U.S. patent application number 17/136993 was filed with the patent office on 2021-04-22 for system and methods for bone transport.
The applicant listed for this patent is NUVASIVE SPECIALIZED ORTHOPEDICS, INC.. Invention is credited to Thomas B. Buford, Michael Moeller, Jeffrey Schwardt, Vijayendran Somasegaran.
Application Number | 20210113247 17/136993 |
Document ID | / |
Family ID | 1000005313025 |
Filed Date | 2021-04-22 |
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United States Patent
Application |
20210113247 |
Kind Code |
A1 |
Schwardt; Jeffrey ; et
al. |
April 22, 2021 |
SYSTEM AND METHODS FOR BONE TRANSPORT
Abstract
A system for bone transport is provided, the system comprising:
an adjustable length implant configured for intramedullary
placement and comprising a first end configured to be coupled to
bone and a second end configured to be coupled to bone, wherein the
first end and the second end are displaceable relative to each
other along a longitudinal axis; and a driving element configured
to be non-invasively activated to displace the first and second
ends relative to one another along the longitudinal axis; and a
support member having distal and proximal ends, wherein the support
member includes a longitudinally extending slot disposed between
the distal and proximal ends of the support member, the slot having
opposing ends, wherein the slot is configured to pass an elongate
anchor such that the elongate anchor is slidable between the first
end and the second end of the slot.
Inventors: |
Schwardt; Jeffrey; (San
Diego, CA) ; Moeller; Michael; (San Diego, CA)
; Buford; Thomas B.; (San Diego, CA) ;
Somasegaran; Vijayendran; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NUVASIVE SPECIALIZED ORTHOPEDICS, INC. |
San Diego |
CA |
US |
|
|
Family ID: |
1000005313025 |
Appl. No.: |
17/136993 |
Filed: |
December 29, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16046909 |
Jul 26, 2018 |
10918425 |
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17136993 |
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PCT/US17/15555 |
Jan 30, 2017 |
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16046909 |
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62288348 |
Jan 28, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 17/7216 20130101;
A61B 17/171 20130101; A61B 17/66 20130101; A61L 2430/02 20130101;
A61B 2017/681 20130101; A61B 17/8866 20130101; A61B 17/8019
20130101; A61B 17/64 20130101; A61B 17/62 20130101; A61B 17/8004
20130101 |
International
Class: |
A61B 17/72 20060101
A61B017/72; A61B 17/80 20060101 A61B017/80; A61B 17/62 20060101
A61B017/62; A61B 17/66 20060101 A61B017/66 |
Claims
1. A system for bone transport comprising: an adjustable length
implant configured to intramedullary placement, the adjustable
length implant including a housing configured to be coupled to a
first bone portion and a rod configured to be coupled to a
transport bone portion, wherein the rod is moveable relative to the
housing; and a support member having a first end configured to be
coupled to the first bone portion and a second end configured to be
coupled to a second bone portion, wherein the rod is configured to
move the transport bone portion relative to the first bone portion
and the second bone portion.
2. The system of claim 1, wherein the support member is configured
to maintain a position of the first bone portion relative to the
second bone portion while the rod moves the transport bone portion
relative to the first bone portion and the second bone portion.
3. The system of claim 1, wherein the support member includes a
longitudinally extending slot disposed between the first end and
the second end of the support member.
4. The system of claim 3, further comprising: an elongate anchor
member configured to extend through the longitudinally extending
slot to be coupled with the rod and the transport bone portion.
5. The system of claim 4, wherein the elongate anchor is slidable
within the longitudinally extending slot of the support member as
the transport bone portion moves relative to the first bone portion
and the second bone portion.
6. The system of claim 1, further comprising: a driving element
configured to be non-invasively actuated to displace the rod
relative to the housing.
7. The system of claim 6, wherein the driving element comprises a
permanent magnet.
8. The system of claim 7, wherein the permanent magnet comprises a
radially poled rare earth magnet.
9. The system of claim 6, wherein the driving element comprises a
motor.
10. The system of claim 6, wherein the driving element comprises an
inductively coupled motor.
11. The system of claim 6, wherein the driving element comprises an
ultrasonically actuated motor.
12. The system of claim 6, wherein the driving element comprises a
piezoelectric element.
13. The system of claim 6, wherein the driving element comprises a
subcutaneous hydraulic pump.
14. The system of claim 6, wherein the driving element comprises a
shape-memory driven actuator.
15. The system of claim 1, wherein the support member comprises one
or more holes at one or more of its distal end and proximal end,
the one or more holes each configured to pass a bone screw.
16. The system of claim 15, wherein the one or more holes each have
a female thread, configured to engage a male thread carried by a
head of a bone screw.
17. The system of claim 1, wherein the adjustable-length implant is
configured such that when the driving element is non-invasively
activated, the distance between the first end and the second end of
the adjustable-length implant can be controllably shortened.
18. The system of claim 1, further comprising: an external
adjustment device configured to cause displacement of the rod
relative to the housing.
19. A system for bone transport comprising: an adjustable length
implant configured to intramedullary placement, the adjustable
length implant including a housing configured to be coupled to a
first bone portion and a rod configured to be coupled to a
transport bone portion, wherein the rod is moveable relative to the
housing; and a support member having a first end configured to be
coupled to the first bone portion and a second end configured to be
coupled to a second bone portion; and an external adjustment device
configured to cause displacement of the rod relative to the
housing, wherein the rod is configured to move the transport bone
portion relative to the first bone portion and the second bone
portion upon, and wherein the support member is configured to
maintain a position of the first bone portion relative to the
second bone portion.
Description
CROSS REFERENCE TO RELATED 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
[0002] Distraction osteogenesis is a technique which has been used
to grow new bone in patients with a variety of defects. For
example, limb lengthening is a technique in which the length of a
bone (for example a femur or tibia) may be increased. After
creating a corticotomy, or osteotomy, in the bone, which is a cut
through the bone, the two resulting sections of bone may be moved
apart at a particular rate, such as one (1.0) mm per day. New bone
may regenerate between the two sections of the bone as they are
moved apart. This technique of limb lengthening can be used in
cases in which one limb is longer than the other, such as in a
patient whose prior bone break did not heal correctly, or in a
patient whose growth plate was diseased or damaged prior to
maturity. In some patients, stature lengthening is desired and may
be achieved by lengthening both femurs and/or both tibiae to
increase the patient's height.
[0003] Bone transport is a similar procedure, in that it makes use
of osteogenesis. But, instead of increasing the distance between
the ends of a bone, bone transport fills in missing bone in
between. There are several reasons why significant amounts of bone
may be missing. For example, a prior non-union of bone, such as
that from a fracture, may have become infected necessitating
removal of the infected section. Also, segmental defects may be
present, the defects often occurring from severe trauma when large
portions of bone are severely damaged. Other types of bone
infections or osteosarcoma may require removal of a large piece of
bone (causing a portion of the natural bone to be missing).
