Note: Descriptions are shown in the official language in which they were submitted.
1 1 57527
BACKGROUND AND BRIEF DESCRlPl'lON OF THE INVENl'ION
This invention relates to the treatment of living tissues and/or
cells by altering ~heir interaction with ~he charged species in their envi-
ronment. In particular, the invention relates to a controlled modification
of cellular and/or tissue growth, repair and maintenance behavior by the ap-
plication of encoded electrical information. Still more particularly, this
invention provides for the application by a surgically non-invasive
.~
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'~
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1 1575~7
dire~t inductive couplin~, of one or more electrical voltage
an~ concomitant current signals conforming to a highly specific'
pattern .
Several attempts have been made in the past to elicit a
5 response of li~ing tissue to electrical signals.
Investigations ha~e been conducted involving the use of
direct current, alternating current, and pulsed signals of
single and double polarity. Invasive treatments in~olv.ing the
'' use of imPlanted electrodes have been followed, as well as non-
... . . . . ...... .
invasive techniques utilizing electrostatic and electroma~netic
fields. Much'of the prior work.tha-t has been done is described
in Volume 238 of thè Annals of The New York Academy o~-Sciences
published 11 October 1974 and entitled "Electrically Mediated
Growth ~Iech~nisms in ~i~ing Systems" (Editors A. R. Libo f'and ..
R. A. Rinaldi~.. See also '~Augmentation of Bone Repair by
Induct~vely Coupled Electromagne~ic Fields" by C. Andrew L.
Bassett, Ro~ert 3; Pawluk and Arthur A. Pilla published in
-Volu~e 184, pages 575-577 of'Sci'ence ~3 May 1974).
The invention herein is based upon basic cellular studies .'
2Q and ~nal~ses whlch'involve a detailed consideration of the
'intexactions of charged species, such as divalent cations and
hormones at a cell's ~nterfaces and junctions..
Basically, it has been established that, by changiny the
electrical and/or elèctrochemical environment of a living cell
and/or'tissue, a modification, often a beneficial therapeutic
effect, of the grow~h, repair and maintenance behavior OL said
tissue and/or cells'can be achieved. ~his modification or
effect is carried out by subjec-ting the desirea area-of tissues
.and/or cells to a specifically encoded electrical vol~age and .
concomitant current, whereby the interactions of charged species
l 157527
at the cellsl surfaces are modified. Such modifications
en~ender a chanye in the s-tate or function of the cell or
tissue ~/hich may result in a beneficial influence on the
treated si-te. For e~ample, in -the specific case of bone
gro~th and repair, it is possible ~?ith one electrical code,
hexeinafter referred to as Mode l, to change -the interaction'
of the ion such as Ca2'~ with a cell's membranes. ~7hereas,
with anot~er eleetrieal code, hereinafter refexred to as
.
Mode 2, a modlfication in -the same cell's pro~ein-s~nthesis
~ 10 eapabilities ean be affeeted.
For e~ample, -tissue-culture experi~ents involving the
study of embryonie ehick~limb rudiments show that the use of
a ~lode 1 code signal elicits enchanced Ca2~ release of up -to
50O from the competent osteogenie eell. This e~fect is highly
specific to the parameters of the electrical code o~ Mode'l.
Thust this eode influences one major step of ossi~ieation, i.e ,'
the mineralization of a bone-~rowth site. Sim}lar tissue-
eulture studies using Mode 2 code siynals have demonstrated
' that this code is responsible *or enhaneed protein produetion
from similar eompetent osteogenic eells. This lat~er effect is
.
also hi~hly speeifie to the parameters oE the electrical eode
of Mode 2~ In other words, this eode af~eets eertain metabolie
processes for these t~pes of cells such as those involved in
ealciu~ uptake or release from mitochrondria as well as the
synthesis of collayen, a basic s-tructural protein of bone.
These studies show that -the electrical codes of Mode 1
and Mode 2'elicit individual tissue and eellular responses,
indicatiny that each code contains a highly specific informa-
tional content therein. Based upon these and other studies,
3~ i-t has been possible to utilize Mode 1 or Mode 2 siynals or a -!
1157527
particular co~ina-tion oE ~lode 1 and ~lode 2 signals to
achiev2 a specific response requixed to enable the
functional healiny of a bone disorder. These electrical
modes have been applied successfully to human and animal
patients for non-healing fractures such as congeni-tal
pseudar~rosis and non-unions as well as fresh -Eractures.
Successes achieved in -the congenital pseudarthrosis cases
are particularly note~orthy, since normally 80~ of children
thus afflicted require amputa-tion, since conventional treat-
ments such as bone yrafting and internal fixation areunsuccess~ul.
While there have been many investigations in the past
of the response of living tissues and/or cells to electrical
signals, clinical results to date using prior techni~ues have
not been uniformly success~ul or generally accepked within the
appropriate professional community, Several xeasons contribute
to this state. First, it has not been realized heretofore that
electrical signals of ~ery specific informational content are
required to achieve a specifically desired beneficial clinical
effect on tissue and/or cells. Second, most of the prior
techniques utilize implanted electrodes, which by vir-tue o~ -
unavoidable faradaic ~e:Lectrolysis) effects are often more toxic
than beneficial in the treated site. Furthermore, ~he cells
- and/or tissues are subjected to a highly uncontrolled current
and/or voltage dis~ribution, thereby co~promising the ability
of the cells to respond, should they do so, to the applied
si~nal. This highly uncontrolled curren~ and/or voltage
distribution also applies in the case of capacita~ively coupled
29 si~nals.
,
1 157527
In contrast, th2 sur~icall~ non-invasive direct
inductive coupling o~ electrical informational con~ent of
specific electrical codes as involved in the present
invention produces within living tissue and/or cells a
con~rolled response.'
In ~rie~, the present invention involves the
recognition that the gro~th, repair and maintenance behavior
or living tissues and/or c211s can be modi~ied beneicially
by the application thbreto of a specific electrical informa
tion, This is achi'eved by applying pulse waveforms of volta'ge
and concomitant current of specîfic time-frequency-ampli-tude
relations to tissue'and~or cells by a surgically non-invasive
means through use of a ~arying electromagnetic field which is
inductively coupled through direct induction'into or upon the
tissue and/or cells under treatment. -The informa-tion furnished
to the cells and/or tissues by these signals is designed to '
., . . : . .
influence the behavior of non-excitable cells such as those
in~olYed in tissue'growth,' repair, and maintenance. These
growth, repair and maintenance phenomena are substantially
different from those`involved in excitable cellular aeti~ity
(e.g., nerves,'muscles, etc.), particularly with respect to '
the type of perturbation required. Thus, the ~-oltages and
concomitant curren~s impressed on the cells and/or tissues
are at least three orders of magnitude lower than those required
2S to effect cellular activities such as cardiac -pacing, bladder
control, etc.
The invention will be more completely understood by
reerence to the following detailed descrip~ion, in conjunction
29 ~Yith the accompanyiny drawinys, in which
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1 15 7~27
Fiy. 1 is a simpli.fied vie~ sho-~ing the treatment
of a bone in accordance with the invention;
Fi~. 2 is a perspective vi~w oE the treatment unik
shown in Flg. l;
Fig. 3 is a vie-~ ~xom the rear) of the unit shown
in Fig. 2, showing the ~ositioning of a coil therein used
for treatment purposes;
Fig. 4 is a block diagram of an electrical system for
energiæing the coil sho~rn in Fig~ 3 for ~ode l treatment~ ..
Fig. 5 is a block diagram of an electrical syste~ for
energizing the coii shown in Fig. 3 for ~ode 2 trea-tment,
Figs. Sa and 5b are pulse waveform diagrams for Mvde l
and Mode 2 treatments, respec~ively, showing presently pre-
fexred pulses as induced in living tissues and cells;
.
lS Fig. 6 shows alternative forms of negative pulse portions
~or Mode 2 treatment;
Fig. 7 i.s a fron~ ~ie~ of a body-treatment device, being
an embodimen-t in substitution for that of Fig~ l, and shown
un~olded, in readiness for wrapped application LO an afflic~ed
boay xegion; .
