U.S. patent application number 14/995503 was filed with the patent office on 2016-07-21 for external adjustment device for distraction device.
The applicant listed for this patent is ELLIPSE TECHNOLOGIES, INC.. Invention is credited to Arvin Chang, Kevin Oberkramer, Timothy John Payne, Scott Pool.
Application Number | 20160206353 14/995503 |
Document ID | / |
Family ID | 45400216 |
Filed Date | 2016-07-21 |
United States Patent
Application |
20160206353 |
Kind Code |
A1 |
Payne; Timothy John ; et
al. |
July 21, 2016 |
EXTERNAL ADJUSTMENT DEVICE FOR DISTRACTION DEVICE
Abstract
An external adjustment device includes at least one permanent
magnet configured for rotation about an axis with a first handle
extending linearly at a first end of the device and a second handle
at a second end of the device, the second handle extending in a
direction substantially off axis to the first handle. The external
adjustment device further includes a motor mounted inside the first
handle and a first button located in the proximity to one of the
first handle or the second handle, the first button configured to
be operated by the thumb of a hand that grips the one of the first
handle or second handle. The first button is configured to actuate
the motor causing the at least one permanent magnet to rotate about
the axis in a first direction.
Inventors: |
Payne; Timothy John; (Santa
Ana, CA) ; Oberkramer; Kevin; (Placentia, CA)
; Pool; Scott; (Laguna Hills, CA) ; Chang;
Arvin; (Yorba Linda, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ELLIPSE TECHNOLOGIES, INC. |
Aliso Viejo |
CA |
US |
|
|
Family ID: |
45400216 |
Appl. No.: |
14/995503 |
Filed: |
January 14, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13172598 |
Jun 29, 2011 |
9248043 |
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14995503 |
|
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61360353 |
Jun 30, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 17/7216 20130101;
A61B 2017/00411 20130101; A61B 2017/00876 20130101; A61B 2017/681
20130101; A61B 17/7074 20130101; A61F 5/02 20130101 |
International
Class: |
A61B 17/70 20060101
A61B017/70; A61B 17/72 20060101 A61B017/72 |
Claims
1. An external adjustment device comprising: at least one permanent
magnet configured for rotation about an axis; a first handle
extending linearly at a first end of the device; a second handle
disposed at second end of the device, the second handle extending
in a direction that angled relative to the first handle; a motor
mounted inside the first handle; a first button located in the
proximity to one of the first handle or the second handle, the
first button configured to be operated by the thumb of a hand that
grips the one of the first handle or second handle; wherein the
first button is configured to actuate the motor causing the at
least one permanent magnet to rotate about the axis in a first
direction.
2. The external adjustment device of claim 1, further comprising
second button located in proximity to the first button, the second
button configured to actuate the motor causing the at least one
permanent magnet to rotate about the axis in a second
direction.
3. The external adjustment device of claim 1, further comprising a
control panel having a plurality of buttons and a display.
4. The external adjustment device of claim 3, wherein the plurality
of buttons comprise a target distraction increase button and a
target distraction decrease button.
5. The external adjustment device claim 1, wherein the at least one
permanent magnet is rotatably disposed in a housing having a window
therein and wherein the at least one permanent magnet contains a
plurality of stripes visible via the window.
6. The external adjustment device of claim 1, wherein the at least
one permanent magnet comprises two permanent magnets.
7. The external adjustment device of claim 1, further comprising an
orientation image on the first handle.
8. The external adjustment device of claim 1, wherein one of the
first handle or second handle comprises a looped shape.
9. The external adjustment device of claim 3, wherein the plurality
of buttons comprises at least one touch key.
10. The external adjustment device of claim 1, further comprising
at least one magnetic sensor configured to sense a change in a
magnetic field of the at least one permanent magnet and to output a
voltage based at least partially on strength of the magnetic
field.
11. An external adjustment device comprising: at least one
permanent magnet configured for rotation about an axis; a motor
configured for rotating the at least one permanent magnet about the
axis; a first handle extending linearly at a first end of the
device; a second handle disposed at a second end of the device, the
second handle extending in a direction that is substantially off
axis with respect to the first handle, wherein one of the first and
second handle comprises a looped shape; a first drive button
located in the proximity to one of the first handle or the second
handle, the first drive button configured to be operated by the
thumb of a hand that grips the one of the first handle or second
handle; and wherein the first drive button is configured to actuate
the motor causing the at least one permanent magnet to rotate about
the axis in a first direction.
12. The external adjustment device of claim 11, further comprising
at least one magnetic sensor configured to sense a change in a
magnetic field of the at least one permanent magnet and output a
voltage based at least in part on a strength of the magnetic
field.
