WO1995031933A1

WO1995031933A1 - Measuring arrangement for analysing the human gait

Info

Publication number: WO1995031933A1
Application number: PCT/DE1995/000651
Authority: WO
Inventors: Heiko Tober; Günther HEGEWALD; Reinhard Tscheuschner
Original assignee: T & T Medilogic
Priority date: 1994-05-20
Filing date: 1995-05-12
Publication date: 1995-11-30
Also published as: DE4418475C2; DE4418475A1; AU2444395A

Abstract

In order to analyse the human gait, a given, reproducible walking rhythm and a substantially constant walking phase is found for the test person concerned using a walking belt (1) by measuring the pace frequency and energy consumption. During the constant walking phase, pressure sensors (6) are used to determine the dynamic pressure effect of the feet together with the change of relative position of selected parts of the body by two-dimensional angle measurements (5) and a muscle potential measurement (8) is made. At the same time, the gait of the test person is monitored via video cameras (2). The results of measurement on the test person's movement and supporting members are monitored or imaged on-line (13, 14) by a computer (3).

Description

MEASURING ARRANGEMENT FOR ANALYZING THE HUMAN WALK

The invention relates to a method and a measuring arrangement for analyzing the human gait by measuring the kinematic and kinetic effects of the body or body segments occurring when walking on a treadmill at a given speed and thus for the quantitative determination of the dynamics of the supporting and musculoskeletal system.

The measurement and assessment of human gait takes place in orthopedics, surgery and other areas of medicine as well as during rehabilitation and serves diagnostic and therapeutic purposes. In orthopedic technology, gait analysis makes an effective contribution to assessing the efficiency of prosthetic fitting or the use of other orthopedic aids by identifying incorrect and excessive loads. On the other hand, the rehabilitation process can be controlled using the gait pattern and at the same time it serves to control and justify therapeutic measures. Another application example is the early detection of pathological changes in the human support and musculoskeletal system in order to be able to prevent later severe pathological changes in good time.

With what is probably the most common procedure for gait analysis, the purely visual assessment of gait during a running test, incorrect movements and loads are often not recognizable. On the other hand, this method is very subjective, since the result of the quality control depends on the respective experience and knowledge of the examining person, for example an orthopedic technician. In particular, with this method, early detection of changes that were not visible until then is not possible.

Recently, the quantitative determination of the dynamics of the human support and musculoskeletal system using technical means has become more important. Kinematic gait analysis systems are known in which the movements of markers attached to the body of the person to be examined are recorded with the aid of cameras or ultrasound. The angle curves determined from this provide information about the walking behavior of the patient to be examined. A disadvantage of this indirect kinematic measuring system, in which, however, the patient can advantageously move freely without a cable connection, is the relatively low level

Measurement frequency with the consequence of a comparatively inaccurate measurement result. In addition, the acquisition costs are high.

In the further known direct kinematic measuring method, in which the changes in angle between the body segments adjoining a joint are measured with the aid of angle-sensitive sensors, high measuring accuracy can be achieved at low cost by using high measuring frequencies, although wiring of the patient is required.

In a further form of gait analysis, multi-component force measuring platforms or force measuring soles are used to measure those of the human body or of the The outgoing force effect is measured in order to draw conclusions about walking behavior. Although the force measuring soles only determine the amount of the spatial force effect, they can be used more flexibly than force measuring platforms and are considerably less expensive. The measurements with load cells are of particular interest when determining incorrect loads and the course of force application points.

The main problem with the aforementioned

Systems for examining the human gait is that, based on the various measurement results, there are considerable difficulties in retrospectively following the course of the movement and in accurately evaluating the gait of a test person solely from the visual evaluation of the measurement curves and parameters. On the other hand, a large number of boundary conditions influencing the measurement results, which can be attributed, for example, to a patient's misconduct during the measurement process, remain undetected in the later evaluation of the measurement curves, so that the result of the gait analysis does not correspond to the actual walking behavior or the measurement results are interpreted incorrectly. That is, in order to arrive at a usable assessment of the condition of the musculoskeletal system, the

Operating the measuring station and evaluating the multitude of different measuring results of an operator who has extensive experience and knowledge in this area. The applicability of the conventional gait analysis measuring systems is therefore limited to large research facilities with particularly qualified technical personnel, although the evaluation is difficult, the examination result is inaccurate and the examination is not reproducible. The invention is therefore based on the object of specifying a method for analyzing human gait including a corresponding measuring arrangement in order to obtain meaningful measurement results corresponding to the actual walking behavior at a low cost and to provide a quick and sound interpretation of the recorded measurement data and a wide range of possible applications in a simple manner guarantee.

