JPH078565A - Magnetic stimulator for bone disease treatment - Google Patents

Abstract

(57) [Summary] [Object] To provide a magnetic stimulator for treating bone diseases, which can effectively prevent decrease of bone mass or increase bone mass with smaller energy. A coil means placed near the surface of a living body, a power source means for supplying a current to the coil, and a current control means for changing a current supplied to the coil, and a change in current in the coil In a magnetic stimulator for treating a bone disease in which a bone is stimulated by an eddy current generated in a living body by a fluctuating magnetic field generated by the current controlling means, the current control means generates a fluctuating magnetic field of substantially sinusoidal wave of 5 Hz or more and 100 Hz or less. There is provided a magnetic stimulator for treating a bone disease.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for treating a bone disease, and more specifically, a sinusoidal electric current is applied to a coil placed on the surface of a living body to generate an in-vivo magnetic field. The present invention relates to a bone treatment device that stimulates bone by eddy currents generated in the bone and promotes bone formation.

[0002]

2. Description of the Related Art Bone is modified through bone resorption and bone formation, but it is known that the balance between the two is lost and the bone mass is reduced with aging. It is known that such a decrease in bone mass is also caused by a rapid change in hormone secretion due to menopause or the like in women. Such an abnormal decrease in bone mass is called osteoporosis, in which bone strength is significantly reduced and a slight impact causes a fracture. The fracture due to osteoporosis lowers the quality of life of the patient and is more likely to be bedridden, and is becoming a major social problem.

In order to prevent the decrease in bone mass and maintain high bone strength, drugs for suppressing bone resorption or promoting bone formation have been actively developed, and various drugs have been clinically applied. There is.

However, in the administration of these drugs,
There is so-called tolerance that the effect gradually decreases with long-term administration, or the onset of the effect is slow,
Once loss of bone density occurs, the risk of bone fractures continues for a long time during the treatment. Further, in the case of administration of a drug, side effects may be observed, or in some cases it may not be possible to administer a sufficient amount due to the occurrence of side effects.

[0005]

DISCLOSURE OF THE INVENTION The present invention is intended to avoid the risk of fracture due to the reduction of bone mass, and to reduce the bone mass of a site which is easy to fracture without side effects in a short time. It is to provide a device for increasing the number.

[0006]

The occurrence of bone fractures in patients with osteoporosis is strongly correlated with bone density (eg, SL Hui et al., J. Clin. Invest. V).
ol. 81 P1804 1988), one of the means for avoiding the risk of fracture is to maintain a high bone density and to promote bone formation and increase a lowered bone density.

As a result of extensive studies on a method for achieving the above object, the present invention focuses on the fact that bone tissue affects bone metabolism in response to a weak electric current, and fractures due to a decrease in bone mass. When the facilitated part is placed in a weakly varying magnetic field, eddy currents generated in the body stimulate bone tissue to promote bone formation and prevent bone loss or increase bone mass. It is an attempt to find and provide a device which fulfills such a condition and thereby avoids the risk of fracture.

That is, according to the present invention, coil means placed near the surface of a living body, power supply means for supplying an electric current to the coil,
A device for treating a bone disease which has a current control means for changing a current supplied to the coil and stimulates bone by an eddy current generated in a living body by a fluctuating magnetic field generated by a change in the current in the coil, The present invention provides a magnetic stimulator for treating bone diseases, characterized in that the current control means generates a substantially sinusoidal fluctuating magnetic field of 5 Hz or more and 100 Hz or less.

In the magnetic stimulator of the present invention, the coil means is composed of two coils installed so as to form a Helmholtz coil pair, and a living body part to be treated can be placed inside the coil pair. Included is a magnetic stimulator, which is arranged in a position.

The apparatus of the present invention further includes a magnetic stimulator in which the current control means can change the frequency and intensity of the substantially sinusoidal current flowing through the coil regularly or irregularly.

According to the magnetic stimulator of the present invention, the bone density is lowered and the fracture risk is high in osteoporosis patients. The fracture sites (radial distal end, femoral neck, lumbar spine, etc.) A fluctuating magnetic field consisting of a sine wave can be given, and the eddy current generated thereby stimulates the bone at the fracture-prone site to reduce bone loss, or promotes bone formation, thereby reducing the risk of fracture. Can be reduced. Further, by using a substantially sinusoidal wave, a conventionally well-known inexpensive pulse generator can be used for the current control means, so that the structure of the device can be easily simplified.

The present invention will be described in more detail below with reference to the drawings if necessary.

The magnetic stimulator used in the present invention is basically a coil for generating a eddy current in a living body by a power supply means for supplying a varying current to the coil and a magnetic field varying by the varying current. And means for controlling the current supplied to the coil system.

The power source means may be any means capable of outputting a sine wave of 5 to 100 Hz. The coil for generating the magnetic field may be a single coil, but a coil in which two coils are installed so as to form a Helmholtz coil pair is preferably used.

FIG. 1 is a block diagram schematically showing the configuration of one embodiment of the magnetic stimulator of the present invention. In the figure, a sine wave having a constant, regular, or irregularly varying frequency is output from the sine wave oscillator 2 in accordance with a setting from the control unit 1. Frequency range is 100Hz or less, which is highly sensitive to living organisms, preferably 50Hz
Use the following:

The frequency is 100H in consideration of chronaxie.
z or less is preferable, and 5 Hz or more is preferably used in order to secure the strength of the fluctuating magnetic field and thus the strength of the generated eddy current. When the frequency is 5 Hz or less, the rate of change of the current flowing through the coil is small, the intensity of the fluctuating magnetic field generated is small, and the eddy current generated corresponding to the rate of change of the fluctuating magnetic field is also small, so 5 Hz or more is preferably used.