Fig~ 7A is a sectional vie~, taken at 7A-7A of Fig. 7;
Fig. ~ is a perspec~ive view of a locating element for
use with t:he device oE Fig. 7;
- Fig. 9 is a simplified schema-tic illustration of à method
o~ use of the device and element OL FigsO 7 and 8;
~ ig. lO is a simplified right-sectional view through a
bod~-limb cast to wQich the device and element of Figs. 7 and
8 have been appliedi
. Figs. ll and 12 are sLmpli~ied views in perspective showin~
30 further body-treatment devices, for particular purposes;
.
.
1 ~5~527
Figure 13 is a diagram to illuminate discussion of dual-coil
placement considerations;
Figures 14 15 and 16 are similar pairs of views a and b respec-
tively schematically representing ~ront and side elevational views for each
of three different generally elliptical dual-coil configurations; and
Figures 17 to 20, appearing on the same drawing sheet as Pigure 11
are views similar to Figures 11 and 12 to show coil arrangements for further
body treatment devices.
D~TAILED DESCRIPTION
_
Referring to Figures 1 to 3 the leg 10 of a person having a broken
bone as indicated as at 12 is shown as repr0sentative of the application
o the invention to the stimulation of bone growth for healing purposes.
A treatment head 14 is positioned outside the skin of the person, and is
held in place by use of a strap 16 ~secured to head 14 by fasteners 16a)
which may include \fielcro material 18 thereon so that the strap may be wrap-
ped about the leg and about the treatment head to maintain the treatment
head in position against the leg. The treatment head 14 may include a
foam material 20 on the inside surface thereof for the purpose of cushioning
and ventilating the treatment head against the leg. It will be noted that
the treatment head 14 is generally curved on the anterior surface thereof
so that it conforms to the shape of the leg under treatment.
The treatment head 14 includes therein a coil 22 which may be of any
- suitable shape. ~s shown in Figure 3 the coil 22 is generally rectangular
in shape so as to define a "window" within the interior portion of the turns
of the coil. The coil 22 may lie in a plane or it may generally be curved
to conform to the curvature of the treatment head 14. The coil 22 includes
terminals 24 which extend away from the treatment head 14 to be coupled to
a cable 26 for connection to a suitable
~ r,y.~ q,~
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1 1575~7
en-r~i~ing circui~, as ~ill be explained below in more
de-tail. ~ diode 27 may be included wikhin the cable 26
for connection across -the coil 22 ~s ~7ill also be explained
belo~.
The treatment heaa la is positioned on the patient so
that the "~indow" formed by the coil 22 is adjacent the
bre2k 12, i e., adjacent the tissue under treatment. The
coil 22 is energized, as will be e~plained in more detail
belot~, and induces an electrical potential within the tissue
10 under trea~ment. It has been found that a paxticular type
of signal should be induced wi~hin the tissue and this is
achieved by energizing the coil 22 by a circuit, such as
shown in Fig. 4 or Fig. 5, to produce the pulse signal shown
in Fig. 5a or Fig. 5~. -
Refexring to Fig. 4, a variable dc supply 3~ is coupled
through a gate 32 to the trea-tment coil 22 (or coils, as the
case may be, and as will be explained in more détail below~.
The gate 32 is under the control of contro]. un ts 34 and 36
which cause a pulse signal consisting of repetitive pulses
of electrical potential to be applied to the trea-tment coil
- 22. Each pulse, as shown in Fig. 5a, is composed o~ a
"positive" pulse portion Pl followed by "negative" pulse
- portion P2 because o~ the stored electrical energy wi~hin
the treatment coil. In the circuit of Fig. 4, a diode clamp-
ing unit 38 may be employed to limit the pe~k potential of
that negative pulse portion. The diode clamping unit 3~ may
be one or more diodes connected across the coil 22, and may
be advantageously located wi-thin the cable 26. The diode 27
29 sho~ln in Flg. 1 constitutes such a clamping unit 38.
.
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--8--
1 157527
~ In Fi~J. 5a, the signals at the trea-bment coil 22
and hence the induced signal ~ithin the ti5sue to be
treated are shown. ~t time tl, i-t is ass~lmed th~t yate
32 is ~ated on by an appropriate signal from control unit
36 (d~signated a pulse ~idth control unit) so that the
electrical potential across the treatment coil 22 is raised
from about zero volts along pulse segment 39 to a potential
designated vl in Fis. 5a. T~e signal across the trea-tment
coil decays in a second pulse segment along th~ portion of
th~e curve designated 40 in Fi~. 5a. The slope oE that curve
is determined ~y the L/~ time constant of the circuit of
Fig. 4, i.e., the inductane of the treatment coil and the
e~fective resistance of the circuit, including distributed
factors of capacitance, inductance and resistance. For
treatm~nt of many tissues ana cells r it is believed desirable
to adjust the circuit parameters so that the portion 40 of
the curve is as fla~ as possible, renaering the signal applied
to the treatment coil 22 as rectangular in shape as possible.
At the time t2, the gate 32 is gated o~r by ~e control unit 36.`
Just prior to bein~ gated off, the signal across -~he trea~ment
coil is at the potential v~ shown in Fig. 5a. The poten~ial
across the treatment coil drops from the level v2 in a third
pulse segment 41 to a potential o~ opposite polarity designated
v3 in Fig. 5a. The magnitude o~ the opposite polari-ty potential
v3 may be limited by the diode clamping unit 38 to a relatively
small value as compared with value vl. The signal across the
treatment coil 22 then decays from the potential level v3 to
the zero or reference potential level, ~inally effectively
- 30 reaching that level a~ time t3. A pre_etermined period passes
-
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7527
beEore t~e pulse-repetition ra-t~ control unit 34 generates
. an appropriate timing SicJnal to trigger the control unit
36 to generate a signal to turn gate 32 on ~gain to continue
the cycle just explained.
The control units may typically be monostable multi-
vibrators, e.g., -to generate appropriate timing signals and
which may be varia~le to control pulse duration and repeti~ion
rate within desired limits. Furthex, the use of a variable dc
supply 30 permits vaxiation of the am~litude of the pulse
signal as desired. - .
Nhen pulse-train operation (Mode 2) is employed,.
additional t~lin-~ circui~ry similar to units 34 and 36 in
Fig. 4 is emplo~ed to provide the burst-segment width and '.
the burst~segment repetition ra-te. Referring to Fig. S,
contxol units 35 and 37 control ga-te 33 -to produce a signal
applied to coilLs) 22 of the wa~eform type as shown in ~ig.
5b. The circuit is otherwise -the same as in Fig. 4, except
that'the diode-'clamping unit 38 is omitted to permit the
large negative-pulse portions as shown in Fig. 5b. The
20' con~xol units 3~ and 37 aetermine ~he number of pulses in a
'.burst and the time between succes'sive bursts.
It has been found that the signal across the treatment
coil 22~ and hence the induced signal within the tissue under
treatment, should satisfy cer~ain criteria. These criteria '
will be specifi'èd with respect to the signal as induced in the
tissue and/or cells under treatment. Such induced signal ma~
... . .
be monitoxed, if desired, by use of an auxiliary monitoring
pickup coil (not shown~ ~hich is positioned at a distance from
the treatment coil 22 corresponding to the distance of the
30 tissue under treatment from that coil, as ~lill be explained..
.
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~ 1575~
in more det~il belo~ n any even-t, it has been ound
that the follo~iing criteria should be satisfied for
eefective treatment of livincJ tissues and cells, in
particular, hard tissue such as bone.
In the following presentation, the signals sho~7n in
Figs. 5a and 5b constitu-te the pulses OL electrical
potential and concomitant current gener ted by the coil
and impressed upon the tissues and~or cells. These pulses
have one polarity upon l'energization" of the coil (~ermed
herein the "po~itive" pul5e portion and shown as the
positive-going portion of the waveform on Figs. 5a and 5b).
These pulses have an opposite pola itv,upon "de-energization"
o the coil Ctermed herei'n the "negative" pulse portion and
shown as ~he neyative-going por-tion of the waveforms o~ Figs.'
