EP0204800A1

EP0204800A1 - Methods and apparatus for investigating muscles and/or joints

Info

Publication number: EP0204800A1
Application number: EP86900196A
Authority: EP
Inventors: Colin Charles Warin
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-12-12
Filing date: 1985-12-11
Publication date: 1986-12-17
Also published as: WO1986003393A1; GB8530527D0; GB2168489B; CA1270908A; GB8431323D0; GB2168489A

Abstract

Un appareil permettant d'examiner ou d'étudier la condition des muscles et le jeu des articulations comprend une sonde (10) munie d'un plongeur déplaçable (14) qui produit des impulsions de force destinées à être appliquées à un corps. La sonde comprend un transducteur de force (18), tel qu'une cellule de charge, produisant une première onde de sortie représentant la réaction du corps à la force de l'impulsion appliquée, et un accéléromètre (24) produisant une deuxième onde de sortie représentant l'accélération du corps due à l'application de l'impulsion. Des informations relatives aux muscles et/ou aux articulations sont obtenues en traitant les deux ondes à l'aide d'un ordinateur (28) pour produire un signal de sortie dépendant aussi bien de la force que de l'accélération. L'impulsion de force présente de préférence un bord d'attaque à pente douce, par exemple sinusoïdal.An apparatus for examining or studying the condition of muscles and joint play includes a probe (10) having a movable plunger (14) which produces force pulses to be applied to a body. The probe includes a force transducer (18), such as a load cell, producing a first output wave representing the body's reaction to the force of the applied pulse, and an accelerometer (24) producing a second wave output representing the acceleration of the body due to the application of the pulse. Information relating to muscles and / or joints is obtained by processing the two waves using a computer (28) to produce an output signal dependent on both force and acceleration. The force pulse preferably has a gently sloping, for example sinusoidal, leading edge.

Description

METHODS AND APPARATUS FOR INVESTIGATING MUSCLES

AND/OR JOINTS

Field of the Invention

This invention relates to methods of and appa¬ ratus for investigating or examining muscles and/or joints.

Various electrical/electronic devices are known which purport to be able to indicate the σoridition or tone of muscles. However, these known devices have various disadvantages and are not really designed to produce the information which would be of greatest value. Chiropractors and other persons who are used to manipulating the body are able to determine by feel both the condition and tone of muscles as well as any assoc¬ iated play or yield in a joint, but this is a subjective impression. It is by exploiting these mechanical impedance properties of muscles and joints that the present invention differs fron previous devices and achieves its advantages.

In order to be able to carry out analysis or treatment it is advantageous to be able to determine variations in muscle tone and joint play both on a local level and on a gross scale. It is an object of the invention to provide a method of and apparatus for achieving this. It is a further object of the present invention to provide methods of and apparatus for inventigating muscles and/or joints whereby the operator can produce a physical record or display indicative of muscle condi¬ tion and joint play or yield. The skilled chiropractor will also be able to recognise patterns of muscle tone and joint play. With the method and apparatus of the present invention one can produce a record or display illustrative of muscle tone and/or joint play over a small or large area of the patient by taking appropriate readings at a multiplicity of sites.

It is yet a further object of the present in¬ vention to provide such a method or apparatus whereby a test procedure carried out on a patient can ^"be compared with previous investigations on the same patient so that a record of progress or deterioration can be achieved.

It is another object of the present invention to provide a method and apparatus suitable for carrying out the procedures mentioned above, in which a' sensing "gun" is used which preferably operates on mechanical or electro-mechanical principles and which can be linked up to electrical and/or electronic recording and/or meas¬ uring and/or display means.

In accordance with the present invention there is provided apparatus for investigating muscles and/or joints, comprising a pulse-generating device to be positioned in contact with a body under investigation to apply a force pulse or pulses to the body, first sensing means providing a first output representative of the reaction of the body to the force of the applied pulse or pulses, second sensing means providing a second output representative of the acceleration of the body resulting from the applied pulse or pulses, and pro¬ cessing means arranged to use said first and second outputs to provide a third output which is based upon a combination of the information in both first and second outputs and which is representative of muscle tone and/or joint yield.

