WO2008089723A1

WO2008089723A1 - Device and method for measuring the position of a first part relative to a second part, and use of such a device

Info

Publication number: WO2008089723A1
Application number: PCT/DE2008/000056
Authority: WO
Inventors: Kasimir Kisielinski
Original assignee: Kasimir Kisielinski
Priority date: 2007-01-24
Filing date: 2008-01-12
Publication date: 2008-07-31
Also published as: DE102007004584A1; WO2008089723B1

Abstract

Disclosed is a device for measuring the position of a first part relative to another part of a joint in a human or animal body. Said device is characterized in that the same triggers a signal only if a movement threshold value allowing for a false position is exceeded.

Description

DESCRIPTION

Apparatus and method for measuring the position of a first part to another part and use of such a device

[1] The invention relates to a device and a method for measuring the position of a first part to another part of a joint in a human or animal body.

[02] Such devices are known in the field of signal generators for computer games. For example, gloves with sensors are used to convey the movement of a hand to a controller. Depending on the quality of the device, even minimal movements of a joint are detected, analyzed and reported to a control device. Such devices have a wide range of applications and the continuous improvement of the sensors enables a virtually error-free imaging of the movement of a human or animal body in a computer program.

[03] It is the object of the invention to further develop such devices and methods in order to expand their field of application. The object underlying the invention is achieved in terms of device in a generic device characterized in that it triggers a signal only when exceeding a malposition permitting movement limit value.

[04] The invention is based on the finding that the selected transmission of a signal opens up completely new fields of application of such devices only in the case of a defined position of a musculoskeletal system. Thus, for example, in the sporting field overuse of a joint can be prevented by early attention is drawn to a malposition. In medical The device allows the device to avoid misalignments, especially after surgery.

[05] A special field of application opens up when the misalignment is a dislocation. A dislocation is, for example, a dislocation with loss of contact of the socket and the head-carrying shaft. Such dislocations occur, for example, after total hip replacement and endanger the success of artificial joint replacement as a very painful complication. Dislocations can lead to illness, prolonged hospitalization and reoperation. They cause a not inconsiderable increase in the cost of treatment.

[06] Dislocation is the leading cause of second surgeries in patients over the age of 70 years. In some studies, the dislocation rate is fifty percent. The prevention of dislocation is therefore a great challenge for patients and is of great importance for orthopedic surgeons and not least for health care providers.

[07] The invention therefore relates above all to devices in which the first part is an artificial joint part, in particular a joint ball, and the second part is an artificial joint part and in particular a joint socket.

[08] In the first 2 months after implantation of an artificial hip joint, patients should be advised to restrict certain ranges of motion in order to avoid dislocation leading to dislocation. An example of a movement limit that permits misalignment is a flexion of more than 90 degrees, a rotational movement of the thigh over 45 degrees (internal / external rotation) or an extension (abduction) as well as an extension in the hip joint , Normal movement sequences are thus not affected by the device and only when a previously defined movement limit value is exceeded, a signal is triggered in order to avoid a malposition. The device according to the invention thus allows uncomplicated movements of daily life, and only for specific movements of the joint, a signal is triggered before reaching a malposition, which prevents a person or possibly also an animal from continuing the movement in this direction of movement.

[10] The device thus constitutes a contemporary simple and effective strategy for minimizing risk of dislocation after endoprosthesis implantation, which does justice to the active early postoperative limitation of the range of motion in the operated hip joint on the one hand, and the related demands on the patients on the other hand. It helps in the early phase after surgery to avoid dislocation-inducing movements and also to learn and maintain safe behaviors in everyday life.

[11] The fear of dislocation can greatly confuse patients and inhibit their activity. On the other hand, certain everyday situations can in turn strongly distract the patient, so that at crucial moments despite the previous training courses, risky movements and positions are carried out or taken which ultimately lead to dislocation. Therefore, the device for measuring the position, especially in the critical phase of 3 months after implantation of an artificial hip joint, is particularly important for encouraging the patient to observe healthy exercise patterns in order to avoid dislocation.