[0004] Historically, limb lengthening was often performed using
external fixation. The external fixation process involves an
external distraction frame which may be attached to two (or more)
separate sections of bone by transdermal pins (i.e., passing
through the skin). Pin-based methods suffer from several
shortcomings. For example, the pins can be sites for infection and
are often painful for the patient, as the pin placement site
remains a somewhat open wound "pin tract" throughout the treatment
process. External fixation frames are also bulky, and can make it
difficult for the patient to comfortably sit, sleep, and move.
Intramedullary lengthening devices also exist, such as those
described in U.S. patent application Ser. No. 12/875,585, which is
incorporated by reference herein.
[0005] Bone transport is frequently performed by either external
fixation, or by bone grafting. In external fixation bone transport,
a bone segment is cut from the remaining sections of bone and moved
by the external fixation, usually at a rate close to one (1.0) mm
per day, until the resulting regenerate bone fills the defect. The
wounds created from the pin tracts in external fixation-based bone
transport procedures are frequently even worse than those created
by external fixation limb lengthening procedures. The pins begin to
open the wounds larger as the pins are moved with respect to the
skin. In bone grafting, autograft (from the patient) or allograft
(from another person) is typically used to create a lattice for new
bone growth. Bone grafting can be more complicated and/or expensive
than the placement of external fixation pins.
SUMMARY
[0006] The present disclosure provides for a method for
transporting a portion of bone within a patient having an
incomplete bone including providing an adjustable-length implant
configured for intramedullary placement and having a first end
configured to be coupled to bone and a second end configured to be
coupled to bone, wherein the first end and the second end are
displaceable relative to each other along a longitudinal axis,
placing the adjustable-length implant at least partially within the
medullary canal of a bone of a subject, the bone having first and
second ends and having at least first and second portions having a
space there between, the first portion of the bone including the
first end of the bone and the second portion of the bone including
the second end of the bone, creating a third portion of the bone by
detaching at least some of either the first portion of the bone or
the second portion of the bone, wherein the third portion of the
bone does not include the first end of the bone or the second end
of the bone, coupling a support member having first and second ends
to the bone by coupling the first end of the support member to an
external surface of the first portion of the bone and coupling the
second end of the support member to an external surface of the
second portion of the bone, coupling the first end of the
adjustable-length implant to one of the first and second portions
of the bone, coupling the second end of the adjustable-length
implant to the third portion of the bone, wherein the
adjustable-length implant includes a driving element configured to
be non-invasively activated such that a distance between the first
end and the second end of the adjustable-length implant is
controllably changed such that the third portion of the bone is
moved along the longitudinal axis in relation to the first and
second portions of the bone, while the first portion of the bone
and second portion of the bone are not moved in relation to each
other.
[0007] The present disclosure additionally provides for a system
for bone transport including an adjustable length implant
configured for intramedullary placement and having a first end
configured to be coupled to bone and a second end configured to be
coupled to bone, wherein the first end and the second end are
displaceable relative to each other along a longitudinal axis, and
a driving element configured to be non-invasively activated such
that a distance between the first end and the second end of the
adjustable-length implant can be controllably along the
longitudinal axis, and a support member having first and second
ends, wherein the support member includes a longitudinally
extending slot disposed between the first and second ends of the
support member, the slot having a first end and a second end,
wherein the slot is configured to pass an elongate anchor such that
the elongate anchor is slidable between the first end and the
second end of the slot.
[0008] The present disclosure further provides for a method for
transporting a portion of bone within a patient having an
incomplete bone including providing an adjustable-length implant
configured for intramedullary placement and having a first end
configured to be coupled to bone and a second end configured to be
coupled to bone, wherein the first end and the second end are
displaceable relative to each other along a longitudinal axis,
placing the adjustable-length implant at least partially within the
medullary canal of a bone of a subject, the bone having first and
second ends and having at least first and second portions having a
space there between, the first portion of the bone including the
first end of the bone and the second portion of the bone including
the second end of the bone, creating a third portion of the bone by
detaching at least some of either the first portion of the bone or
the second portion of the bone, wherein the third portion of the
bone does not include the first end of the bone or the second end
of the bone, coupling an external fixator to the bone, the external
fixator having an external base, a first pin and a second pin, by
coupling the first pin of the external fixator to the first portion
of the bone and coupling the second pin of the external fixator to
the second portion of the bone, coupling the second end of the
adjustable-length implant to the third portion of the bone, wherein
the adjustable-length implant includes a driving element configured
to be non-invasively activated such that a distance between the
first end and the second end of the adjustable-length implant is
controllably changed such that the third portion of the bone is
moved along the longitudinal axis in relation to the first and
second portions of the bone, while the first portion of the bone
and second portion of the bone are not moved in relation to each
other.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIGS. 1-2 illustrate various views of an intramedullary
device configured for bone transport.
[0010] FIG. 3 illustrates a sectional view of the intramedullary
device of FIG. 2 taken along line 3-3.
[0011] FIG. 4A illustrates detailed view 4 of FIG. 3.
[0012] FIG. 4B illustrates a sectional view of another embodiment
of an intramedullary device.
[0013] FIG. 4C illustrates a ring gear insert of the device shown
in FIG. 4B.
[0014] FIG. 4D illustrates a coupling assembly of the device shown
in FIG. 4B.
[0015] FIG. 5 illustrates an exploded view of the intramedullary
device shown in FIGS. 1-4A.
[0016] FIG. 6 illustrates detailed view 6 of FIG. 5.
[0017] FIG. 7 illustrates a sectional view of another embodiment of
an intramedullary device.
[0018] FIG. 8 illustrates a maintenance member of the
intramedullary device of FIG. 7.
[0019] FIGS. 9-12 schematically illustrate various driving elements
of an intramedullary device.
[0020] FIG. 13 illustrates a bone with a portion missing.
[0021] FIG. 14 illustrates a system for bone transport coupled to a
bone.
[0022] FIG. 15 illustrates the system of FIG. 14 after the
transport of a portion of bone.
[0023] FIG. 16 illustrates a system for bone transport coupled to a
bone in a retrograde manner.
[0024] FIG. 17 illustrates the system of FIG. 16 after the
transport of a portion of bone.
[0025] FIG. 18 illustrates an external adjustment device.
[0026] FIG. 19 illustrates an exploded view of a magnetic hand
piece of the external adjustment device of FIG. 18.
[0027] FIG. 20 illustrates another embodiment of a system for bone
transport.
[0028] FIG. 21 illustrates the system of FIG. 20 coupled to a
bone.
[0029] FIG. 22 illustrates the system of FIG. 21 after the
transport of a portion of bone.
[0030] FIG. 23 illustrates a kit for an adjustable-length
implant.
[0031] FIG. 24 illustrates an adjustable-length implant constructed
from the kit of FIG. 23.