13. The external adjustment device of claim 12, further comprising
a second magnetic sensor configured to sense a change in a magnetic
field of the at least one permanent magnet and output a voltage
based at least in part on a strength of the magnetic field.
14. The external adjustment device of claim 13, further comprising
a processor configured to compare respective output voltages from
the first and second magnetic sensors.
15. The external adjustment device of claim 13, further comprising
a second button located in proximity to the first button, the
second button configured to actuate the motor causing the at least
one permanent magnet to rotate about the axis in a second
direction.
16. The external adjustment device of claim 11, further comprising:
a distraction device configured for implantation within a subject;
and a processor disposed in the external adjustment device and
configured to actuate the motor causing the at least one permanent
magnet to rotate about the axis in a first direction when the
distraction device is implanted an antegrade orientation and in a
second direction when the distraction device is implanted in a
retrograde orientation.
17. The external adjustment device of claim 16, further comprising
a read/write RFID chip disposed on the distraction device.
18. The external adjustment device of claim 17, wherein the
external adjustment device comprises an antenna configured to
receive and transmit data to the read/write RFID chip.
19. The external adjustment device of claim 18, wherein the data
comprises the orientation of the distraction device.
20. The external adjustment device of claim 16, wherein the
processor is configured to receive instructions from a user as the
antegrade or retrograde orientation of the distraction device.
Description
RELATED APPLICATION
[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.
FIELD OF THE INVENTION
[0002] The field of the invention generally relates to medical
devices for treating disorders of the skeletal system.
BACKGROUND
[0003] Scoliosis is a general term for the sideways (lateral)
curving of the spine, usually in the thoracic or thoracolumbar
region. Scoliosis is commonly broken up into different treatment
groups, Adolescent Idiopathic Scoliosis, Early Onset Scoliosis and
Adult Scoliosis.
[0004] Adolescent Idiopathic Scoliosis (AIS) typically affects
children between ages 10 and 16, and becomes most severe during
growth spurts that occur as the body is developing. One to two
percent of children between ages 10 and 16 have some amount of
scoliosis. Of every 1000 children, two to five develop curves that
are serious enough to require treatment. The degree of scoliosis is
typically described by the Cobb angle, which is determined, usually
from x-ray images, by taking the most tilted vertebrae above and
below the apex of the curved portion and measuring the angle
between intersecting lines drawn perpendicular to the top of the
top vertebrae and the bottom of the bottom. The term idiopathic
refers to the fact that the exact cause of this curvature is
unknown. Some have speculated that scoliosis occurs when, during
rapid growth phases, the ligamentum flavum of the spine is too
tight and hinders symmetric growth of the spine. For example, as
the anterior portion of the spine elongates faster than the
posterior portion, the thoracic spine begins to straighten, until
it curves laterally, often with an accompanying rotation. In more
severe cases, this rotation actually creates a noticeable
deformity, wherein one shoulder is lower than the other. Currently,
many school districts perform external visual assessment of spines,
for example in, all fifth grade students. For those students in
whom an "S" shape or "C" shape is identified, instead of an "I"
shape, a recommendation is given to have the spine examined by a
physician, and commonly followed-up with periodic spinal
x-rays.
[0005] Typically, patients with a Cobb angle of 20.degree. or less
are not treated, but are continually followed up, often with
subsequent x-rays. Patients with a Cobb angle of 40.degree. or
greater are usually recommended for fusion surgery. It should be
noted that many patients do not receive this spinal assessment, for
numerous reasons. Many school districts do not perform this
assessment, and many children do not regularly visit a physician,
so often, the curve progresses rapidly and severely. There is a
large population of grown adults with untreated scoliosis, in
extreme cases with a Cobb angle as high as or greater than
90.degree.. Many of these adults, though, do not have pain
associated with this deformity, and live relatively normal lives,
though oftentimes with restricted mobility and motion. In AIS, the
ratio of females to males for curves under 10.degree. is about one
to one, however, at angles above 30.degree., females outnumber
males by as much as eight to one. Fusion surgery can be performed
on the AIS patients or on adult scoliosis patients. In a typical
posterior fusion surgery, an incision is made down the length of
the back and Titanium or stainless steel straightening rods are
placed along the curved portion. These rods are typically secured
to the vertebral bodies, for example with hooks or bone screws, or
more specifically pedicle screws, in a manner that allows the spine
to be straightened. Usually, at the section desired for fusion, the
intervertebral disks are removed and bone graft material is placed
to create the fusion. If this is autologous material, the bone is
harvested from a hip via a separate incision.
[0006] Alternatively, the fusion surgery may be performed
anteriorly. A lateral and anterior incision is made for access.
