one or two screws, or no screws, may be used in a particular
procedure, if desired. The positions and orientations of the screw
holes of hub 450 relative to previously described hub 400 may take
better advantage of cortical bone locations in some procedures for
better anchoring of bone screws. In particular, a screw passing
through hole pairs 456/464, 458/466, 460/468 or 462/470 of hub 450
will have a reduced angle relative to a longitudinal axis of a bone
as compared with the screw trajectories of similar screws in hub
400. Similarly, a screw passing through either hole 472 or 474 will
have a different angle from the same screw in hub 400, which in
many cases allows the screw of hub 450 to hit harder bone.
Additionally, screw paths of hole pairs 460/468 and 462/470 are
closer to the proximal end of hub 450 than similar screw paths in
hub 400, allowing the screws to fixate in harder bone located near
the end of a bone. All of the new screw trajectories provided by
hub 450 may be used with the in vivo hole forming hubs that will be
later described below. The trajectories of hole pairs 456/464,
458/466, 460/468 or 462/470 also form an angle with a central,
longitudinal plane containing the curve of hub 450 (in other words,
a plane of symmetry of the hole pairs.) In some embodiments, the
hole pairs each form an angle with the plane falling in a range of
about 5 to 30 degrees.
[0130] FIGS. 14A-14E show another exemplary embodiment of a bone
fixation device hub 500. Hub 500 is of similar construction to hubs
400 and 450 described above and includes proximal end 502 and
distal end 504. As best seen in FIG. 14C, hub 500 includes slotted
holes 506, 508, and 510 through the wall
[0131] thickness on its concave side. As best seen in FIG. 14D, hub
500 also includes slotted holes 512, 514, and 516, and angled hole
518 through the wall thickness on its convex side. Holes 506 and
512 on opposite sides of hub 500 are aligned to allow a first bone
screw to be inserted through the two holes across the hub.
Similarly, holes 508 and 514 are aligned to receive a second bone
screw, and holes 510 and 516 are aligned to receive a third bone
screw. Hole 518 is aligned with the opening in the proximal end 502
of hub 500 to receive a fourth bone screw.
[0132] The slotted configuration of hole pairs 506/512, 508/514,
and 510/516 allows a bone screw to be received through each of the
pairs in a variety of orientations. This arrangement permits a
surgeon the flexibility to place bone screws where most appropriate
in a particular procedure. For example, a first bone screw may be
placed through holes 506 and 512 such that it resides in the left,
middle, or right portion of hole 506, as viewed in FIG. 14C. The
same screw will have another section that may reside in the left,
middle, or right portion of hole 512. With these various
combinations, it can be appreciated that the screw can take one of
nine basic orientations through holes 506 and 512, as well as many
other orientations between these nine. In other embodiments, a
slightly enlarged round hole may be provided on one side of the hub
while a slotted hole on the opposite side forms the other hole of
the pair.
[0133] In this exemplary embodiment, the width of slotted holes
506, 508, 510, 512, 514, and 516 is 2.0 mm. This provides a pilot
hole in which a drill bit or screw tip may engage. Material from a
portion of the sides of each hole may be removed when the drill bit
forms a larger hole in one location of the slotted hole, and/or
when a screw is inserted to form threads through the hole. No
drilling or threading may be necessary, such as when the slot width
is generally the same as the minor diameter of the screw, and the
thickness of the hub walls is generally the same as the screw
pitch. The slotted holes may also stretch or deform when receiving
the screw. As shown in FIG. 14F, relief slit(s) 520 may be provided
adjacent to a slotted hole 506 to allow the slot to more easily
expand when receiving a screw 522. Such slits may be formed by
laser cutting, electron beam melting (EBM), electrical discharge
machining (EDM), etching, stamping, milling, or other fabrication
techniques.
