U.S. patent application number 13/337584 was filed with the patent office on 2013-06-27 for orthopedic fixation device with magnetic field generator.
The applicant listed for this patent is Richard A. Rogachefsky. Invention is credited to Richard A. Rogachefsky.
Application Number | 20130165733 13/337584 |
Document ID | / |
Family ID | 48655238 |
Filed Date | 2013-06-27 |
United States Patent
Application |
20130165733 |
Kind Code |
A1 |
Rogachefsky; Richard A. |
June 27, 2013 |
ORTHOPEDIC FIXATION DEVICE WITH MAGNETIC FIELD GENERATOR
Abstract
A medical device includes an orthopedic fixation device and an
electromagnetic field emitter carried by the fixation device. The
device preferably further includes a power source for powering the
electromagnetic field emitter, which may be implanted in the human
body with the fixation device and the electromagnetic field
emitter. The power source may be a battery.
Inventors: |
Rogachefsky; Richard A.;
(Torrance, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Rogachefsky; Richard A. |
Torrance |
CA |
US |
|
|
Family ID: |
48655238 |
Appl. No.: |
13/337584 |
Filed: |
December 27, 2011 |
Current U.S.
Class: |
600/12 |
Current CPC
Class: |
A61B 17/80 20130101;
A61N 2/02 20130101; A61B 17/86 20130101; A61N 2/002 20130101; A61N
2/008 20130101; A61B 17/72 20130101 |
Class at
Publication: |
600/12 |
International
Class: |
A61N 2/00 20060101
A61N002/00; A61B 17/68 20060101 A61B017/68; A61B 17/72 20060101
A61B017/72; A61N 2/02 20060101 A61N002/02 |
Claims
1. An orthopedic device comprising: an internal orthopedic fixation
device; and a magnetic field emitter carried by the fixation
device.
2. The orthopedic device of claim 1, further comprising a power
source for modulating a magnetic field emitted by the magnetic
field emitter.
3. The orthopedic device of claim 2, wherein the power source is a
battery implanted in the human body with the fixation device and
the magnetic field emitter.
4. The orthopedic device of claim 2, wherein the power source is a
field generator generating a field that will charge the
electromagnetic field emitter.
5. The orthopedic device of claim 4, wherein the field generated by
the field generator is different from the field generated by the
magnetic field emitter.
6. The orthopedic device of claim 1, wherein the fixation device
comprises a hollow rod and the magnetic field emitter is disposed
in the hollow rod.
7. The orthopedic device of claim 1, wherein the fixation device is
a plate.
8. The orthopedic device of claim 7, wherein the plate comprises a
cutout adapted to receive the magnetic field emitter therein.
9. The orthopedic device of claim 7, wherein the magnetic field
emitter is affixed to the plate.
10. The orthopedic device of claim 1, wherein the fixation device
is non-ferrous.
11. The orthopedic device of claim 1, wherein the fixation device
is a screw and the magnetic field generator is an electromagnetic
field emitter disposed proximate a head of the screw.
12. The orthopedic device of claim 1, wherein the magnetic field
emitter comprises an electromagnetic coil.
13. The orthopedic device of claim 12, further comprising a
controller for controlling the electromagnetic field emitted by the
electromagnetic coil.
14. A method of treating an injury comprising: placing an
orthopedic fixation device in a patient; placing an electromagnetic
field emitter carried by the device into the patient; and
activating the electromagnetic field emitter to emit an
electromagnetic field proximate the injury.
15. The method of claim 14, wherein the step of activating the
electromagnetic field emitter comprises controlling the emitter to
deliver a prescribed electromagnetic field regimen.
16. The method of claim 15, wherein the regimen includes one or
more of predetermined frequencies and durations.
17. The method of claim 14, further comprising securing the
fixation device to a bone of the patient.
18. The method of claim 14, further comprising powering the
electromagnetic field emitter with a power supply.
19. The method of claim 18, wherein the power supply is placed in
the patient along with the fixation device.
20. A device for stabilizing a fracture and promoting healing,
comprising: an intramedullary orthopedic fixation device having an
opening therein; an electromagnetic field emitter disposed in the
opening of the orthopedic fixation device; a controller disposed in
the opening of the orthopedic fixation device and communicating
with the electromagnetic field emitter to control the field emitted
by the electromagnetic field emitter; and a power source providing
power to the controller and the electromagnetic field emitter.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This disclosure relates to orthopedics. More specifically,
the invention relates to an orthopedic fixation device with an
integrated magnetic field generator for placement in a patient to
promote healing of a fractured bone and surrounding tissue, to
reduce infection, reduce both acute and chronic pain, in
arthrodesis procedures, and to reduce edema, as well as for other
purposes.