[12] In order to determine joint positions and joint movements, the device preferably has a sensor which detects the position from the distance of a point on the first part to a point - A - the second part determined. This sensor can be arranged in an artificial hip joint and for determining the position of the distance fixed points on the socket and ball joint and / or rotation between these parts can be measured to each other.

[13] It is advantageous if the device has a plurality of sensors that detect the position. As a result, flexion, extension, abduction and external and internal rotation can be determined. The sensors are generally intended to record the position and movement of joint-defined reference points within a coordinate system in space and to provide corresponding data about the joint position.

[14] It is advantageous if at least one sensor is arranged outside the body. In this case, sensors in the form of strips or punctiform, but also be mounted as flat plates on the body, for example, over an artificial hip joint.

[15] In an advantageous embodiment, at least one sensor is a strain gauge. In particular, for the measurement of rotational movements, it is advantageous if strain gauges are arranged crossing each other.

[16] A simple embodiment provides that sensors are arranged on a textile fabric. For example, their integration on or in clothing is conceivable. A placement of the sensors in an endoprosthesis itself is possible. Especially for patients after hip joint surgery, it is advantageous if the sensors are attached to a pair of pants. Accordingly, the sensors can be arranged for example for shoulder injuries in a shirt or jacket.

[17] The sensors can be measured by impedance measurement (inductance capacitance measurement), resistance measurement, induction measurement and Phase shift work. As movement limit values, diffraction, extension, rotation, abduction, spread and force, negative and positive accelerations can be determined. The measurement is carried out accordingly with goniometers, strain gauges, inclinometers, pressure sensors, ac- celerometers or force sensors. For example, goniometers bridging an articular joint can measure the angle of the joint position of an endoprosthesis in different planes. Correspondingly, strain gauges positioned above and next to a joint can provide further data about movements of a joint or, in particular, of an artificial joint replacement via their change in length.

[18] A special embodiment provides that at least one sensor is arranged on a part of the joint.

[19] It is also proposed that sensors act on a signal generator via an analyzer. In this case, the signal is preferably an optical or acoustic signal. Depending on the application, vibration can also serve as the preferred signal.

[20] It is advantageous if a signal generator is attached to a textile. This leads for example to a pair of pants with sensors, analyzer and signal generator, which avoids malpositions of a musculoskeletal system as an easy-to-wear textile.

[21] In terms of the method, the invention is solved by a method for measuring the position of a first part to another part of a joint in a human or animal body in which a signal is triggered only when a movement limit value permitting misalignment is exceeded.

[22] A preferred use of the device according to the invention is the use for avoiding dislocations, in particular in the medical field. A further description of the invention and its advantages will be given below with reference to exemplary embodiments, which are illustrated in drawing figures.

Show it:

1 shows schematically a view of an artificial hip joint, FIG. 2 shows schematically an X-ray image of a dislocated one

total hip replacement,

FIG. 3 schematically shows a view of the basin from the front for clarification of the movements,

FIG. 4 schematically shows a view of the basin from the right

Page to illustrate the movements, Figure 5 is a diagram of the alarm system,

Figure 6 schematically shows a rear view and a side view of a first embodiment of a pair of pants and

Figure 7 schematically shows a rear view and a side view of a second embodiment of a pair of pants.

FIG. 1 shows a hip joint prosthesis 1 with a pentaline metal back 2, a polyethylene socket inlay 3, a plug head 4 made of metal or ceramic, and a shaft 5 made of metal. The polyethylene pan inlay 3 in this case forms a receptacle for the plug-in head 4, which is arranged movably therein. On the plug head 4 is a first part 6 of a sensor 7, which cooperates with a further part 8 of this sensor. The sensor can thereby measure the distance between the parts 6 and 8 or a relative rotation of the plug head to the pan inlay.

[25] If certain movement limit values are exceeded, the prosthesis head 4, as shown in the schematic X-ray image shown in FIG. 2, can pop out of the cup inlay 3, resulting in an unacceptable dislocation. [26] To avoid this, the sensor 7 measures the relative position between the prosthetic head and the cup inlay and reports corresponding values to an analyzer that triggers an alarm system when a limit value is exceeded.