According to the invention the object is achieved in a method for analyzing human gait according to the preamble of claim 1 in that at an individually predetermined treadmill speed, a measurement of the energy consumption and the step frequency of the test person is carried out and during a constant running phase determined by uniform energy consumption and constant step duration the pressure distribution and pressure peaks prevailing on the sole of the foot when the foot rolls off are measured together with a change in position of certain body segments relative to one another, determined by two-dimensional angle determination.

The basic idea of the invention is therefore firstly that constant and repeatable running conditions which are essentially free of external influences are created. In an embodiment of the invention, this is done in such a way that the patient moves on a speed-adjustable treadmill during the measurement. His cadence is determined and an energy consumption measurement is carried out. The treadmill specifies a specific task for the test person, and on the other hand it is possible that the Measuring devices remain in place. The energy consumption measurement by pulse measurement provides information about the achievement of stable movement conditions after the running-in phase, so that the actual gait analysis measurement is carried out at the right time. On the one hand, measurement errors are largely avoided, and on the other hand it is possible to compare different measurements - including follow-up measurements with one and the same test person; This means that the determined measurement parameters and graphic representations - regardless of the experience of the operator - provide immediate information about the respective gait behavior.

For the actual determination of walking behavior, three different measuring components are determined and combined with each other, namely the force distribution and pressure peaks during running, changes in angle in the area of the hip, knee and ankle joint as well as the muscle potential of individual muscles, which provides information about the movement chain of the muscles as well whose activity allows. The measurement processes are limited to a few parts of the body and are therefore straightforward. Nevertheless, a sufficiently precise statement about the gait behavior is made possible. The two-dimensional direct angle measuring method allows high measuring frequencies to achieve high measuring accuracy.

According to a further essential basic idea of the invention, the test person is visually monitored during the measurement using video cameras in front of, behind and on both sides of the treadmill. This can be done by linking the measurement curves and measurement parameters with the corresponding actual movements, preferably by superimposing them on the video images Analyze gait behavior precisely using the measured values - even at a later point in time and using the stored images. In addition to the immediate evaluation, training of the patients is also possible on the basis of the images, which can preferably also be displayed in slow motion.

A last essential idea of the invention is finally that all measurement results including the video images, the running conditions specified by the treadmill and the measurement values necessary for the decision on the start of the actual measurement are linked synchronously in a computer under the operating system "Windows" and the execution of the Measurement and evaluation of the measurement results takes place "on-line". By displaying the measurement results - via the link to the computer - during the measurement process, it is possible to modify and improve the measurement conditions and to directly and directly influence the behavior of the test person. Connections between cause and effect, ie between movement and measurement result, are immediately recognizable. The advantages of the measurement method according to the invention for carrying out the gait analysis ultimately lie in the fact that measurements of a comparatively small extent allow sufficiently precise statements about the gait behavior. The proposed measuring method is particularly convincing due to its practical relevance, since the implementation and evaluation of the measurement is not tied to the skills and experience of a few specialized operators and can therefore also be used in smaller facilities, for example in an orthopedic workshop, and yet delivers meaningful results. This is ultimately the prerequisite for an improved Diagnosis and therapy in the field of orthopedics and surgery as well as during the rehabilitation process created.

Further features and expedient developments of the measuring method according to the invention are listed in subclaims 2 to 8.

According to a further feature of the invention, the measuring arrangement for carrying out the method is characterized in that a treadmill and video cameras assigned to the treadmill are connected to a computer and angle sensors and pressure sensors attached to the test person and a pulse measuring device and muscle potential sensors are connected to the computer via a separating device .

In an advantageous development of the invention, a video camera is arranged on each side of the barrel, the speed of which can be controlled interactively via the computer, each camera being connected via a four-quadrant selector which is controlled via the computer. This makes it possible to view the patient on the treadmill simultaneously from four sides on a video monitor, i. H. assess its movements in connection with the measurement curves and parameters provided by the measuring devices at a specific belt speed or step frequency.

An essential feature of the invention is the separator arranged between the measuring devices on the patient and the computer, which is based on the principle of linear opto-couplers. A variety of am Patients of recorded measurement signals are routed to the computer by means of a single three-channel cable, in which 48 incoming signals are combined to form three outgoing signals. A large number of signals are thus combined into a single signal, and the patient is connected to the computer by only one cable. The patient, who is moving on the treadmill anyway, is not impaired in his freedom of movement, so that practical results that correspond to the actual gait behavior are achieved.

