DEVICE FOR MEASURING THE INTERNAL ROTATION OF A HIP JOINT

Abstract

Device for measuring the internal rotation of a hip joint, whereby the following steps are performed: a) Positioning a person to be examined (1) on the seating surface (8) of a chair-like positioning aid (5) in a sitting position;b) Fixating at least one of the upper thighs to be examined (3) of the person (1) on the seating surface (8) against translational motions, so that a rotation of the upper thigh (3) around its longitudinal axis is still possible;c) Moving the corresponding lower thigh (4) across the sagittal plane (20) by using a force K of a constant value Z acting on the lower thigh (4), so that the distal end of the lower thigh (4) is deviated from the sagittal plane; andd) Measuring the angle α between the sagittal plane (20) and the longitudinal axis of the lower thigh (4).

Description

FIG. 1 is a schematic representation of a form of embodiment of the positioning aid according to the invention, mounted on a medical examination table.

The positioning aid 5 shown in FIG. 1 essentially comprises a pedestal 12 with a seating surface 8 and a backrest 6 having a resting surface (not shown), fastening means 13 for fixating both upper thighs 3 of the person to be examined 1 to the seating surface 8 against corresponding translational motions, so that a rotation of the upper thighs 3 around their longitudinal axis (vertical to the drawing plane) is still possible, and means 15 to generate a force K parallel to an axis of action, which can unilaterally and detachably be fastened, by means of fixation devices 16, to the corresponding lower thighs 4.

The pedestal 12 of the positioning aid 5 is for instance, by means of commonly employed clamping elements (not shown), fastened to a medical examination table 10 so that the longitudinal axes of the upper thighs 3 of the person to be examined 1 extend in a direction parallel to the short side of the table surface of the examination table 10, and the lower thighs 4 project beyond one of the long sides of the table surface of the examination table and hang out freely.

In the form of embodiment pictured here, weights 22 capable of being fastened to a tackle 23 are used as means 15 for generating a force K. The tackle 23 comprises a cable and a deviating roller 24, whose distance to the examination table 10 is adjustable and which can for instance be fastened to the examination table 10 by a screw clamp 25. One end of the cable is fastened to the weights 22, while the other end of the cable is connected to the lower thigh 4 through fixation devices 16, for instance by belts fastened at the ankle joint. The form of embodiment shown here comprises, symmetrically to the sagittal plane 20, one tackle 23 each for the left leg and the right leg of the person to be examined 1.

The lower thigh 4 is, thanks to the pulling force exerted on the same, turned around the longitudinal axis of the corresponding upper thigh, so that the ankle joint is deviated from the sagittal plane 20 (vertical to the drawing surface) and the upper thigh 3 is turned around its longitudinal axis by the angle α

Moreover, the backrest 6, which can be rotated with respect to the seating surface 8, is fixated so that its resting surface (not shown) for the back of the person to be examined 1 encloses an angle β of 90° (not drawn) with the seating surface 8.

The measurement of the angle α between the sagittal surface 20 and the longitudinal axis 9 of the lower thigh 4 is performed by using the goniometer 19 set up on the pedestal 12.

Claims

1: A device for measuring an internal rotation of a hip joint through a positioning aid comprising: a pedestal fitted with a seating surface and a backrest with a resting surface;a fastening means for fixating at least one upper thigh of a person to be examined to the seating surface against translational motions, so that a rotation of the upper thigh around its longitudinal axis is still possible;a means to generate a force K of a constant value Z in a direction parallel to an axis of action, that can unilaterally and detachably be fastened by means of a fixation device to a corresponding lower thigh, anda means for measuring an angle α between the sagittal plane and the longitudinal axis of the lower thigh of the person to be examined.

2: The device according to claim 1 further comprising a timing device.

3: The device according to claim 1 wherein the means for generating the force K comprises a dynamometer.

4: The device according to claim 1, wherein the pedestal can be detachably fastened to a medical examination table.

5: The device according to claim 1, wherein the means for generating the force K is detachably fastened to a medical examination table.

6: The device according to claim 1, wherein the backrest can be rotated with respect to the seating surfaces so that the resting surface encloses an angle β between 85° and 95° with the seating surface.

7: The device according to claim 1, wherein the fixation device presents, measured in a direction orthogonal to the seating surface, a selectable distance X>0 to the seating surface.

8: The device according to claim 1, wherein a line of action of the force K encloses an angle γ between 80° and 100° with the normal to the seating surface.

9: The device according to claim 1, wherein the value Z of the force K amounts to at least 40 Newton.

10: The device according to claim 1, wherein the means for generating the force K is capable of being detachably fastened to a medical examination table and comprises at least a weight, a tackle and at least one deviating roller for the tackle and wherein a first end of the tackle is connected to the weight and a second end of the tackle can be fastened to the lower thigh of the person to be examined.