[0003] 2. Related Art
[0004] Electromagnetic fields have been proposed for use for
therapeutic purposes for many years. Heretofore, fields have been
generated externally and oriented so as to pass through the tissue
or bone to be treated. The systems, while effective, have the
disadvantage that they require bulky signal generating apparatus
and electromagnetic field generating coils to be worn by the
patient. This is a particular problem for patients who are
ambulatory and a lesser but still significant problem for patients
confined to bed.
SUMMARY OF THE INVENTION
[0005] The present disclosure remedies the foregoing shortcomings
of the prior art by providing an improved medical device for
implanting in a patient.
[0006] In one aspect of the invention, a device includes an
orthopedic fixation device and an electromagnetic field emitter
carried by the fixation device. The orthopedic fixation device may
be a rod or plate or similar device. The device preferably further
includes a power source for powering the electromagnetic field
emitter, and a controller that may be separate from or integrated
with the power source for generating a varying signal that is
applied to the electromagnetic field emitter, all of which may be
implanted in the human body with the fixation device and the
electromagnetic field emitter. The power source may be a
battery.
[0007] In another aspect of the invention, a device for use in
healing a broken bone includes an internal fixation device having
an opening or cavity therein and an electromagnetic field emitter
disposed in the opening or cavity.
[0008] In accordance with another aspect of the invention a device
for use in healing a broken bone and for other uses includes an
internal fixation device carrying an electromagnetic field
generator, a signal generator, and a rechargeable power source,
together with an external device for recharging the power
source.
[0009] An understanding of these and other aspects, features, and
benefits of the invention may be had with reference to the attached
figures and following disclosure, in which preferred embodiments of
the invention are illustrated and described.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0010] FIG. 1 is a diagram of a fixation device according to a
first embodiment of the disclosure.
[0011] FIG. 2 is a diagram of an electromagnetic field emitter used
in a fixation device according to the disclosure.
[0012] FIGS. 3A-3C are cross-sectional views of other embodiments
of fixation devices according to the disclosure.
[0013] FIG. 4 is a cross-sectional view of another embodiment of a
fixation device according to the disclosure.
[0014] FIG. 5 is a perspective view of a fixation device according
to another embodiment of the disclosure.
[0015] FIG. 6 is a perspective view of a fixation device according
to another embodiment of the disclosure.
[0016] FIG. 7 is a perspective view of a fixation device according
to another embodiment of the disclosure.
[0017] FIG. 8 is a cross-sectional view of a fixation device
according to another embodiment of the disclosure.
[0018] FIG. 9 is a cross-sectional view of a fixation device
according to another embodiment of the disclosure.
[0019] FIG. 10 is a perspective view of a fixation device according
to another embodiment of the invention.
[0020] FIG. 11 is a perspective view of a field generator and an
associated generated field.
[0021] FIG. 12 is a perspective view of a series of coils on a
substrate, according to another embodiment of the invention.
[0022] FIG. 13 is a schematic illustrating a system according to
another embodiment of the invention.
[0023] FIG. 14 is a perspective view of a fixation device according
to another embodiment of the invention.
[0024] FIG. 15 is a plan view of a fixation device according to
another embodiment of the invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0025] The invention relates generally to fixation devices. More
specifically, the invention relates to fixation devices that are
useful for assisting in fracture and wound healing, treating
infection, reducing pain, and for other therapeutic purposes.
Preferred embodiments of the invention now will be described with
reference to the figures.
[0026] FIG. 1 shows a fixation device 10 according to a first
embodiment of the invention. The fixation device generally includes
a hollow rod 14 which is an intramedullary fixation device. Such
intramedullary fixation devices are conventionally known for
placement within a bone cavity, especially longer bones such as the
femur or the tibia to aid in proper realignment of a bone 2 having
a fracture 4. Like conventional intramedullary rods, the hollow rod
14 illustrated in FIG. 1 may be held in place using screws 12 such
as locking screws. Preferably the rod is fabricated in a size and
shape that give it sufficient strength to stabilize the fracture
during healing. The rod is fabricated from a material that permits
a magnetic field to pass there through, either because the material
itself permits the passage of a magnetic field or the rod is
provided with a section through which the magnetic field may
pass.