[0134] FIGS. 15A-15D show another exemplary embodiment of a bone
fixation device hub 500'. Hub 500' is similar to hub 500 described
above, but has slotted holes that are oriented longitudinally
rather than transversely. Hub 500' includes proximal end 502' and
distal end 504'. As best seen in FIG. 15C, hub 500' includes
slotted holes 506', 508', and 510' through the wall thickness on
its concave side. As best seen in FIG. 15D, hub 500' also includes
slotted holes 512', 514', and 516', and angled hole 518' through
the wall thickness on its convex side. Holes 506' and 512' on
opposite sides of hub 500' are aligned to allow a first bone screw
to be inserted through the two holes across the hub. Similarly,
holes 508' and 514' are aligned to receive a second bone screw, and
holes 510' and 516' are aligned to receive a third bone screw. Hole
518' is aligned with the opening in the proximal end 502' of hub
500' to receive a fourth bone screw. Exemplary axis lines 524, 526,
528, and 530 are shown in FIG. 15A to show examples paths for the
first, second, third, and fourth screws, respectively.
[0135] FIGS. 16A-16E show another exemplary embodiment of a bone
fixation device hub 550. As best seen in FIG. 16D, hub 550 includes
at its proximal end 552 a transversely elongated hole 554. Hole 554
allows a screw 556 to be located along the central axis, or
off-axis in either direction as may be desired for engaging harder
bone or securing additional bone fragment(s). This of arrangement
of hole 554 may be configured to hold screw 556 tightly at all
angles. This may be accomplished, for example, by using a hole 554
slot width that is equal to or smaller than the minor diameter of
screw 556. The wall thickness of hub 550 may fit into the screw
threads, providing additional locking of screw 556. In other
embodiments, the angle of elongated hole 554 may be oriented
differently as desired.
[0136] Special screws may be used to provide additional locking. As
shown in FIG. 16E, screw 558 has a tapered edge 560 below its head
562. Tapered edge 560 serves to wedge screw 558 into slot 554,
securing the screw in place. A screw with an expanding head (not
shown) may also be used. With this arrangement, a taper or other
expanded section may be created once the screw is in place, thereby
locking it in position.
[0137] FIGS. 17A-17C show another exemplary embodiment of a bone
fixation hub 600. Hub 600 is provided with an array of pilot holes
602 over most of its surface. Each hole 602 may be 0.015 to 0.020
inches in diameter, for example, and serves as a starting point to
allow a drill bit or screw tip to penetrate the wall thickness of
hub 600. This makes in vivo screw hole formation possible, while
allowing the hub to remain a rigid structure. Holes 602 may be
closely spaced such that a screw or screws may be positioned in
vivo virtually anywhere the surgeon desires during each particular
procedure. Once the drill bit and/or screw is inserted, the hole
602 becomes enlarged to generally the minor diameter of the screw
thread, such as to 2.7 mm in diameter, for example. Screw holes may
be formed in this way on both sides of hub 600 in a continuous
operation, allowing screw(s) to be positioned across the hub as
previously described.
[0138] As shown in FIG. 17C, pilot holes 602 may be placed closer
to one another so that multiple perforations are consumed by the
screw diameter 604 when the screw hole is formed. This can make in
vivo hole formation even easier. Other hole patterns than those
shown in FIGS. 17A-17C may be used.
[0139] Holes 602 may be fabricated in hub 600 by laser cutting,
electron beam melting (EBM), electrical discharge machining (EDM),
etching, stamping, drilling, or other fabrication techniques.
[0140] FIGS. 18A and 18B show another exemplary embodiment of a
bone fixation hub 650. Hub 650 has at least a portion that is
fabricated from a mesh structure, forming a plurality of diamond or
other shaped apertures 652. Apertures 652 may be configured with
dimensions smaller than the major diameter of the threads of the
bone screws to be used. Aperture dimensions may even be smaller
than the minor thread diameter, such that the apertures are
stretched and/or deformed as the screw enters the aperture, thereby
providing an increased ability to hold the screws in place. The use
of a mesh hub 650 may reduce the amount or possibility of debris
being formed and released inside the body during in vivo screw hole
formation.