DETAILED DESCRIPTION
[0032] Various adjustable devices for implanting into the body that
are capable of changing or working/acting on a portion of the
skeletal system of a patient are disclosed herein. In some
embodiments, the adjustable implants are configured for
transporting a segment of bone to replace lost portions of bone.
Methods for using the adjustable implants for transporting a
segment of bone in order to replace lost portions of bone are also
provided. In some embodiments, the method may incorporate one or
more plates. Adjustable devices may include distraction or
retraction devices, for example, distraction or retraction devices
configured for orthopedic applications, including, but not limited
to scoliosis, limb lengthening, bone transport, spinous process
distraction, lumbar lordosis adjustment, tibial wedge osteotomy
adjustment, and spondylolisthesis. Adjustable devices configured
for bone transport may include intramedullary limb lengthening
devices.
[0033] FIGS. 1 and 2 illustrate an intramedullary device 300 (e.g.,
an intramedullary lengthening device) comprising a distraction rod
302 and a housing 304. The housing 304 extends between a first end
310 and a second end 312, as may be better appreciated in the
sectional view of FIG. 3. The housing 304 may be formed as a
unitary structure with no seams or joints. Alternatively, the
housing 304 may be formed in pieces that are fused together at
seams or joints. As shown in FIG. 3, the distraction rod 302 has a
first end 318 and a second end 320, and is configured to be
telescopically extendable and retractable relative to the housing
304 (e.g., within the housing 304). Like the housing 304, the
distraction rod 302 may be a unitary structure with no seams or
joints connecting various sub-components. Alternatively, the
distraction rod 302 may be formed in pieces that are fused together
at seams or joints. Both the distraction rod 302 and the housing
304 may be made from any of a number of biocompatible materials,
including titanium, for example Titanium-6AL-4V, cobalt chromium
alloys, and stainless steel. Because the distraction rod 302 and
the housing 304 are the primary load bearing members of the
intramedullary device 300, and because neither has any external
circumferential weld(s), the intramedullary device 300 can be
capable of withstanding improved loading challenges in comparison
to conventional intramedullary limb lengthening devices. The
housing 304 contains at least one transverse hole (e.g., two
transverse holes 301) for passing bone screws, with which to attach
the intramedullary device 300 to the bone. The distraction rod 302
contains at least one transverse hole (e.g., three transverse holes
303), also for the passing of bone screws. As will be readily
understood, the number and orientation of the transverse holes 301,
303 may be varied as necessary, useful, or desired for any given
application. At the second end 312 of the housing 304, a coupling
feature 323, provides an interface to releasably engage with an
insertion instrument, such as a drill guide. The drill guide may
include a male thread and the coupling feature 323 may have a
complementary or mating female thread. The intramedullary device
300 comprises a magnet 338 which is bonded within a magnet housing
340 and configured for rotation between a radial bearing 344 and a
thrust bearing 342 (shown more clearly in FIG. 4A). Between the
thrust bearing 342 and the magnet housing 340 is at least one
planetary gear stage (e.g., three planetary gear stages 305, 307,
309, as seen in FIG. 4A). Each planetary gear stage (e.g.,
planetary gear stages 305, 307, 309) comprises a sun gear (e.g.,
sun gear 311A, 311B, 311C) and a plurality of planetary gears
(e.g., three planetary 313), which are rotatably held within a
frame 315 by pins 317. The sun gear 311 is either a part of the
magnet housing 340, as in the case of the sun gear 311A of
planetary gear stage 305, or a part of the frame 315, as in sun
gear 311B of gear stage 307 and sun gear 311C of gear stage 309.
The rotation of the sun gear 311 causes the planetary gears 313 to
rotate and track along inner teeth 321 of a ring gear insert 319.
Each gear stage has a gear reduction ratio (e.g., of 4:1), which
results in a total gear reduction (e.g., a total gear reduction of
64:1--provided by three planetary gear stages each having a
reduction ratio of 4:1). It should be understood that other gear
reductions, and numbers of stages may be used.
[0034] The frame 315 of the final gear stage (e.g., gear stage 309)
passes through the thrust bearing 342 and is attached to a lead
screw coupler 366 such that rotation of the frame 315 of the final
gear stage 309 causes one-to-one rotation of the lead screw coupler
366. The lead screw coupler 366 and a lead screw 358 each contain
transverse holes through which a locking pin 368 is placed, thus
rotationally coupling the lead screw 358 to the final gear stage
(e.g., gear stage 309). A locking pin retainer 350 is slid over and
secured (e.g., tack welded) to the lead screw coupler 366 to
radially maintain/retain the locking pin 368 in place. The
distraction rod 302 has an internally threaded end 363, into which
external threads 365 of a nut 360 are threaded and bonded, for
example with epoxy. The nut 360 has internal threads 367 which are
configured to threadably engage with external threads 325 of the
lead screw 358, thereby allowing rotation of the lead screw 358 in
a first direction to distract or extend the distraction rod 302 in
relation to the housing 304. Rotation of the lead screw 358 in a
second (opposite) direction retracts or withdraws the distraction
rod 302 in relation to the housing 304. Rotation of the magnet 338
and the magnet housing 340 causes rotation of the lead screw.
Depending on the gearing included, rotation of the magnet 338 and
the magnet housing 340 can cause rotation of the lead screw 358 at
1/64 the rotational speed, but with significantly increased torque
(64 times, minus frictional losses), and thus an amplified
distraction or extension force. O-rings 362 are placed in ring
grooves 388 on the exterior of the distraction rod 302 to create a
dynamic seal between the housing 304 and the distraction rod 302
that protects the internal contents from body fluids. A split
washer stop 364, located between the distraction rod 302 and the
lead screw coupler 366, guards against jamming that could otherwise
be caused as the distraction rod 302 approaches the lead screw
coupler 366, for example if intramedullary device 300 is fully
retracted with a high torque (e.g., a high torque applied by an
external moving magnetic field).
[0035] A maintenance member 346, comprising a curved plate made
from a magnetically permeable material (e.g., 400 series stainless
steel), is secured to/bonded within the inner wall of the housing
304 (e.g., using epoxy, adhesive, resistance welding, or other
suitable process(es)). The maintenance member 346 attracts a pole
of the magnet 338, thus keeping the limb lengthening device 300
from being accidentally adjusted by movements of the patient.
However, a strong moving magnetic field, such as that applied by
magnetic adjustment devices known in the art, is capable of
overcoming the attraction of the magnet 338 to the maintenance
member 346, rotate the magnet 338, and thereby adjust the length of
the intramedullary device 300. The maintenance member 346 can have
has a thickness of approximately 0.015 inches and can span a
circumferential arc of less than about 180.degree. (e.g., an
exemplary arc is 99.degree.). Of course, other dimensions for the
maintenance member 346 are contemplated, as long as it provides
sufficient attractive force(s) to the magnet 338 to appropriately
hold it in place when not being actuated.