[0027] Unlike conventional intramedullary rods, a fixation device
10 according to the illustrated embodiment includes an
electromagnetic field emitter 16 disposed in the cavity 15 of the
hollow rod 14. The electromagnetic field emitter 16 may take any
conventional shape, and preferably includes an electromagnetic coil
such as a solenoid coil through which a current is passed to create
a magnetic field.
[0028] A controller 18 which may be fabricated on a printed circuit
board and/or as an integrated circuit is provided in communication
with the electromagnetic coil of the electromagnetic field emitter
16 for generating a signal to energize the electromagnetic field
emitter 16. In the embodiment of FIG. 1, a power source 20, such as
a battery, also is provided within the hollow rod, in communication
with the electromagnetic field emitter 16 and the controller 18.
Leads or wires 22 also are provided in the hollow rod 14 to
interconnect the electromagnetic field emitter 16, the controller
18, and the power source 20. Generally speaking, the controller is
energized by the power source to generate the signal that when
applied to the electromagnetic field emitter creates a field,
preferably a varying field that intersects the fracture or
wound.
[0029] In one example of the invention, the controller 18 is
programmed with a series of instructions for controlling the field
emitted by the electromagnetic field emitter 16. More specifically,
the controller may be programmed with a routine such as a series of
intensity and/or time dependent instructions. Depending upon the
program routine, the controller will manipulate the power from the
power source to supply a current to the electromagnetic field
emitter 16, which in turn will create an electromagnetic field
corresponding to the applied current. By varying the current and
the time, any number of routines may be used, as required by the
patient.
[0030] The controller may be preprogrammed with a number of
routines for application of varied electromagnetic fields to the
injury site. For example, routines may be included that depend upon
the location and/or severity of a fracture or accompanying wounds
to nearby tissue and/or muscle. In still other embodiments, the
controller may be programmable either before implantation into the
patient, or after being inserted. One lead may be accessible
through the skin to allow tethering to a computer or the like
useable in programming the controller 18. Preferably, the
controller will include a wireless receiver configured to receive
programming instructions wirelessly from a computer or the like
equipped with a transmitter. Further, the controller may include a
wireless transmitter for transmitting data corresponding to the
signal generated by the controller.
[0031] Although in the illustrated embodiment of FIG. 1, the power
source and controller are disposed within the hollow rod with the
electromagnetic field emitter, in other embodiments the power
source and/or the controller may be disposed in the body, but
remote from the electromagnetic field emitter. In such an
arrangement, the wires or leads 22 may extend outside of the hollow
rod 14 and connect to the remotely disposed controller 18 and/or
power supply 20. In still other embodiments, the controller and/or
the power source may be disposed completely outside of the body.
For example, the power source may be a field emitter disposed
outside the body that emits an electromagnetic field and when
placed in proximity to an induction coil disposed in the body, will
charge the coil to power the electromagnetic field generator.
Preferably, the field emitter used as the power supply 20 emits a
field that is different from the field generated by the
electromagnetic field emitter, and which will not adversely affect
the wound healing sought to be accomplished by the electromagnetic
emitter.
[0032] The electromagnetic field emitter generally is a
conventional structure that will emit an electromagnetic field at a
frequency of between about 5 and about 100 Hz, more preferably
between about 5 Hz and about 30 MHz, and at 60-400 Gauss within a
treatment volume. As a result of the invention, the emitter can be
placed in close proximity to a fracture in a bone and/or proximate
nearby afflicted muscle or other tissue. Although two emitters are
illustrated in FIG. 1, more or fewer emitters may be provided. The
emitter(s) preferably are at fixed positions inside the hollow rod
14. The position of the emitter 16 within the hollow rod 14 will be
dictated by the position of the rod relative to the position of the
fracture. When the rod 14 is placed in the bone 2, the
electromagnetic field emitter 16 will closely align with the
position of the fracture to expose the fracture to the
electromagnetic field. In a preferred embodiment, the emitter(s)
will be affixed to the inside of the hollow rod using any known
fastener, such as a physical fastener like a set screw, or an
implant grade adhesive.
[0033] As will be appreciated by those of ordinary skill in the
art, known electromagnetic field emitters produce electromagnetic
fields having a known size and shape. FIG. 2 shows a conventional
electromagnetic field emitter 160 including a conductive wire, such
as copper, 162 wound along an axis to form a coil. When an
electrical current is passed through the coil, an electromagnetic
field is created as depicted by flux lines 168. Although not
required, the illustrated coil 162 is wrapped around a cylindrical
core 164, which is preferably a ferrous core, to intensify the
field.