Usually, one of the lungs is deflated in order to allow access to
the spine from this anterior approach. In a less-invasive version
of the anterior procedure, instead of the single long incision,
approximately five incisions, each about three to four cm long are
made in several of the intercostal spaces (between the ribs) on one
side of the patient. In one version of this minimally invasive
surgery, tethers and bone screws are placed and are secured to the
vertebra on the anterior convex portion of the curve. Currently,
clinical trials are being performed which use staples in place of
the tether/screw combination. One advantage of this surgery in
comparison with the posterior approach is that the scars from the
incisions are not as dramatic, though they are still located in a
visible area, when a bathing suit, for example, is worn. The
staples have had some difficulty in the clinical trials. The
staples tend to pull out of the bone when a critical stress level
is reached.
[0007] In some cases, after surgery, the patient will wear a
protective brace for a few months as the fusing process occurs.
Once the patient reaches spinal maturity, it is difficult to remove
the rods and associated hardware in a subsequent surgery, because
the fusion of the vertebra usually incorporates the rods
themselves. Standard practice is to leave this implant in for life.
With either of these two surgical methods, after fusion, the
patient's spine is now straight, but depending on how many vertebra
were fused, there are often limitations in the degree of
flexibility, both in bending and twisting. As these fused patients
mature, the fused section can impart large stresses on the adjacent
non-fused vertebra, and often, other problems including pain can
occur in these areas, sometimes necessitating further surgery. This
tends to be in the lumbar portion of the spine that is prone to
problems in aging patients. Many physicians are now interested in
fusionless surgery for scoliosis, which may be able to eliminate
some of the drawbacks of fusion.
[0008] One group of patients in which the spine is especially
dynamic is the subset known as Early Onset Scoliosis (EOS), which
typically occurs in children before the age of five, and more often
in boys than in girls. This is a more rare condition, occurring in
only about one or two out of 10,000 children, but can be severe,
sometimes affecting the normal development of organs. Because of
the fact that the spines of these children will still grow a large
amount after treatment, non-fusion distraction devices known as
growing rods and a device known as the VEPTR--Vertical Expandable
Prosthetic Titanium Rib ("Titanium Rib") have been developed. These
devices are typically adjusted approximately every six months, to
match the child's growth, until the child is at least eight years
old, sometimes until they are 15 years old. Each adjustment
requires a surgical incision to access the adjustable portion of
the device. Because the patients may receive the device at an age
as early as six months old, this treatment requires a large number
of surgeries. Because of the multiple surgeries, these patients
have a rather high preponderance of infection.
[0009] Returning to the AIS patients, the treatment methodology for
those with a Cobb angle between 20.degree. and 40.degree. is quite
controversial. Many physicians proscribe a brace (for example, the
Boston Brace), that the patient must wear on their body and under
their clothes 18 to 23 hours a day until they become skeletally
mature, for example to age 16. Because these patients are all
passing through their socially demanding adolescent years, it is
quite a serious prospect to be forced with the choice of either
wearing a somewhat bulky brace that covers most of the upper body,
having fusion surgery that may leave large scars and also limit
motion, or doing nothing and running the risk of becoming
disfigured and possibly disabled. It is commonly known that many
patients have at times hidden their braces, for example, in a bush
outside of school, in order to escape any related embarrassment.
The patient compliance with brace wearing has been so problematic
that there have been special braces constructed which sense the
body of the patient, and keep track of the amount of time per day
that the brace is worn. Patients have even been known to place
objects into unworn braces of this type in order to fool the
sensor. Coupled with the inconsistent patient compliance with brace
usage, is a feeling by many physicians that braces, even if used
properly, are not at all effective at curing scoliosis. These
physicians may agree that bracing can possibly slow down or even
temporarily stop curve (Cobb angle) progression, but they have
noted that as soon as the treatment period ends and the brace is no
longer worn, often the scoliosis rapidly progresses, to a Cobb
angle even more severe than it was at the beginning of treatment.
Some say the reason for the supposed ineffectiveness of the brace
is that it works only on a portion of the torso, and not on the
entire spine. Currently a prospective, randomized 500 patient
clinical trial known as BrAlST (Bracing in Adolescent Idiopathic
Scoliosis Trial) is enrolling patients, 50% of whom will be treated
with the brace and 50% of who will simply be watched. The Cobb
angle data will be measured continually up until skeletal maturity,
or until a Cobb angle of 50.degree. is reached, at which time the
patient will likely undergo surgery. Many physicians feel that the
BrAIST trial will show that braces are completely ineffective. If
this is the case, the quandary about what to do with AIS patients
who have a Cobb angle of between 20.degree. and 40.degree. will
only become more pronounced. It should be noted that the
"20.degree. to 40.degree." patient population is as much as ten
times larger than the "40.degree. and greater" patient
population.