5a and 5b~. The terms "positive" and "negative" are intended
to be relative'only, and are used herein only for the purpose of
indicating that pulse pbrtions of opposite polarity'r with
respect to a reference potential level, are involved.
It has heen determined tha~ the "positlve" pulse portions
should bear a predetermined relationship to the "negative'l '
- pulse portions'in order to modi~y beneficially and with uniform
results kile behavior of living tissues and cells. This pre-
dete~lined realtionship has been achieved by the utilization
of -two di:Eferent signal modesr as well as combinations thereof.
In Mode 1 (see Fig. 5a~, the asy~metrical waveform induced
in tissue or cells by the alternate energization and de-enersiza-
tion of an'electromagnetic coil is repeated-at a rrequency such
that the overall duty cycle is no less than about 2%. This
fre~uencyr in Mode 1, has typically been about 10-100 Hz with
du~y cycles of 20-30~, The basic relationship for ~,od~ 1 of
--11--
1 ~ 575~7
the respective frequ2ncy ~mplitucle content of the '!positive"
and "ne~ative" pulse por-tlons is as follows: pulse sig~al
should be of a particular shape, namely, each "positive"
pulse portion should be composed o~ at least three segments,
5 e.g., the segments 39, 40 and 41 in Fig. Sa. As noted above,
it has been ~ound that a substantially rectangular shaped
"positive" pulse signal portion is particularly use~ul in the
treatr~ent o~ tissuè and cells. However, it is possible that
other puls~ con:Eigurations tother than a simple two-sesment
spi~e) may be use~ul. The peak amplitude of the final.seyment
o each `'positive" pulse portiont e.g., the potential v2 in
Fig. 5a should be no less than about 25% of the peak amplitude
of the first se~men-t 39 of the 'Iposltive" pulse portion, eOg.,
the potential vl in Fig. 5a
The peak "ne~ative" portion amplitude is deno-ted by V3
in Fig. 5a. This peak amplitude should be no more ~han about
1/3 the peak amplitude oE the "positive" pulse por-tion. .The time
duration of each "positive" pulse portion ~the period that
elapses between times tl and t2 in Fig. Sa) should be no longer
than about ~/9 the time du~ation of the followlng "negative"
pulse portion tthe time elapsing between times t2.and t3 in
- Fig. 5a~. Because the treatmen-t system uti.lizes an electro-
magnetic coil, the energy of each "positive" pulse por-~ion is
equal to the energy oE each "negative" pulse portion, i.e.,
the area in Fig. 5a er~raced by -the "positive" pulse portions
is equal to the area embraced by the "negative" pulse portions.
By satisfying the criteria just mentioned, the energy of each
"negative" pulse por~ion is dissipated over a rëlatively lon~
period of tirne, and the average amplitude of that negative
pulse portion is limiled. It has been found ~at such average
. -12- .
1157527
negative amplitude snould be no greater than ahou-t 1/6 the
average ampli~ude of -the l'positive" pulae portion
These relationshlps also ensure that the l'positive"
and "negative" pulse portions have the proper frequency-
amplitude characteristics within themselves and to eachother such that a beneficial modification of the behavio.r
of tissues and cells is accomplished.
Besides the relationships just mentioned, it has been
found t~at the average magnitude o~ the "positive" pulse
portioIl peak potential should be within ~he range of about
0.0001 to 0.01 volt per centimeter of tissue or cells,
corresponding to be~een about 0.1 ana 10 microam~re per
square centimeter of treated tissue and/or cells (based upon
typical cell and -tissue reslstivities) It has been found
that hi~her or lo~er pulse potentials will not result in a
.. beneficial effect, It has al.so been found that the duration
of each "posi-tive" pulse portion.(the tLme.elapsed be~ween
.
times tl and t2 in ~ig. 5a~ should be at least about 200 micro-
seconds. If the time duration of each "positive" pulse portion
20 is less than about 200 microseconds, the tissues and cells ~re.
not stimulated sufficien~ly to modify the repair or other
processes~ From a practical standpoin~, the "positive" pulse
portion duratlon should not be greater than about 1 millisecond.
. It has also been found that the repetition rate of the pulses
shoul~ be within the range of about 65 -to 75 Hz for bone and
other hard tissues. Pulse treatments wi-thin this range have
been found to be particularly efEective with re~roducible
results for tissues and cells of this -type. In general, ho~ever,
pulse repetition rate should be be~een about lQ and 100 Hz for
~ood results in tissues and cells.
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-13- .
1 ~57527
For the treatm2nt of bone disorders, and particularly
for the treatment oE pseudarthrosis, it has been found that
for ~lod~ 1 an optimum induced "positive" pulse si~nal portion
having a peak amplitude of between about'l and 3 millivolts
per centimeter o treated tissue (1 to 3 microam2eres per
s~uare centimeter of treated tissue and/or cells) with the
dura-tion of each ~Ipositive~ pulse portion being about 300 .
microseconds and the duration of eac~ o the "negative" pulse
portions about 3300 microseconds, and a pulse repetition rate.
10 .o~ about 7Z ~Iz, rep.resents a presently pre~erred and optimum
induced pulse treatment as long as the pulse-shape requirements
~ . .
noted above are me-t. Total treatment times may vary. It is
presently ~elieved that pulse-signal treatments.for periods
' e~ch lasting for at least about 15 minutes, with one or more
periods of trea-~nent during a prescribed number of days, may .
be eflective-in.stimulating tissue and cell behà~iort A pre-
. ferred treatment regime using,Mode 1 has been found to b.e a
- . minimum o~ 8 hrs/day for,a period of four months in di~ficul~
cases, and two weeks in less difficul-t cases.
. In Mode 2 treatment ~Fig. 5b)-, the asymmetrical waveform
induced in tissue or cells by the alterna~e.energization and
de-ener~ization of an electromagnetic coil is .applied in a .
pulse-train modality, which contains bursts tpulse groups) of
as~mmetrical waveforms. Each burst of asymmetrical pulses has
a duration such that the duty cycle of the buxst portion is no
less than about'1%. The burst ~requency has typically been-
about from 5-50 ~Iz.
The basic relationships for Mode 2 of the respective
requency-amplitude con-tent of the "positive" and "negative"
pulses within the burst section o~ the pulse train are as .,,
-l~t~
1 ~57527
follo~ls: ~ach "positive" pulse portion should be co~posed
o~ at least three segmen-ts, e.y , the segments 39', 40'
and ~1' in ~'iCJ . 5b. For -this mode, it has also been ~ound
t~at a substantially rect~Ilgular shaped "positive" pulse-
signal portion is particularly useful in the treatment oftissues and cells. However, it is possible that pulse con-
figurations other than a simple two segment spike may be
useful. The peak amplitude of the final se~men-t of each
"positive" pulse portion, e.g., the potential v2 in Fig. 5b,
should be no less than about 25% o:E khe peak amplitude o~
the first segm~llt 3~'of -the "positive" pulse portion, e.g.,
the potential vl :in Fi~. 5b.
The peak "nec~ative" amplitude ls denoted by V3 in Fig.
5b. This `'negative" pea~ amplitude should be no more than
about ~0 times the "positive" pea~ amplitude ~in -this case vl~.
This re~uirement may ~e met by utilizing l'negative" pulse
portions having several different waveshape forms, e.g./
substantially rectangular, ~rapezoidal with exponential decay,
bell-shaped, or single-spike with exponential decay, as in
xepresentative waveforms a, b, c an~ d in Fig~ 6~
The duration of ~ach "positive" pulse portion (-the time
that elapses between times tl and t2 in Fig. 5b) should be at
least about 4 times the duration of the followin~ "negativel'
pulse portion ~the time tha-t elapses be-t~een times t2 and t3
in Fig~ 5b)~ As noted above, since the treatment system
utilizes an electromagnetic coil, the energy of each "pos-itive"
pulse portion is equal to the energy of each "ne~ative" pulse
portlon, i.e., the area in Fig. 5b embraced by -the "posl~ive"
pulse portions is equal to the area embraced by the "negative"
pulse portions.
