CH703692B1 - Navigation Ball head with measurement markings. - Google Patents

Abstract

The invention relates to a navigation ball head (10) for selecting and positioning a joint endoprosthesis for spherical joints of a human or animal body, in particular a hip joint endoprosthesis, wherein the joint endoprosthesis can be inserted into a medullary cavity of a bone prosthesis shaft (20) from which a prosthesis neck (30). includes a hinge head attachable to the free end of the prosthetic neck (30) and a bone socketable socket (40) forming a ball joint together with the hinge head, the navigation ball head (10) being connected to the inner diameter of the socket (40). corresponding outer diameter and with a recess (11) for attachment to the free end of the prosthesis neck (30) and provided on its surface, at least partially encircling measuring markings (12) is equipped. The measuring markings (12) on the navigation ball head (10) are a three-dimensional image of a mathematical calculation model which indicates an ideal range of the relative position of the prosthesis shaft (20) and the joint cup (40) relative to the flexibility of the joint endoprosthesis, referred to as the "safe zone". The measuring markings (12) are mounted parallel to one another in two or more marking planes (E 1, E 2) in such a way that, for an optimum relative position of the components of the joint endoprosthesis, the measuring markings (12) are parallel to the edge (41) of the joint socket (40) in the installed position. are arranged.

Description

The invention relates to a navigation ball head for selecting and positioning a joint endoprosthesis for spherical joints of a human or animal body, in particular a hip joint endoprosthesis, according to the preamble of claim 1.

In particular, the invention relates to a navigation ball head, which as a universal measuring instrument for the visual selection and ideal positioning of different models of hip arthroplasty, both models with a one-piece symmetrical or one-piece anatomically shaped prosthesis stem attached to the neck of the prosthesis, as well as multi-part modular models with a modular prosthesis stem, which is connectable to a separate replaceable prosthesis neck serves.

Endoprostheses for shoulder or hip joints are in various forms and designs for a long time proven tools for the replacement of a damaged by an accident or by signs of wear and tear, such as osteoarthritis, joint. In this case, usually a fixation or shaft part is inserted into the medullary cavity of the correspondingly prepared bone, which continues in a joint part, which cooperates with a further prosthesis part, which is inserted into the other bone of the prosthetic joint to be supplied. Such an endoprosthesis for a hip joint is known for example from the document WO 95/13 757.

From DE 4 407 227 A1 a joint prosthesis is further known, which provides a controlled angular alignment of the neck piece with respect to the shaft by means of modulartigem structure of the prosthetic neck between a femoral stem and a femoral head.

A similarly designed prosthesis is also known from the document WO 00/64 384. This describes an endoprosthesis in the form of a conically shaped at its ends implant, which is inserted into the bone, wherein the implant consists of two parts. One part is designed as a splined profile with meandering or wave-shaped elevations, which thus enable a positive fixation in the complementarily shaped insertion opening in the thigh shaft. The other part consists of a conical neck section with a smooth surface, at the free end of a femoral head can be placed. The axis of this neck portion is at a defined angle to the axis of the end portion, which is positively fixed in the femoral shaft. By turning the end section in the thigh shaft corresponding to the elevations and by exchanging different lengths of neck sections, the prosthesis can be gradually adjusted to the anatomical conditions.

Furthermore, from DE 9 216 094 U1 a thigh part of a hip joint endoprosthesis is known, wherein the longitudinal axes of the two conically shaped end portions have a parallel offset. To fix the position of the prosthesis fastening means such as screws are provided at the end part, which is received in the femoral stem, or this end part is due to its special geometric shape to fix positively in the recess of the femoral stem. The free other end of the prosthesis protrudes into a corresponding conical recess of the condyle.

A disadvantage of the known from the prior art prostheses is that they offer the surgeon no help to determine the optimal installation position of the joint socket and thigh shaft or their relative position to each other according to the individual anatomical conditions of the patient.

From EP 0 363 019 A2, a trial joint head with partially circulating markings is known, which can be inserted into an artificial joint socket. The approximately hemispherical trial joint head is flattened on one side, which protrudes when inserting the artificial joint socket, for easier handling.

A disadvantage of this trial joint head that this is not connectable to the adjacent or adjoining parts of the joint endoprosthesis. Thus, it can not be determined whether a joint head used later instead of the trial joint head can be connected to an intermediate or connecting piece adjacent thereto in the respectively optimum installation position.

WO 2003/057 087 A2 shows an aid for implanting a hip joint endoprosthesis comprising a manipulation cup, a manipulatory joint head and a device for holding the aligned position of the manipulation cup. With this device, then a bone cutter and a Einschlaginstrument for the placement of the acetabulum are aligned accordingly.

