Modification of the growth repair and maintenance behavior of living tissue and cells by a specific and selective change in electrical e

Claims

What is claimed is:

1. A surgically non-invasive method of treating living tissues and/or cells comprising electromagnetically inducing voltage and concomitant current pulses of a specific frequency-amplitude relation within said tissue and/or cells, wherein said pulses satisfy the following criteria:

(a) each pulse is composed of a positive pulse-signal portion followed by a negative pulse-signal portion;

(b) each positive pulse signal portion is composed of at least three segments, of which the peak amplitude of the final segment is no less than about 25 percent of the peak amplitude of the first segment;

(c) the duration of each positive pulse signal portion is between about 200 microseconds and 1 millisecond, and is no longer than about 1/9 the duration of the following one of the negative pulse signal portions;

(d) the repetition rate of the pulses is between about 10 and 100 Hz;

(e) each positive pulse signal portion has an average amplitude of between about 0.0001 and 0.01 volts per centimeter of treated tissue and/or cells corresponding to between about 0.1 and 10 microamperes per square centimeter of treated tissue and/or cells;

(f) each negative pulse signal portion has an average amplitude no greater than about 1/6 the average amplitude of each positive pulse signal portion;

(g) each negative pulse signal portion has a peak amplitude from which it exponentially decays to about a zero reference level, and said negative pulse signal portion peak amplitude is no greater than about 1/3 the peak amplitude of said positive pulse signal portion.

2. The method of claim 1 in which said pulses occur at a pulse repetition rate of between about 65 and 75 Hz.

3. The method of claim 1 in which said positive pulse signal portions are substantially rectangular in shape.

4. The method of claim 1 in which said pulses are inductively induced by non-invasive means within said tissue and/or cells for one or more periods during a predescribed number of days, each period lasting for at least about 15 minutes.

5. The method of claim 1 in which the average amplitude of each negative pulse signal portion is between about 0.16 and 0.5 millivolts per centimeter of treated tissue and/or cells, corresponding to between about 0.16 and 0.5 microamperes per square centimeter of treated tissue and/or cells, and in which the average amplitude of each positive pulse signal portion is between about 1 and 3 millivolts per centimeter of treated tissue and/or cells, corresponding to between about 1 and 3 microamperes per square centimeter of treated tissue and/or cells.

6. The method of claim 5 in which the duration of each of said positive pulse signal portions is at least about 300 microseconds, and the duration of each of said negative pulse signal portions is at least about 3000 microseconds.

7. The method of claim 1 in which the duration of each of said positive signal portions is no more than about 1/12 the duration of the following one of said negative pulse signal portions.

8. The method of claim 1 applied to human hard tissue.

9. The method of claim 1 applied to a human oral cavity.

10. The method of claim 1 applied to human bone.

11. The method of claim 1 applied to non-human animal hard tissue.

12. The method of claim 1 applied to a non-human animal oral cavity.

13. The method of claim 1 applied to non-human animal bone.

14. The method of claim 1 including in combination therewith electromagnetically inducing an additional set of voltage and concomitant current pulses within said tissue and/or cells, wherein the waveform of said additional set of voltages and concomitant current pulses is a repetitive sequence of pulse groups, each pulse group including a series of asymmetrical pulses; each pulse of each pulse group comprises an initial positive-pulse portion and a succeeding negative-pulse portion, each positive-pulse portion being composed of at least three segments, the peak amplitude of the final segment being no less than about 10 per cent of the peak amplitude of the first segment, each negative-pulse portion having a peak amplitude no greater than about 40 times the peak amplitude of said positive-pulse portion, the duration of each positive-pulse portion being at least about 4 times the duration of the following negative-pulse portion, each negative-pulse portion having a duration no greater than about 50 microseconds, the frequency of the pulse portions within each pulse group being between about 2000 and 10000 Hz., and the duration of each pulse group being no less than about 1/100 and no more than 1/2 of the duration of the time between successive pulse groups.

15. The method of claim 14 in which said first mentioned voltage and concomitant current pulses and said additional set of pulses are sequentially applied to said tissue and/or cells.