[0034] In use, the coil should be positioned such that the bone
fracture and/or any other tissue to be healed is disposed in the
electromagnetic field. An advantage of the invention over
previously-used, non-implanted electromagnetic field emitters, is
that the field can be generated very near to the fracture or other
wound to be treated so that the high flux portion of the field can
intersect the wound/fracture. This close positioning allows for a
lower power requirement, because the field need not be as strong as
it would need to be if it were generated farther from the fracture
and increased biological healing response because the field is not
interfered with by passing through surrounding tissue. When the
fixation device is a rod, as in FIG. 1, a series of electromagnetic
field emitters like those illustrated in FIG. 2 may be disposed
along the length of the hollow rod, such that the electromagnetic
fields overlap along the length of the rod. In this embodiment any
position along the rod will be affected by an electromagnetic
field. While the care giver could opt to energize all coils to
provide a field along the full length of the rod, the controller
could alternatively be configured to allow for selective energizing
of the coils. In other embodiments fewer emitters may be provided
that are positioned specifically for affecting the fracture/wound.
One or more emitters may be provided that are moveable within the
rod prior to placement of the rod, to allow the emitters to be
placed at positions that will best promote healing. In yet another
embodiment of the invention, the emitters may be placed at
predetermined positions within different rods, with the orthopedic
surgeon choosing a rod that will align the emitter with the
fracture/wound for healing promotion.
[0035] In conventional intramedullary nail placement procedures, a
guide wire is passed longitudinally through a fractured bone, a
reamer is passed over the guide wire to bore the bone out
longitudinally, and the rod is fed over the guide wire into
position. Once in position, screws may be inserted transversely
through the bone and into the rod, to lock the rod in place. A rod
according to the present disclosure may be inserted using the same
procedure. To do so, the rod preferably also has a longitudinal
opening, which may require that each of the electromagnetic field
emitters and other components occupy less than the full
cross-sectional area of the opening in the rod or have openings
extending axially therethrough.
[0036] For example, each electromagnetic field emitter could have a
hole formed therethrough, large enough to allow for passage of the
guide wire there through. In one embodiment, each of the emitters
is a wound coil such as that shown in FIG. 2. The illustrated coil,
also referred to as an air coil, is illustrated in which a wire is
wound continuously along an axis preferably in multiple layers to
form a cylindrical coil defining an open middle. The coil is
preferably sized to allow passage of the guide wire through the
open middle. In another embodiment it may be desirable to wrap the
air coil around a ferrite core. To facilitate passage of the nail
over a guide wire, the ferrite core may have a longitudinal opening
formed therein.
[0037] Other embodiments may also allow use of a guide wire to
insert an intramedullary rod by ensuring that the footprint of the
electromagnetic field emitter has a smaller area than the area of a
cross-section of the opening in the hollow rod. This could be
particularly useful when it is desired to dispose a solid core in
the coil. For example, the emitter could be attached to a sidewall
of the opening, sized small enough such that space is provided next
to the emitter large enough to pass a guide wire. A sleeve or
conduit could also be provided in the rod to guide the guide wire
through a more tortuous path along the length of the rod. The
sleeve or conduit feeds the guide wire in any number of ways,
including through the sidewall of the hollow rod. This would be
particularly useful in applications in which the emitter occupies
substantially all of the opening in the hollow rod at axial
positions along the rod. In a further example, the hollow rod may
include a completely separate, substantially axial, guide opening
21, which is parallel to the cavity 15. An example of this separate
opening is illustrated in FIG. 3A, and is formed in a sidewall of
the hollow rod. To this end, the hollow rod may not be cylindrical,
but could instead include a profile allowing for both the cavity 15
and the guide opening 21. Some exemplary profiles are illustrated
in FIGS. 3B and 3C.
[0038] As will be appreciated, large, concentrated forces are often
applied to intramedullary nails and rods during insertion and
during healing, and the components disposed within the rod must be
firmly affixed in the rod to avoid damage or dislodgement during
insertion and healing.
[0039] In another embodiment of the disclosure, the electromagnetic
field emitter (and power source and controller) may be inserted
into the rod after the rod is inserted into the bone. A stop, such
as a constriction or protuberance, may be provided in the cavity 15
of the hollow rod in such an embodiment, to attain proper axial
positioning of the inserted components. An adhesive may be applied
to the inserted components to maintain their position once
inserted. Alternatively, a packing or mechanical stop may be
inserted after the inserted components to maintain positioning of
the emitter in the rod. An advantage of the after-inserted
components is that the components do not undergo the pounding and
potential destruction accompanying insertion of the rod.