Preferably, the first sensing means comprises a force transducer providing an electrical waveform output, and the second sensing means comprises an accel¬ erometer providing an electrical waveform output. Preferably, the pulse-generating device produces a pulse having a slowly rising leading edge. In a preferred embodiment, the processing means comprises computer means arranged to divide one of said first and second outputs by the other, thereby to produce said third output.

Brief description of the drawings

In order that the invention may be more fully understood, a number of embodiments of apparatus in accordance with the invention will now be described by way of example and with reference to the accompanying drawings, in which:

Fig. 1 is a block schematic diagram of a first embodiment of apparatus in accordance with the invention; Fig. 2 is a schematic illustrationof an alter- native system for generating the force pulses;

Fig. 3 is a schematic diagram of a further system for generating the force pulses;

Fig. 4 is a schematic diagram illustrating an alternative embodiment in which the transducers are separated;

Fig. 5 is a waveform diagram showing typical force and acceleration waveforms when the apparatus of the present invention is used on soft tissue; and,

Fig. 6 is an equivalent waveform diagram showing typical force and acceleration waveforms when the apparatus of the present invention is used on hard muscle or joints.

Description of the preferred embodiments

Referring first to Fig. 1, the apparatus is shown as comprising a sensing "gun" or probe which is indicated generally at 10. The sensing gun shown in the drawing is designed to be hand-held during use. The gun comprises a body portion 12 which serves as a housing for a spring-loaded piston 13 attached to a piston rod 14 which functions as a plunger. The piston/piston rod assembly is provided with latch means within the housing 12 so that the piston and piston rod can be "cocked" for subsequent release by the actuation of a trigger mech¬ anism 16. In response to actuation of the trigger mechanism 16 the plunger 14 is displaced axially out¬ wardly of the housing 12 with a stroke which is pre¬ ferably of the order of k inch (6mm). The force pulse which is generated by the act¬ uation of the plunger 14 should advantageously have a slowly rising pulse waveform, and is preferably part of a sinusoidal waveform. The force pulse generated by the plunger 14 preferably has a duration of about 0.2 sec- onds and a peak amplitude values of the order of 1 Newton. However, these figures are to be considered as examples only and the force pulse parameters may vary from the figures given and may indeed be selected in dependence upon the particular patient or upon the particular tissues or joints to be examined. In carrying out the investigation in accordance with the invention one is seeking to determine the compliance of tissue and the yield of joints. A force pulse with a slowly rising leading edge is considered to be most advantageous for this purpose. Additionally, the force pulse amplitude should not be too great, otherwise one creates such dis¬ tortion within the body that muscle mobility and joint yield cannot readily be determined.

Adjacent to the end of the gun remote from the end of the plunger 14 which contacts the patient, there is provided a force transducer 18 which measures the force exerted by the plunger against the body as the plunger moves forward. This of course is representative of the reaction force exerted by the body on the end of the plunger. The force transducer 18 may comprise a load cell, a strain guage, or other transducer mechanism appropriate to measure forces of the magnitude involved here. For example, the transducer 18 may be a mini¬ ature quartz force transducer suitable for measuring dynamic and quasistatic forces. The force to be re¬ corded acts on the quartz element within the transducer. On the occurrence of the force pulse, the longitudinal piezoelectric effect which is produced causes an elec¬ trostatic charge to be generated in the quartz element. The transducer 18 is connected by an output lead 20a to a charge amplifier 22a. The output signals from the force transducer 18 are transformed into proportional output voltages in the charge amplifier 22a.