[0010] Distraction osteogenesis, also known as distraction
callotasis and osteodistraction has been used successfully to
lengthen long bones of the body. Typically, the bone, if not
already fractured, is purposely fractured by means of a
corticotomy, and the two segments of bone are dually distracted
apart, which allows new bone to form in the gap. If the distraction
rate is too high, there is a risk of nonunion, if the rate is too
low, there is a risk that the two segments will completely fuse to
each other before the distraction period is complete. When the
desired length of the bone is achieved using this process, the bone
is allowed to consolidate. Distraction osteogenesis applications
are mainly focused on the growth of the femur or tibia, but may
also include the humerus, the jaw bone (micrognathia), or other
bones. The reasons for lengthening or growing bones are multifold,
the applications including, but not limited to: post osteosarcoma
bone cancer; cosmetic lengthening (both legs-femur and/or tibia) in
short stature or dwarfism/achondroplasia; lengthening of one limb
to match the other (congenital, post-trauma post-skeletal disorder,
prosthetic knee joint), nonunions.
[0011] Distraction osteogenesis using external fixators has been
done for many years, but the external fixator can be unwieldy for
the patient. It can also be painful, and the patient is subject to
the risk of pin track infections, joint stiffness, loss of
appetite, depression, cartilage damage and other side effects.
Having the external fixator in place also delays the beginning of
rehabilitation.
[0012] In response to the shortcomings of external fixator
distraction, intramedullary distraction nails have been surgically
implanted which are contained entirely within the bone. Some are
automatically lengthened via repeated rotation of the patient's
limb. This can sometimes be painful to the patient, and can often
proceed in an uncontrolled fashion. This therefore makes it
difficult to follow the strict daily or weekly lengthening regime
that avoids nonunion (if too fast) or early consolidation (if too
slow). Lower limb distraction rates are on the order of one mm per
day. Other intramedullary nails have been developed which have an
implanted motor and are remotely controlled by an antenna. These
devices are therefore designed to be lengthened in a controlled
manner, but due to their complexity, may not be manufacturable as
an affordable product. Others have proposed intramedullary
distractors containing an implanted magnet, which allows the
distraction to be driven electromagnetically by an external stator.
Because of the complexity and size of the external stator, this
technology has not been reduced to a simple and cost-effective
device that can be taken home, to allow patients to do daily
lengthenings.
SUMMARY
[0013] In one embodiment, an external adjustment device includes at
least one permanent magnet configured for rotation about an axis.
The external adjustment device further includes a first handle
extending linearly at a first end of the device and a second handle
disposed at a second end of the device, the second handle extending
in a direction that is angled relative to the first handle. The
external adjustment device includes a motor mounted inside the
first handle and a first button located in the proximity to one of
the first handle or the second handle, the first button configured
to be operated by the thumb of a hand that grips the one of the
first handle or second handle. The first button is configured to
actuate the motor causing the at least one permanent magnet to
rotate about the axis in a first direction.
[0014] In another embodiment, an external adjustment device
includes at least one permanent magnet configured for rotation
about an axis and a motor configured for rotating the at least one
permanent magnet about the axis. The external adjustment device
includes a first handle extending linearly at a first end of the
device and a second handle disposed at a second end of the device,
the second handle extending in a direction that is substantially
off axis with respect to the first handle, wherein one of the first
and second handle comprises a looped shape. A first drive button is
located in the proximity to one of the first handle or the second
handle, the first drive button configured to be operated by the
thumb of a hand that, grips the one of the first handle or second
handle. The first drive button is configured to actuate the motor
causing the at least one permanent magnet to rotate about the axis
in a first direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 illustrates an external adjustment device configured
to operate a distraction device.
[0016] FIG. 2 illustrates a detailed view of the display and
control panel of the external adjustment device.
[0017] FIG. 3 illustrates the lower or underside surfaces of the
external adjustment device.
[0018] FIG. 4 illustrates a sectional view of the external
adjustment device taken along line 4-4 of FIG. 3.
[0019] FIG. 5 illustrates a sectional view of the external
adjustment device taken along line 5-5 of FIG. 3.
[0020] FIG. 6 schematically illustrates the orientation of the
magnets of the external adjustment device while driving an
implanted magnet of a distraction device.
[0021] FIG. 7 illustrates various sensors connected to a printed
circuit board of the external adjustment device.
[0022] FIG. 8 illustrates a view of the clock positions of Hall
effect sensors on the printed circuit board of the external
adjustment device.