;
-15- ,
1~57~27
The pulse-repetition rate o~ the pulses within the
burst se~.ent of the ~lude ~ pulse train (the time elapsing
between times tl and t~) can be bett~een abou-t 2000 Hz and
10, ooo }~z,
The width of the burst segment of the pulse train (the
time elapsed between tl and t5) should be at least abou-t 1
of the time elapsed between tl and t6.
By satisfying the criteria just mentioned, -these
relationships also ensure tha-t the "positive" and "nega-tive"`
pulse portions have thè proper frequency-amplitude character-
istics within the~lselves and to each other such that a
beneficial mocliE.ication o the behavior of tissues and cells
is accomplished.
Beside~ the re~.ationships just mentioned, it has also
been found that -the average magnitude of the "positive" peak
potential should be within the xange of about O.OOOOl to 0.01
~olts per centimeter of tissues and/or cells (bet~een about
0.01 and 10 microampere per square centimeter of treated tissue
and/or cellsl~
It has been found that hi~her or lower pulse potentials .
will not result in a beneficial effect on tissues andJor cells.
It has also been found that the duration o each "positive!'
pulse portion in the burst seyment of the pulse train (i,e ,
the time elapsed between tl and t2 in Fi~. 5b~ should be at
least about 1000 microseconds. It has also been found that the
repetition rate of the burst segment should be within the ranye
Gf about 5-15 Hz for bone and o-ther hard -tissues
Each negative-pulse portion within the burst segment of
the pulse txaill should be of a duration no greater than about
50 microseconds and of an averaye amplitude no greater than
'~`
-16-
1 157~27
about 50 l~v/cm of tr~ated tissu~ and/or c~lls (about 50
~icroa~?eres per squ~r~ centimeter of treat~d tissue and/or
cells).
For the trea-bment of bone disorders, and particularly
for the trea~ne~t of pseudarthroses and non-unions, i-t has
been lound that an optimum induced "positive" pulse signal
portion naving a peak am~litude of between about 1 and 3
millivol~s/centime-ter of treated tissue ~i.e., 1 to 3 micro-
amperes per square centimeter of treated tissue and/or cells),
wi,h the duration of each "positive" pulse portion being about
2Q0 mic~oseconds, and the duration of each of the "negative"
pulse oortions being about 30 microseconds, and a time elapsed
bet~een times t3 and t4 oE Fig 5b o 10 microseconds, and a
pulse repe~ition rate of abou~ 4000 ~z, and a burst segment
width of a~out S milliseconds, and a burst repetition rate o
about lQ Hz, represen-ts a presently preferred and op-timum
induced pulse treatment in bone -for Moae 2, as long as the
pulse re~uirements noted above are met.
It is also believed that a single asymme~rical pulse as
described in the burst segment of Mode 2 can be employed at
a repe~ition rate similar to that used in Mode 1 ~or beneficial
modification of tissue gro~th and repair.
Trea~ment of livin~ -tissues and cells by -~he above me~ods
herein, in particular for hard tissue such as bone, has demon-
~5 st~ated an increased repair response and generally uniformresults have been at-tained throughout all patient and animal
trea~ments. Particularly beneficial results have been obtained
in the cases oE treatment of pseudarthrosis in whlch a bone
union has been achieved followin~ previous unsuccessful a-t~empts
by o~her treatment me-thods and in which amputatiOn has been
discussed as a possible alterna~ive to regain function
,
_7 7_
I 1 57~27
In pr~ctlce, it is beli~ved desirable to utilize
as large a coil "windo~" as possi~le and to posi tion th~
coil such that an adequate flux density is impressed upon
the tissu2 and/or ceIls bein~ trea-ted. As is known, a
time-varving magnetic field induces a time~vary~ng voltage
field orthogonal to it. That is, the ~eometry of the
magnetic-field lines determines the geometry of the induced-
voltage field. Because a relatively uni~orm induced-voltage
field i5 dèsired, ~he geometry of the magnetic-field lines
should be as uniform as possible, which may be achieved by
rendering the size o-f the coil relatively large with respect
to th~e area ~Inder -treatment. At this particular time, it is
not believed that thère need be a particular orientation
between the magnetic-field lines and the -tissue and/or cells
being treated.
It is believed that the uniformi~ of the induced-vol~age
field possi~le through electromagnetic trea-tment is responsible
in many rèspects for the good treatment results which have been
cbtained, in distinction to ~e non-uniform ~ields which may
and probably do resul-t uith other types o~ trea-tments, for
example, utilizing electrostatic fields or by the creation of
a potential gradient through the use of electrodes implanted
within or on tissues or cells~ In particular, an induced
voltage field is present in a vacuum as well as in a conducting
medi~ or an insulator~ Tne field characteristics will in
general be -the same ~within one percent~ in these three cases,
except in the case for which an induced curren-t flow i5
suf~ficien-tly great to create a back electromotlve force to
distort the magnetic field lines. This condition occuxs when
the conduc-ting medium has a high conductivity, eOg., a metal,
~,3 _
~ :a57s~7
and is lars~ enough to .intercept a substantial number of
ma~netic-field l.ines~ I,iviny systems, i.e., tissue and/or
cells, are much le5s of a con-luctor ~han a t~pical metal
(generally by ~t least 105, i.e. five orders of maqnitude). Because
o these considerations, the geometry of the magnetic field
present in tissue'and/or cells is undisturbed and remains
unchanged as the tissue and/or cell gro~th process continues. .
Thus, with non-invasive electromagnetic treatment, it is
believed that the potential gradient that is produced ~Ji-thin
the tissue and~or cells is constant re~ardless of the stage
or condition o~ the treatment.
Such uni~o~ity oE induced potential is virtually
impossible to be achieved through the use of implanted
electrodes or b~ eIectrostatic coupling or b~ a transformer
coupled to electrocles, or by implanted coils coupled to '
electrodes. Since't~ese'latter types of treatments are.
dependent upon conducti~ity, which wiil vary within tissue
and/or cells, the'induced potential gradient will not be
constant as the conditiQn oE the tissue and/or cells Ghanges.
Additionally, at any particular time within tissue and/or '.
.cells, individual localities of the material being ~reated
will have different conductivity characteristics r which will
result in differing;potential gradients throughout the material
treated.
~5 For these reasons, it is believed that a surgically
non-inYasiYe electromagnetic treatment oE tissue and/or cells
i5 greatly preferable to electrical trea-tment by o~her means.
Regarding ty~ical coil parameters, it is believed that
for -typical bone breaks, coil ~Jindows oE about 2.0`' ~ 2.75"
(for an adult) and 2" x 1.5" Ofor a child) are suitab~e.
~l9-
1 1 57527
The wirc em~loyed in the coils may be B&S c~au~e 12 copper
wire tha~ is varnish-coated to insulate the turns one from
another. Coils of about 60 turns for an adult and 70 turns
for a child seem to be suitable. For treatments in the
oral cavity, coil sizes would be correspondingly smaller.
It is believecl that the inductance of the treatment
coil should be between about 1-5000 microhenries, and pre-
ferably between about lO00 and 3000 microhenries, with
suf~ieiently low resistance (e.g., 10 2 to 1 ohm) and a high
input coil driving signal between about 2 and 30 volts, to
induce the appropriate pulse potential in the tissue and/or
cells treated. The lessier the inductance of the treatment
coil, the steeper the slope of the eurves 40 and 40' as shown
in Figs. 5a and 5h; the greater the inductance, the flatter or
more reetangular is the "positive" pulse that is produeed.
The monitoring o the induced potential may be by actual
electrodes making eontact with the tissue and/or cells being
treated or by use of a pi.ckup coil positioned ac1jacent to the
treatment coil 22 at a distance corresponding to the distanee
of the material under treatment from the coil. A typical pick-
up eoil tnat has been employed is circular, about one-half
eentimeter in diameter, with about 67 to 68 turns of wire. The
potential developed by the coil is divided by the length of the
wire (in centimete.rs) to provide.an induce.d voltage per centi-
mete.r number that is elosely related to the volts per centimeter
induced in the tissue and/or cells under trea-tment.