Also mounted at the end of the sensing gun remote from the body-contact end of the plunger 14 is an accelerometer 24. The accelerometer 24 is preferably a miniature konic accelerometer, although other forms of accelerometer could be used as alternatives. An accel¬ erometer having a low resonant frequency is preferred. With force pulses having parameters of the order of magnitude referred to above, accelerations of the order of 1 g will be generated. The accelerometer 24 is connected by an output cable 20b to a second charge amplifier 22b where the output signal from the accel- erometer is similarly transformed into a proportional output voltage. The outputs of the charge amplifiers 22a and 22b are fed to an analogue-to-digital converter 26, the digital output of which is fed to a computer 28. The computer 28 can incorporate or be connected to any appropriate measuring /recording/display apparatus or instruments 29.

The sensing gun or probe 10 is preferably pro¬ vided with a depth control adjustment mechanism, in¬ dicated schematically at 30' in Fig. 1, whereby the axial stroke of the piston rod 14 can be adjusted.

Various alternatives to the particular sensing gun described above may be used. For example, the force transducer 18 and accelerometer 24 may alternatively be positioned on the plunger 14 itself, externally of the housing, instead of at the trigger end of the gun^'.^' The body-contact end of the plunger 14 may be provided, if appropriate, with a resilient end cap, for example of rubber. The accelerometer 24 may be replaced by any equivalent device which will satisfactorily measure the acceleration and damping waveforms generated by the reaction of the muscle and/or joint to the imposed force pulse. An optical detector mechanism could for example be used. It should be understood that the reference herein to "acceleration" includes also deceleration, as occurs when damping takes place.

Although the sensing gun shown in Fig. 1 is designed to be hand-held against the patient undergoing examination, one can alternatively arrange for the gun to be fixed or clamped in position so that one avoids any errors arising from movement of the operator. If the gun is to be a hand-held instrument then it should be heavy in order to increase its inertia.

Fig. 2 shows an alternative to the trigger mech¬ anism 16 for generating the force pulses. Here, a cam 30 is controlled as to its rotation by a spring 32. The -7-

cam 30 is mounted on a central shaft 34. A cam follower 36 in the form of a tappet is positioned so that it is struck by the cam 30 in its rotational movement. Rotation of the cam follower 36 initiates a linear dis- placement of the plunger 14. The force pulse waveform can thus be chosen by suitable choice of the cam profile and of the force of the spring 32 which determines the speed of rotation of the cam. If the cam 30 is detach¬ able, one can select any one of a plurality of cams. A double-acting cam can be used to cancel out kickback of the plunger. By providing the individual cams with different profiles one can select the force pulse shapes, depending upon the condition of the patient and the nature of the tissues and/or joints to be investi- gated.

Fig. 3 shows yet another method of generating the necessary force pulse. As shown in Fig. 3, the plunger 14 is displaced by the action of a solenoid mechanism 38 which is driven by an output waveform from a waveform generator 40. The waveform generator 40 may be triggered to produce an output initiating pulse by operation of a push-button 42.

Fig. 4 is a diagrammatic representation of an alternative embodiment, in which the accelerometer 24 is not mounted on the gun 10 but is separate from it. With this arrangement the force transducer 18 which is still coupled to the plunger 14 remains as part of the sensing gun, but the accelerometer 24 is in the form of a separate unit which can be positioned as appropriate on the skin of the patient. When the plunger is actu¬ ated, the force pulse is transmitted through the tissue and/or joint and the damping wave is picked up by the accelerometer 24. The arrangement can be such that the plunger 14 and accelerometer 24 are physically linked so that the two are moved over the patient as one, i.e. the plunger 14 and accelerometer 24 are maintained a con¬ stant distance apart, or alternatively the accelerometer 24 can be in the form of a roving probe which the operator can position as he wishes.