[0040] In other embodiments, a guide wire is not used for insertion
of the hollow rod, so no provisions for an axial passageway through
the rod need be made. In this example, the opening through the bone
is bored or reamed out using known techniques, and the rod is then
inserted.
[0041] Because the fixation device 10 is generally intended to be
left in the patient permanently, each of the components should be
implant grade. Moreover, the hollow rod 14 of the embodiment of
FIG. 1 preferably is a non-ferrous material, such as a polymer or
titanium so as not to affect the electromagnetic field emitted by
the electromagnetic field emitter 16. The components should be
chosen such that the electromagnetic field emitted by the
electromagnetic field emitter 16 will pass freely through the
fixation device 10 to the fractured bone and/or the damaged
tissue.
[0042] The invention is not limited to an embodiment in which the
electromagnetic field emitter is disposed within a hollow rod
comprising a fixation device. In an alternative to the foregoing
embodiments, the electromagnetic field emitter could be disposed on
a side of the hollow rod 14 or at an end thereof. In such an
embodiment, it may not be necessary that the hollow rod 14 be
hollow at all. A solid rod could be used instead, because no
components are intended to be disposed within the rod.
[0043] In another embodiment, the coil comprising the emitter could
be wrapped around the rod. This embodiment is shown in FIG. 4. In
that figure, emitters 16 are formed at spaced positions along the
rod 14 by wrapping wire around the rod 14. Although this embodiment
shows a plurality of discrete coils along the length of the rod,
the wire may be wrapped continuously along the entire length of the
rod, to create a larger field. In these embodiments, all or a
portion of the rod may be ferrous, to intensify the field at each
coil. Alternatively, the rod could still be hollow, but with
ferrous material disposed in the hollow rod. The control and power
supply could also be disposed in a hollow rod.
[0044] The embodiment illustrated in FIG. 4 also includes a
protective layer 26 formed over the coils. This protective layer 26
preferably is chosen to shield the coils from damage when the rod
is inserted by an orthopedic surgeon. For example, the protective
layer may be a polymeric or foil wrap disposed over the coil, and
which will not affect the field emitted by the coils. FIG. 4 also
shows a leading protrusion 24 disposed axially adjacent to each
coil. The protrusion extends radially from the rod further than the
coil and is disposed such that when the rod is inserted along the
direction of arrow in FIG. 4, the protrusion first enters the bone.
In this manner, the protrusion forges a path through the bone to
minimize contact of the bone with the coil, thereby reducing the
potential for damage to the coil.
[0045] In alternatives to FIG. 4, one or both of the protective
layer 26 and the protrusion 24 may not be provided. The protrusion
may be an annular ring disposed about the circumference of the rod,
or it may be a series of protrusions disposed about the
circumference. Moreover, as illustrated in FIG. 4, the protrusion
preferably is angled, to promote ease of insertion of the rod into
the bone.
[0046] The invention also is not limited to an intramedullary rod
or nail. FIG. 5 shows an embodiment of the invention in which a
fixation device 110 is incorporated in a screw 112 having a
threaded shaft 112a and a head 112b. There, an electromagnetic
field emitter 116 comprising a plurality of windings as a coil like
that in FIG. 2 is disposed on a shaft of the screw 112, proximate
the head 112b. The electromagnetic field emitter thus will not
inhibit access to the head of the screw, for example, for
insertion, but the emitter can be placed wherever a screw can be
inserted. The screw may be a locking screw such as the type used in
connection with an intramedullary rod or a plate, or it may be any
other type of screw, including but not limited to a pedicle screw
for use in spinal procedures.
[0047] As also illustrated in FIG. 5, the screw 112 further
includes an annular stop 128 arranged between the threads and the
coil. When an orthopedic surgeon inserts the screw, rotation of the
screw will be stopped when the stop 128 contacts the bone or plate
into which the screw is being inserted. In this way, the surgeon
will not overtighten the screw in a manner that will cause the coil
to contact the bone or plate, resulting in potential damage to the
coil. Although not illustrated, leads will extend from the coil to
the controller and/or power source, as in previous embodiments.
Such components may be provided on the screw, or in a separate
implant.
[0048] Yet another embodiment of the invention is illustrated in
FIG. 6. FIG. 6 is similar to the previous embodiments in that it
shows a fixation device 210 including an implant 214 and an
electromagnetic field emitter 216. Unlike the other embodiments,
the implant is a plate 214, such as a surgical or orthopedic plate,
and the emitter 216 is a coil carried on the plate. The plate may
be any known plate or plate-like structure, for example, such as
used to maintain position of a fractured bone for healing that bone
or for fusion of bones, as in spinal surgery. In the preferred
embodiment, the emitter 216 is carried on a side of the plate 214
that does not contact the bone. The emitter 216 may be fixed to the
plate in any number of ways, including fasteners and adhesives.