16. The method of claim 15, in which the sequential application comprises one or more pulses of said first mentioned voltage and concomitant current pulses in sequential interlace with one or more pulse groups of said additional set of pulses.

17. The method of claim 14, in which said first mentioned voltage and concomitant current pulses and said additional set of pulses are concurrently applied to said tissue and/or cells.

18. The method of claim 1, in which each said pulse in a given repetition period is one of a group of successive and like pulses, said repetition rate applying to the recurrence frequency of said groups.

19. The method of claim 1, in which the step of subjecting tissue and/or cells to electromagnetic induction involves selection of two electrical treatment coils, placement of said coils on opposite sides of the tissue and/or cell region to be treated, and exciting said coils in flux-aiding polarity and phase.

20. A surgically non-invasive method of treating living tissue and/or cells comprising subjecting said tissue and/or cells by electromagnetic induction to voltage and concomitant current pulses therewithin, wherein the waveform of said voltage and concomitant current pulses is a repetitive sequence of pulse groups, each pulse group comprising a plurality of asymmetrical positive and negative pulse portions; each positive portion comprising at least three segments, wherein:

(a) the peak amplitude of the final segment is no less than about 10 per cent of the peak amplitude of the first segment,

(b) each negative pulse portion has a peak amplitude no greater than about 40 times the peak amplitude of said positive pulse portion,

(c) the duration of each positive pulse portion is at least about 4 times the duration of the following negative pulse portion,

(d) each negative pulse portion has a duration no greater than about 50 microseconds,

(e) the frequency of the pulse portions within each pulse group is between about 2000 and 10000 Hz., and

(f) the duration of each pulse group is no less than about 1/100 and no more than about 1/2 of the duration of time between successive pulse groups.

21. The method of claim 20 in which each positive pulse portion within a pulse group persists for at least about 100 microseconds.

22. The method of claim 20 in which the pulse groups repeat at a frequency of between about 5 and 50 Hz.

23. The method of claim 20 in which the positive pulse portions in the pulse groups are each of an average potential of between about 0.00001 and 0.01 volts per centimeter of treated tissue and/or cells corresponding to between about 0.01 and 10 microamperes per square centimeter of treated tissue and/or cells.

24. The method of claim 20 in which said positive pulse portions each persist for at least about 100 microseconds and are each of an average potential of between about 0.00001 and 0.01 volts per centimeter of treated tissue and/or cells corresponding to between about 0.01 and 10 microamperes per square centimeter of treated tissue and/or cells, said negative pulse portions each persist for at least about 10 microseconds, and said pulse groups repeat at a frequency in the range between about 5 and 50 Hz.

25. The method of claim 24 in which the average amplitude of each positive pulse portion within each pulse group is between about 0.001 and 0.003 volts per centimeter of treated tissue and/or cells corresponding to between about 1 and 3 microamperes per square centimeter of treated tissue and/or cells, the duration of each of said positive pulse portions is at least about 200 microseconds and the duration of each of said negative pulse portions is less than about 40 microseconds, the duration of each combined positive and following negative pulse portion is no more than about 300 microseconds, and the repetition rate of the pulse groups is at least about 10 Hz.

26. The method of claim 20 in which said tissue and/or cells are treated for one or more periods during a prescribed number of days, each period lasting for at least about 15 minutes.

27. The method of claim 20 applied to human hard tissue.

28. The method of claim 20 applied to a human oral cavity.

29. The method of claim 20 applied to human bone.

30. The method of claim 20 applied to non-human animal hard tissue.

31. The method of claim 20 applied to a non-human animal oral cavity.

32. The method of claim 20 applied to non-human animal bone.

33. The method of claim 20, in which the step of subjecting tissue and/or cells to electromagnetic induction involves selection of two electrical treatment coils, placement of said coils on opposite sides of the tissue and/or cell region to be treated, and exciting said coils in flux-aiding polarity and phase.

