DE202007014520U1 - Device for determining the angular position of an acetabular cup in a pelvic bone - Google Patents

Abstract

contraption for determining the anteversion angle (α) of an acetabular cup (16) in a pelvic bone (14) with a navigation system (3), with a navigated position sensor (10; 11) for striking points of the pelvic bone (14) and with a data processing system (12), which is programmed to take from the location data of the spina iliaca anterior superior (A) or B)) on one side of the pelvic bone (14) and the location data of the posterior superior iliac spine (D)) on the same side of the pelvic bone (14) and the position data of a Transverse plane (20) of the pelvic bone (14) a perpendicular to calculates the individual plane (23) standing on the transversal plane (20), through the anterior superior iliac spine (A) or B)) and the Spinal iliac posterior superior (D)) goes through this individual Plane (23) about a perpendicular to the transverse plane (20) standing Rotated axis by a known angular amount (δ) between 35.6 ° and 40.4 ° and the angle between the twisted individual plane (23) and a frontal plane (15) as anteversion angle (α) ...

Description

The The invention relates to a device for determining the anteversion angle and / or the inclination angle of an acetabular cup in a pelvic bone.

At the Implant an acetabular cup, the generally has an approximately hemispherical shape, the Location of the acetabular cup and their angular position relative to the pelvic bone prior to implantation be determined exactly. The situation is relatively easy determine that before implantation the center of rotation of the hip joint is determined, for example, by pivoting the femur against the Pelvic bone. This center then corresponds to the center of the sphere the hemispherical one Acetabulum.

More difficult is the determination of the angular position of the acetabular cup. The acetabular cup points a lower edge on which the hemispherical acetabulum defined at the lower end limiting level, and at this level is a central axis of the hemispherical acetabulum perpendicular, the through the center of the acetabular cup goes. This central axis of the acetabular cup is generally arranged in space so that it communicates with the main levels of the pelvic bone includes different angles. When Main planes of the pelvic bone come into question the transverse plane, So an upright pelvis horizontally extending plane, the Sagittal plane, so with upright pelvis a perpendicular to the Transversal plane and running from front to back Plane, and the frontal plane, on the two aforementioned Layers is vertical.

to Description of the position of the central axis relative to these main planes is it common for the Indicate the anteversion angle and the inclination angle. The anteversion angle describes the angle that a vertical axis containing the central axis at the transversal level anteversion level opposite one Includes frontal plane, the angle of inclination describes the angle that a perpendicular on the central axis of the acetabular cup vertical inclination plane perpendicular to a frontal plane occupies relative to a sagittal plane.

In In practice, the anteversion angle and angle of inclination determined by complicated preliminary examinations in the patient, for example by radiographs at different levels or through ultrasound examinations that are very expensive and especially in X-ray examinations the patient burden with a high radiation dose.

It It is an object of the invention to provide a device for determining this Specify angle sizes, in a simple manner - if necessary intraoperatively - the Anteversion angle and / or the inclination angle can be determined can.

These Task is in the determination of the anteversion angle according to the invention by solved a device having the features of the protection claim 1.

at the determination of the inclination angle, this object is achieved by a Device having the features of the protection claim 3.

Further Embodiments of these devices are in the claims 2 and 4 to 6 described.

at Use of the devices described so it is sufficient, a few striking Non-invasively determining points of the pelvic bone, for example by pressing from prominent points of the pelvic bone through the Through the skin or through an ultrasound examination, and from these points as well as data on the major levels of the pelvic bone and using the previously known angle amount can be calculated both the anteversion angle and the inclination angle determine. This results in sizes for the anteversion angle and the inclination angle, which depends on the respective geometry of the Depend on pelvic bone, so individually for every single pelvic bone can be determined. Complicated X-ray examinations are not necessary.

The following description of preferred embodiments of the invention used in conjunction with the drawings for further explanation. Show it:

1 a schematic representation of a stored on an operating table patient and a navigation system for determining the position of navigated position sensors;

2 a schematic front view of a patient in determining a frontal plane of the pelvic bone;

3 a schematic view of a pelvic bone, a frontal plane, a transverse plane and an anteversion plane;

4 : a view similar 3 with a frontal plane, a sagittal plane and an inclination plane;

5 FIG. 2: a schematic plan view of a transverse plane of a pelvic bone with an individual plane through and through prominent points of the pelvic bone. FIG

6 Figure 11 is a plan view of a frontal plane of the pelvic bone with an individual plane through distinct points of the pelvic bone.