FIG. 6 also shows a controller 218 and power source 220 carried on
the plate, and electrical leads 222 interconnecting the foregoing
components. It is preferred that the plate be made from a material
that will not distort the field generated by the emitter, but the
emitter and plate may be designed to cooperate in creating a field
that will effectively intersect with a fracture/wound.
[0049] The emitter may be mounted on any position of the plate, to
ensure maximum exposure of the fracture to the generated field. In
some embodiments, the orthopedic surgeon will affix the emitter
during surgery, using known fastening means, such as adhesives or
mechanical fasteners. In other embodiments, an emitter or emitters
may be fixed at predetermined position(s) on the plate. The surgeon
will then choose the appropriate plate, and place the plate to
ensure that the emitted field is properly aligned with the injury.
FIG. 6 also illustrates indicia or a registration mark 224 (a
dotted line in the figure) that will allow a user to readily
properly align the plate for healing using the emitter. In the
illustrated embodiment, the surgeon aligns the dotted line 224 with
the break to ensure that the emitter will be properly aligned.
[0050] In yet another embodiment, illustrated in FIG. 7, an emitter
316 includes a coil 328 such as those described above and a
protrusion 330 depending from the coil. The protrusion 330 is sized
to allow for registration of the emitter 316 with any standard hole
315 formed in an orthopedic plate 314. As will be appreciated,
orthopedic plates generally have a plurality of holes 315, to allow
a surgeon maximum flexibility for affixation of the plate to the
bone. Any hole or holes aligning with the fracture are generally
not used, because a screw is rarely used at the break. However, it
is beneficial to align the emitter with the break, for reasons
discussed above. The protrusion 330 of this embodiment allows for
registration of the emitter with the plate at the break. The
protrusion may form a press or interference fit with the plate,
facilitating connection of the emitter with the plate.
Alternatively, the emitter with protrusion may be fixed to the
plate using any known fastening method, such as adhesives. A
controller and/or a power source may be included with the emitter
or may be positioned anywhere on or spaced from the plate.
[0051] Although the foregoing embodiments describe securing the
emitter to the top of the plate, the emitter may be disposed
anywhere on the plate, including on an edge of the plate or the
bottom of the plate, proximate the bone to which the plate is
affixed. In another embodiment, illustrated in FIG. 8, an
electromagnetic field emitter 316 is disposed in a recess 313
formed in a plate 314. The plate 314 further includes holes 315 for
affixation of the plate. A controller 318 and a power source 320
are also illustrated in the recess 313. The recess 313 allows for a
lower-profile arrangement than can be achieved by placing the
emitter on top of the plate. The recessed portion of the plate
should be configured to provide sufficient rigidity to stabilize
the fracture and minimize the formation of stress risers.
[0052] FIG. 9 is a modification of the embodiment of FIG. 8 in
which an emitter 416, a controller 418 and a power supply 420, with
interconnections 422, are completely encapsulated within an
orthopedic plate 414. In this embodiment, a cavity 413 is provided
in the plate 414 and the components are disposed in the cavity. To
facilitate formation of the plate 414, the plate may be made of
multiple pieces that are assembled after affixation of the emitter
416 and other components to one of the pieces. For example, the
plate may have first and second opposing pieces, e.g., a top and a
bottom having facing horizontal surfaces that when assembled define
a cavity sized to receive the emitter and other components, as
appropriate. Alternatively, the plate may be formed with a recess,
as in FIG. 8, the components placed in the recess, and then a cover
applied to substantially encapsulate the components in the plate.
In such embodiments, the surgeon will preferably receive a unitary
piece in which is embedded the components, such as the emitter,
controller and power supply.
[0053] As with previous embodiments, the plate used in FIGS. 6-9
preferably is non-ferrous, such that the emitted electromagnetic
field will readily pass through the plate to the treatment
area.
[0054] Although the embodiments illustrated until now utilize air
or axial coils such as those illustrated in FIG. 2, other types of
coils may be used. FIG. 10 shows an embodiment in which the
electromagnetic field emitter is a flat or pancake coil 516
disposed on a plate 514, such as an orthopedic plate. A pancake
coil generally emits a field having flux lines 568 such as those
illustrated in FIG. 11. FIG. 11 also illustrates treatment regions
570, which are areas disposed in the magnetic field. In practice,
the afflicted bone or tissue to be healed should be disposed in
these treatment regions 570 for maximum efficacy of the emitter
516.