[0023] FIG. 9A illustrates a particular configuration of Hall
effect sensors according to one embodiment.
[0024] FIG. 9B illustrates output voltage of the Hall effect
sensors of the configuration in FIG. 9A.
[0025] FIG. 9C illustrates the configuration of FIG. 9A, with the
magnets in a nonsynchronous condition.
[0026] FIG. 9D illustrates the output voltage of the Hall effect
sensors of the configuration in FIG. 9C.
[0027] FIG. 10A illustrates a particular configuration of Hall
effect sensors according to another embodiment.
[0028] FIG. 10B illustrates the output voltage of the Hall effect
sensors of the configuration in FIG. 10A.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0029] FIGS. 1-3 illustrate an external adjustment device 700 that
is configured for adjusting a distraction device 1000. The
distraction device 1000 may include any number of distraction
devices such, as those disclosed in U.S. patent application Ser.
Nos. 12/121,355, 12/250,442, 12/391,109, 11/172,678 which are
incorporated by reference herein. The distraction device 1000
generally includes a rotationally mounted, internal permanent
magnet 1010 that rotates in response to the magnetic field applied
by the external adjustment device 700. Rotation of the magnet 1010
in one direction effectuates distraction while rotation of the
magnet 1010 in the opposing direction effectuates retraction.
external adjustment device 700 may be powered by a rechargeable
battery or by a power cord 711. The external adjustment device 700
includes a first handle 702 and a second handle 704. The second
handle 704 is in a looped shape, and can be used to carry the
external adjustment device 700. The second handle 704 can also be
used to steady the external adjustment device 700 during use.
Generally, the first handle 702 extends linearly from a first end
of the external adjustment device 700 while the second handle 704
is located at a second end of the external adjustment device 700
and extends substantially off axis or is angled with respect to the
first handle 702. In one embodiment, the second handle 704 may be
oriented substantially perpendicular relative to the first handle
702 although other
[0030] The first handle 702 contains the motor 705 that drives a
first external magnet 706 and a second external magnet 708 as best
seen in FIG. 3, via gearing, belts and the like. On the first
handle 702 is an optional orientation image 804 comprising a body
outline 806 and an optional orientation arrow 808 that shows the
correct direction to place the external adjustment device 700 on
the patient's body, so that the distraction device is operated in
the correct direction. While holding the first handle 702, the
operator presses with his thumb the distraction button 722, which
has a distraction symbol 717, and is a first color, for example,
green. This distracts the distraction device 1000. If the
distraction device 1000 is over-distracted and it is desired to
retract, or to lessen the distract of the device 1000, the operator
presses his thumb retraction button 724 which has a retraction
symbol 719.
[0031] Distraction turns the magnets 706, 708 one direction and
retraction turns the magnets 706, 708 in the opposite direction.
Magnets 706, 708 have stripes 809 that can be seen in window 811.
This allows easy identification of whether the magnets 706, 708 are
stationary or turning, and in which direction they are turning.
This allows quick trouble shooting by the operator of the device.
The operator can determine the point on the patient where the
magnet of the distraction device 1000 is implanted, and can then
put the external adjustment device 700 in correct location with
respect to the distraction device 1000, by marking the
corresponding portion of the skin of the patient, and then viewing
this spot through the alignment window 716 of the external
adjustment device 700.
[0032] A control panel 812 includes several buttons 814, 816, 818
820 and a display 715. The buttons 814, 816, 818, 820 are soft
keys, and able to be programmed for an array of different
functions. In one configuration, the buttons 814, 816, 818, 820
have corresponding legends which appear in the display. To set the
length of distraction to be performed on the distraction device
1000, the target distraction length 830 is adjusted using an
increase button 814 and a decrease button 816. The legend with a
green plus sign graphic 822 corresponds to the increase button 814
and the legend with a red negative sign graphic 824 corresponds to
the decrease button 816. It should be understood that mention
herein to a specific color used for a particular feature should be
viewed as illustrative. Other colors besides those specifically
recited herein may be used in connection with the inventive
concepts described herein. Each time the increase button 814 is
depressed, it causes the target distraction length 830 to increase
0.1 mm. Each time the decrease button 816 is depressed it causes
the target distraction length 830 to decrease 0.1 mm. Of course,
other decrements besides 0.1 mm could also be used. When the
desired target distraction length 830 is displayed, and the
external adjustment device 700 is correctly placed on the patient,
the operator then holds down the distraction button 722 and the
External Distraction Device 700 operates, turning the magnets 706,
708, until the target distraction length 830 is achieved. Following
this, the external adjustment device 700 stops. During the
distraction process, the actual distraction length 832 is
displayed, starting at 0.0 mm and increasing until the target
distraction length 830 is achieved. As the actual distraction
length 832 increases, a distraction progress graphic 834 is
displayed. For example a light colored box 833 that fills with a
dark color from the left to the right. In FIG. 2, the target
distraction length 830 is 3.5 mm, and 2.1 mm of distraction has
occurred. 60% of the box 833 of the distraction progress graphic
834 is displayed. A reset button 818 corresponding to a reset
graphic 826 can be pressed to reset one or both of the numbers back
to zero. An additional button 820 can be assigned for other
functions (help, data, etc.). This button can have its own
corresponding graphic 828. Alternatively, a touch screen can be
used, for example capacitive or resistive touch keys. In this
embodiment, the graphics/legends 822, 824, 826, 828 may also be
touch keys, replacing or augmenting the buttons 814, 816, 818, 820.