34. A surgically non-invasive method of treating living tissue and/or cells comprising subjecting said tissue and/or cells by electromagnetic induction to voltage and cooncomitant current pulses therewithin, wherein the waveform of said voltage and concomitant current pulses is a repetitive sequence of individual pulses, each pulse comprising a plurality of asymmetrical positive and negative pulse portions; each positive portion comprising at least three segments, wherein:

(a) the peak amplitude of the final segment is no less than about 10 per cent of the peak amplitude of the first segment,

(b) each negative pulse portion has a peak amplitude no greater than about 40 times the peak amplitude of said positive pulse portion,

(c) the duration of each positive pulse portion is at least about 4 times the duration of the following negative pulse portion,

(d) each negative pulse portion has a duration no greater than about 50 microseconds, and

(e) the frequency of the pulse portions is between about 10 and 100 Hz.

35. The method of claim 34 in which each said positive pulse portions persists for at least about 100 microseconds and is of an average potential of between about 0.00001 and 0.01 volts per centimeter of treated tissue and/or cells corresponding to between about 0.01 and 10 microamperes per square centimeter of treated tissue and/or cells, each said negative pulse portions persists for at least about 10 microseconds.

36. The method of claim 34, in which the average amplitude of each positive pulse portion is between about 0.001 and 0.003 volts per centimeter of treated tissue and/or cells corresponding to between about 1 and 3 microamperes per square centimeter of treated tissue and/or cells, the duration of each positive pulse portion is at least about 200 microseconds and the duration of each negative pulse portion is less than about 40 microseconds, the duration of each combined positive and following negative pulse portion is no more than about 300 microseconds.

37. The method of claim 34, in which the step of subjecting tissue and/or cells to electromagnetic induction involves selection of two electrical treatment coils, placement of said coils on opposite sides of the tissue and/or cell region to be treated, and exciting said coils in flux-aiding polarity and phase.

38. A surgically non-invasive method of treating living tissues and/or cells, comprising electromagnetically inducing quasi-rectangular asymmetrical voltage and concomitant current pulses of a specific frequency-amplitude relation within said tissue and/or cells, wherein said pulses satisfy the following criteria:

(a) each pulse is composed of a pulse-signal portion of a first polarity and greater magnitude and lesser time duration, in alternation with a second pulse-signal portion of opposite polarity and lesser magnitude and greater time duration;

(b) the peak magnitude of said first-mentioned pulse-signal portions is no greater than about 40 times the peak magnitude of said second-mentioned pulse-signal portions;

(c) the time duration of each of said first-mentioned pulse-signal portions is no greater than about 1/4 the time duration of an adjacent one of said second-mentioned pulse-signal portions;

(d) the repetition rate of said pulses is between about 10 ad 10000 Hz., and

(e) each of said first-mentioned pulse-signal portions has an average amplitude of between about 0.0001 and 0.01 volts per centimeter of treated tissue and/or cells corresponding to between about 0.1 and 10 microamperes per square centimeter of treated tissue and/or cells.

39. The method of claim 38, in which each first-polarity pulse-signal portion is composed of at least three segments, of which the peak amplitude of the final segment is no less than about 25 percent of the peak amplitude of the first segment; the duration of each first-polarity pulse-signal portion is between about 200 microseconds and 1 millisecond, and is no longer than about 1/9 the duration of an adjacent one of the opposite-polarity pulse-signal portions; and the repetition rate of the pulses is between about 10 and 100 Hz.

40. The method of claim 38, in which the waveform of said voltage and concomitant current pulses is a repetitive sequence of discrete pulse groups, each pulse group comprising a plurality of said first and second pulse-signal portions, the duration of each pulse group being no less than about 1/100 and no more than about 1/2 of the time duration between successive pulse groups.

41. The method of claim 38, in which each first-mentioned pulse-signal portion has a duration no greater than about 50 microseconds, and the frequency of the pulses is between about 10 and 100 Hz.