[0036] The distraction rod 302 and the housing 304 may be
individually manufactured, for example by machining processes
incorporating manual or automated lathes. Included within this
manufacturing operation may be the forming of an axially-extending
cavity within the housing 304. Post-processing may be included in
this operation, for example bead blasting, passivation, and/or
anodizing. The distraction rod 302 and the housing 304 are then
prepared for mating. In this operation, the nut 360 is bonded into
the distraction rod 302 and the O-rings 362 are placed into the
ring grooves 388 as described. The maintenance member 346 is bonded
to the housing 304. Then, the magnet 338 is placed into the cavity
390 of the housing 304. In this operation the magnet 338 and the
magnet housing 340 are bonded together, and then assembled with the
radial bearing 344 into the housing 304 (see FIG. 3). Prior to
assembling the radial bearing 344 into the housing 304, the
longitudinal depth of the cavity 390 of the housing 304 is
measured, and, if necessary, one or more shims may be placed before
the radial bearing 344. Ideally, the axial play in the assembled
components is not so low as to cause binding, yet not so high as to
risk disassembly. Next, the lead screw 358 is prepared for coupling
to the magnet 338 that is in the cavity 390 of the housing 304. In
this operation the ring gear insert 319 is slid into the cavity 390
of the housing 304 until it abuts ledge 392. First and second
planetary gear stages 305, 307 are then placed into the assembly as
seen in FIG. 4A. The locking pin retainer 350 is preloaded over the
lead screw coupler 366 prior to welding the lead screw coupler 366
to the final planetary gear stage 309, and is then slid in place
over the locking pin 368 after the locking pin 368 is placed. Final
planetary gear stage 309 is inserted through the thrust bearing 342
and is welded to the lead screw coupler 366, allowing for some
axial play of the thrust bearing 342. The split washer stop 364 is
then placed onto the lead screw 358. The lead screw 358 is then
attached to the lead screw coupler 366 with the locking pin 368,
and then the locking pin retainer 350 is slid over a portion of the
ends of the locking pin 368 and tack welded to the lead screw
coupler 366. Thrust bearing retainers 354, 356 are two matching
pieces which form a cylindrical clamshell around the thrust bearing
342 and the lead screw coupler 366. The internal diameter of the
housing 304 is tinned with solder, as are the outer half diameter
surfaces of each of the thrust bearing retainers 354, 356. Next,
the thrust bearing retainers 354, 356 are clamped over an assembly
comprising the thrust bearing 342, lead screw coupler 366,
planetary gear stage 309, and lead screw 358, and the thrust
bearing retainers 354, 356 are pushed together into place within
the housing 304, for example with the aid of a tool pressed against
chamfers 352 of the thrust bearing retainers 354, 356. The sun gear
311C of the final planetary gear stage 309 engages with the planet
gears 317 of the final planetary gear stage 309 and then chamfered
edges 394 of the thrust bearing retainers 354, 356 are pushed
against a chamfer 348 of the ring gear insert 319 and a compressive
force is held. Next, the thrust bearing 342 and the magnet 338 are
axially retained. In this operation, the thrust bearing retainers
354, 356 are soldered to the housing 304 at the tinned portions,
thus maintaining compressive force. This may be accomplished using
induction heating. The friction of the ledge 392 and the chamfered
edge 394 against opposing ends of the ring gear insert 319, as well
as the wedging between the chamfered edge 394 and the chamfer 348,
create a resistance to rotation, thus holding the ring gear insert
319 rotationally static in relation to the housing 304.
Alternatively, the ring gear insert 319 may have a keyed feature
that fits into a corresponding keyed feature in the housing 304, in
order to stop the ring gear insert 319 from turning relative to the
housing 304 (this may be useful if/when the friction on the ends of
the ring gear insert 319 is not sufficient to hold the ring gear
insert 319 static).
[0037] The distraction rod 302 can then be engaged with the lead
screw 358. In this operation, an assembly tool, such as a high
speed rotating magnet, is used to make the magnet 338 and,
consequently, the lead screw 358 rotate and the distraction rod 302
is inserted into the housing 304 while the lead screw 358 engages
and displaces with respect to the nut 360 of the distraction rod
302. After the distraction rod 302 is inserted into the housing 304
as described and retracted at least somewhat, the distraction rod
302 is still free to rotate with respect to the housing 304. For
the stability of the bone pieces being distracted, it may be
desirable to inhibit rotation between the distraction rod 302 and
the housing 304. One possible method and structure of doing so is
described in relation to FIGS. 5 and 6. The distraction rod 302 may
be rotationally locked with respect to the housing 304 by placing
an anti-rotation ring 370 over the distraction rod 302 by engaging
protrusions 374, one on each side, into grooves 372 extending along
the distraction rod 302 and then by sliding the anti-rotation ring
370 up to a tapered inner edge 376 of the housing 304. The
anti-rotation ring 370 and the distraction rod 302 may then be
rotated until guide fins 382 can be inserted (e.g., slide) into
guide cuts 380 in the end of the housing 304. The anti-rotation
ring 370 can be axially snapped into the housing 304 so that flat
edge 384 of the anti-rotation ring 370 is trapped by undercut 378.
The undercut 378 has a minimum diameter which is less than the
outer diameter of the flat edge 384 of the anti-rotation ring 370,
and is temporarily forced open during the snapping process. As
assembled, the anti-rotation ring 370, the housing 304 and the
distraction rod 302 are all held substantially rotationally static
in relation to each other. In addition, when the intramedullary
device 300 reaches its maximum distraction length, the ends 386 of
grooves 372 abut the protrusions 374, thereby keeping the
distraction rod 302 from falling out of the housing 304.
[0038] An alternative embodiment of the intramedullary device 300
of FIGS. 1-4A is shown in a sectional view in FIG. 4B. Much of this
embodiment can be similar or identical to the embodiments shown in
FIGS. 1-4A. However, this embodiment varies at least in that it
need not have thrust bearing retainers 354, 356. Instead, it may
incorporate a thrust bearing ferrule having an external tapered end
347. A thrust bearing retainer 337, a locking pin retainer 341, and
the thrust bearing ferrule 335 are placed over the thrust bearing
342 and a lead screw coupler 339 and the final planetary gear stage
309 are inserted through the thrust bearing 342 and welded to the
lead screw coupler 339. As shown in FIG. 4D, the locking pin
retainer 341 has a relief 361 to allow the passage of the locking
pin 368. After the locking pin 368 is placed, the locking pin
retainer 341 may be rotated so that the relief 361 is no longer
directly over the locking pin 368 and the locking pin retainer 341
is tack welded or secured by other methods to the lead screw
coupler 339, thus retaining the locking pin 368. These assembled
components are then inserted into the cavity 390 of the housing
304, where the final planetary gear stage 309 is coupled to the
other planetary gear stages 305, 307 and the magnet 338. In this
embodiment, a ring gear insert 333 (FIG. 4C) has an indentation 351
(e.g., a notch) on each side. A tab 349 on each side of the thrust
bearing ferrule 335 inserts into each indentation 351 and inhibits
rotation of the ring gear insert 333 in relation to the housing 304
once the thrust bearing ferrule 335 is engaged into the housing
304. Also in this embodiment, the housing 304 contains internal
threading 343. The engagement of the thrust bearing ferrule 335 is
achieved by tightening external threading 345 of the thrust bearing
retainer 337 into the internal threading 343 of the housing 304. A
tool (not shown) may be engaged into cut outs 357 on either or both
sides of the thrust bearing retainer 337 and is used to screw the
thrust bearing retainer 337 into the internal threading 343 of the
housing 304. As shown in FIG. 4B, this wedges an internal taper 353
of the thrust bearing retainer 337 against the external tapered end
347 of the thrust bearing ferrule 335, allowing the thrust bearing
ferrule 335 to apply a controlled load on the ring gear insert 333,
locking the ring gear insert 333 axially and rotationally with
respect to the housing 304. The thrust bearing retainer 337
contains an axial split on the opposite side (not shown). The split
in the thrust bearing retainer 337, allows the outer diameter of
the thrust bearing retainer 337 to be slightly reduced (by
compression) while it is inserted into the housing 304, prior to
being threaded, so that the internal portion of the housing 304 is
not scratched during insertion. A ledge 355 is visible on the lead
screw coupler 339 in FIG. 4D. As noted earlier, the split washer
stop 364 butts up against this ledge 355 to prohibit jamming when
the distraction rod 302 is retracted completely.