A typical treatment utilizing a coil having a "window"
2" x 2.75" and 60 turns of number 17 gauge wire, includi.ng a
diode at the coil such as the diode 27 in Fig. l, produced the
following induced voltages in a pickup coil* for the pulse times
*These voltage values may bë translated into millivolts per centi-
meter of ~issue, by dividing by a factor of substant.ially ten.
. -20-
1 1S7~27
(in microseconds) as follows (vol-tages ~nd times axe with
reEerenc~ to the waveorm o~ Fi~. 5~:
Induced Vo:Lta~e vl ~2 v3 tl-t2 t2-t3
S ~la~imum (at face
of treatmQnt eoLl) 22 17 3.7 300 4200
5/~" fro~ face of
treatment coil 15 11.5 2.5 300 4200
1 1/2" from ace
of treatment coil 6.0 4.2 1.0 300 4200
The use of pulsing electromagnetic fields to control
bone fo~mation in a variety of conditions, no~, is on a
sound e~perimerltal and clinical basis. Thus far, the
develop~ents have had application in treating sueeessfully
congenital and acquired pseuaarthrosis and ~resh fractures
in humans~ increasing the rate of fracture and reactive
periostitis repair in animals, and reducing bone loss in dis~
use QS teoporosis of long bones. Success with the method
hinges on the discovery of pulse patterns with specifie time-
frequency-amplitude relationships as outlined above
- ~X~PLES
In order to demonstrate efficacy,the utilization of
direet inductive coupling of eleetromagne-tically induced
pulsing voltages-and concomitant-current via Modes 1 and 2
and combinations thereof for hard tissue growt~ and repair
t~as initially applied in cases of congenital and acquired
pseudarthrosis. In a group of pa-tients,only individuals
who had been -treated previously by one or more unsuccessful
surgical attempts (grafting, internal fixa-tion) were accepted.
For most of these patients, amputation had been reco~mended
by at least one qualified orthopedis~. Throughout this study,
the necessity for pulse specificity was illustrated again and
33 again. For e~amole, when lac~ of ossification was the primary
~ 157527
problc~ (usua]ly the case for congenita~ pseudarthroses),
~1ode 1 tr~a~ment~s u-tilized ~ith final functional bony
union occurring on~y when the parame-ters of the pulse
corresponded to those given above. On the o-ther hand,
wh~n lack of bony matr:ix was the primaxy problem, Mode 2
treatment was employed in order to achieve the production
of collagen which is the primary supporting protein in bone
structure. Since protein procluction and ossification are
two completely different steps in bone formation, the highly
selective na-ture oE each of the sig}lals utilized in Modes 1
and 2 could be synergistically combined when neither matrix
production nor os-;ification were present in a given patient's
treatment history~ Thus, a combination of Modes 1 and 2 was
utilized ~ith benefit in this type of si-tuation.
In the caCe of congenital pseudarthroses, the typical
patien~ is ~e~ween one and ten years of age. The afflicted
part is normally the distal tibia of one extremity. The
patients were presented with an average of three prior un-
success~ul surgical procedures and had the condltion ~or an
~verage o~ 5 years,and all were candidates for amputation.
The treatment;o~ such a patient was noxmally carried out
using Mode 1 treatment regime since the primaxy pxoblem was
due to a lack of ossification in the affected area.
The patient is prescribed the appropriate equipment by
the attending orthopedic surgeon and carries out his txeaument
on an out-patient basis. Treatment time is typically lZ to 16
hours a day for about an average of 4 months.
Some 20 of this type of disorder have been treated to
date with successful ossification achieved in approximately
90~- of the treated individuals.
.
-22-
l 1S752~
~ or acquired pseudarthrosls, either traumatic or
operat:ive, pa-tients are mostly adults and had an average
number o~ three failed operations and an averaye of 2.5
years from on~et oE non-union~ ~mputation had been
discussed for s-even-ty percent o~ these individuals. Since
- in so~e cases the primary problem was lack of bony matrix,
typically visible radiographically as gaps in the bone of
more than 2 mm in the frac-ture site, such a pztient was
treated com~encing with Mode 2 modality. When it was thought
that sufficient non-ossified bony matrix was presen-t, Mode 1
modality was employed to ~ain rapid immobilization of the
fracture si-te.
~ ecause o~ the particular pathology of several patients
in this group, a combination of Modes 1 and 2 was employed
with this ttreatment being specifically Mode 2 follo~ed by
Mode 1~ ~s in the case of congeni~al pseudar-throsis, the
proper e~uipmçnt was prescribed by the attending orthopedic
surgeon and treat~ent was performed on an out-patient hasis.
Trea~ment time is typically 10-14 hours/day for periods
ranging from 3 to 9 months.
~ ome 30 of this -type of disorder have been treated to
date with successful bony union observed in 75% of the treated
individuals. ;
These clinical results clearly demons~rate that once the
particular pathology of a bone disorder is dia~nosed it can be
select:ively ~eneficially treated by the application of properly
encoded changes in electrical environment.
Similar findin~s have been obtainea from a study of
bilateral fermoral and radial osteotomies in 160 rats. These
animals were divided into two ma~or groups; field exposed and -
.
1 15752~
con~rol for an interval of :L4 days aEter opera~ion.~ollo~in~ sacrifice, the e~tent oE fracture repair was
judged on the basis oE X-ray and histolo~ic evaluation,
cou~led ~tith non-destructive mechanical testing. These
animal mo-lel~ ~rere employed to evalua-te the effectiveness
of treatrent modalities of ~odes 1 and 2 and combinations
thereof~ Generally, when the osteoiomy gap was less than
1 . n mm, a Mode 1 signal was ef~ective since very little
bony m~tri~ was r~tired for solidification. On the other
hand, for wider 05 teotomies, substantially increased matrix
production ~qas ob.served over control animals when Mode 2
was employ2d. ~ co~bination o Modes 1 and 2 was employed
in the lat-ter case to obtain a stiffer repalr site for an
equivalent treatment time.
Th~s ~as fur-ther evaluated by -the response o~ these
bones to mechanical testing. This was performed b~ subjecting
~he bone of t~e rats following sacrifice to cantilever loading
at ~arious de~o~mations .~n accoxdance with,the tes-ting proced-
ures described in "AcceIeration of Fr,acture Repair by-Electro-
magnetic Fields. ~ Surgically Non-invasive Method" by C. A. L.
Bassett, R. ~, Pa~lùk and A. ~. Pilla, published on pp~ 242-262
o~ the Annals of_The New York Academ,y of Sciences referenced
abo~e, The specimens were deformed in the antero-posterior,
lateral-medial, pos-tero-an-terior, medlal-lateral and again ~he
antero-posterior positions.
The avera~e response o~ a femur to this test at a
delormation of 0.05 inch is shown in Table I as follows:
,
2 7
'Ta~le I
ech~nic~l Lo~d Values In Electrical
Stimulation of Arti~icial Osteotomies
__ In Adul~ Female Rat Femur '
Load at 0.05 in.
Stimulation ~ De'formation
.. . . . _ .
Control ~untrea-ted) 4~ gms~ ~ 5.2 gms.
~ode 1 Signal ~Figure 5a~ 580 gms _ 65 gms.
In addition to radiographic and mechanical evidence
of the e fectiveness o~ the signa~ em~loyed, histologic
evidence furtner attests to this effectiveness.
~ emoto~ylin and eosin stained longitudinal specimens
sho-.~ a much higher degree o~ maturation for the Mode 1
signal than in t~le control case.
For wider osteotomy gaps, treatmen-t times of fourteen
days shoT~ed th~lt the active animals had a significantly
larger callus than controls. Histologic evidence shows that
the increase is at least 15~% over controls.
Limited tooth'extraction studies have been performed and
sho~ th~t pulses of the'Mode 1 ~ype may have a highly beneficial
effect on the rate of healing and on bone loss ln the oral
cavity. The latter'effec~ in the'oral cavity is particularly
important for the maintenance of mandibular and maxillar crestal
bone height, a very important factor for implant fixation
These observations all point -to the fact that electro-
magnetic ~ields with highly specific pulse charac~eristics
can be non-invasively inductively coupled -to biological systems
to control cell behavior. In the initial application o~ these
principles, effects on bone cells have been investigated.
