Apparatus for promoting healing processes

Abstract

An apparatus for promoting healing of body tissue composed of a coil arranged to be applied to the affected body part and to be connected to a low frequency a.c. source to produce a magnetic field within the region to be treated, and at least two sheet-like electrodes associated with the coil and spaced from one another, the electrodes being arranged to be located at respectively opposite sides of the region to be treated and to be connected to a source of a low frequency voltage to produce an electric field within the region to be treated at the same time as the magnetic field.

Description

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus for promoting healing processes of the type including a coil adapted to be applied to a part of the body to be treated and which is adapted to be connected with a source for a varying current with a low frequency and makes it possible to produce a corresponding magnetic field, which pervades the part of the body to be treated.

The German Pat. Specification (Patentschrift) No. 1,918,299, corresponding to my U.S. Pat. No. 3,745,995, and the German Patent Specification (Offenlegungsschrift) No. 2,115,869, corresponding to my pending U.S. application Ser. No. 241,727, filed April 6, 1972, and also the Munchner Medizinische Wochenschrift 42 (1972), pages 1814 to 1819 refer to the promotion of healing of fractured bones by a low frequency AC pervading the injured bone zone galvanically. The AC has preferably a frequency below 100 Hz and a curve form without steep leading and trailing flanks.

The AC prevading the injured bone zone can be induced by an implanted receiving coil, provided with corresponding electrodes, using a magnetic field, which is produced by a coil which is applied to the part of the body to be treated and is connected with a suitable AC generator.

Furthermore, the above-mentioned German Pat. Specification No. 2,116,869 refers to the fact that the influence of a suitably directed low frequency magnetic alternating field alone leads to an encouragement of healing processes and to enhanced vascularisation (formation of blood vessels).

SUMMARY OF THE INVENTION

One aim of the present invention is that of creating an apparatus which makes possible a still more pronounced encouragement of healing processes than the above-mentioned forms of apparatus.

This aim is to be achieved in accordance with the invention by an apparatus of the above-mentioned type which is characterised in that the coil is provided with two sheetlike electrodes which are arranged with a spacing between them and are adapted to be connected with a source of low frequency varying voltage for the production of an electric field which pervades the part of the body to be treated simultaneously with the magnetic field.

It has thus been found that the regeneration of damaged bone and soft tissue can be substantially promoted by the simultaneous application of slowly varying electricl and magnetic fields, preferably with approximately the same strength.

The sheet-like electrodes are electrically insulated from the part of the body to be treated or are so arranged at a distance from it that through the body part to be treated there flows no galvanic conduction current and instead only the displacement and polarisation current flows through the part of the body, this current being produced by the electric field between the sheet-like electrodes arranged like the plates of a capacitor.

Further developments and forms of the invention are defined in the subordinate claims.

An important feature of the invention resides in that the electric and magnetic fields, preferably having approximately the same energy content, vary with the same frequency but are shifted in phase relative to each other, the phase shift being approximately about 90.degree..

In what follows, embodiments of the invention will be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic representation of an apparatus in accordance with a first embodiment of the invention, which is especially suitable for treating extremities of the human body.

FIG. 2 is a diagrammatic representation of a second embodiment of the invention.

FIG. 3a is a diagrammatic view of a third embodiment of the invention.

FIG. 3b shows an enlarged cross-section through a marrow pin belonging to the apparatus in accordance with FIG. 3a.

FIG. 4 shows a view similar to FIG. 3a of a further embodiment of the invention.

FIGS. 5 and 6 show partly sectioned views of further embodiments of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiment of the invention shown in FIG. 1 comprises a substantially cylindrical coil 10 (solenoid coil), which can be slid over the extremity, for example a leg 12 indicated in broken lines, to be treated. On the inner wall of the coil 10, on opposite sides, two electrodes 14 are arranged, which each consist for example of a thin metal sheet material, and are provided with insulation, not shown, which prevents galvanic or conductive contact between the electrodes 14 and the leg 12 to be treated, or another part of the body. The coil 10 and the electrodes 14 are connected respectively with wires 16, only indicated diagrammatically, leading to an electrical function generator 18, which supplies a current for the supply of the coil 10 and a voltage for supply of the electrodes 14.