[0039] An alternative embodiment of the intramedullary device 300
of FIGS. 1-4A is shown in a sectional view in FIG. 7. A maintenance
member 397 replaces the curved plate maintenance member 346. The
maintenance member 397 is spaced axially in relation to the magnet
338 within the housing 304 of the limb lengthening device 300, but
because of its proximity to the magnet 338, maintenance member 397
is still capable of attracting a pole of the magnet 338, thus
keeping the limb lengthening device 300 from being accidentally
adjusted by movements of the patient. The maintenance member 397
comprises a body 395 and a securement portion 391. The securement
portion 391 is illustrated as comprising four tabs 393, each having
an outer radius that is greater than the radius of cavity 379 in
the housing 304. The interference between the tabs 393 and the
cavity 379 is sufficient to hold the maintenance member 379 in
place, so that it cannot turn or move axially in relation to the
housing 304. Alternatively, the securement portion 391 may be
adhesively bonded, welded, or secured by another means to the
cavity 379. The maintenance member 397 includes a ledge 381 which
is configured to seat the radial bearing 344. Similar to the
embodiments of FIGS. 1-4D, a nose 377 of the magnet housing 340 is
pressed into the inner hole of the radial bearing 344. In the
embodiment of FIGS. 7 and 8, a through hole 399 in the maintenance
member 397 is configured to allow non-contact extension of the nose
377 of the magnet housing 340, thus allowing the magnet housing
340, and thus magnet 338, to freely rotate. Ears 387, 389 are
separated by gaps 383, 385, and comprise a magnetically permeable
material (e.g., 400 series stainless steel, iron, mu-metal, or
another similar material that can attract a pole of the magnet
338). An edge 375 of each ear 387, 389 may be flat, in order to
allow a maximal amount of material to be located in proximity to
the magnet 338.
[0040] FIG. 18 illustrates an external adjustment device 1180 that
is used to non-invasively adjust the devices and systems described
herein. The external adjustment device 1180 comprises a magnetic
hand piece 1178, a control box 1176 and a power supply 1174. The
control box 1176 includes a control panel 1182 having one or more
controls (buttons, switches or tactile, motion, audio or light
sensors) and a display 1184. The display 1184 may be visual,
auditory, tactile, the like or some combination of the
aforementioned features. The external adjustment device 180 may
contain software that allows programming by the physician.
[0041] FIG. 19 shows the detail of the magnetic hand piece 1178 of
the external adjustment device 1180. There is a plurality of, e.g.,
two (2), magnets 1186 that have a cylindrical shape (also, other
shapes are possible). In some embodiments, the magnetic hand piece
1178 comprises only one magnet 1186. In some embodiments, the
magnetic hand piece 1178 uses one or more electromagnets. The
magnets 1186 can be made from rare earth magnets (such as
Neodymium-Iron-Boron), and can in some embodiments be radially
poled. The magnets 1186 are bonded or otherwise secured within
magnetic cups 1187. The magnetic cups 1187 each include a shaft
1198, one of which is attached to a first magnet gear 1212 and the
other of which is attached to a second magnet gear 1214. The
orientation of the poles of each the two magnets 1186 are
maintained in relation to each other by means of the gearing system
(by use of center gear 1210, that meshes with both first magnet
gear 1212 and second magnet gear 1214). In one embodiment, the
north pole of one of the magnets 1186 turns synchronously with the
south pole of the other magnet 1186, at matching clock positions
throughout a complete rotation. The configuration has been known to
provide an improved delivery of torque, for example to magnet 338.
Examples of methods and embodiments of external adjustment devices
that may be used to adjust the intramedullary device 300, or other
embodiments of the present invention, are described in U.S. Pat.
No. 8,382,756, and U.S. patent application Ser. No. 13/172,598,
both of which are incorporated by reference herein.
[0042] The components of the magnetic hand piece 1178 are held
together between a magnet plate 1190 and a front plate 1192. Most
of the components are protected by a cover 1216. The magnets 1186
rotate within a static magnet cover 1188, so that the magnetic hand
piece 1178 may be rested directly on the patient, while not
imparting any motion to the external surfaces of the patient. Prior
to distracting the intramedullary lengthening device 1110, the
operator places the magnetic hand piece 1178 over the patient near
the location of the magnet 338. A magnet standoff 1194 that is
interposed between the two magnets 1186 contains a viewing window
1196, to aid in the placement. For instance, a mark made on the
patient's skin at the appropriate location with an indelible marker
may be viewed through the viewing window 1196. To perform a
distraction, the operator holds the magnetic hand piece 1178 by its
handles 1200 and depresses a distract switch 1228, causing motor
1202 to drive in a first direction. The motor 1202 has a gear box
1206 which causes the rotational speed of an output gear 1204 to be
different from the rotational speed of the motor 1202 (for example,
a slower speed). The output gear 1204 then turns a reduction gear
1208 which meshes with center gear 1210, causing it to turn at a
different rotational speed than the reduction gear 1208. The center
gear 1210 meshes with both the first magnet gear 1212 and the
second magnet gear 1214 turning them each at the same rate.
Depending on the portion of the body where the magnets 1186 of the
external adjustment device 1180 are located, it is desired that
this rate be controlled, to minimize the resulting induced current
density imparted by magnet 1186 and magnet 338 through the tissues
and fluids of the body. For example a magnet rotational speed of 60
RPM or less is contemplated although other speeds may be used such
as 35 RPM or less. At any time, the distraction may be lessened by
depressing the retract switch 1230, which can be desirable if the
patient feels significant pain, or numbness in the area holding the
device.