The amplifier 3 amplifies the signal from the sine wave oscillator while changing it constantly, regularly or irregularly according to the setting of the control circuit 1. The amplified substantially sinusoidal voltage is supplied to the coil 4. The coil uses a single coil or a pair of coils configured to form a Helmholtz coil pair as required.

The strength of the fluctuating magnetic field used in the apparatus of the present invention is 0.03 to 0.5 millitesla (0.3
It is desirable that the strength of the varying magnetic field can be adjusted according to the coil diameter by the number of turns of the coil and the supply voltage.

The intensity and frequency of the fluctuating magnetic field may be constant throughout the treatment period, or may be changed regularly or irregularly. Therefore, it is desirable that the current control means has a function for that purpose.

As the coil means to be used, for example, when the treatment control is the distal end of the radius, a single coil may be used because the bone position is close to the body surface. When treating the femoral neck or lumbar spine, the strength of the magnetic field generated by a single coil is attenuated, and a strong fluctuating magnetic field is required to obtain the required current density at the treatment control position. As such, it is preferred to use coil means capable of forming a Helmholtz coil pair and having the site to be treated placed within the coil pair.

In the apparatus of the present invention, it is possible to add a lamp for indicating energization, a timer for displaying the treatment time or the remaining time of a predetermined treatment time, and an alarm device for displaying an abnormality such as disconnection of a coil.

When the device of the present invention is used, there is no problem to use it together with the conventionally known administration of a drug for improving bone mass. By the combined use of both, the effect of the drug for improving the whole-body bone metabolism, and the effect of improving the bone density of the present invention, which is concentrated in a portion with a low fracture, can obtain a larger risk of fracture avoidance. I can.

Animal experiment examples using the apparatus of the present invention will be described below. As a method of stimulating a living body with an eddy current generated in a living body by applying a pulsed magnetic field from outside the living body, there is a bone stimulating device for treatment of intractable fracture. In this conventionally known method, for example, Japanese Patent Publication No. 58-4311
A rectangular asymmetric pulse is used as disclosed in US Pat. According to this technique, a pulse train (pulse burst) in which dozens of pulses having a frequency of several kHz are connected
st), or a single pulse is preferably used.

In order to compare the magnetic stimulation method using the pulse train with the magnetic stimulation method using the device of the present invention,
Ovariectomized rats were placed in a plastic container and magnetic stimulation was performed using a Helmholtz coil consisting of a coil having a diameter of 350 mm set outside the container.

In the magnetic stimulation method using a pulse train, a burst in which 20 rectangular waves each having a pulse width of 250 microseconds are continuously provided at 15 Hz. In the magnetic stimulation method using the device of the present invention, a 20 Hz sine wave was used. In order to obtain the same magnetic field strength (50 micro terraces), the pulse train method requires a 24 V power source, whereas the method of the present invention requires 5 V or less.

After stimulating once a day for 30 minutes each for 12 weeks, the tibia was extracted and their bending strengths were compared. The rats in the control group that had undergone ovariectomy and were not magnetically stimulated
It was stored in the same plastic container for the same time.

A decrease in bone strength was observed in each group, but the rate of decrease was small in the magnetic stimulation group, and the decrease was about 30% in the stimulation group using the pulse train method. On the other hand, in the group of methods using the sinusoidal fluctuating magnetic field of the present invention,
The reduction was reduced by 60-70% and the reduction in bone strength was only about 3% of the bending strength of untreated rats.

That is, in the magnetic stimulation using the pulse train, by stimulating the living body with an eddy current, the decrease in bone mass due to the ovariectomy can be suppressed, but with the sinusoidal stimulation by the device of the present invention, it is small. Highly effective in energy.

Generally, it is known that a load applied to bone is required for bone formation, and that bone density decreases unless a load is applied. It is also said that bone tissue has a piezoelectric property, and an electrical signal is generated by a load applied to the bone tissue in a living body, which serves as a signal for bone formation.

The method of applying a weak electric current to the bone is used for the treatment of refractory fractures / prolonged fractures, and fusion is achieved by applying a direct current or pulsed electric current to the fracture site. The mechanism of action is unclear.

The fluctuating magnetic field obtained by the method using the device of the present invention produces an eddy current in the living body by the change of the magnetic flux, and stimulates the bone tissue by the eddy current, thereby affecting the bone metabolism, It is possible to prevent decrease in bone mass or increase bone mass.

[0032]

The fluctuating magnetic field generated by the device of the present invention produces an eddy current in the living body, and stimulates bone tissue by this eddy current to effectively promote bone formation and reduce bone mass. It can prevent or increase bone mass.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating the configuration of a magnetic stimulation apparatus of the present invention.

Claims (3)

[Claims] 1. A coil means placed near the surface of a living body,
Power source means for supplying a current to the coil and current control means for changing a current supplied to the coil are provided, and bone is generated by an eddy current generated in the living body by a fluctuating magnetic field generated by a change in the current in the coil. In a magnetic stimulator for treating a bone disease that stimulates bone, the current control means generates a substantially sinusoidal fluctuating magnetic field of 5 Hz or more and 100 Hz or less. apparatus. 2. The coil means is composed of two coils arranged in a Helmholtz coil pair, and is arranged so that a living body part to be treated can be placed inside the coil pair. The magnetic stimulator of claim 1. 3. The magnetic stimulator according to claim 1, wherein the current control means can change the frequency and intensity of the substantially sinusoidal current flowing through the coil regularly or irregularly.