This aid is an alignment gauge for determining the aligned position of the manipulation cup with respect to its angle to the acetabulum. A disadvantage of this embodiment is that during the operation, a guide rod on which the Ausrichtlehre is postponed, must be screwed into the pelvic bone of the patient. The guide rod is surgically removed from the pelvic bone after insertion of the joint endoprosthesis. Furthermore, it is disadvantageous that only a predetermined, non-replaceable prosthesis neck is provided for attachment to the joint head. An individual connection of the prosthetic neck with the joint shaft, each with a different antetorsion angle, is not possible here.

A manipulation system for the visual selection and positioning of components of a multi-part joint endoprosthesis, preferably a hip joint endoprosthesis, is known from the document WO 2010/046 470 A1. In this case, a navigation ball, which is provided on its surface with markings, attached during the operation of the free end of a replaceable connecting neck to decide based on the marks, which of several differently shaped, exchangeable connecting necks ideally combined with the prosthesis shaft in different angular positions is.

By computer-assisted procedures (English: "Computer assisted implantation"), however, require a very high equipment cost, can now performed the complete measurement and positioning of all components of the prosthesis, thus achieving an improved result of the range of motion become. Robots are used as navigation devices. [Widmer et al: "The impact of the CCD angle on motion and cup positioning in total hip arthroplasty". Clinical Biomechanics 20, (2005), pp. 723-728]; [Haaker et al: "Comparison of Conventional Versus Computer-Navigated Acetabular Component Insertion". J. Arthroplasty 22 (2), (2007), pp. 151-159]

The disadvantage here is that not all hospitals are equipped with such computer-controlled robots for measuring the body geometry or for computer-assisted implantation and such measurement and operation methods are expensive in terms of equipment and time. Another disadvantage is that medical personnel need their own training to operate these computer-assisted surgical procedures.

The object of the present invention is therefore to provide a universal measuring instrument, which provides a simple visual aid for the selection of a particular Gelenkendoprothesenmodells and serves to determine the optimal three-dimensional positioning of components of different Gelenkendoprothesenmodelle. The use of such a universal measuring instrument to be created should therefore by no means be restricted to use for the visual assessment of a single, particular model of prosthesis.

The optimal positioning of the prosthesis components is typically prosthesis specific. The invention is thus intended to provide the surgeon with a visual assessment of the ideal relative position of the prosthetic socket and socket both for one-piece symmetrically shaped and one-piece anatomically shaped prosthesis stems with attached neck of the prosthesis, and for multi-part modular prosthesis stems with separate neck of the prosthesis.

This should make it possible to achieve the best possible reconstruction of the defective ball joint for the patient, even without great expenditure on equipment. A further object of the present invention is to avoid as far as possible possible post-operative complications following the total replacement of a spherical joint by means of a visual assessment and setting of an optimal position of the prosthesis. This should on the one hand follow-up costs be minimized by further treatments and on the other hand make a significant contribution to the well-being of the patient.

General objective of the reconstruction of a ball joint, in particular a hip joint, must be to restore intraoperatively the original range of motion (English: "Range of Motion") as far as possible. Only when this is achieved, the risk of impingement (FAI, Femoro-acetabular impingement in hip joints, a bony stop between the joint-proximal portion of the thigh and the joint cup) or dislocation is banned. For a successful reconstruction of the ball joint, the individual adjustment of the CCD angle (abbreviation for caput-collum diaphyseal angle, describes the angle between the femoral neck and the shaft of the femur) and the Antetorsionswinkels increasing importance. It is therefore also an object of the subject invention to provide the surgeon with assistance for the individual adjustment of the CCD angle and Antetorsionswinkels to restore the original mobility of the ball joint.

These objects are achieved with a navigation ball head according to the preamble of claim 1 with the features of the characterizing part of claim 1. The dependent claims relate to particularly advantageous embodiments of the invention.

In an inventive navigation ball head according to the preamble of claim 1, the measurement marks on its surface a three-dimensional image of a mathematical calculation model, which indicates an ideal for the mobility of the joint endoprosthesis value range of the relative position of the prosthesis stem and joint cup each other.

The navigation ball head according to the invention serves the surgeon intraoperatively as a universal measuring instrument for visual assessment of his choice, with which prosthesis model, each individually tailored to the particular patient, the best possible reconstruction of the defective joint and the maximum mobility (range of motion) can be achieved ,

Furthermore, the navigation ball head according to the invention is also particularly versatile for the visual assessment of the ideal relative position of the prosthesis shaft and joint socket of the respectively selected prosthesis model.