In one particular embodiment, touch keys at 822, 824, 826, 828
perform the functions of buttons 814, 816, 818, 820 respectively,
and the buttons 814, 816, 818, 820 are eliminated.
[0033] The two handles 702, 704 can be held in several ways. For
example the first handle 702 can be held with palm facing up while
trying to find the location on the patient of the implanted magnet
of the distraction device 1000. The fingers are wrapped around the
handle 702 and the fingertips or mid-points of the four fingers
press up slightly on the handle 702, balancing it somewhat. This
allows a very sensitive feel that allows the magnetic field between
the magnet in the distraction device 1000 and the magnets 706, 708
of the external adjustment device 700 to be more obvious. During
the distraction of the patient, the first handle 702 may be held
with the palm facing down, allowing the operator to push the device
down firmly onto the patient, to minimize the distance between the
magnets 706, 708 of the external adjustment device and the magnet
1010 of the distraction device 1000, thus maximizing the torque
coupling. This is especially appropriate if the patient is large or
somewhat obese. The second handle 704 may be held with the palm up
or the palm down during the magnet sensing operation and the
distraction operation, depending on the preference of the
operator.
[0034] FIG. 3 illustrates the underside or lower surface of the
external adjustment device 700. At the bottom of the external
adjustment device 700, the contact surface 836 may be made of
material of a soft durometer, such as elastomeric material, for
example PEBAX.RTM. or Polyurethane. This allows for anti-shock to
protect the device 700 if it is dropped. Also, if placing the
device on patient's bare skin, materials of this nature do not pull
heat away from patient as quickly, and so they "don't feel as cold"
as hard plastic or metal. The handles 702, 704 may also have
similar material covering them, in order to act as non-slip
grips.
[0035] FIG. 3 also illustrates child friendly graphics 837,
including the option of a smiley face. Alternatively this could be
an animal face, such as a teddy bear, a horsey or a bunny rabbit. A
set of multiple faces can be removable and interchangeable to match
the likes of various young patients. In addition, the location of
the faces on the underside of the device, allows the operator to
show the faces to a younger child, but keep it hidden from an older
child, who may not be so amused. Alternatively, sock puppets or
decorative covers featuring human, animal or other characters may
be produced so that the device may be thinly covered with them,
without affecting the operation of the device, but additionally,
the puppets or covers may be given to the young patient after a
distraction procedure is performed. It is expected that this can
help keep a young child more interested in returning to future
procedures.
[0036] FIGS. 4 and 5 are sectional views that illustrate the
internal components of the external adjustment device 700 taken
along various centerlines. FIG. 4 is a sectional view of the
external adjustment device 700 taken along the line 4-4 of FIG. 3.
FIG. 5 is a sectional view of the external adjustment device 700
taken along the line 5-5 of FIG. 3. The external adjustment device
700 comprises a first housing 868, a second housing 838 and a
central magnet section 725. First handle 702 and second handle 704
include grip 703 (shown on first handle 702). Grip 703 may be made
of an elastomeric material and may have a soft feel when gripped by
the hand. The material may also have a tacky feel, in order to aid
firm gripping. Power is supplied via power cord 711, which is held
to second housing 838 with a strain relief 844. Wires 727 connect
various electronic components including motor 840 which rotates
magnets 706, 708 via gear box 842, output gear 848, center gear 870
respectively, center gear 870 rotating two magnet gears 852, one on
each magnet 706, 708 (one such gear 852 is illustrated in FIG. 5).
Output gear 848 is attached to motor output via coupling 850, and
both motor 840 and output gear 848 are secured to second housing
838 via mount 846. Magnets 706, 708 are held within magnet cups
862. Magnets and gears are attached to bearings 872, 874, 856, 858,
which aid in low friction rotation. Motor 840 is controlled by
motor printed circuit board (PCB) 854, while the display is
controlled by display printed circuit board (PCB) 866 (FIG. 4).