In 1 is a patient 1 on an operating table 2 In this situation, operations on the patient can be performed. Next to the operating table 2 is a navigation system 3 arranged with several radiation transmitters 4 . 5 . 6 , which are also designed as a radiation receiver simultaneously. The emitted radiation may be infrared radiation. This radiation is from reflection surfaces 8th These can be spheres that act as marking elements 9 on various instruments 10 may be arranged, for example, a feeler instrument 10 and an ultrasonic sensor 11 ,

The Navigation system can in a conventional manner thereby the location determine the instruments in the room, ie their exact position and their orientation.

The navigation system 3 is also a data processing system 12 associated with a display device 13 , In the illustrated embodiment in the form of a monitor.

• A) Spina iliaca anterior superior links (linker vorderer oberer Darmbeinstachel)
• B) Spina iliaca anterior superior rechts (rechter vorderer oberer Darmbeinstachel)
• C) Symphysis pubis (Schambein).

To the location of the pelvic bone 14 To describe a patient, it is known to use three prominent points of the pelvic bone, which define a so-called pelvic entrance level. It is a special frontal plane characterized by distinctive landmarks that lie in this frontal plane. These are the following points:

• A) Anterior superior left iliac spine (left anterior upper iliac spine)
• B) iliac spine anterior superior right (right anterior upper iliac spine)
• C) Symphysis pubis (pubis).

These three points can be touched percutaneously, for example manually or with the help of the navigated palpation instrument 10 , It is also possible to determine these points with the aid of the navigated ultrasonic sensor, in each case in this way the position of the three points A), B) and C) can be determined in space, and the navigation system can record the situation the points A), B) and C) corresponds to the data processing system 12 submit.

By The determination of these points will determine the position of the pelvic bone in the Defined space, this level serves as a reference plane for all other spatial and orientation regulations.

In 3 is a pelvic bone 14 shown, also a frontal plane 15 , In this is schematically an acetabular cup 16 drawn in such a way that one through the lower edge 17 clamped lower termination level of the acetabular cup 16 perpendicular to the frontal plane 15 stands. This is a central axis 18 of the acetabular cup, which is perpendicular to this lower closure plane of the acetabular cup 16 stands and through the center of the hemispherical acetabulum 16 goes through, in the presentation of 3 in the frontal plane 15 ,

A Such an arrangement of the acetabular cup would one Anteversion angle of 0 ° correspond, which is not realistic.

Actually, the central axis lies 18 the acetabular cup 16 in an anteversion level 19 that as well as the frontal plane 15 perpendicular to a transverse plane 20 stands and the opposite the frontal plane 15 one perpendicular to the transverse plane 20 standing axis of rotation is twisted. The one between the anteversion level 19 and the frontal plane 15 included angle α is called the anteversion angle.

Similarly, in 4 a pelvic bone 14 along with a frontal plane 15 and a sagittal plane 22 also shown with an inclination level 21 with the lower, by the lower edge 17 the acetabular cup 16 collapsed completion level coincides. The inclination level 21 corresponds to the actual installation position of the acetabular cup 16 in the pelvic bone 14 , as well as the anteversion level 19 corresponds to the actual installation position.

The angle β between the inclination plane 21 and the sagittal plane 22 is called inclination angle.

To determine the anteversion angle, as shown in the schematic representation of 5 In addition, another prominent point of the pelvic bone can be seen 14 noninvasively determined in the manner described above, namely the point D) posterior superior iliac spine.

Through this additionally determined point D) and through the anterior superior iliac spine on the same side of the pelvic bone 14 becomes an individual level 23 passed through, which is perpendicular to a transverse plane. This level closes with the frontal plane 15 an individual angle γ.