Other biological processes, however, may eventually be proven
to be controlled by similar techniques, e.g., malignancyr
- . .
'
' -25-
1~S7~2~7
neuro-rc~air, inflal~natory processes and immune response,
among others.
In summary, it i5 believed that a unique elec-tromagne-tic
and sur~ically non-invasive treatmen-t techni~ue has been
discovered. Induced pulse characteristics appear to be highly
si~nificant, especially those relating to the time-frequency-
amplitude relationships of tne entire pulse or pulse se~uence.
It is believed -tha-t selection of particular time-frequency-
amplitude relat:ionships may be the key to successful treatments
of varying cellular behaviox in a variety of tissues.
Througho~lt the specification for Mode 1, a preferred
pulse repetition rate of bet~een àbout 65 and 75 Hertz had
been specified :Eor bone and other hard -tissue. The exact
limits of the pulse-repetition rate are not known for all types
of tissues and cells, It is believed-that preferred operating
ranges Will var~ dependin~ on the tissue and cell type. Positive
results have been o~tained, for example, in soft-tissue treat-
ment at 20 Hertz.
~t ~ill be appreciated that the methods and apparatus
described above are susceptible of modification. For example,
~hile Figs. 1 and 2 illustrate a treatment uni~ which may be
strapped to the leg, treatment units lncorpora-ted in casts,
e.g., may be employe~. Further, treatment may be carried out
by use o one or more coils of var~ing shapes positloned
adjacent to tissue and/or cells to be treated. In fact, some
trea-tments o~ humans have involved coils positioned upon
opposite sides of a bone break. Coils ~Jith metal cores may
also be used. In the case of trea~men~ within -the oral cavi~y,
it is believed that double coils are advantageous, positioned,
for example, on opposite sides o~ a tooth soc~et -to stimulate
rep`air of that socket. Some specificall~ beneficial trealment
units and procedures ~ill be described in connection with Figs.
7 ~o 16.
1 1 5 7 5 2 7
Fiys. 7 and 7A illustrate a body-treat~ent or
ap?licator device which is most heneficially applied to
tlle treatment of bone br~ks or non-unions in arm or leg
members, i.e., wherein the bone recJion to be trea~ed is
relati~ely elongate. The device comprises two coil-mounting
u~its 50-51 each of which contains an electrical coil OL
the character already described, and they are ~lexibly
interconnected to p~rmit ready adaptability to oppos~te
sides o~ the region to be treated. Each of the UllitS 50-51
ma~ be OL like constr~lction, essentially involving a rigid .
pottins ol its coil turns in a consolida-ting mass of cured
elasto~eric or p:lastic material, however, in the pre~erxed
form, each unit, such as un~t 50, comprises a casing consisting
of flanged concave-front and convex-back panels 5~-53, with
the peri~heral flange 54 of fron-t panel 52 in continuous`
telescopin~ overlap to the similar flange 55 of back panel 53
Registering and abutting inwardl~ projecting boss~or foot
form~tions in panels 52~53, as at 56, enable the t~Jo panels
to be bolted together in the precisely spaced relation shown
in Fig. 7A. The respective inner and outer panels of unit S1
are precisely the same as for unit 50s except that as a further
feature of the invention a rectangular recess 57 is inwardly
for~ed in panel 52, or a locating or key purpose to be later
explained. The secured boss or foot formations at 56 are
preferably of-Eset inwardly from the flan~ed peripheries of
panels 52-53, thereby defining peripherally spaced means for
locating the inner limit of turns of coil 58 within the flange
55 of back panel 53. .The coil turns may be rigidly bonded in
place, -to and within flange 55, or they may be adequately
retained by. compressible material such as urethane foam, com-
pressed as the bolted connections are established at 56.
5 ~ ~
The fle~ible interconnection o~ units 50-Sl is shown
to include an electrical cable 59 ~or establishing the
el~ctrically parallel interconnection oE like coils 58 in
the respective units 50-51, the polarity o~ such inter-
connection being such that magnetic-~lu~ lines within the
t~Jo coils 58 and in khe space therebet~1een are flux-aiding
when the ~ront ~concave~ panels of units 50-51 are in face-
to-f2ce relation. Removable connection of ~e coils 58 to
the energizin~ circuitry of Figs. 4 ox S is shown by way of
the single plu~ an-l socket means 24-26, via uni-t 51. Typically,
each of the two coils 58 has an .inductance in the order o~
5000 microhenries, so that in their preferred parallel relation
the inductance p.resented to ~he outpu~ of the applicable one of
the circuits o.E I?i~s. 4 and 5 is 2500 microhenries.
The flexible intexconnection of units S0-51 also includes .
articulating strap means, as of ~elcro material, to enable
,
s~mple adapt~tion to t~e dimensional requirements of each
patient's particular.circumstances. Thus, unit 50 is shown
with a ~irst such strap element 60 secured to its back panei .
20 53 and having a ~ree end e~tending a distance Ll to one laterai
side of unit 50; similarly, unit-51 is shown with ano~her strap
element fixed.to.its.back panel and having a first free end 61
of leng~h Ll extending laterally for adjustable overlapping
connection to t~e free end of strap 60. The opposite end 62
of the strap carried by uni-t 51 is also free but of substantiall~
greater length L2, -to permit.full circumerential completion of
the strap connection as the means of removably applying both
units 50~51 to the body-member treatment region; preferably,
the length L2 is sufEicient to enable the ~elcro-material
region 63 at the inner or front face of the free end 62 to
.
-2~~ . .
1 ~ ~)75~7
circumferent:ially envelop the body member and to enable Tegion
63 to have removable velcro engagement with a suitably equipped
back surface of the same strap member, as at the region of its
fixed mounting to the back panel of uni~ 51.
The coils 58 are shown to be of generally elliptical
configuration. These coils should be of sufficiently large in-
ternal dimensions, in relation to their ultimately installed
positioning for bone treatment, as to assure relatively uni-
formly distributed concentrated flux within the treatment zone.
Elementary principles and preferred dimensional relationships
for a two-coil flux-aiding circular configuration will be later
discussed, with a view to minimiæing the establishment of stray-
flux lines between the two coils. It suffices here to point out
that by employing the cylindrically concave-convex configurations
described for panels 52-53, the coils 58 are necessarily also
conformed to a geometrical shape which is cylindrically arcuate~
the major-axis direction of the ellipse being parallel to the
axis about which each coil 58 is cylindrically arcuate. Thus,
when units 50-51 are positioned for body treatment, the concave
sides of both coils 58 are in face-to-face relation, with the
minor-axis spaced coil regions m-n of unit 50 in closer adja-
cency to the corresponding minor-axis spaced coil regions m'-n'
of unit 50 than is the case for coil-to-coil spacing of corre-
sponding major-axis spaced coil regions ~-q and ~-q'; as a re-
sult of this relation, any tendency to establish stray-flux
lines between corresponding minor-axis coil regions m-n' and
m'-n is minimized.
-
S~ecific use of the body-treatment device of Figures 7 and
7A will be more clearly understood through additional reference
- 29 -
:````~
l 157~7
to E~igs 9 and 10, utilizing a locating-block or keying
device ~sho~m in Fi~. 8) which may be expendable and of
suitable molded plastic such as polyprop~rlene. The
locating device of Fi~. 8 comprises a rectangular-
prismatic block 65 which is dimensioned ~or removablelocating reception in the rectangular recess formation 57
that is c~ntral to the concave panel 52 of unit 50.
Integrally formed ~Jith and extending in opposite longi-
tudinal directions Erom the base o prism 65 are elongate
mounting strips ~,fi which'are relativel~ sti~ly'compliant
for slight bending adaptation to particular body or cast
configurations. ~iso, the'thickness and material of strips
66 should be s-~ch as to permit sheared cut o~f to shorter
length, as may be needed ~or s~me applications. A pressure-
sensitiye tape 67 r which may incorporate metal foil, wire orother material opaque to radiological irradia-tion is shown
to be ~emova~l~ adhered to the peripheral edge of block 65.