Display PCB 866 is attached to frame 864.
[0037] FIG. 6 illustrates the orientation of poles of the first and
second external magnets 706, 708 and the implanted magnet 1010 of
the distraction device 1000 during a distraction procedure. For the
sake of description, the orientations will be described in relation
to the numbers on a clock. First external magnet 706 is turned (by
gearing, belts, etc.) synchronously with second external magnet 708
so that north pole 902 of first external magnet 706 is pointing in
the twelve o'clock position when the south pole 904 of the second
external magnet 708 is pointing in the twelve o'clock position. At
this orientation, therefore, the south pole 906 of the first
external magnet 706 is pointing is pointing in the six o'clock
position while the north pole 908 of the second external magnet 708
is pointing in the six o'clock position. Both first external magnet
706 and second external magnet 708 are turned in a first direction
as illustrated by respective arrows 914, 916. The rotating magnetic
fields apply a torque on the implanted magnet 1010, causing it to
rotate in a second direction as illustrated by arrow 918. Exemplary
orientation of the north pole 1012 and south pole 1014 of the
implanted magnet 1010 during torque delivery are shown in FIG. 6.
When the first and second external magnets 706, 708 are turned in
the opposite direction from that shown, the implanted magnet 1010
will be turned in the opposite direction from that shown. The
orientation of the first external magnet 706 and the second
external magnet 708 in relation to each other serves to optimize
the torque delivery to the implanted magnet 1010. During operation
of the external adjustment device 700, it is often difficult to
confirm that the two external magnets 706, 708 are being
synchronously driven as desired. Turning to FIGS. 7 and 8, in order
to ensure that the external adjustment device 700 is working
properly, the motor printed circuit board 854 comprises one or more
encoder systems, for example photointerrupters 920, 922 and/or Hall
effect sensors 924, 926, 928, 930, 932, 934, 936, 938.
Photointerrupters 920, 922 each comprise an emitter and a detector.
A radially striped ring 940 may be attached to one or both of the
external magnets 706, 708 allowing the photointerrupters to
optically encode angular motion. Light 921, 923 is schematically
illustrated between the radially striped ring 940 and
photointerrupters 920, 922.
[0038] Independently, Hall effect sensors 924, 926, 928, 930, 932,
934, 936, 938 may be used as non-optical encoders to track rotation
of one or both of the external magnets 706, 708. While eight (8)
such Hall effect sensors are illustrated in FIG. 7 it should be
understood that fewer or more such sensors may be employed. The
Hall effect sensors are connected to the motor printed circuit
board 854 at locations that allow the Hall effect sensors to sense
the magnetic field changes as the external magnets 706, 708 rotate.
Each Hall effect sensor 924, 926, 928, 930, 932, 934, 936, 938
outputs a voltage that corresponds to increases or decreases in the
magnetic field. FIG. 9A indicates one basic arrangement of Hall
effect sensors relative to sensors 924, 938. A first Hall effect
sensor 924 is located at nine o'clock in relation to first external
magnet 706. A second Hall effect sensor 938 is located at three
o'clock in relation to second external magnet 708. As the magnets
706, 708 rotate correctly in synchronous motion, the first voltage
output 940 of first Hall effect sensor 924 and second voltage
output 942 of second Hall effect sensor have the same pattern, as
seen in FIG. 9B, which graphs voltage for a full rotation cycle of
the external magnets 706, 708. The graph indicates a sinusoidal
variance of the output voltage, but the clipped peaks are due to
saturation of the signal. Even if Hall effect sensors used in the
design cause this effect, there is still enough signal to compare
the first voltage output 940 and the second voltage output 942 over
time. If either of the two Hall effect sensors 924, 938 does not
output a sinusoidal signal during the operation or the external
adjustment device 700, this demonstrates that the corresponding
external magnet has stopped rotating, for example due to adhesive
failure, gear disengagement, etc. FIG. 9C illustrates a condition
in which both the external magnets 706, 708 are rotating at the
same approximate angular speed, but the north poles 902, 908 are
not correctly synchronized. Because of this, the first voltage
output 940 and second voltage output 942 are now out-of-phase, and
exhibit a phase shift (o). These signals are processed by a
processor 915 and an error warning is displayed on the display 715
of the external adjustment device 700 so that the device may be
resynchronized.