[0043] Throughout the embodiments presented, a magnet 338 is used
as a driving element to remotely create movement in an
intramedullary device 300. FIGS. 9-12 schematically show four
alternate embodiments, wherein other types of energy transfer are
used in place of permanent magnets.
[0044] FIG. 9 illustrates an intramedullary device 1300 comprising
an implant 1306 having a first implant portion 1302 and a second
implant portion 1304, the second implant portion 1304 being
non-invasively displaceable with respect to the first implant
portion 1302. The first implant portion 1302 is secured to a first
bone portion 197 and the second implant portion 1304 is secured to
a second bone portion 199 within a patient 191. A motor 1308 is
operable to cause the first implant portion 1302 and the second
implant portion 1304 to displace relative to one another. An
external adjustment device 1310 has a control panel 1312 for input
by an operator, a display 1314 and a transmitter 1316. The
transmitter 1316 sends a control signal 1318 through the skin 195
of the patient 191 to an implanted receiver 1320. Implanted
receiver 1320 communicates with the motor 1308 via a conductor
1322. The motor 1308 may be powered by an implantable battery, or
may be powered or charged by inductive coupling.
[0045] FIG. 10 illustrates an intramedullary device 1400 comprising
an implant 1406 having a first implant portion 1402 and a second
implant portion 1404, the second implant portion 1404 being
non-invasively displaceable with respect to the first implant
portion 1402. The first implant portion 1402 is secured to a first
bone portion 197 and the second implant portion 1404 is secured to
a second bone portion 199 within a patient 191. An ultrasonic motor
1408 is operable to cause the first implant portion 1402 and the
second implant portion 1404 to displace relative to one another
(e.g., a piezoelectric actuator). An external adjustment device
1410 has a control panel 1412 for input by an operator, a display
1414 and an ultrasonic transducer 1416 that is coupled to the skin
195 of the patient 191. The ultrasonic transducer 1416 produces
ultrasonic waves 1418 which pass through the skin 195 of the
patient 191 and operate the ultrasonic motor 1408.
[0046] FIG. 11 illustrates an intramedullary device 1700 comprising
an implant 1706 having a first implant portion 1702 and a second
implant portion 1704, the second implant portion 1704 being
non-invasively displaceable with respect to the first implant
portion 1702. The first implant portion 1702 is secured to a first
bone portion 197 and the second implant portion 1704 is secured to
a second bone portion 199 within a patient 191. A shape memory
actuator is operable to cause the first implant portion 1702 and
the second implant portion 1704 to displace relative to one
another. An external adjustment device 1710 has a control panel
1712 for input by an operator, a display 1714 and a transmitter
1716. The transmitter 1716 sends a control signal 1718 through the
skin 195 of the patient 191 to an implanted receiver 1720.
Implanted receiver 1720 communicates with the shape memory actuator
1708 via a conductor 1722. The shape memory actuator 1708 may be
powered by an implantable battery, or may be powered or charged by
inductive coupling.
[0047] FIG. 12 illustrates an intramedullary device 1800 comprising
an implant 1806 having a first implant portion 1802 and a second
implant portion 1804, the second implant portion 1804 being
non-invasively displaceable with respect to the first implant
portion 1802. The first implant portion 1802 is secured to a first
bone portion 197 and the second implant portion 1804 is secured to
a second bone portion 199 within a patient 191. A hydraulic pump
1808 is operable to cause the first implant portion 1802 and the
second implant portion 1804 to displace relative to one another. An
external adjustment device 1810 has a control panel 1812 for input
by an operator, a display 1814 and a transmitter 1816. The
transmitter 1816 sends a control signal 1818 through the skin 195
of the patient 191 to an implanted receiver 1820. Implanted
receiver 1820 communicates with the hydraulic pump 1808 via a
conductor 1822. The hydraulic pump 1808 may be powered by an
implantable battery, or may be powered or charged by inductive
coupling. The hydraulic pump 1808 may alternatively be replaced by
a pneumatic pump.
[0048] FIG. 13 illustrates a bone 100 which is incomplete and
missing a portion. The bone 100 includes a proximal portion 102 and
a distal portion 104. The bone 100 has a proximal end 106 and a
distal end 108, and a medullary canal 110 extending between the
two. The bone may represent a number of different long bones, for
example, a femur, a tibia, a fibula, a humerus, or others, or even
other bones (e.g., a mandible). An open area 112 between the
proximal portion 102 and the distal portion 104 represents the
missing bone. The open area 112 may exist for any of a number of
reasons. For example, that portion of the bone 100 may have been
lost during a traumatic accident or during one or more surgical
procedures after a traumatic accident. Or, it may have been removed
along with the resection of a portion of cancerous bone, for
example, a tumor caused by one or more types of sarcoma.
[0049] In FIG. 14, a system for bone transport 400 is shown
attached to the bone 100. The system for bone transport comprises
an adjustable-length implant 401 and a support member 403. The
adjustable-length implant 401 may in some embodiments comprise an
intramedullary limb lengthening device, such as the intramedullary
device 300 of FIGS. 1-8 or any embodiments shown in FIGS. 9-12. The
adjustable implant 401 comprises a rod 402 which is telescopically
displaceable from a housing 404. The rod 402 may be distracted out
of or retracted into the housing 404 by a driving element 405. In
use, the adjustable-length implant 401 may be implanted within the
medullary canal 110 of the bone 100 after the medullary canal 110
has been drilled or reamed to remove material or to increase its
inner diameter. Prior to or following the implantation of the
adjustable-length implant 401, an osteotomy 406 can be made, by
cutting, sawing, etc., to create a transport portion 114 of the
bone 100. In FIG. 14, the transport portion 114 is created from the
distal portion 104 of the bone 100. In other cases, the transport
portion 114 may be made from the proximal portion 102 of the bone
100. In FIG. 14, the adjustable-length implant 401 is inserted from
the proximal end 106 of the bone 100 (i.e., in an antegrade
manner). But, in other cases, the adjustable-length implant 401 may
be inserted from the distal end 108 (i.e., in a retrograde manner).