In use, the sensing gun or probe 10 is placed against a muscle and/or joint to be examined. This is so whether the gun is hand-held or is clamped in a fixed position. The firing of the gun will cause the piston rod 14 to move axially relative to the housing and thus to impart a single shock pulse to the patient. The use of just single pulses is preferred. As mentioned above, this force pulse preferably has a slowly rising leading edge and is preferably substantially sinusoidal in shape. Because the plunger 14 is in contact with the body surface, the body will react to the pulse. The force transducer 18 will measure the force imposed on the body and its output on lead 20a will represent the force pulse waveform, as shown at 50a and 50b in Figs. 5 and 6. After the force pulse is generated one is looking for information from the reaction of the body which will enable one to determine the answers to two questions. The first question is whether the muscle and/or joint moves easily, and the second question is how hard does the muscle and/or joint try to stop moving after it has begun to move in response to the force pulse. These two parameters may be thought of as mobility and damping. The reaction of the body to the force pulse is determined by the accelerometer 24, whether this is monitoring the movement of the plunger

14 directly or is sensing movement of the body at a distance from the gun, as in the system shown in Fig. 4.

The output of the accelerometer 24 on lead 20b will thus be an acceleration or damping waveform, for example of the type shown at 52a and 52b in Figs. 5 and 6. It should be appreciated that the generation of a "standard" force pulse wil result in different shapes of "force" waveform 50, depending upon the mobility of the patient at the site which is being investigated. The reaction of the body modifies the basic force pulse and is what is measured by the force transducer 18; this reaction can thus be thought of as a mobility wave. Fig. 5 illustrates typical waveforms when a force pulse is applied to soft tissue, whereas Fig. 6 shows the equi- valent typical waveforms when the same pulse is applied to "hard" material, such a a joint or a hard muscle. It will be seen from a comparison of Figs. 5 and 6 that in the case of the hard material the mobility wave 50b falls away from its peak more sharply. As will be seen from Figs. 5 and 6, the accel¬ eration or damping wave. 52a, 52b is of substantially different form when one is considering soft tissue as compared with harder material. As will be seen from Fig. 5, in the case of soft tissue, there is an initial acceleration of the tissue in the direction away from the plunger 14, followed by an acceleration in the opposite direction, back towards the plunger. In the case of harder material, as shown in Fig. 6, there is little or no initial acceleration in the direction away from the plunger, and the first indication is an accel¬ eration of the material in the direction back towards the plunger. It is emphasised that the waveforms shown in Figs. 5 and 6 are by way of example only and that the actual waveforms in any particular case will vary, depending upon the shape of the generated force pulse, and the nature of the material to which the force pulse is applied.

With the generation of a force pulse having a duration of the order of 0.2 seconds, it is desirable to record the mobility waveform 50a, 50b and damping waveform 52a, 52b over a period of about 0.5 seconds from the triggering of the force pulse. That sort of period will be adequate to enable the essential inform¬ ation contained in those waveforms to be picked up. In order to be able to provide the operator with the desired information as to the condition of the muscles and/or joints, it is necessary to process the information contained in the mobility and damping waves 50, 52 within the computer 28. The characteristics of the two output waveforms contain information which can be used objectively to determine muscle tone and/or joint play. An important feature of the present inven¬ tion lies in using the computer 28 to produce an output which is based upon the interaction or interrelationship _. of the two output waveforms 50 and 52. Analysis of the mobility waveform will give the operator a certain degree of information, and analysis of the damping waveform would also give the operator certain infor- mation. However, in accordance with the present inven- tion, it is use of these two waveforms jointly which ^• enables the operator to gain more definitive information about the condition of the muscle or joint being invest¬ igated. By the use of appropriate programmes in the computer 28, together with an appropriate data base, a comparison is made of two waveforms 50 and 52 and an output is produced which is representative of that comparison. Although the way in which the comparison of the two waveforms is carried out can be varied, accord¬ ing to particular circumstances and conditions, it is considered that division of the instantaneous values of one waveform by the instantaneous values of the other waveform will ^"provide a meaningful output which is more informative than what can be gained from a study of either waveform alone. Division of one waveform by the other will produce an output waveform with a shape whose characteristics can be used by the skilled operator to determine muscle tone and joint play. The computer 28 can also be used to make comparisons between such resultant waveforms and predetermined "standard" wave- forms. By means of the apparatus of the present inven¬ tion one can produce an output, either graphically, or numerically, or as a display or in some other way which will not only tell the operator the condition of a muscle or joint in relation to a predetermined standard but which can also be used for comparison purposes, for example by monitoring a patient's muscles or joints on a regular basis and comparing the results to indicate the improvement or deterioration in the muscles or joints.