The current supplied to the coil 10 can be a symmetrical or asymmetrical AC or DC with superimposed AC components or it can be a pulsating current. The frequency of the AC or of the AC component of the coil current produced by the function generator 18 is preferably adjustable and lies in the range of 1 to 100 Hz for example and preferably between approximately 5 and 30 Hz. The oscillation form of the AC or AC component respectively is preferably relatively low in harmonics (for example less than 20% or 10% harmonics). The leading and trailing flanks of the AC half cycles should not be abrupt and instead should be gradual. Therefore, in contrast to a sinusoidal or triangular wave current a square wave current is undesired.

The function generator preferably comprises means for producing current characteristics or functions which are copied from physiological variations in the human body, for example the course of the movement of the ribs during breathing, the pressure characteristic or function in the lungs or the course of the pulse wave form, and more particularly the systol or a healthy, normal person.

Much the same applies for the voltage which is supplied by the function generator 18 to the electrodes 14.

Electrical circuit arrangments for the supply of voltages and currents of a complicated wave form are described in the book "Waveforms" Radiation Laboratory Series, McGRaw-Hill, New York, 1949 for example. Voltage and current functions copied from physiological functions can be produced for example by using suitably constructed sensors applied to the body and using amplifier circuits for the supply of the coils and electrodes respectively with the required current strength or voltage respectively. Finally, also signals of the desired shape can be stored on a loop of magnetic tape, which is then played back with a suitable speed and the played back signals are amplified in the manner required for supply of the coil and the electrodes respectively.

The amplitudes of the AC current and voltage are preferably adjustable and preferably have such values that the energy content of the magnetic field pervading the part of the body treated and the energy content of the electric field simultaneously pervading the treatd part of the body are at least approximately the same. The magnetic field strength in tissue can lie for example between 20 and 200 Gauss, while the electrical field strength for the treatment of tissue regions close to the electrodes can amount to approximately 0.1 V/cm to approximately 1 V/cm. For the treatment of deeper regions or parts of the body it is also possible to operate with substantially higher field strengths.

The function generator 18 can comprise setting members for simultaneous and independent variation of the amplitudes of the AC voltage and of the AC current.

Preferably the function generator 18 furthermore comprises a device which makes it possible to adjust the phase position between the AC current and the AC voltage. Preferably the AC current and the AC voltagbe and, respectively, the AC current and the AC voltage components of the current supply to the coil 10 and of the voltage applied to the electrodes 14 have a phase shift of approximately 90.degree..

The coil 10 and the electrodes 14 associated with it are preferably so constructed that the magnetic field lines diagrammatically shown are substantially parallel to the principal direction of the flow of blood in the part of the body treated or, respectively, in the longitudinal direction of an extremity being treated. The electrical fields should, on the other hand, be approximately perpendicular to the magnetic fields and therefore be generally perpendicular to the physiological orientation, for example the direction of the fibers in the bone.

The device or apparatus in accordance with FIG. 1 is especially suitable for encouraging the healing of closed bone fractures, in the case of which the repositioning fixation of the parts of the fractured bone in relation to each other) is not carried out by an operation and instead is brought about by external fixing with plaster. In the case of such fractures the duration of healing and therefore the danger of atrophic interference, more particularly in the case of older persons, can be substantially reduced.

FIG. 2 shows an embodiment of the invention with a magnetic coil arrangement 10', which comprises a number of flat coils 10a to 10f, which can be regarded as flattened cylinder coils and are connected, at their longitudinal edges running parallel to the axis of coiling, with each other in a jointed manner so that they can be applied for example externally to the torso or head and then produce an axial magnetic field in the respective part of the body. The flat coils 10a to 10f are connected electrically in series and are connected with a function generator 18, as has been explained with reference to FIG. 1.