[0055] In the embodiment of FIG. 10, a plurality of pancake coils
is provided in a two-dimensional array, i.e., a 1.times.4 matrix,
on a plate 514. Using appropriate controls, the coils may be
selectively energized at desired frequencies and for preferred
durations. For example, when a plate such as that illustrated in
FIG. 10 is used, the coil or coils closest to the fracture site
will be energized according to a first treatment methodology. Other
coils may be energized differently or not at all. In other
embodiments, more or fewer pancake coils may be provided. Moreover,
the pancake coils may be encapsulated in the plate, instead of
disposed on the plate, as in the embodiment of FIG. 9.
[0056] Another embodiment of the invention is illustrated in FIG.
12. There, a plurality of pancake coils 616 is provided on a
flexible substrate 614. The flexible substrate allows for
form-fitting of the array of coils to a surface. The array of coils
may be formed from wrapped wire, but more likely will be formed by
depositing a metal, such as copper, onto the substrate as a coil
using known deposition, including known masking and/or etching,
techniques. The deposited coil may be a single-layer coil or may
include turns in multiple layers. That is, deposited pancake coils
may be stacked one on top of the next. In such a configuration, an
intermediate layer, such as an insulating layer, may also be
provided between stacked coils. Such an arrangement will provide an
increased number of turns for the coil, but still provide a
relatively low profile.
[0057] The substrate according to the embodiment of FIG. 12
preferably is made of a polymer-blend. The flexible substrate may
be affixed to a plate, such as a conventional plate, or in some
embodiments could be affixed directly to a patient's bone. An
adhesive may be disposed between the back of the substrate and the
site to be treated to adhere the substrate. The adhesive may be
pre-applied and exposed by removing a backing or other protective
coating, or it may be applied at the time of affixation of the
substrate. The substrate could otherwise be affixed using any known
methodology.
[0058] The flexible substrate with electromagnetic emitters has the
benefit of allowing for adaptation of existing orthopedic devices,
i.e., by affixing the substrate to such devices. Any number of
fixation devices could be modified to include a substrate including
coils. For example, one or more coils on a flexible substrate may
be disposed on an intramedullary rod, either wrapping around the
rod, or along the length of the rod. In other uses, the substrate
could be applied directly to a bone or other anatomical structure
in the body.
[0059] In any of the foregoing embodiments, it is preferable to
arrange the electromagnetic field emitter such that in use the
emitted field acts on the desired treatment area. Although the
embodiments of FIGS. 6-11 generally illustrate coils with axes
perpendicular to a top surface of a plate, the coils could readily
be provided "on their side" such that their axis is parallel to the
top surface of the plate without departing from the spirit and
scope of the invention.
[0060] In several embodiments described above, a device according
to the invention generally includes an implantable device, such as
a conventional device like a rod or plate, adapted to carry a field
emitter and a signal generator. Other combinations also are
contemplated. The field emitter and signal generator also may be
carried by an implant such as a prosthesis. For example, during a
hip replacement, a portion of the femur is removed and replaced
with an implant including a new ball attached to a stem and a
cooperating piece including a socket. The field emitter and signal
generator may be carried by the ball or by the shaft of the
implant. In one embodiment, the ball and/or shaft may be hollow,
with the field emitter and signal generator being disposed in the
hollow ball or shaft. Those of ordinary skill in the art will
appreciate that alternative, similar embodiments can also be
achieved using the teachings of this disclosure.
[0061] The power source provided in the invention may be any known
or developed power source sufficient to power the coil. Batteries
have been conventionally implanted into the human body, e.g., in
pace makers, and such powering technology may be applicable with
embodiments of the invention.
[0062] The control circuitry preferably is provided to allow for
user selection of strength and duration of currents applied to the
electromagnetic emitters. The controller may be programmable, i.e.,
via remote control through an input device external to the patient,
to allow for custom treatment of each patient. In other
embodiments, the controller could be pre-programmed with a
treatment methodology and merely turned on to run through that
pre-determined treatment regimen. The control circuitry may further
include wake-up circuitry or the like, to allow for delayed
operation. For example, an orthopedist may determine that they
would prefer not to use the electromagnetic field therapy until
some amount of time after surgery. Thus, the emitter should not be
energized until that time, if at all.