[0141] Apertures 652 may be fabricated in hub 650 by laser cutting,
electron beam melting (EBM), electrical discharge machining (EDM),
etching, stamping, drilling, or other fabrication techniques.
Apertures 652 may also be fabricated by forming slits in plate or
tube stock and expanding the material to form the apertures.
Another fabrication technique that may be used is forming wires or
bands around a mandrel and then welding, brazing, soldering,
pressing, melting, gluing, or otherwise joining the wires or bands
to each other at their intersections. Other types of porous
structures, either with or without more random aperture locations,
may be used as well. Multiple layers of mesh may also be
combined.
[0142] FIGS. 19A and 19B show another exemplary embodiment of a
bone fixation hub 700. Hub 700 is provided with a plurality of thin
slots 702 along its length. Slots 702 permit in vivo screw hole
formation by acting as long pilot holes for drill bits or bone
screws. A bone screw tip may be inserted into one of the slots 702
without pre-drilling. Upon insertion, the slot and surrounding
slots will deform to make way for the screw, and will provide
circumferential pressure to retain the screw.
[0143] Although shown staggered and in the longitudinal direction,
in other embodiments (not shown) thin slots may be provided in a
transverse or other orientation, and/or in other patterns. Slots
702 may be fabricated in hub 700 by laser cutting, electron beam
melting (EBM), electrical discharge machining (EDM), etching,
stamping, drilling, or other fabrication techniques. Thin slots 702
may generally require less material removal than other hub
embodiments.
[0144] FIGS. 20A and 20B show another exemplary embodiment of a
bone fixation hub 750. Hub 750 comprises three separately formed
hubs assembled together: an inner hub 752, a mid-hub 754, and an
outer hub 756. Mid-hub 754 has a larger diameter than inner hub 752
so that mid-hub 754 may be placed over inner hub 752, as
illustrated in FIGS. 20A and 20B. Similarly, outer hub 756 has a
larger diameter than mid-hub 754 so that outer hub 756 may be
placed over mid-hub 754, as also illustrated in the figures. In
this embodiment, all three hub components 752, 754, and 756 have
the same bend radius and the same arc length. Once assembled, the
three hub components 752, 754, and 756 may be retained at one or
both ends by other components of the associated bone fixation
device, and/or may be welded or otherwise fastened together.
[0145] As seen in FIG. 20B, inner hub 752 and outer hub 756 have
spirally formed slots 758 and 760, respectively. Slots 758 and 760
may be formed such that they line up when the individual hubs are
assembled. Each hub 752 and 756 may also be provided with an upper
spine (762 and 764, respectively), and a lower spine (not seen in
FIG. 20B). The spines are solid regions running the length of the
hubs that provide rigidity, and are positioned in areas that do not
typically receive screws. Mid-hub 754 has longitudinally extending
slots 766 rather than spiral slots. When the three slot patterns
are assembled in a coaxial unit, as shown in FIG. 20A, a hub is
formed that may be quite rigid. Pilot holes are formed where slots
760, 766, and 758 line up radially to facilitate in vivo screw hole
formation. When a screw is inserted in such a pilot hole, one or
more of the slots may deform to receive the screw.
[0146] One, two, three, four, or more hub layers may be used in
this manner to form a single layer or composite hub. Other slot
patterns and widths may be used as appropriate. Some of the layers
may incorporate round or other aperture shapes instead of or in
addition to the slots shown in this example.
[0147] In many of the hub embodiments described above, one or more
screws may be placed into just a single side of the hub, or
completely across the hub through both sides.
[0148] While exemplary embodiments of the present invention have
been shown and described herein, it will be obvious to those
skilled in the art that such embodiments are provided by way of
example only. Numerous variations, changes, and substitutions will
now occur to those skilled in the art without departing from the
invention. It should be understood that various alternatives to the
embodiments of the invention described herein may be employed in
practicing the invention.
* * * * *
References