- In the initial stages of use of the device of Fis. 7,
.
i.e., during the period in ~ich the separate halves o~ a
bone breaX or non-union are to ~e'fixedly retained ~or electro- '
'magnetically induced ~reatment of the invention~ the afflicted
limb, for example, the leg''70 of-Fig. 9,' is irst placed in a '
c~st 71 ~hich overlaps the afflicted region. The leg is then
placed on a tahle 72 so that t~e afflicted region can be viewed
under radiological irradiation, schematically designated by an
arrow, with the legend "~~Rays", instantaneous and current
viewing being provided by suitable video-scannin~ and display
means 73-7~. The device of FLg. 8 is then placed upon a local
region of the cast 71 such that the opaque periphery of prism
65 is viewable at 7~ as a rectangular frame, surrounding the
.
~30-
l :157527
central 7,0ne of the bone-brea~ or non-union region to be treatecl.
~7nen the opaque fr~me is seen in the displ~ in proper surround-
in~ registry with the aflicted bone region, i.e., after such
positioning adjustments as may be needed to assure such registry,
the strip ends 66 are fastened to the c~st 71, as by means of
adhesive taoe su~gested at 68. The cast 71 may then be further
develo~ed over the strip ends 66 to assure permanence of the
locating prism as a fixed part of cast 71. When prism 65 is thus
fixea to cas, 71, strip 67 may be removed and discarded, and the
patie~t i5 ready for the device, of Fig. -7, which is assembled by
first locatin~ ~i.e., keying~ unit'50 vla recess 57 to the prism
65, by then adjustiny t~e ~elcro overlap 60-61 to position uni-t
51 in diametrically opposite relation to unit 50 (on the other
' side of cast 711, and'~y then using the strap end 62 or comple-'
tion and securincJ o-f the'circum-ferential overlap described for '
the inner-sux~ace region ~3. The electrical'connection is then
comoleted at 24-26, and treabment may commence in the manner
- already described. It should be noted that, if the surface of
the conca~e panel of each unit 50-51 is not soft-textured, -there
may ~ a tendency to generate chal~ dust upon local mechanical
fretting of the cast 71, with repeated assembly and disassembly
o units 50-51 thereto.' Such fretting can be minimized by adher-'
ing a oam~d-plas-tic or the like yieldable liner'to -the concave'
panel of one or both units 50-51) such a liner being shown at 75
in ~ig. 10. Still ~urther, the use of a foamed-plas-tic liner wil
assure greater patient comfort while frictionally contributing to
stable p'l~cement and retention of the trea~ment coils.
Fig. 11 depicts a body-treatment device which is
a 7~ c ~
- particularly suited to the treatment of bone a~lic~sn in
the regio~ o~ the heel. For simplicity in Fig. 11, the sho.~ing
- is limited to relatively rigid structural comoonents~ and the
., . `
~ -31-
~ 15~527
foamed-plastic lining carried by such st:ructure for patient
comfort (i.e., to avoid chafin~ has been omitted. Basically,
the rigid structure of Fig. 11 comprises a tubular shell 80,
as o meth~lmethacr.ilate, being open at its longitudinal ends
and locally open at 81, over an angular span (about ~he shell
axis) and intermedia-te the longitudinal ends of shell 80. An
"S"-shaped strap 82, which may be of -the same material as shell
80, has its upp._r end secured at 83 to the back end of shell
B0, at oDening Bl, and i~s lower end 8~ ex~ends along the
10 diametrlcally opposite region of.the inner surface of shell 80,
to define a plate for basic support oE the bottom of a foot 85,
to be inserted vi~ the opening 81. The respective courses of
two arcuately cuxved ellip~ical coils 86-86' are schematically
indicated by heavy dashed lines. These coils will be understood
lS to be ~onaed to shell 80 in vertically opposed relation, the
upper coil 86 beinct bonded to the inner surface of shell 80,
just inslde -~he edge of opening 81, and the.lower coil 86'
being similarly bondea at the diametrically opposite location.
Coils 86-86' thus have a permanent relation to each other~
much the same as described for.the coils 58 of units 50-51 t ,
. .
once the latter.are in body-assembled relation; and it will be
understood ~hat coils 86-86' are preferably electrically . .
connected in parallel~ in flux-aiding polarity; being exci-ted
b~ one or the other of the ener~izing circuits o~ Figs~ 4 and 5. .
Xn addition to the described coil-positioning and foot-
suppor~ing structure, the device of Fig. 11 includes side-bumper
guards 87-88 ~hich may be bowed strips of the same pla~tic
material as shel~ 80, suitably bonded at hoth ends to ~he
respecti~e longituainal ends of shell B0~ Strips 87-88 are
prcferably stiffly yieldable, to cushion the treated region
- -32- .
1157~
fro~ mecr.anical shoc~ in ~he event o~ un-~itting contact
witn furni-ture or other objects.
Fig. 12 is a simplifled dia~rt~m similar to Fig. 11
to illust~ate ano~her body-treatment device, configurated
for ap?lication to an af~licted ankle region, or to a lower
tibia/~emur region. Again, the basic riyid structure is
seen LO com~rise a tubular shell 90, as of suitable plastic.
A single local side-wall opening 91 in shell 90 has a straight
lo-.~er edge, contiguous -to a bottom plate or rest 92 which
diametrically spc~ns .the`lower end oE shell 90. ~pposed
electrical coils 93~94 are bonded to the inner sur~ace o~ .
shell 90 a L an e.~evation suc~ that the alignment 95 of their
centers OL symmetry ~ill geometrically intersect -the center
. OL the aLlicted region, preferably as con~irmed by X-ray
observation on the alignment 95. The configuration o coils
~3-9~ may be circular or elliptical, but is preferably
cylindrically arcuate, in con~armance with the loca- shell
~urface to which each of them is bonded; in the event o
elli~tical coil conigurations, the major-axis orien-tation
is preLerably vertical, consistent with the discussion above
as to coils S8 in Fig. 7. Interconnection and excitation o~ .
coils 93-9~ is as described for other two-coil devices.
It ~Jill be seen that the described devices and techniques
represent major advances in surgically non-invasive treatment
of body cells, particularly as they may be involved in bone
repair and healing~ ~lith respect to the body~treatment devices
hich have been desGribed, we have not yet established -the full
range of di~ensional limi-tations, but certain beneicial ranges
can be described in general terms, particularly for dual-coil
e~bodime~ts, illus-tratively disclosed in connection wi-th Figs.
7 to 12.
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11575~7
On an elemental basis, it is convenient to consider
the circular~coil situation depicted in Fig. 13, wherein
li~c circular coils ~-~ of inside diameter Dl are positioned
on a co~non central axis of symmetry, at parallel p].anes
which are spaced apart b~ the distance S, and wherein the
coils A-B are e~ci-ted in flux-aiding relation. If the . .
spacing S is sufficiently small .in relation to the diame-ter
Dl, then substantially all flu~ lines within coils ~-B will
extend continuously therebetween, on a ~enerally straight
alignment whicll may even neck down as suggested by the profile
96. If the spaoi~c~ S is greater (again in relation to the
diame~er Dll, some stray-flux lines 97 will develop, to ~ e
detriment of the development of uniform hlgh-density flux in
-the central span S. Generally, in view of the necking down
.15 (96~, and in v.ie~ o~ the treabment ~one being genexally at
the center of span S, it is convenient to ~onsider the coils
A-B as being desirably effective in producing the un~form
~lux distrl~ution over an imaginary cylinder 98 of diameter
D2, tangent to the neck-down profile 96. From our experience
to date, we can state that for body applica-tion of the ch~rac~er
presently described, the span S.should.be equal to ox less than
~he diameter Dl, and o~ course D2 (the efEec-ti~e diameter o~ ~he
zone of body treatment~ will always be considerably less than Dl,
being substantially e~ual to Dl onl~ when coils A-B are closely
adjacent. As a practical consideration in the application of
dual coils to the body, we consider that the nominal inside
diameter Dl of the coils should be at least 1.5 times the
diameter ~2 of the ef~ective bod~-treatment zone, and this has
been found to be a reliable approach for coil spacin~ S substan-
tially equal to the inside diameter Dl.