With the transport portion 114 separated from the distal portion
104 of the bone 100 by the osteotomy 406. The transport portion 114
and the proximal portion 102 may be coupled to the
adjustable-length implant 401 in order to move the transport
portion 114 with respect to the proximal portion 102 and distal
portion 104. To attach the pieces of the bone 100, the proximal
portion 102 of the bone 100 may be drilled on an axis through one
or more holes 410 in the housing 404 and one or more bone screws
408 are placed through the one or more holes 410 and secured to the
proximal portion 102 of the bone 100. The transport portion 114 of
the bone 100 may be drilled on an axis through one or more holes
412 in the rod 402 and one or more bone screws 414 can be placed
through the one or more holes 412 and secured to the transport
portion 114 of the bone 100. The transport portion 114 may then be
non-invasively moved along a longitudinal axis Z of the
adjustable-length implant 401. The adjustable-length implant 401 as
depicted in FIG. 14 may be supplied to the user in a fully or
mostly extended condition (with the rod 402 fully or substantially
distracted from the housing 404), so that the transport process
moves the transport portion 114 away from the distal portion 104
and towards the proximal portion 102. In this traction manner, the
transport portion 114 is pulled not pushed. Pulling on the
transport portion 114 tends to provide increased dimensional
stability and less drift as the transport portion 114 is being
moved. Once a callus begins to acceptably form at the osteotomy
406, the transport process may be started. For example, the
transport portion 114 may be moved between about 0.5 mm per day and
about 1.50 mm per day, or between about 0.75 mm per day and about
1.25 mm per day, or around 1.00 mm per day. Each daily distraction
amount may be achieved in one non-invasive adjustment per day, or
may be broken up into two, three, or more separate adjustments (for
example, three adjustments of about 0.33 mm each). Due to the
osteogenesis that can occur during controlled transport of the
transport portion 114, a new bone portion 416 is created. When the
bone transport proceeds to the extent such that a proximal end 418
of the transport portion 114 reaches a distal end 420 of the
proximal portion 102, a compressive force may be applied to the
transport portion 114 and the proximal portion 102. Such
compressive forces can help fuse or adhere the transport portion
114 to the proximal portion, and is aided by the fact that it is
being applied by pulling the transport portion 114.
[0050] As mentioned above, the system for bone transport 400 may
also include a support member 403, which may comprise a bone plate
configured to be secured to a location on an external surface 422
of the bone 100. The bone plate may comprise a cortical bone plate.
The support member 403 may include one or more holes 424 at its
distal end 426 for placement of one or more bone screws 428. The
support member 403 may also include one or more holes 430 at its
proximal end 432 for placement of one or more bone screws 434, 436.
The bone screws 434, 428 may be bicortical bone screws and the bone
screw 436 may be a unicortical bone screw. Bicortical bone screws
may advantageously be used at locations on the bone 100 that are
proximal or distal to the adjustable-length implant 401, while
unicortical bone screws may advantageously be used at locations on
the bone 100 that are adjacent the adjustable-length implant 401.
The bone screws 428, 434, 436 that are used to secure the support
member 403 to the bone 100 may have threaded shafts and tapered,
threaded heads that are configured such that the threaded shafts
engage with bone material and the tapered threaded heads engage
with tapered threaded holes (e.g., the one or more holes 424, 430)
in the support member 403. The support member 403 maintains the
proximal portion 102 and the distal portion 104 of the bone 100
static and stable with respect to each other, thereby optimizing
the precision of movement of the transport portion 114 as it is
moved in relation to the proximal portion 102 and the distal
portion 104. One or more cerclages 429, 431 may be used to further
secure the system in place, for example, to further secure the
support member 403 to the bone 100. While the cerclages 429, 431
are omitted in FIG. 15, it should be understood that they may be
used with any embodiment of apparatus or methods described herein.
In some embodiments, the support member 403 may include
considerably more holes for placement of bone screws. For example,
a portion of the support member 403 configured to be placed at the
proximal end of a femur may have three, four, or more holes for
placement of bone screws which are configured to be secured into
bone and extend into the femoral neck, the greater trochanter, or
other portions of the femur, including one or more bone
fragments.
[0051] FIGS. 16 and 17 illustrate the system for bone transport 400
secured to the bone 100. The adjustable-length implant 401,
however, has been inserted into the medullary canal 110 from the
distal end 108 of the bone (i.e., in a retrograde manner). The
osteotomy 406 is thus made in the proximal portion 102 of the bone
100, and the transport portion 114 is detached from the proximal
portion 102 of the bone. The transport portion 114 is transported
away from the proximal portion 102 of the bone 100 and towards the
distal portion 104 of the bone 100, to create the new bone portion
416.
[0052] An alternative anatomical setup may be created during
surgery, by placing the adjustable-length implant 401 in an
orientation similar to that of FIG. 14 (e.g., rod 402 extending
distally or oriented downward and housing 404 extending proximally
or oriented upward), but by inserting it retrograde (i.e., from the
distal end 108 of the bone 100) as shown in FIG. 16. Still another
alternative anatomical setup may be created in surgery, by placing
the adjustable-length implant 401 in an orientation similar to that
of FIG. 16 (e.g., rod 402 extending proximally or oriented upward
and housing 404 extending distally or oriented downward), but by
inserting it antegrade (i.e., from the proximal end 106 of the bone
100) as shown in FIG. 14.
[0053] FIG. 20 illustrates a system for bone transport 500. The
system for bone transport comprises an adjustable-length implant
501 and a support member 503 (for example, a plate). The
adjustable-length implant 501 may in some embodiments comprise an
intramedullary limb lengthening device, such as the intramedullary
device 300 of FIGS. 1-8 or any of the alternative embodiments of
FIGS. 9-12. The adjustable implant 501 may comprise a rod 502,
which is telescopically displaceable from a housing 504. The rod
502 may be distracted out of or retracted into the housing 504 by a
driving element 505 (shown in FIGS. 21-22). In use, the
adjustable-length implant 501 is implanted within the medullary
canal 110 of the bone 100, after the medullary canal 110 has been
drilled or reamed, to remove material or to increase its inner
diameter. Prior to or following this, an osteotomy 406 is made, by
cutting, sawing, etc., to create a transport portion 114 of the
bone 10. In FIG. 21, the transport portion 114 is created from the
distal portion 104 of the bone 100. In other cases, the transport
portion 114 may be made from the proximal portion 102 of the bone
100. FIG. 21 illustrates the adjustable-length implant 501 after
having been inserted in an antegrade manner. But in other cases the
adjustable-length implant 501 may be inserted in a retrograde
manner. After separation of the transport portion 114 from the
distal portion 104 of the bone 100 (e.g., by the osteotomy 406),
the transport portion 114 and the proximal portion 102 may be
coupled to the adjustable-length implant 501 in order to move the
transport portion 114 with respect to the proximal portion 102 and
distal portion 104. The proximal portion 102 of the bone 100 may be
drilled on an axis through one or more holes 510 in the housing 504
and one or more bone screws 508 may be placed through the one or
more holes 510 and secured to the proximal portion 102 of the bone
100. The transport portion 114 of the bone 100 may be drilled on an
axis through one or more holes 512 in the rod 502 and one or more
bone screws 514 may be placed through the one or more holes 512 and
secured to the transport portion 114 of the bone 100. The transport
portion 114 may then be non-invasively moved along a longitudinal
axis Z of the adjustable-length implant 501. The adjustable-length
implant 501 as depicted in FIG. 21 may be supplied to the user in a
fully or mostly extended condition (with the rod 502 fully or
substantially distracted from the housing 504), so that the
transport process moves the transport portion 114 away from the
distal portion 104 and towards the proximal portion 102 In this
traction manner, the transport portion 114 is pulled not pushed.