42. A surgically non-invasive method of altering the behavior of living cells and/or tissues, said method comprising subjecting said living cells and/or tissue to the electromagnetic induction of a generally rectangular electrochemical information signal which controllably modifies fundamental cellular processes involved in growth, repair and maintenance when applied in predetermined time and informational sequence, said electrochemical informational signal being contained in a waveform having within said cells and/or tissues the following electrical parameters:

(a) said waveform comprising multi-segment voltage and concomitant current pulses each of which is composed of a pulse-signal portion of one polarity and greater magnitude and lesser time duration, alternating with an adjacent pulse-signal portion of opposite polarity and lesser magnitude and greater time duration;

(b) the peak magnitude of one of said pulse-signal portions being no greater than about 40 times the peak magnitude of an adjacent pulse-signal portion;

(c) the time duration of said one of said pulse-signal portions being no greater than about 1/4 the time duration of the adjacent pulse-signal portion;

(d) the repetition rate of said pulse-signal portions being between about 10 and 10000 Hz.; and

(e) said one of said pulse-signal portions having an average amplitude of between about 0.0001 and 0.01 volts/cm of treated tissue and/or cells, corresponding to between about 0.1 and 10 microamperes/square centimeter of treated tissue and/or cells.

43. A surgically non-invasive method of altering the behavior of living cells and/or tissues, said method comprising subjecting said living cells and/or tissues to the electromagnetic induction of generally rectangular electrochemical informational signals which controllably modify fundamental cellular processes involved in growth, repair and maintenance when applied in predetermined time and informational sequence, said signals each comprising at least two asymmetrical pulse-signal portions of different polarity and amplitude and time, asymmetry of said pulse-signal portions being both as to amplitude and time and to an extent of at least about 4:1, the minimum time duration of one of said pulse-signal portions being no greater than about 50 microseconds, and the minimum average magnitude of the other of said pulse-signal portions being at least about 0.00001 volts per centimeter of tissues and/or cells corresponding to at least about 0.01 microampere per square centimeter of treated tissue and/or cells.

44. Apparatus for electromagnetically treating living tissue and/or cells, comprising coil means adapted to be positioned in therapeutically beneficial proximity to the tissue and/or cells to be treated, pulse generator means connected to said coil means for exciting the same with a repetitive voltage pulse, whereby said coil means may create a varying electromagnetic field within said tissue and/or cells to thereby induce within said tissue and/or cells repetitive therapeutic pulses of electrical energy that satisfy the following criteria:

(a) each therapeutic pulse is composed of positive pulse-signal portion followed by a negative pulse-signal portion;

(b) each positive pulse-signal portion is composed of at least three segments, of which the peak amplitude of the final segment is no less than about 25 percent of the peak amplitude of the first segment;

(c) the duration of each positive pulse-signal portion is between about 200 microseconds and 1 millisecond, and is no longer than about 1/9 the duration of the following one of the negative pulse-signal portions;

(c) the repetition rate of the pulses is between about 10 and 100 Hz.;

(e) each positive pulse-signal portion has an average amplitude of between about 0.001 and 0.01 volts per centimeter of treated tissue and/or cells corresponding to between about 0.1 and 10 microamperes per square centimeter of treated tissue and/or cells;

(f) each negative pulse-signal portion has an average amplitude no greater than about 1/6 the average amplitude of each positive pulse-signal portion;

(g) each negative pulse-signal portion has a peak amplitude from which it exponentially decays to about a zero reference level, and said negative pulse-signal portion peak amplitude is no greater than about 1/3 the peak amplitude of said positive pulse-signal portion.

45. Apparatus for electromagnetically treating living tissue and/or cells, comprising coil means adapted to be position in therapeutically beneificial proximity to the tissue and/or cells to be treated, pulse-generator means connected to said coil means for exciting the same with a repetitive sequence of electrical pulses, whereby said coil means may create a varying electromagnetic field within said tissue and/or cells to thereby induce within said tissue and/or cells a repetitive sequence of therapeutic pulse groups, each pulse group comprising a plurality of asymmetrical positive and negative pulse portions; each positive portion being composed of at least three segments, wherein:

(a) the peak amplitude of the final segment is no less than about 10 per cent of the peak amplitude of the first segment,

(b) each negative pulse portion has a peak amplitude no greater than about 40 times the peak amplitude of said positive pulse portion,

(c) the duration of each positive pulse portion is at least about 4 times the duration of the following negative pulse portion,

(d) each negative pulse portion has a duration no greater than about 50 microseconds,

(e) the frequency of the pulse portions within each pulse group is between about 2000 and 10000 Hz., and

(f) the duration of each pulse group is no less than about 1/100 and no more than about 1/2 of the duration of time between successive pulse groups.