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1 1~7527
}laving thus conaidered criteria factors for the
simplified case of flat circular coils, it is possible
to develop general criteria applic~bl~ to elliptical
coils which ,are "wrapped" in general con-~ormance,with .
a cylindrical arc. Fig. la schematically depic~s the
- coil-58 relationship discussed for Fig. 7, wherein the -,
c~lindrical arc oE "wrapped" coil curvature is about a
central axis lO0, which is paxallel to the majox a~Yis of
the coil ellipse. And Fig. 15 schematicaily depicts a ,
coil~5~' relationship.whexein the cylindrically arcuate
curv~ture of ~he coils is parallel to the minor axis of
each coil. In bo-th cases, the typical resultant treat-
ment zone sec-tion is sugge5ted by aashed outline in the
ront vie~ tr~ig. l4a and Fig. 15a).
. 15For purposes of deducing central magnetic-fiela
distr;bution between opposed coils 58, their major-axis
. . re~ionsi (designated p-q-p'-q' in Fig. 7~ ma~ be aeemed to.
be at maximum separation Sl and their minor-axis regions,
~designated m-n-m'-n' in Fig., 72 ma~ be deemed to be a~ ,,
~20 minimum separcation S2r as viewed in Fig. 14b. :This being
;the case, ma30r-axis-region contributions to the magne~ic
field may be deemed-to-appl-y Eor the span S (of Fig. 13)
e~ual to Sl (of Fi~. 14b) in the context o:E an effective
inside diameter Dmaj which corresponds to the major axis
of the ellipse; by the same toXen, minor-axis-region contri-
butions to the magnetic field may be deemed to apply~for a
span.S~ lo~ Fig. 15~) in the context.o~ an effective inside
diameter Dmin ~hich corresponds to the minor axis of the
ellipse. For sectional considerations at planes intermediate
those of the major axes and of the minor axes/ the field ~ill.
.
.
1 1575~7
ollow distribution considerations intermediate those
controlling distribution in planes o~ the major axes
and of thc minor axes, respectively.
Reasoning applied above as to maynetic-~ield
distribution for -the ~ig. 1~ configuration can also be
applied to that of Fig. 15 r e~cept of course ~hat patterns
`Jill difer by reason of the cylindxical curvature about
an axis parallel to the minor ellip-tical axis.
The arrallCJement of Fig. 16 depicts use of t~o
gener~lly cylincir:ic~ arcua-te coils 58" trherein the
c~lindrical arc3 ~re nes'ted in spaced relation appropriate
to the des'ired ~plication, electrical connection being
again understooc1 to be or flux-aiding. The coil arrangement
of Fig. 16 will }~ ~mderstood to have appllcation over a
genexally cylinc~rically arcuate treatment zone, as in the
case of a ~aw segment or group of teeth, the latter heing
su~gested schematically at 101 in Fig. 16b. Depending upon
~he size o~ coils 58", it will be understood that they may
be retained in fixed spacing, using a suitable bracket
(suggested at 102~ ~hic~ bridges onl~ teeth in the case of
' insertion of both'coils in the mouth, and which bridges -teeth
as well as the` adjacent cheek (via the mou-th~' in the case o~
one coil inside and the other coil outside the mouth. It will
also be understood t~at for purposes of certain desired ~lux
distribution within the mouth, as for dental and/or jaw
osteogenesis, the inner coil 58" may be of smaller physical
size ~han the outer coil 58".
It will be understood that the foregoing discussion of
general principles is with a view to illustration and n~t
limitation, and that modifications may be made without de~arting
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1 1 ~7527
from the scope of the invention. For example, if for
certain purposes, it is not possible -to construct bo-th
coils of a dual-coil e~bodiment so as to completely,match
in ~eometr~ and electrical properties, as suggested above
for a dental or ja~ application, there can still be a useful
em~loyment of the` invention, using magnetic-flux distxibution ~.
hich may not be as uniform as discussed in connection with ,.
Fiss. 13 to 16, but whi'ch nevertheless,derives benefit from
the fl~L~:-aidincJ cooperation of' tt~o colls in opposite sides
o. the afflicte~l regio.n under treatment, such benefit flowing
of course from the~ e~citation of such'coils by the specially
characterized inp~lts discussed in connection with Figs. 4 to
G.
Figs. 17 to 20 are.concerned with coil configurations
applicable to'flux development along and therefore generally
parallel to,-the'longitudinal direction of a body member to be
treatea. ~n ~ig. 17,.a sin~le coil of like plural turns 105
is helically developed along the length of a supporting tubulax
member 106 of sui-table pIastic or other non-magnetic material.
20 .The turns 105 may be on the inner or the outer surface o tube
106, and the axial length of the w;nding should be such as to
overlap both longituainal ends of the bone fracture or the like'
to be treated.
In Fig. 18, a single winding is again shown carried by
one of the c~lindrical surfaces of a ~ubular member 108, but
the latter is locall~ cut at an opening 109 (as in the manner
described at 81 in Fig.. 11) tQ permit insertion of a joint
region such as the elbow, with the forearm projecting out one
axial end of tubular member 108, and with -the upper arm pro-
jecting xadially out~ard via opening lO9. The single wind~ng'
q . . .
I :l57527
is sho~.n as a firs~ plurality 110 oE helical -turns contin-
uousl~f connect~d b~ an axially e~panded t~rn 111 to a
s~cond plurality 112 of similar turns, the pluralities 110-112
being posi~ioned on opposite longitudinal sides of the opening
109 and at a spacing which is a-t least no greater -than the
effective diameter of the turns 110-112.
T'ne arran~ement of Fig. 19 is similar to that of Fig. 18
excep~ that the respective pluralities of turns 110-112 are
electricall~ connected in parallel, in flux-aiding relation.
~ central acccss port ~ill be ~mderstood -to be provided in '
, tubular member 108 at a location opposite the opening 109, to
perm~t excitation ~ir~ng connections to be provided external
to all turns, i.~, no supply lines passing within any of the
, turns at 110~112.
In the arrallclement Q~ Fig. 20, two coil subassemblies
115-116 are cons~ructed for assembly to'the,respective ends
of a longitudinall~ split compliant-supporting me~ber 117 of
non-magnetic material. The lonyitudinal split at 118 permits
a degree of-flexibility in apPlication to a body me~berr as
for example durin~ the course of its assembly past the heel
' region to a leg part to be treated. Each of -the coil sub-
assemblies is shown to be'a relatively rigid annular assembly
of a winding to apotting o~ cured hardenable material, and
formed with a counterbore 119 at which the coil subassembly
is telescopically assembled over the end of,the adjacent end
of tubular member 117. The inner end of each counterbore
de~ines an inward flange to limit coil assembly, a~d to
determine repeatably accurate spaced retention of the t~lo
coil subassemblies. Electrical connections to the coil sub-
3~ assemblies are sho~n to be parallel, and should be in flux-
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1 ~7~27
ai~ing relation, and a f-lexible-cable interconnection is
sug~ested at 12~.
It ~-ill be understood that various simplifyiny
techniques have been adopted to make for more readily
understood reference to the dra~7ings. For example, in
the riyid-frame coil-supporting embodlments of Fig5. 11,
12, and 17 to 20, it will be unders-tood that in application
to the bod~ certain cushioning liner materials such as
urethane IOam are preferably adhered to the described
structure for cc~m:Eol^ta~le enga~ement with the body at the
region of application, bu-t to have shown such liners would
only encumber the.d.rawings. Also, in connection wi~h Fig. 9,
the showing of tlle cast 71 is merely illustrative, in that
the key device 65 may be othen~ise e~ternally mounted, as for
example to an exl:ernal fixation device such as a puttee, or
to the bod~ limb itself ~i.e., without a cast, as in.latter
stages of a bone repairl, and the cast may be of materials
18 oth_r th-n plas~_r, e.g., the ~tB~isl h~owr as crthoplas_.
.
-' ~_ .
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