[0039] If independent stepper motors are used, the
resynchronization process may simply be one of reprogramming, but
if the two external magnets 706, 708 are coupled together, by
gearing or belt for example, then a mechanical rework may be
required. An alternative to the Hall effect sensor configuration of
FIG. 9A is illustrated in FIG. 10A. In this embodiment, a third
Hall effect sensor 928 is located at twelve o'clock in relation to
the first external magnet 706 and a fourth Hall effect sensor 934
is located at twelve o'clock in relation to the second external
magnet 708. With this configuration, the north pole 902 of the
first external magnet 706 should be pointing towards the third Hall
effect sensor 928 when the south pole 904 of the second external
magnet 708 is pointing towards the fourth Hall effect sensor 934.
With this arrangement, the third Hall effect sensor 928 outputs a
third output voltage 944 and the fourth Hall effect sensor 934
outputs a fourth output voltage 946 (FIG. 10B). The third output
voltage 944 is by design out of phase with the fourth output
voltage 946. An advantage of the Hall effect sensor configuration
of FIG. 9A is that the each sensor has a larger distance between it
and the opposite magnet, for example first Hall effect sensor 924
in comparison to second external magnet 708, so that there is less
possibility of interference. An advantage to the Hall effect sensor
configuration of FIG. 10A is that it may be possible to make a more
compact external adjustment device 700 (less width). The
out-of-phase pattern of FIG. 10B can also be analyzed to confirm
magnet synchronicity.
[0040] Returning to FIGS. 7 and 8, additional Hall effect sensors
926, 930, 932, 936 are shown. These additional sensors allow
additional precision to the rotation angle feedback of the external
magnets 706, 708 of the external adjustment device 700. Again, the
particular number and orientation of Hall effect sensors may vary.
In place of the Hall effect sensors, magnetoresistive encoders may
also be used.
[0041] In still another embodiment, additional information may be
processed by processor 915 and may be displayed on display 715. For
example, distractions using the external adjustment device 700 may
be performed in a doctor's office by medical personnel, or by
patients or members of patient's family in the home. In either
case, it may be desirable to store information from each
distraction session that can be accessed later. For example, the
exact date and time of each distraction, and the amount of
distraction attempted and the amount of distraction obtained. This
information may be stored in the processor 915 or in one or more
memory modules (not shown) associated with the processor 915. In
addition, the physician may be able to input distraction length
limits, for example the maximum amount that cart be distracted at
each session, the maximum amount per day, the maximum amount per
week, etc. The physician may input these limits by using a secure
entry using the keys or buttons of the device, that the patient
will not be able to access.
[0042] Returning to FIG. 1, in some patients, it may be desired to
place a first end 1018 of the distraction device 1000 proximally in
the patient, or towards the head, and second end 1020 of the
distraction device 1000 distally, or towards the feet. This
orientation of the distraction device 1000 may be termed antegrade.
In other patients, it may be desired to orient the distraction
device 1000 with the second end 1020 proximally in the patient and
the first end 1018 distally. In this case, the orientation of the
distraction device 1000 may be termed retrograde. In a distraction
device 1000 in which the magnet 1010 rotates in order to turn a
screw within a nut, the orientation of the distraction device 1000
being either antegrade or retrograde in patient could mean that the
external adjustment device 700 would have to be placed in
accordance with the orientation image 804 when the distraction
device 1000 is placed antegrade, but placed the opposite of the
orientation image 804 when the distraction device 1000 is placed
retrograde. Alternatively, software may be programmed so that the
processor 915 recognizes whether the distraction device 1000 has
been implanted antegrade or retrograde, and then turns the magnets
706, 708 in the appropriate direction when the distraction button
722 is placed.
[0043] For example, the motor 705 would be commanded to rotate the
magnets 706, 708 in a first direction when distracting an antegrade
placed distraction device 1000, and in a second, opposite direction
when distracting a retrograde placed distraction device 1000. The
physician may, for example, be prompted by the display 715 to input
using the control panel 812 whether the distraction device 1000 was
placed antegrade or retrograde. The patient may then continue to
use the same external adjustment device 700 to assure that the
motor 705 turns the magnets 706, 708 in the proper directions for
both distraction and retraction. Alternatively, the distraction
device may incorporate an RFID chip 1022 which can be read and
written to by an antenna 1024 on the external adjustment device
700. The position of the distraction device 1000 in the patient
(antegrade or retrograde) is written to the RFID chip 1022, and can
thus be read by the antenna 1024 of any external adjustment device
700, allowing the patient to get correct distractions or
retractions, regardless of which external adjustment device 700 is
used.
[0044] While embodiments have been shown and described, various
modifications may be made without departing from the scope of the
inventive concepts disclosed herein. The invention(s), therefore,
should not be limited, except to the following claims, and their
equivalents.
* * * * *