46. Apparatus for electromagnetically treating living tissue and/or cells, comprising coil means adapted to be positioned in therapeutically beneficial proximity to the tissue and/or cells to be treated, pulse-generator means connected to said coil means for exciting the same with a repetitive voltage pulse, whereby said coil means may create a varying electromagnetic field within said tissue and/or cells to thereby induce within said tissue and/or cells therapeutic pulses of electrical energy that satisfy the following criteria:

(a) each therapeutic pulse comprises a plurality of asymmetrical positive and negative pulse portions;

(b) each positive portion is composed of at least three segments;

(c) the peak amplitude of the final segment is no less than about 10 per cent of the peak amplitude of the first segment;

(d) each negative pulse portion has a peak amplitude no greater than about 40 times the peak amplitude of said positive pulse portion;

(e) the duration of each positive pulse portion is at least about 4 times the duration of the following negative pulse portion,

(f) each negative pulse portion has a duration no greater than about 50 microseconds, and

(g) the frequency of the pulse portions is between about 10 and 100 Hz.

47. Apparatus for electromagnetically treating living tissue and/or cells, comprising coil means adapted to be positioned in therapeutically beneficial proximity to the tissue and/or cells to be treated, pulse-generator means connected to said coil means for exciting the same with a repetitive voltage pulse, whereby said coil means may create a varying electromagnetic field within said tissue and/or cells to thereby induce within said tissue and/or cells therapeutic pulses of electrical energy that satisfy the following criteria:

(a) each pulse is composed of a pulse-signal portion of a first polarity and greater magnitude and lesser time duration, in alternation with a second pulse-signal portion of opposite polarity and lesser magnitude and greater time duration;

(b) the peak magnitude of said first-mentioned pulse-signal portions is no greater than about 40 times the peak magnitude of said second-mentioned pulse-signal portions;

(c) the time duration of each of said first-mentioned pulse-signal portions is no greater than about 1/4 the time duration of an adjacent one of said second-mentioned pulse-signal portions;

(d) the repetition rate of said pulses is between about 10 and 10000 Hz., and

(e) each of said first-mentioned pulse-signal portions has an average amplitude of between about 0.0001 and 0.01 volts per centimeter of treated tissue and/or cells corresponding to between about 0.1 and 10 microamperes per square centimeter of treated tissue and/or cells.

48. Apparatus according to claim 47, in which said criteria are limited in the following respect: each first-polarity pulse-signal portion is composed of at least three segments, of which the peak amplitude of the final segment is no less than about 25 percent of the peak amplitude of the first segment; the duration of each first-polarity pulse-signal portion is between about 200 microseconds and 1 millisecond, and is no longer than about 1/9 the duration of an adjacent one of the opposite-polarity pulse-signal portions; and the repetition rate of the pulses is between about 10 and 100 Hz.

49. Apparatus according to claim 47, in which said criteria are limited in the following respect: the waveform of said voltage and concomitant current pulses is a repetitive sequence of discrete pulse groups, each pulse group comprising a plurality of said first and second pulse-signal portions, the duration of each pulse group being no less than about 1/100 and no more than about 1/2 of the time duration between successive pulse groups.

50. Apparatus according to claim 47, in which said criteria are limited in the following respect: each first-mentioned pulse-signal portion has a duration no greater than about 50 microseconds, and the frequency of the pulses is between about 10 and 100 Hz.

BACKGROUND AND BRIEF DESCRIPTION OF THE INVENTION

This invention relates to the treatment of living tissues and/or cells by altering their interaction with the charged species in their environment. In particular, the invention relates to a controlled modification of cellular and/or tissue growth, repair and maintenance behaviour by the application of encoded electrical information. Still more particularly, this invention provides for the application, by a surgically non-invasive direct inductive coupling, of one or more electrical voltage and concomitant current signals conforming to a highly specific pattern.

Several attempts have been made in the past to elicit a response of living tissue to electrical signals.