In Figure 2, only the hip bone 9 is indicated schematically with a dashed line, in which the pan-metal-back 10 is fixed by means of screws 11 and 12. Therein lies the polyethylene cup inlay 3, in which the plug-in head 4 should be arranged. In the dislocation shown, however, the plug-in head 4 is located far outside of the pan inlay 3.

[28] A dislocation is triggered or favored by special movements. FIGS. 3 and 4 show, with the arrows drawn, movements of the thigh bone relative to the pelvis. Here, the arrow 13 shows an internal rotation and the arrow 14 an external rotation. The arrow 15 describes an adduction and in FIG. 4 the arrow 16 shows an extension, while the arrow 17 describes a flexion.

[29] The simple abstracted scheme shown in FIG. 5 shows how sensors 18 report control signals 19 to an analyzer 20 which communicates with an alarm system 22 via a wired or wireless line 21. This makes it possible to check any signals from sensors with regard to their relevance in the analysis device and, if appropriate, to compare with predetermined values in order to trigger an alarm system 22 in the case of defined deviations.

FIG. 6 shows an example of a minimal variant of the system for monitoring the flexion, extension and adduction in a hip joint prosthesis 1 with goniometers 23 and 24. The goniometer 24 is an adduction-measuring sensor, while the goniometer 23 is used as flexion and extension measuring sensor is formed. The measured values are sent to an individually programmable micropro- reported processor or controller 25, which is also located on the pants 26 and with an alarm system (not shown) in communication.

FIG. 7 shows an embodiment of a pair of pants 27 with two intersecting strain gauges 28, 29 for monitoring internal rotation and external rotation in a hip joint prosthesis 1. The strain gauge 28 measures external rotation and the strain gauge 29 is a sensor for measuring internal rotation. In the hip area, an individually programmable microprocessor / controller 30 with integrated alarm transmitter is arranged on the side of the pants 27. This alarm announces a wrong movement, eg. B. by acoustic or visual warning salvos and possibly also by vibration.

Claims

A CLAIM AND DEVICE FOR MEASURING THE POSITION OF A FIRST PART TO ANOTHER PART AND USE OF SUCH A DEVICE

1. A device for measuring the position of a first part to another part of a joint in a human or animal body, characterized in that it triggers a signal only when a malposition permitting movement limit value is exceeded.

2. Apparatus according to claim 1, characterized in that the malposition is a dislocation.

3. Device according to one of the preceding claims, characterized in that the first part is an artificial joint part.

4. Device according to one of the preceding claims, characterized in that the first part is a joint ball.

5. Device according to one of the preceding claims, characterized. that the second part is an artificial joint part.

6. Device according to one of the preceding claims, characterized in that the second part is a socket.

7. Device according to one of the preceding claims, characterized in that a sensor determines the position from the distance of a point on the first part to a point on the second part.

8. Device according to one of the preceding claims, characterized in that it comprises a plurality of sensors which determine the position.

9. Device according to one of the preceding claims, characterized. at least one sensor is arranged outside the body.

10. Device according to one of the preceding claims, characterized. at least one sensor is a strain gauge.

11. Device according to one of the preceding claims, characterized. that strain gauges are arranged crossing each other.

12. Device according to one of the preceding claims, characterized. that sensors are arranged on a textile fabric.

13. Device according to one of the preceding claims, characterized. that sensors are attached to a pair of pants.

14. Device according to one of the preceding claims, characterized. at least one sensor is arranged on a part of the joint.

15. Device according to one of the preceding claims, characterized in that sensors act via an analyzer on a signal generator.

16. Device according to one of the preceding claims, characterized. that the signal is an acoustic signal.

17. Device according to one of the preceding claims, characterized. that the signal is a vibration.

18. Device according to one of the preceding claims, characterized. that a signal generator is attached to a textile.

19. A method for measuring the position of a first part to another part of a joint in a human or animal body, characterized. that a signal is triggered only when a movement limit value that permits a misalignment is exceeded.

20. Use of a device according to one of claims 1 to 18 for avoiding dislocations.