Thus, the inventive navigation ball head is used to select and position different prosthesis models both with symmetrical or anatomically shaped one-piece prosthesis stem and attached prosthesis neck, as well as for multi-part modular prosthesis stems with a separate replaceable prosthesis neck.

Likewise, the inventive navigation ball head is suitable, both in the realization of the so-called "first-first" method, in which the prosthesis stem is first implanted and then the Gelenkpan, as well as in the "femur first" method used as a measuring instrument ,

The ideal range of values of the relative position of the prosthesis socket and joint socket characterized by measuring marks is an image of the "safe zone" as described in the relevant technical literature.

As an optimization criterion of the range of motion of the joint to be reconstructed serves the size of the "safe zone" with the aim to achieve the greatest possible margin to the prosthetic impingement.

With the help of the marker on the Navigationskugelkopf the actual state of the relative position of prosthesis stem and joint socket is detected during installation. This makes it possible to visually assess the inclination and anteversion of the pan as well as the CCD angle and the anti-torsion angle of the shaft.

The exact angle or orientation of the markers on the navigation ball head is specific to each model of prosthesis and is determined or determined for each combination of prosthetic socket or neck, joint head of the prosthesis and joint socket each as a three-dimensional image of a mathematical calculation model.

Particularly useful is an inventive navigation ball head in its attached to the free end of the respective prosthesis neck state based on its measurement marks a measure of the relative position of the prosthesis stem and joint socket ready.

In a navigation ball head according to the invention, the arrangement of the measurement marks on the navigation ball head is particularly advantageous in accordance with a calculation of the ideal value range of the relative position of the prosthesis stem and the joint cup with respect to one another using a mathematical function containing at least one of the following calculation parameters: Prosthesis CCD angle, Antetorsion angle of the prosthesis stem, Anteversion angle of the joint socket, Inclination angle of the joint cup, Offset distance of the femur to the hipbone, Diameter ratio of the joint head and prosthesis neck taken.

It should be noted that not the isolated placement of a single prosthesis component, but the correct orientation of the prosthesis stem and joint socket is essential to each other. In each case, the sum angles for the combined anteversion and for the combined inclination of the joint socket and prosthesis socket, taking into account the pelvic tilting, must be within the ideal value range, the "Safe Zone". The optimum pan orientation in the "Safe Zone" can be determined for each prosthesis neck alignment using the above calculation parameters. for each stem antetorsion and each neck / stem angle or prosthetic CCD angle. Furthermore, the ratio of the diameter of the joint head and neck of the prosthesis should be made as large as possible.

According to the invention, in a navigation ball head, the measuring markings are mounted on its surface in two or more marking planes parallel to each other such that for optimum relative position of the components of Gelenkendoprothese the measuring markings of Navigationskugelkopfes are arranged in the installed position parallel to the edge of the Gelenkpan and preferably one of the measurement marks with this one level.

Particularly advantageous in a navigation ball head according to the invention, the marking levels on the surface of the navigation ball head in a frontal plane view with the axis of the prosthesis neck a frontal plane angle of 50 ° to 130 °, preferably from 60 ° to 110 °, a.

Conveniently close in a navigation ball head, the marker planes on the surface of the navigation ball head in a transverse plane view with the axis of the prosthesis neck a transverse plane angle of 70 ° to 150 °, preferably from 80 ° to 120 °.

In an expedient variant of the invention, the measuring marks are provided on its surface in three marker planes parallel to each other in a Navigationskugelkopf, the middle marker plane is arranged in an ideal mounting position parallel to the edge of the joint socket and preferably lies with this in a plane.

In one embodiment of the invention, the measurement marks on the surface of the Navigationskugelkopfes in three marker planes are provided parallel to each other, the middle marker plane is preferably in an ideal mounting position with the edge of Gelenkpan in a plane and the two marginal marking levels a tolerance interval of + / -5 ° angular deviation around center position.

In a navigation ball head, which is designed, for example, with circumferential grooves as measuring markings, while the middle groove indicates the desired orientation of the plane of the edge of the joint cup for each specific prosthesis model. The parallel outer grooves of the measuring mark indicate the 5 ° tolerance zone. If, for example, the orientation of a provisionally inserted socket does not coincide with the grooves of the measuring marking, the socket can, if necessary, be reoriented and then hammered into the hipbone of the patient.

In an alternative embodiment, the measurement marks on the surface of the navigation ball head as depressions, in particular as notches, or as lines executed.