On the other hand, the separator also serves the purpose of making it possible, for example, for the measuring frequency required for angular encoders to detect rapid body movements. In particular, however, a complete separation between the patient connected to the measuring devices and the computer is brought about by means of the separating device by means of galvanic separation into a battery part and a power pack. Electrical

Errors in the field of computing technology can therefore not be transferred to the patient.

In a further embodiment of the invention, the transmission of the measurement signals to the computer can also be contactless, for

Example via radio. In this case, the connection cable between patient and computer is omitted and a special electrical isolating device is not required.

The measuring station for performing the gait analysis is thus simple and inexpensive and requires little space. It is possible to immediately, ie still during the measurement, very precise measurement results in the form of parameters and graphical representations, directly in connection with the video images. The use of a video recorder likewise offers the possibility of comparing the measurement results in connection with the video images at a later point in time or of comparing gait examinations carried out on the same patient at different points in time. The gait behavior of a patient can thus be checked at intervals over a longer period of time in order to draw conclusions about the effect of therapeutic measures or to precisely control the course of rehabilitation. This is possible because the respective measurement data are actually comparable due to identical, reproducible boundary conditions. Likewise, a comparison can be made with standard values

Further features of the measuring arrangement according to the invention are listed in the subclaims.

An embodiment of the invention is explained in more detail with reference to the drawing. Show it:

1 shows a schematic illustration of a gait analysis measuring station for routine use;

2 shows a graphical representation of the result of angle measurements carried out on the knee joint during a double step in a healthy test person and a prosthesis wearer;

3 shows a cyclical representation of the body's center of gravity when walking; and Fig. 4 shows the result of a center of gravity measurement in a standing test.

1, a gait analysis measuring station comprises a treadmill 1 as the core of the measuring arrangement, the control of which takes place interactively via a computer 3. A video camera 2a to 2d is arranged on each side of the treadmill 1. The video cameras 2a to 2d are connected to a four-quadrant selector 10, which in turn is connected to a video recorder 12 and a video monitor 11. The four-quadrant selector 10 is also controlled via the computer 3.

The test person 4 on the treadmill 1 is in the area of the hip joint, the knee joint and the

Ankle angle encoder 5a, 5b and 5c attached to determine the change in position of individual body segments to each other when walking. 2 shows, by way of example, graphic information about the knee angle profiles in a double step, the solid lines representing the angles for a prosthesis wearer and the dashed lines showing the knee angles of a healthy test person. On the basis of otherwise identical boundary conditions, comparisons with normal gait behavior can be made and useful conclusions can already be drawn from this about the condition and fit of a prosthesis and suitable measures can be initiated. In the area of the soles of the test person's feet there are pressure sensors 6 in the form of force measuring soles with which pressure peaks or high pressure areas are determined. On the other hand, the force distribution at the foot is measured from the beginning to the end of the rolling process. Such a dynamic measurement provides information about the patient's walking behavior, for example based on the distribution of the center of gravity during running, but also in a standing test, as shown in FIGS. 3 and 4. Overloads are determined, for example, on the basis of the measured pressure peaks, so that orthopedic insoles for shoes can then be optimally formed.

As indicated in FIG. 1, muscle potential sensors (EMG sensors) 8 are arranged on individual muscle areas of the patient. Based on the corresponding measurement result, a statement is made about the activity of individual muscles with conclusions about gait behavior.

Finally, a pulse measuring device 7 is attached to the body of the test person. This

Energy consumption measuring device serves in particular to display the energetic conditions of the patient's movement behavior. When an energetically stable state is reached, the measurement for the gait analysis is carried out, which can therefore be repeated under constant conditions.

The measuring devices 5 to 8 are connected to a separating device 9 which is attached to the patient, but is shown separately in the drawing for the sake of clarity. In the separating device 9, a large number of measurement data, which are also recorded at a high frequency, for example with 500 measurements per second, are converted into three signals and sent to the computer 3 via a three-channel cable 15. An essential function of the separating device 9 designed as an opto-coupler is, however, the separation of the patient from the medical-electrically insecure computer part by means of galvanic separation. Due to the connection to the computer 3 established in this way, all measured data, including the belt speed or step frequency, can now be tracked "online" on the computer 3 or on the monitor 13, with the possibility of directly influencing the patient in order to to create optimal, reproducible boundary conditions for the measuring process. The measurement results can be synchronized and superimposed or displayed on the monitor in comparison with previous measurements. At the same time, the movements corresponding to the current measurement data can be observed from four sides on the video monitor 11. The storage of the video images with the help of the video recorder 12 also allows for a later one

Time the evaluation of the measurement results based on the actual movements.