It should be emphasised that although division of the one waveform by the other in the computer 28 is one method of obtaining useful information as to the muscles and joints, the present invention also includes other ways of processing the information from those two waveforms in order to produce a single output which is based upon information from both waveforms.

The use of a single force pulse for application to the patient is generally preferred. However, a multiple shock pulse method may be used if appropriate. Also, there may be advantages sometimes in using a steady state system with sinusoidal excitation, instead of a single shock, and in such a situation carrying out frequency analysis of the response.

The apparatus and method of the present inven¬ tion can be used not only on humans but also on animals.

Claims

CLAIMS:

1. Apparatus for investigating muscles and/or joints, comprising a pulse-generating device to be positioned in contact with a body under investigation to apply a force pulse or pulses to the body, first sensing means providing a first output representative of the reaction of the body to the force of the applied pulse or pulses, second sensing means providing a second output representative of the acceleration of the body resulting from the applied pulse or pulses, and processing means arranged to use said first and second outputs to provide a third output which is based upon a combination of the information in both said first and second outputs and which is representative of muscle tone and/or joint yield.

2. Apparatus as claimed in claim 1, in which said first sensing means comprises a force transducer providing an electrical waveform output.

3. Apparatus as claimed in claim 1 or 2, in which said second sensing means comprises an accelerometer providing an electrical waveform output.

4. Apparatus as claimed in any preceding claim, in which the pulse-generating device comprises a probe having a displaceable plunger, the movement of which causes said pulse or pulses to be applied to the body.

5. Apparatus as claimed in claim 4, in which the first and second sensing means are mounted on or are coupled in a force-transmitting manner to the plunger.

6. Apparatus as claimed in claim 4, in which said second sensing means is separate from said probe and can be positioned on the body at different positions in relation to the probe.

7. Apparatus as claimed in any preceding claim, in which the pulse-generating device incorporates a mechanically operating trigger mechanism for the initiation of the pulse or pulses.

8. Apparatus as claimed in any of claims 1 to 6, in which the pulse-generating device comprises a solenoid mechanism driving a displaceable plunger.

9. Apparatus as claimed in any of claims 1 to 6, in which the pulse-generating device comprises a spring-controlled cam or cams.

10. Apparatus as claimed in any preceding claim, in which the pulse-generating device produces a pulse having a slowly rising leading edge.

11. Apparatus as claimed in any preceding claim, in which the pulse-generating device produces a pulse having a generally sinusoidal• waveform.

12. Apparatus as claimed in any preceding claim, in which the pulse-generating device produces a pulse having a duration of the order of 0.2 seconds.

13. Apparatus as claimed in any preceding claim, which includes means to select the shape of th_ pulse produced by the pulse-generating device.

14. Apparatus as claimed in any preceding claim, in which said pulse-generating device comprises a displaceable element which has its one end for contact with the body under investigation and which has a stroke of the order of 1/4 inch (6 mm).

15. Apparatus as claimed in any preceding claim, in which said processing means comprises computer means arranged to divide one of said first and second outputs by the other, thereby to produce said third output.

16. Apparatus as claimed in any preceding claim, in which said processing means includes means to compare said first and/or second and/or third output with predetermined reference values, and to provide an output based on such comparison. - 1 4 -

17. A method of providing a physical display or record of the condition of muscles and/or joints, which comprises applying a force pulse or pulses to a body under investigation, determining the reaction of the body to the force of the applied pulse or pulses with first sensing means, determining the acceleration of the body resulting from the applied pulse or pulses with second sensing means, and using outputs from both said sensing-means to provide a third output which is based upon a combination of the information from said two sensing means and which is representative of muscle tone and/or joint yield.

18. A method as claimed in claim 17, in which the third output is produced by dividing one of the outputs from said first and second sensing means by the other.