The side, facing in a certain direction, of each flat coil 10a to 10f carries a corresponding plate-like electrode 14a to 14f, whose surface is provided with insulation coating which is not shown.

The electrodes, arranged on the flat coils 10a to 10c, are connected with a lead connected with the function generator 18, while the other lead connected with the function generator 18 is connected with the electrodes of the flat coil 10d to 10f. The electric and magnetic field distribution occurring in this embodiment of the invention is shown in FIG. 2 the magnetic field lines being represented by long broken lines and the electric field lines being represented by short broken lines.

FIG. 3a shows in section a fractured bone 20, which has been reset by means of a marrow nail 22. The marrow nail 22 comprises a receiving coil 24 (FIG. 3b) of a rodshaped ferrite core, on which a solenoid winding is arranged. In contrast to the above-mentioned known "electro marrow nails" the ends of the receiving coil 24 are, however, not connected with the electrodes on the surface of the marrow nail, which are in galvanic contact with the bone to be healed, and instead are connected with electrodes 14', whose surfaces are insulated, so that no galvanic currents can flow between them. The electrodes 14' can be embedded for example in the marrow nail, which at least for this part consists of a dielectric material.

The marrow nail 22 described is mounted as is conventional in the injured bone 20 and the injured extremity comprising the marrow nail 22 with the receiving coil 24 is then brought into the field of a coil 10 placed over the injured extremity. The coil 10 is connected with a function generator 18 of the type described with reference to FIG. 1. The voltage induced by the magnetic field of the coil 10 in the receiving coil 24 passes to the insulated electrodes 14' so that in the bone zone an electrical field is produced which runs generally perpendicularly to the magnetic field. The coil 10 can, as has been explained with reference to FIG. 1, additionally be provided with electrodes 14, which are directly supplied with a voltage by the function generator 18 and this voltage preferably has the same frequency as the AC in the coil 10, but with respect to this voltage is shifted in amplitude by approximately 90.degree..

In the case of the apparatus in accordance with FIG. 3 it is naturally also the magnetic field of the receiving coil 24 which is effective, which can therefore be regarded as an equivalent to the coil 10.

The apparatus in accordance with FIG. 4 is similiarly constructed to the apparatus in accordance with FIG. 3a and for components equivalent in function the same reference numerals have been used. In the case of FIG. 4 the fractured bone 20 is, however, not pinned or nailed and instead, since it is a question of a closed fracture, it is fixed by a plaster cast or the like. In the plaster, insulated field electrodes 14 are embedded and are connected by flexible electrical leads with the function generator. Another possibility resides in providing windows in a plaster or plastic cast and fixing the field electrodes in the windows acting as frames adjacent to the surface of the extremity to be treated so that the electrodes are separated by an air gap from the surface of the patient. The coil 10 and the electrodes 14 are supplied by a function generator 18' with a low frequency current or a low frequency voltage. The function generator 18' is synchronised or controlled in the case of this embodiment by means of a pulse receiving means 30, that is to say in the latter case the course of the AC or of the AC voltage corresponds to the pulse pressure wave. he function generator 18' can as an alternative measure also be synchronised by an electrocardiogram or controlled with respect to the curve shape.

In the case of the apparatus in accordance with FIG. 4 the pulse receiving means 30 can for example be a pressure sensor or a very low frequency microphone M and the function generator 18' can comprise the following circuit units: A pre-amplifier, whose input is connected with the pulse receiving means 30 and whose output is connected on the one hand directly with the input of a current amplifier and on the other hand is connected with an adjustable phase shifting device for connection with the input of a voltage amplifier. The output of the current amplifier supplies the magnet coil 10, while the output of the voltage amplifier is connected with the electrodes 14 it being understood that in practice there are two output leads from the voltage amplifier rather than the one shown.

FIGS. 5 and 6 show two embodiments of the present device, which comprise a pin-like body 32 with rounded ends, which can consist of a fluorine carbon polymer for example. In the body there is a substantially cylindrical shaped receiving coil 24 which can comprise a rod-shaped magnetic core which is not especially shown.

