WO1986003392A1 - Device for determining the mobility of body limbs - Google Patents

Abstract

In order to determine the mobility of body limbs, their position is measured by means of ultrasonic transmitters (1) and receptors (2, 3, 4), disposed partly on the body and partly spatially fixed in the different coordinate axes, based on the measure of the pulse delay. In order to prevent the measures of the pulse delay from interfering with one another, said measures are taken in succession, e.g. so that the pulses of all the ultrasonic transmitters are reciprocally and cyclically time-shifted. Interference and resonance effects are avoided since the frequency ratios of the pulses provided by the ultrasonic transmitters form a prime number sequence.

Description

Device for determining the mobility of body parts

The invention relates to a device for determining the mobility of parts of the body by measuring the position with the aid of field-generating and receiving devices which are partly fixed to the body and partly fixed in space.

Measurements of the human movement system are currently mainly used as excursion measurements, i.e. Measurement of the end position mobility of various joints (e.g. hips, knees etc.) carried out. The end position movement is measured or determined with the aid of a measuring circle (or magnetic needle or gravity needle). This procedure is very rough, since only a few defined (standardized) end positions are noted. It is therefore not possible to record the entire end position mobility.

The dynamic movement in terms of quality and quantity in all possible directions of movement (hips: eg rotation, flexion, extension, adduction, abduction or combination of these movements) can currently only be achieved by very expensive, apparatus-intensive processes. consequences. These methods are therefore almost only accessible to research and are unsuitable for further dissemination, for example in the practice, hospitals, etc. The current measurement methods use, for example, two or more video cameras with correspondingly complex electronic data processing or light scanner methods using rotating mirrors or other moving light (also laser light) with recording of the light signal by special cameras or reflector systems with photosensitive elements.

These systems sometimes require correspondingly large examination rooms and are only able to restrict three-dimensional secondary movements, e.g. of the head.

It is known to monitor the movements of bodies using fields. For example, DE-OS 1 541 180 has disclosed a method and a device for postoperative monitoring of patients, the patient being exposed to a high-frequency radiation field, the changes in the radiation field caused by the patient's body movements being indicated optically or acoustically will. A device described in DE-OS 2 715 106 with a field generator, which generates a defined irregular field, the position of which in space is detected by a large number of sensors, is used to detect changes in location and position of a rigid body. In particular, magnetic fields are used for this purpose and Hall generators are provided as sensors.

All these known devices only allow a one-dimensional and imprecise determination of the location and movement of the body to be examined, which would be insufficient for determining the mobility. The invention has set itself the task of accurately detecting the spatial movement of parts of the body and achieves this by determining the position of a measurement of the coordinates of one or more body areas marked by ultrasound receivers or transmitters with the aid of pulse-running time measurements between further assigned ones , spatially arranged ultrasonic transmitters or receivers is provided, with a temporal and / or frequency staggering of the individual transit time measurements serving to avoid mutual interference.

In ultrasound recordings, disturbances due to echoes and resonance phenomena often occur, which would lead to incorrect results if different components were measured simultaneously. This is avoided in the invention by the temporal or frequency grading of the individual transit time measurements assigned to the coordinates. This can be achieved either by the pulses of all ultrasound transmitters being temporally offset from one another in cyclical order, or by the fact that, according to a further feature of the invention, the pulses delivered by the ultrasound transmitters have ratios of their ultrasound frequencies that are graded according to prime numbers. This suppresses integer frequency relations and corresponding resonance phenomena.

As an exemplary embodiment of the invention, the drawing shows the basic structure of the devices and the basic circuit diagram of a device for measuring the position of body parts, which is particularly suitable for determining the mobility of these body parts.

On this part of the body, which is not shown in the drawing itself, a microphone 1 with a spherical characteristic is attached, which advantageously consists of a bundle of individual microphones oriented in different directions. The arrangement shown permits the detection of all movement components by the interaction of three spatially arranged ultrasound transmitters (transmitters) 2, 3 and 4 radiating in different directions of the room with the microphone 1, in such a way that the ultrasound transmitters 2, 3 and 4 Send out short ultrasonic pulses, the transit times of which are measured on the way from the respective ultrasonic transmitter to the microphone 1, after which the distances of these paths are calculated from these time measurements.

The circuit used to generate the ultrasonic pulses and to evaluate the received pulses is delimited by dashed lines.

A microprocessor 5, which is controlled by a clock generator 6, is used to control all of these processes. From the clock frequency of the clock generator 6, the ultrasonic frequencies required for the operation of the ultrasonic transmitters 2, 3 and 4 are obtained with the aid of frequency dividers 7, 8 and 9. In order to avoid mutual interference of the ultrasound signals by echoes or resonances, these frequencies are in prime numbers to one another. The. Alternating voltages with the frequencies obtained in this way are fed to the signal inputs of three switching amplifiers 10, 11 and 12, which are only switched through briefly to emit pulses (wave packets). These connections are carried out as a function of a control carried out by the microprocessor 5 and in such a way that the switching amplifiers 10, 11 and 12 actuate the ultrasonic transmitters 2, 3 and 4 in cyclical order.

The sound pulses emitted by the ultrasound transmitters 2, 3 and 4 are received by the microphone 1 with the corresponding delay delays. The electrical signals obtained therefrom by the microphone 1 are amplified broadband by means of an amplifier 13 and fed to three narrowband frequency filters 14, 15 and 16. Connected to the outputs of the frequency filters 14, 15 and 16 are three pulse shaping elements 17, 18 and 19, respectively, which feed the pulses received by the individual ultrasound transmitters 2, 3 and 4 separately to the microprocessor 1, each of which compares individual of the received pulses with its associated triggering pulse with regard to its transit time. The distance values resulting from the transit times are also calculated by the microprocessor 1 and fed to a computer or an output unit 20.