In a further alternative embodiment, the measurement marks on the surface of the navigation ball head are designed as color-contrasting, circumferential ribbons.

In a further development of the invention, the measuring marks on the surface of the navigation ball head as a differently colored ball parts, in particular hemispheres executed at a Navigationskugelkopf, said in the installed position outside the Gelenkpan available ball portion of the Navigationskugelkopfs, in particular a hemisphere, in a different color, as the located in the installed position within the Gelenkspfanne ball part is designed.

Conveniently, the measurement marks on the surface of the navigation ball head are designed as at least one paragraph, the lying in the installed position outside the Gelenkspfanne ball portion of the Navigationskugelkopfs, in particular a hemisphere, a smaller radius relative to the located in the installed position within the joint cup ball part and has thereby settles.

Particularly advantageous has a erfmdungsgemässer navigation ball head a recess for attachment to the free end of a prosthesis neck, which is fixed by a corresponding shape of this recess, preferably by a molding with a tongue and groove, the rotational position of the navigation ball head relative to the neck of the prosthesis.

Preferably, the recess of the navigation ball head is designed for attachment to the free end of the neck of the prosthesis such that the navigation ball head smoothly and as possible by hand on the neck of the prosthesis or can be separated again from this. In a particular embodiment, such a navigation ball made of a plastic, which is also commonly used in the construction of prostheses and tested for its compatibility with the human organism made.

A variant of the invention comprises a navigation ball head, which in the patch with its recess to the free end of the respective neck prosthesis based on its measurement marks a measure of the relative position of Gelenkpan and a symmetrical prosthesis stem, which with a prosthesis neck in one piece to a symmetrical Monoblockschaft without integrated anti-torsion angle provides.

A symmetrical monoblock shaft, in which prosthesis shaft and prosthesis neck are integrally connected, offers the advantage, due to its symmetrical design without integrated antetorsion angle, that one and the same monobloc shaft can be used both for the prosthetic reconstruction of a right and a left ball joint.

A further variant of the invention relates to a navigation ball head, which in its attached to the free end of the respective prosthesis neck condition based on its measurement marks a measure of the relative position of Gelenkpan and an anatomically shaped prosthesis stem, which integrally with a prosthesis neck to an anatomical Monoblock shaft connected with integrated antetorsion angle provides.

An anatomically shaped monoblock shaft, in which the prosthesis shaft and prosthesis neck are integrally connected to one another, offers the advantage that due to its design with integrated antetorsion angle, an individual prosthetic reconstruction of a ball joint is already possible. Such an anatomically shaped monoblock shaft is individually shaped for the reconstruction of a left or right ball joint.

Compared to a multi-part module shaft, which comprises a prosthesis socket with a recess for attaching a replaceable separate neck of the prosthesis monoblock shanks offer besides the advantage that they are more cost-effective in the storage, further the advantage that during surgery not a separate prosthesis neck must be selected and connected to the prosthesis stem.

Conveniently, in another embodiment, a navigation ball head according to the invention in its attached to the free end of the respective prosthesis neck condition is suitable, based on its measurement marks a measure of the relative position of Gelenkpan and a modular prosthesis stem, which with a modular interchangeable neck prosthesis to a multi-part module shaft with variably adjustable Antetorsionswinkel connectable to provide.

The Navigationskugelkopf corresponding with such a multi-part module shaft differs in the arrangement of its measurement marks as an image of the ideal range of values, the so-called "safe zone" against Navigationskugelköpfen, which are provided for placement on a one-piece symmetrical or a one-piece anatomical Monoblockschaft.

The outer diameter of the navigation ball head is to be adjusted in each case to the curvature diameter of the corresponding joint socket. Depending on the anatomical conditions of the patient a Gelenkpan is selected with a certain size. The outer diameter of the navigation ball head is thus determined by this selection. Advantageously, the operator is thus provided with a set of several navigation ball heads according to the invention with different outer diameters graduated from one another.

The invention will now be explained in more detail by means of exemplary embodiments with reference to the schematic drawings.