A printer 14 is also connected to the computer 3 and reproduces the parameters and graphic information of the gait analysis, as shown for example in FIGS. 2 to 4, in paper form.

Reference symbol list:

1 treadmill

2a - 2d video camera

3 computers

4 test person (patient)

5a angle sensor on the hip joint

5b angle encoder on the knee joint

5c angle sensor on the ankle

6 pressure sensor

7 heart rate monitor

8 muscle potential sensors (EMG sensors

9 separator

10 four-quadrant selector

11 video monitor

12 video recorders

13 monitor

14 printers

15 three-channel cables

Claims

Claims:

1. Method for analyzing human gait by measuring the kinetic and kinematic effects of the body when walking on a treadmill at a given speed on the basis of the forces exerted by the feet of a subject and the muscle potential, the movement of the subject on the treadmill using video technology is observed, characterized in that a measurement of the energy consumption and the step frequency of the test person is carried out at an individually predetermined treadmill speed and during a constant running phase determined by uniform energy consumption and constant step duration, the pressure distribution prevailing on the sole of the foot as well as pressure peaks along with the foot rolling a change in position of certain body segments relative to one another, determined by two-dimensional angle determination.

2. The method according to claim 1, characterized in that a pulse measurement is carried out to determine the energy consumption.

3. The method according to claim 1, characterized in that with the help of the graphical representation of the pressure curve or the pressure peaks, Schwerpunktsver¬ bearings are shown while standing and walking.

4. The method according to claim 1, characterized in that in order to determine changes in position when walking, changes in angle are measured on the ankle and / or on the knee joint and / or on the hip joint.

5. The method according to any one of claims 1 to 4, characterized in that the running regime determined by the belt speed or step frequency and the energy consumption and the measurement data resulting from the gait behavior are displayed "on line" via a computer connected to the test subjects.

6. The method according to claim 1, characterized in that the video monitoring is carried out on four sides of the subject and the gait obtained are displayed side by side or individually.

7. The method according to claim 6, characterized in that the gait images are displayed in slow motion.

8. The method according to any one of claims 1 to 7, characterized in that the measurement data of the gait analysis taken from the subject are shown in the form of parameters and / or as graphic information in connection with the video images of the gait behavior.

9. Measuring arrangement for performing the method according to claim 1, using a treadmill with adjustable speed, this associated camera system and the subject applied to muscle potential sensors and a force measuring device with a computer connected to it, characterized in that the force measuring device from force measuring soles forming There are pressure sensors (6) distributed on the soles of the test subject, angle sensors (5) are attached in the area of the body joints that determine the gait behavior, and a pulse measuring device (7) is provided, the measuring elements provided on the body of the test person being provided via a separating device ( 9) are connected to the computer (3).

10. Measuring arrangement according to claim 9, characterized in that four on each side of the treadmill (1) angeord¬ nete video cameras (2) are provided and connected via a four-quadrant selector (10) to the computer (3).

11. Measuring arrangement according to claim 10, characterized in that the four-quadrant selector (10) for simultaneous or individual display of the video images on one

Video monitor (11) - both at normal speed and in slow motion - can be controlled by the computer (3).

12. Measuring arrangement according to one of claims 9 to 11, characterized in that the video monitor (11) is assigned a video recorder (12).

13. Measuring arrangement according to claim 9, characterized in that the separating device (9) for passing on a plurality of signals measured on the subject's body to the computer (3) and for separating the electrical penetration from the computer to the subject is a linear optocoupler.

14. Measuring arrangement according to claim 13, characterized in that the separating device (9) is connected via a three-channel cable (15) for forwarding all signals measured on the subject's body in only three combined signals to the computer.

15. Measuring arrangement according to claim 9, characterized in that in order to avoid the cable connection between the test band and the computer, the signals determined can be transmitted to the computer by radio and / or infrared.

16. Measuring arrangement according to claim 9, characterized in that the speed of the treadmill (1) via the computer (3) can be controlled interactively.

17. Measuring arrangement according to one of claims 9 to 16, characterized in that a monitor (13) and a printer (14) are connected to the computer (3) for numerical reproduction and graphic representation of the measurement results.