Investigations have been conducted involving the use of direct current, alternating current, and pulsed signals of single and double polarity. Invasive treatments involving the use of implanted electrodes have been followed, as well as non-invasive techniques utilizing electrostatic and electromagnetic fields. Much of the prior work that has been done is described in Volume 238 of the Annals of the New York Academy of Sciences published Oct. 11, 1974 and entitled "Electrically Mediated Growth Mechanisms in Living Systems" (Editors A. R. Liboff and R. A. Rinaldi). See also "Augmentation of Bone Repair by Inductively Coupled Electromagnetic Fields" by C. Andrew L. Bassett, Robert J. Pawluk and Arther A. Pilla published in Volume 184, pages 575-577 of Science (May 3, 1974).

The invention herein is based upon basic cellular studies and analyses which involve a detailed consideration of the interactions of charged species, such as divalent cations and hormones at a cell's interfaces and junctions.

Basically it has been established that, by changing the electrical and/or electrochemical environment of a living cell and/or tissue, a modification, often a beneficial therapeutic effect, of the growth, repair and maintenance behavior of said tissue and/or cells can be achieved. This modification or effect is carried out by subjecting the desired area of tissues and/or cells to a specifically encoded electrical voltage and concomitant current, whereby the interactions of charged species at the cells' surfaces are modified. Such modifications engender a change in the state or function of the cell or tissue which may result in a beneficial influence on the treated site. For example, in the specific case of bone growth and repair, it is possible with one electrical code, hereinafter referred to as Mode 1, to change the interaction of the ion such as Ca.sup.2+ with a cell's membranes. Whereas, with another electrical code, hereinafter referred to as Mode 2, a modification in the same cell's protein synthesis capabilities can be affected.

For example, tissue culture experiments involving the study of embryonic chick limb rudiments show that the use of a Mode 1 code signal elicits enhanced Ca.sup.+2 release of up to 50% from the competent osteogenic cell. This effect is highly specific to the parameters of the electrical code of Mode 1. Thus this code influences one major step of ossification, i.e., the mineralization of a bone growth site. Similar tissue culture studies using Mode 2 code signals have demonstrated that this code is responsible for enhanced protein production from similar competent osteogenic cells. This latter effect is also highly specific to the parameters of the electrical code of Mode 2. In other words, this code affects certain metabolic processes for these types of cells such as those involved in calcium uptake or release from mitochondria as well as the synthesis of collagen, a basic structural protein of bone.

These studies show that the electrical codes of Mode 1 and Mode 2 elicit individual tissue and cellular responses, indicating that each code contains a highly specific informational content therein. Based upon these and other studies, it has been possible to utilize Mode 1 or Mode 2 signals or a particular combination of Mode 1 and Mode 2 signals to achieve a specific response required to enable the functional healing of a bone disorder. These electrical modes have been applied successfully to human and animal patients for non-healing fractions such as congenital pseudarthrosis and non-unions as well as fresh fractures. Successes achieved in the congenital pseudarthrosis cases are particularly noteworthy, since normally 80% of children thus afflicted require amputation, since conventional treatments such as bone grafting and internal fixation are unsuccessful.

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 techniques have not been uniformly successful or generally accepted within the appropriate professional community. Several reasons contribute to this state. First, it has not been realized heretofore that electrical signals of very 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 virtue of unavoidable faradaic (electrolysis) effects are often more toxic than beneficial in the treated site. Furthermore, the cells and/or tissues are subjected to a highly uncontrolled current and/or voltage distribution, thereby comprising the ability of the cells to respond, should they do so, to the applied signal. The highly uncontrolled current and/or voltage distribution also applies in the case of capacitatively coupled signals.

In contrast, the surgically non-invasive direct inductive coupling of electrical informational content of specific electrical codes as involved in the present invention produces within living tissue and/or cells a controlled response.