In a further step, the individual level 23 rotated about a given vertical axis of rotation on the transverse plane by a predetermined angle δ, this is in the anteversion in the range between 35.6 ° and 40.4 ° and is preferably 38 °. After twisting, the twisted plane closes with the frontal plane 15 an angle, and this angle is the anteversion angle α. The twisted plane thus forms the anteversion plane after twisting 19 off or coincides with this.

Similarly, the determination of the inclination angle in the 6 schematically illustrated manner. Through the points B) and C), ie through the anterior superior iliac spine on one side of the pelvic bone and through the pubic symphysis, an individual level is created 33 placed perpendicular to a frontal plane 15 and which includes with this an individual angle γ '. This individual level 33 is then rotated about a perpendicular to the frontal plane axis of rotation by a predetermined angle δ ', which is in the determination of the inclination angle in the range between 14.1 ° and 17.9 °, and preferably at 16 °. After twisting, the individual level falls 33 with the inclination level 21 together, this concludes with a sagittal plane 22 the inclination angle β.

By determining the position of the prominent points of the anterior superior iliac spine, the posterior superior iliac spine, and the pubic symphysis, it is possible to determine the shape of the pelvic bone individually 14 determine dependent values for the anteversion angle and the inclination angle, without the need for elaborate X-ray examinations or the like.

The described method steps can be performed by the data processing system 12 due to the navigation system 3 provided location data are readily carried out, so that the surgeon can be displayed immediately after determining the position of the described prominent points, the values of the inclination angle and anteversion angle.

It has surprisingly found that the previously known angle amounts to the the connection levels the striking points, ie the individual levels, are rotated need to, um into the inclination level or the anteversion level to convict, regardless of the individual dimensioning of the pelvic bones at different Patients can be used and that doing results for obtained the values of inclination angle and anteversion angle which correspond to those without further ado, which by very much more complex X-ray examinations could be found.

Claims (6)

Device for determining the anteversion angle (α) of an acetabulum ( 16 ) in a pelvic bone ( 14 ) with a navigation system ( 3 ), with a navigated position sensor ( 10 ; 11 ) for prominent points of the pelvic bone ( 14 ) and a data processing system ( 12 ) programmed to derive from the location data of the anterior superior iliac spine (A) or B)) on one side of the pelvic bone ( 14 ) and the location data of the posterior superior iliac spine (D)) on the same side of the pelvic bone ( 14 ) and the position data of a transverse plane ( 20 ) of the pelvic bone ( 14 ) one perpendicular to the transverse plane ( 20 ) individual level ( 23 ) passing through the anterior superior iliac spine (A) or B)) and the posterior superior iliac spine (D)), this individual plane (FIG. 23 ) about a perpendicular to the transverse plane ( 20 ) rotational axis by a known angular amount (δ) between 35.6 ° and 40.4 ° rotated and the angle between the twisted individual plane ( 23 ) and a frontal plane ( 15 ) is determined as the anteversion angle (α). Device according to claim 1, characterized in that that the known angular amount is 38 °. Device for determining the inclination angle (β) of an acetabulum ( 16 ) in a pelvic bone ( 14 ) with a navigation system ( 3 ), with a navigated position sensor ( 10 ; 11 ) for prominent points of the pelvic bone ( 14 ) and a data processing system ( 12 ) programmed to derive from the location data of the anterior superior iliac spine (A) or B)) on one side of the pelvic bone ( 14 ) and the location data of the symphysis pubis (C)) and the position data of a transverse plane ( 20 ) of the pelvic bone ( 14 ) one perpendicular to the frontal plane ( 20 ) individual level ( 33 ) passing through the anterior superior iliac spine (A) or B)) and the posterior superior iliac spine (D)), this plane ( 33 ) around one perpendicular to the frontal plane ( 20 ) rotating rotation axis by a known angular amount (δ ') between 14.1 ° and 17.9 ° and the angle between the twisted individual plane ( 33 ) and a sagittal plane ( 2 ) as the inclination angle (β). Device according to claim 3, characterized in that that the known angular amount is 16 °. Device according to one of claims 1 to 4, characterized in that the navigated position sensor is a push button sensor ( 10 ). Device according to one of claims 1 to 4, characterized in that the navigated position sensor is an ultrasonic sensor ( 11 ).