Pulling on the transport portion 114 tends to provide increased
dimensional stability and less drift as the transport portion 114
is being moved. The support member 503 is similar to the support
member 403 of FIGS. 14-17, except that the support member 503
comprises a longitudinal slot 587 extending between a proximal slot
end 589 and a distal slot end 597. The slot 587 is located between
the proximal end 532 and the distal end 526 of the support member
503. As in the embodiments shown in FIGS. 14-17, the support member
502 may be secured to the bone 100 with one or more bicortical bone
screws 528, 534 (which can be placed through holes 524, 530) and
one or more unicortical bone screws 536 (which are placed through
holes 524, 530). As shown in FIG. 20, certain holes 524a. 524c may
be offset to one side of centerline 599 of the support member 503,
while other holes 524b, may be offset to another side of centerline
599 of the support member 503. Offsetting the holes in this fashion
may aid the placement of bicortical bone screws, in cases wherein
the adjustable-length implant 501 extends to the level of the holes
524a-c. The offset location of the holes 524a-c, for example, may
allow the bicortical bone screws to extend past the rod 502 on
either side of the rod 502. The transport portion 114 of the bone
100 can be secured to the rod 502 by the bone screws 514 by
drilling the bone 100 in the transport portion along the axes of
the holes 512 in a manner such that when the bone screws 514 are
secured, they extend from an external location 593 of the slot 587
of the support member 503, through the slot 587, and into the bone
100 of the transport portion 114. The bone screws 514 are aligned
in a manner such that when the rod 502 is non-invasively translated
with respect to the housing 504, the shaft 597 of the bone screws
514 slide within the slot 587. As will be readily appreciated, the
diameter of the shaft 597 of the bone screw 514 is less than the
width of the slot 587. In some embodiments, the diameter of the
head 595 of the bone screw 514 is greater than the width of the
slot 587, thereby further stabilizing the transport portion 114 and
limiting its ability to displace in along an x-axis. Turning to
FIG. 22, the transport portion 114 itself is limited by the support
member 503 so that the transport portion 114 does not translate
(drift) substantially in the positive x direction. The transport
portion 114 may also be limited by the head 595 of the bone screw
514 so that the transport portion 114 does not translate
substantially in the negative x direction, either during
longitudinal adjustment of the transport portion, or when at
rest.
[0054] In bone transport or limb lengthening, the transport or
distraction lengths can vary greatly from procedure to procedure
and/or patient to patient. In bone transport procedures, the
transport length may be a function of the length of bone that is
missing and the length of the transport portion 114 created during
surgery. An adjustable-length implant kit 600 (shown in in FIG. 23)
may be configured to allow the user to create an adjustable-length
implant, for example the adjustable-length implant 601 of FIG. 24,
tailored to the particular transport length or distraction length
of the patient to be treated. The adjustable-length implant kit 600
may include a base actuator 605 comprising a housing 604, a base
rod 602, and one or more rod extensions (e.g., rod extensions 606,
608, 610). The base rod 602 may be telescopically moveable within
the housing 604 (as described elsewhere herein) and has an
internally threaded portion 612. Each of the rod extensions 606,
608, 610 has an externally threaded portion 614 which is configured
to be screwed into the internally threaded portion 612 of the base
rod 602. A user (e.g., surgeon or physician) may choose the
appropriate rod extension 606, 608, 610 for the particular patient.
For example, rod extension 606 may be chosen if a relatively long
transport or distraction length is required, whereas rod extension
610 may be chosen if a relatively short transport or distraction
length is required. It will be understood that the rod extensions
606, 608, 610 may have varying properties, including but not
limited to: numbers of anchor holes 616; axial orientation of
anchor holes 616; anchor hole diameters (e.g., for use with bone
screw of different diameters); etc. The rod extensions 606, 608,
610 may include a hollow portion. For example, an interior passage
618 may pass through the end of the rod extension 610 (or any other
rod extension 606, 608) which has the externally threaded portion
614. In that way, the lead screw (not shown) may extend into the
interior passage 618, e.g., if the lead screw extends from the
interior of the base rod 602. In some embodiments, the lead screw
may be extendible (i.e., may have an end that may be augmented by
an extension portion of lead screw). The internally threaded
portion 612 and the externally threaded portion 614 may each have a
locking feature, incorporating, for example, a latch, snap, detent,
hook, or friction fit feature that secures the rod extension 606,
608, 610 and the base rod 602 when the rod extension 606, 608, 610
to the base rod 602 are coupled (e.g., screwed together). In an
alternative embodiment, the base rod 602 may include an externally
threaded portion and the rod extensions 606, 608, 610 may each
include an internally threaded portion. The adjustable-length
implant kit 600 of FIGS. 23-24 may be used in standard limb
lengthening procedures, or in bone transport procedures, including,
but not limited to, those described herein. By having the
adjustable-length implant kit 600 available during surgery, a
surgeon or physician may more easily select and/or construct a
device most appropriate for the patient being treated. In some
embodiments, the rod extensions 606, 608, 610 may be easily
sterilized (e.g., steam sterilization/autoclave, gas) which may
lower the cost of the procedure, especially if the base actuator
605 must be supplied sterile by the supplier. In use, a surgeon or
physician (which should be understood to include any other medical
professional, such as those under the control or direction of a
surgeon or physician) may attach one rod extension, and remove it
and replace it with another, if it does not fit the patient
properly. In alternative embodiments and methods, the support
member 403, 503 may be replaced by an external fixator comprising a
base which is configured to be located external to the patient, a
first pin configured to attach at one end to the base and at
another end to be coupled to the first portion of the bone, and a
second pin configured to attach at one end to the base and at
another end be coupled to the second portion of the bone.
[0055] Although this invention has been disclosed in the context of
certain preferred embodiments and examples, it will be understood
by those skilled in the art that the present invention extends
beyond the specifically disclosed embodiments to other alternative
embodiments and/or uses of the invention and obvious modifications
and equivalents thereof. In addition, while a number of variations
of the invention have been shown and described in detail, other
modifications, which are within the scope of this invention, will
be readily apparent to those of skill in the art based upon this
disclosure. It is also contemplated that various combinations or
sub-combinations of the specific features and aspects of the
embodiments may be made and still fall within the scope of the
invention. Accordingly, it should be understood that various
features and aspects of the disclosed embodiments can be combined
with or substituted for one another in order to form varying modes
of the disclosed invention. Thus, it is intended that the scope of
the present invention herein disclosed should not be limited by the
particular disclosed embodiments described above, but should be
determined only by a fair reading of the claims that follow.
[0056] Similarly, this method of disclosure, is not to be
interpreted as reflecting an intention that any claim require more
features than are expressly recited in that claim. Rather, as the
following claims reflect, inventive aspects lie in a combination of
fewer than all features of any single foregoing disclosed
embodiment. Thus, the claims following the Detailed Description are
hereby expressly incorporated into this Detailed Description, with
each claim standing on its own as a separate embodiment.
* * * * *