[0063] As noted above, a number of arrangements of electromagnetic
field emitters, signal generating electronics, i.e., to instruct
energizing of the coil, and power sources, which provide power for
energizing the coil, will be appreciated from this disclosure. In a
relatively simple embodiment, a battery, as the power source, the
signal generating electronics, and a wire coil are implanted
directly in a patient. The signal generating electronics will
include pre-programmed operational sequences as treatment routines
that will energize the coil as desired.
[0064] In addition to a battery, signal generating electronics and
a magnetic coil, the implanted device may further include a
receiver and a transmitter, allowing the device to communicate with
an external device. Such an arrangement would allow for downloading
to the implanted device signal patterns and schedules, e.g., for
specific treatments, as well as updates, and for receiving
information from the device, for example, about the treatment, such
as accumulated dosimetry and/or other treatment
characteristics.
[0065] In yet another embodiment of the invention, to assist in
providing useful information about the device implanted into the
body, the device may further include sensory coils. Such coils are
spaced from the electromagnetic field emitters to receive the
generated magnetic field at a known distance from the generating
coil. The receiver coil is placed at a position, such as a position
spaced along the implanted device away from the emitter or an
opposite side of a fracture to be treated, to measure the magnitude
and duration of the generated magnetic field. Using the
aforementioned transmitter, the results measured by the sensor coil
are then forwarded to the remote device, for interpretation by a
doctor or technician.
[0066] Although many of the foregoing embodiments entail implanting
a battery as a power source, in some applications a battery may not
be the best power source. For example, it may be impractical to use
a conventional battery, for example, because the battery may not
last long enough. When chronic pain is being treated using a device
according to the invention, it is preferable that the device
function as long as the patient requires. Thus, the device may
further include an induction coil as a rechargeable power source.
More specifically, the induction coil is implanted in the patient
and an induction device, such as an induction wand, is used
external to the patient to charge the device. The wand may take any
known form including being provided in a wearable device that could
charge the device, for example, when the user is sleeping.
[0067] FIG. 13 illustrates a schematic of a system according to the
invention. There, a battery 42 is the power source, and an
induction loop 44 is provided to charge the battery 42. A receiver
46 and transmitter 48 are also illustrated, as is an example of the
signal generator 50. The signal generator 50 is illustrated as
including a signal shape memory 52, which stores one or more signal
shapes used to drive the coil 60; a signal playback generator 54;
signal level controls 56; and final treatment amplifier 58. These
components all are connected to the treatment coil 60. The
schematic also shows a sensor coil 62, such as that described
above, and controls 64 for receiving information from the sensor
coil 62. This schematic is provided merely as an example; other
systems and configurations will be apparent to those of ordinary
skill in the art upon being educated by this disclosure.
[0068] The invention has been generally described herein as
utilizing a coil as an electromagnetic field emitter. Other
embodiments may include different field generators. For example, an
alternative embodiment may include a permanent magnet, having a
known field strength and shape. The magnet could then be vibrated,
rotated or otherwise moved to modulate the field, to apply the
desired bioeffect. FIG. 14 shows an example of this. There, a
permanent magnet 716 generates a magnetic field having a known
strength and shape. The magnet 716 is disposed on a shaft 790,
rotatable by a rotary actuator 792, such as a piezoelectric
actuator. By rotating the magnet, the magnet's field is modulated,
which modulation may be optimized for treatment of a broken bone or
wound. Thus, the actuator/permanent magnet combination forms a
controllable magnetic field emitter. Although not illustrated, the
actuator/permanent magnet field emitter will be carried on a
fixation device or other implantable carrier, such as an orthopedic
plate, intramedullary rod, replacement implant, or the like.
[0069] Although a rotary actuator is illustrated in FIG. 14, this
is merely for illustrative and exemplary purposes. In an
alternative embodiment, shown in FIG. 15, the magnet 816 is
provided on a linear actuator 892, such as a piezoelectric
actuator, disposed to move along the direction indicated by the
arrow in FIG. 15. By actuating the actuator 892, a fracture 804 in
a bone 802 is selectively disposed in and spaced from the magnet's
field, indicated by flux lines 868. A signal generator for driving
the actuator also is shown in FIG. 15. The magnet 816 and the
actuator 892 are illustrated in this embodiment as being disposed
in a hollow rod 814. In other embodiments those components could be
carried on any other implant, including but not limited to those
described above
[0070] While the invention has been described in connection with
several presently preferred embodiments thereof, those skilled in
the art will appreciate that many modifications and changes may be
made therein without departing from the true spirit and scope of
the invention which accordingly is intended to be defined solely by
the appended claims.
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