The ends of the receiving coil are connected respectively with two electrodes, which are embedded in the body 32. Preferably the surface of each electrode is insulated so that no galvanic currents can flow from it. The electrodes 24a of the embodiment in accordance with FIG. 5 have the shape of parts of the cylindrical casing and are arranged on opposite sides of the body 32. The electrodes 14b of the embodiment in accordance with FIG. 6 are annular and arranged on the body 32 with an axial spacing.

The embodiment in accordance with FIGS. 5 and 6 can be mounted in the marrow channel of a bone, for example in the case of osteomyelitis, and furthermore they are suitable for producing autologous replacement of fibers by growing round or encapsulation.

The present apparatus is particularly suitable for encouraging healing processes in and under closed skin, that is to say in the case of closed fractures and also in the case of pathological processes in tissue. The polarisation force of the electrical field has a substantial influence on the recovery of the structure of the damaged tissue, while the distribution of blood vessels within the structure is directly influenced by the magnetic field. Owing to the combination of electrical and magnetic fields the essential conditions for regeneration of a functioning structure, that is to say healing, are provided.

A further possiblity of influencing the biological processes in the tissues is based in the fact that the magnetic and/or electrical alternating field, more particularly the latter, can have DC components superimposed on it, which may possibly be so large that no reversal of polarity of the field occurs and instead a pulsating field with a predetermined polarity comes into play. In this case the function generator 18 or 18' respectively can comprise circuitry features which make it possible to superimpose on the AC supplied to the coil 10 DC preferably with adjustable amplitude and if necessary adjustable polarity and/or make it possible to superimpose on the AC voltage supplied to the electrodes 14 a DC voltage, preferably with an adjustable amplitude and polarity.

The preferred phase shift between electrical and magnetic fields can, however, also be produced by a delay member, possibly adjustable, in the function generator or also by a differentiating member, which derives AC voltage from AC supplied to the coil 10, and whose course or shape corresponds to the differential with respect to time of the AC current. The use of a differentiating member for the production of the desired phase shift between the magnetic and electrical fields is particularly suitable in the case of the use of non-sinusoidal current or voltage shapes or characteristics, for example when the course of the fields is to be adapted to a biological magnitude, for example the pulse pressure wave or systole.

Claims

What I claim is:

1. In apparatus for promoting healing processes and comprising a coil adapted to be applied to a part of the body to be treated and adapted to be connected with a source for a varying current with a low frequency for causing the coil to produce a corresponding magnetic field in the longitudinal direction of and which pervades the part of the body to be treated, the improvement comprising two sheet-like electrodes associated with said coil, disposed with a spacing between them and arranged to be connected with a source of low frequency varying voltage for producing an electric field which pervades the part of the body to be treated simultaneously with the magnetic field, said electrodes extending at least approximately parallel to the surface occupied by the windings of the coil.

2. An apparatus in accordance with claim 1 wherein the coil is composed of a number of flat coils connected to each other in a jointed manner, with at least two of said coils being provided with a respective one of said sheet-like electrodes.

3. An apparatus in accordance with claim 1 further comprising a rod-shaped body of a tissue-compatible insulating material, and a receiving coil carried by said body, and wherein said two electrodes are electrically connected to said receiving coil and extend adjacent to the surface of said body.

4. An apparatus in accordance with claim 3 wherein said electrodes are provided with an insulating surface.

5. In apparatus for promoting healing processes and comprising a coil adapted to be applied to a part of the body to be treated and adapted to be connected with a source for a varying current with a low frequency for causing the coil to produce a corresponding magnetic field, which pervades the part of the body to be treated, the improvement comprising two insulated sheet-like electrodes, disposed with a spacing between them and arranged to be connected with a source of low frequency varying voltage for producing an electric field which pervades the part of the body to be treated simultaneously with the magnetic field, a bone splint implantate member; a receiving coil arranged on such implantate member and magnetically linked to said first-recited coil, said receiving coil having terminals each connected to a respective one of said two insulated sheet-like electrodes and constituting said source of voltage.