In brief, the present invention involves the recognition that the growth, repair and maintenance behavior of living tissues and/or cells can be modified benefically by the application thereto of specific electrical information. This is achieved by applying pulse waveforms of voltage and concomitant current of specific time-frequency-amplitude relations to tissue and/or cells by a surgically non-invasive means through use of a varying electromagnetic field which is inductively coupled through direct induction into or upon the tissue and/or cells under treatment. The information furnished to the cells and/or tissues by these signals is designed to influence the behavior of non-excitable cells such as those involved in tissue growth, repair, and maintenance. These growth, repair and maintenance phenomena are substantially different from those involved in excitable cellular activity (e.g. nerves, muscles, etc.), particularly with respect to the type of perturbation required. Thus, the voltages and concomitant currents impressed on the cells and/or tissues are at least three orders of magnitude lower than those required to affect cellular activities such as cardiac pacing, bladder control, etc.

The invention will be more completely understood by reference to the following detailed description:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified view showing the treatment of a bone in accordance with the invention.

FIG. 2 is a perspective view of the treatment unit shown in FIG. 1.

FIG. 3 is a view (from the rear) of the unit shown in FIG. 2, showing the positioning of a coil therein used for treatment purposes.

FIG. 4 is a block diagram of an electrical system for energizing the coil shown in FIG. 3 for Mode 1 treatment.

FIG. 5 is a block diagram of an electrical system for energizing the coil shown in FIG. 3 for Mode 2 treatment.

FIGS. 5a and 5b are pulse waveform diagrams for Mode 1 and Mode 2 treatments, respectively, showing presently referred pulses as induced in living tissues and cells.

FIG. 6 shows alternative forms of negative pulse portions for Mode 2 treatment.

DETAILED DESCRIPTION

Referring to FIGS. 1 to 3, the leg 10 of a person having a broken bone as indicated as at 12 is shown as representative of the application of 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 strapped in place by use of a strap 16 (secured to head 14 by fasteners 16a) which may include velcro material 18 thereon so that the strap may be wrapped 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 interior 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. As shown in FIG. 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 energizing circuit, as will be explained below in more detail. A diode 27 may be included within the cable 26 for connection across the coil 22, as will also be explained below.

The treatment head 14 is positioned on the patient so that the "window" formed by the coil 22 is adjacent the break 12, i.e., adjacent the tissue under treatment. The coil 22 is energized, as will be explained in more detail below, and induces an electrical potential within the tissue under treatment. It has been found that a particular type of signal should be induced within 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. 5b.

Referring to FIG. 4, a variable dc supply 30 is coupled through a gate 32 to the treatment coil 22 (or coils as the case may be and as will be explained in more detail below). The gate 32 is under the control of control units 34 and 36 which cause a pulse signal consisting of repetitive pulses of electrical potential to be applied to the treatment coil 22. Each pulse, as shown in FIG. 5a, is composed of a "positive" pulse portion P1 followed by "negative" pulse portion P2 because of the stored electrical energy within the treatment coil. In the circuit of FIG. 4, a diode clamping unit 38 may be employed to limit the peak potential of that negative pulse portion. The diode clamping unit 38 may be one or more diodes connected across the coil 22, and may be advantageously located within the cable 26. The diode 27 shown in FIG. 1 constitutes such a clamping unit 38.

In FIG. 5a, the signals at the treatment coil 22 and hence the induced signal within the tissue to be treated are shown. At time t1, it is assumed that gate 32 is gated on by an appropriate signal from control unit 36 (designated a pulse width 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 v1 in FIG. 5a. The signal across the treatment coil decays in a second pulse segment along the portion of the curve designated 40 in FIG. 5a. The slope of that curve is determined by the L/R time constant of the circuit of FIG. 4, i.e., the inductance of the treatment coil and the effective resistance of the circuit, including distributed factors of capacitance, inductance and resistance. For treatment of many tissues and cells, it is believed desirable to adjust the circuit parameters so that the portion 40 of the curve is as flat as possible, rendering the signal applied to the treatment coil 22 as rectangular in shape as possible. At the time t2, the gate 32 is gated off by the control unit 36. Just prior to being gated off, the signal across the treatment coil is at the potential v2 shown in FIG. 5a. The potential across the treatment coil drops from the level v2 in a third pulse segment 41 to a potential of opposite polarity designated v3 in FIG. 5a. The magnitude of the opposite polarity potential v3 may be limited by the diode clamping unit 38 to a relatively small value as compared with value v1.