However, it is also possible to reverse the arrangement of ultrasound transmitters and receivers shown and accordingly to attach an ultrasound transmitter to the relevant part of the body, the movement of which is to be measured, and to determine its position relative to fixed microphones. A wireless connection between the ultrasonic transmitters and receivers on the one hand and the microprocessor on the other hand would only be possible with the aid of VHF signals.

In order to move body parts with a large excursion such as Experience has shown that in these cases the use of up to 4 ultrasound transmitters at one point is necessary to ensure an upper arm (shoulder joint) or thigh (hip) a connection between the transmitter and receiver in order to achieve a uniform radiation characteristic.

For the concrete application of the device according to the invention for medical diagnosis, the following should be stated:

1. Measurement of hip mobility a) The patient lies on the back. The transmitter with a fan-shaped arrangement of 3 ultrasound transmitters is fastened over the kneecap of the bent knee and the knee or thigh is moved in a circular arc in the maximum excursion (flexion, abduction, adduction, extension). The position of the femoral head can be calculated by means of coordinate transformation and the excursion of the knee can be entered on a pie chart (similar to visual field determination).

b) The patient lies on the back. The ultrasound transmitter is attached to the knee, the extended leg is maximally adducted and abducted to determine the degree of admission or abduction. c) The patient lies on the back. The hip is bent 90 degrees, one transmission system is attached over the kneecap, the second over the ankle. From this position (knees and hips bent 90 degrees) the internal and external rotation is measured and shown in a corresponding diagram.

2. Measurement of head mobility

In order to determine the excursion and the course of movement of the head or cervical spine, the patient sits upright in a chair, 4 ultrasound transmitters (two different frequencies) are fastened in a headband or helmet. 4 ultrasound transmitters are therefore necessary in order to avoid the drop shadow when there is a large excursion option for the head, so that 2 ultrasound transmitters can be detected by the receiver system. Flexion, extension, lateral inclination and rotation can be detected by a standardized examination method.

3. Investigations of spinal movements

By attaching several transmitters (with different frequencies) in the area of the spine e.g. In the crown region, cervicothoracal, thoracolumbal, lumbosacral, movement measurements of the spine can be carried out on the standing or seated patient, with specific standardized examination methods being able to give statements about movement inhibitions of individual sections. To measure the rotation, it is necessary to attach an additional transmission system around the shoulders.

4. Measurement of the knee joint

By attaching an ultrasound transmitter over the ankle, the degree of maximum flexion and extension can be determined in the seated patient. The rotation could be measured by attaching a transmitter system in the forefoot area. 5. By attaching the ultrasound transmitter to the teeth of the lower jaw (for example by means of plastillin or tooth clamp), the biting, speaking or arbitrary movements of the lower jaw can be measured with the head fixed. A further optimization of the measurement result can be achieved by using two ultrasound transmitters on the front and outside of the lower jaw (approx. 3rd and 4th tooth on both sides).

6. In order to be able to register gait sequences, an individual system can be attached to each foot (e.g. via an archilles tendon), which means that the gait sequence can be recorded precisely in terms of quality and quantity over a longer walking distance (corridor).

The device according to the invention is characterized in that only a receiver system that is easy to install in the room is necessary and that the sensor or sensors can be easily attached to the corresponding parts of the body.

The peculiarity of the entire system lies in the fact that an automatic standardized evaluation and graphical representation of the respective measurement results can take place by means of special user programs for data processing, so that the examining doctor only has to enter the type of examination (for example hip), the sensor on The knee is fastened and the measurement result is automatically evaluated, for example with additional information, such as the length of the thigh, etc. In the case of active movements, ie movements carried out by the patient, an analysis of the speed of movement, deceleration or acceleration during the movement (for example walking with Parkinsonists) can take place . Movements can be started with the aid of acoustic signals, which makes it possible, for example, to measure the delay (in the case of diseases of the central nervous system, muscle diseases, etc.). Through specific examination arrangements and corresponding software programs specific questions (such as spasticity, rigor) are examined. Shaking (tremor) of outstretched hands can be determined exactly.

The measuring system should be designed in such a way that the "measuring window" is set accordingly, i.e. the sensitivity range e.g. from 3 cm to 10 m is available.

Claims

Claims: 1. Device for determining the mobility of parts of the body by measuring the position with the aid of field-generating and receiving devices which are partly fixed to the body and partly fixed in space, since ¬ characterized in that for determining the position a measurement of the coordinate data of one or more by ultrasonic receivers (1) or - Transmitter (2, 3, 4) of marked body parts is provided with the aid of pulse transit time measurements between further assigned, spatially arranged ultrasound transmitters (2, 3, 4) or receivers (1), with a temporal staggering of the individual transit time measurements. sungeπ serves to avoid mutual interference. 2. Device according to claim 1, d a d u r c h g e k e n n ¬ z e i c h n e t that the pulses of all ultrasonic transmitters (2, 3, 4) are offset in time in a cyclical order. 3. Apparatus according to claim 1 or 2, characterized in that the pulses delivered by the Ult ^' rapid transmitters (2, 3, 4) have ratios of their ultrasound frequencies which are graded according to prime numbers.