[0053] In the drawings: <Tb> FIG. 1 <SEP> a first embodiment of a navigation ball head designed according to the invention for optimal positioning of a hip joint endoprosthesis in a perspective view; <Tb> FIG. 1A <SEP> in detail a schematic view of a navigation ball head according to the invention with its recess for attachment to a prosthesis neck; <Tb> FIG. 1B is a side view of a navigation ball head with a particular embodiment of a mark on its surface in the form of a heel; <Tb> FIG. 2A <SEP> is a first embodiment of a one-piece symmetrical monoblock shaft in a frontal plane view; <Tb> FIG. FIG. 2B shows the one-piece symmetrical monobloc shank shown in FIG. 2A in a transverse plan view; FIG. <Tb> FIG. 3A <SEP> a one-piece anatomically shaped monoblock shaft in a frontal plane view; <Tb> FIG. FIG. 3B shows the one-piece anatomically shaped monoblock shaft shown in FIG. 3A in a transverse plan view; FIG. <Tb> FIG. 4A <SEP> a multi-part module shaft in a frontal plane view; <Tb> FIG. 4B <SEP> the multi-part module shaft shown in FIG. 4A in a transverse plane view; <Tb> FIG. 5 <SEP> in an exploded view in frontal plane view of a hip joint endoprosthesis with attached joint head; <Tb> FIG. 6 <SEP> in an exploded view in transversal plane view of a hip joint endoprosthesis with attached joint head; <Tb> FIG. 7 <SEP> in an exploded view in frontal plane view of a hip joint endoprosthesis with attachable navigation ball head according to the invention; <Tb> FIG. 8 <SEP> in an exploded view in transversal plane view of a hip joint endoprosthesis with attachable navigation ball head according to the invention.

Fig. 1 shows, in a schematic perspective view, a first embodiment of a hip joint endoprosthesis already implanted on a human body, but with the human body parts such as e.g. Bones are not shown. The hip joint endoprosthesis comprises a prosthesis shaft 20, from which a prosthesis neck 30 extends. Denture stem 20 and prosthesis neck 30 are here connected together to form a one-piece symmetrical Monoblockschaft 21. The prosthesis neck 30 projects with its other preferably conically shaped free end 33 into the corresponding recess 11 of a navigation ball head 10 according to the invention, which is used during the operation and later with optimal positioning of the prosthesis model against a spherical joint head of comparable geometry, not shown here replaced and replaced by this. The navigation ball head 10 protrudes into a joint socket 40, which has an inner curvature with an inner diameter 43, which corresponds to the outer diameter 13 of the navigation ball head 10. Ideally, the navigation ball head 10 encounters the joint cup 40 in the center of curvature.

As shown in Fig. 1, a plurality of mutually parallel measuring marks 13 are provided as circumferential lines on the surface of the navigation ball head 10. The two visible marking planes ε1, ε2 in FIG. 1 are parallel to the edge 41 of the joint socket 40, wherein the middle of preferably three marking planes ε1, ε2, ε3 lies in the plane 42 of the edge 41 of the joint socket 40. When using such a prosthesis-specific navigation ball head 10 is at neutral adjusted joint for the expert recognizable that here the prosthesis CCD angle 50 and the total antetorsion angle vote and the joint endoprosthesis is thus ideally positioned.

FIG. 1A shows in a detailed view a further embodiment of a navigation ball head 10 according to the invention from the prosthesis neck side. The circumferential measuring markings 12 and a recess 11, which corresponds to a prosthesis neck not shown in FIG. 1A, can be seen. The recess 11 is here designed with a groove 14, by means of which the rotational position of the navigation ball head 10 is fixed relative to the neck of the prosthesis.

FIG. 1B shows the navigation ball head 10 shown in FIG. 1A in a further detail view from the side. In this special case, the measuring mark 12 is provided as a shoulder between the ball part with a larger radius or a larger outside diameter 13, which is in the installed position of the ball Navigationskugelkopfs 10 is located within the Gelenkpan, and the ball part with a smaller radius, which is located in the installed position outside the Gelenkpan. In Fig. 1B, the recess 11 is shown by dashed lines for receiving the prosthesis neck, not shown here.

FIGS. 2A to 4B show components of different prosthesis models, each in different viewing planes. The navigation ball head according to the invention is suitable as a universal measuring instrument for the selection and positioning of all these different prosthesis models and can be fixed in its rotational position relative to the prosthesis neck 30 at the free end 33 of a prosthesis neck 30.

Fig. 2A shows a first embodiment of a one-piece symmetrical monoblock shaft 21 in a frontal plane view. In this symmetrical Monoblockschaft 21 of the prosthesis stem 20 and the prosthesis neck 30 are integrally connected to each other without integrated Antetorsionswinkel. At the free end 33 of the neck of the prosthesis 30, a navigation ball head according to the invention is inserted intraoperatively and also removable again.

FIG. 2B shows the one-piece symmetrical monoblock shaft 21 shown in FIG. 2A in a transverse plane view. The axis 32 of the prosthesis neck 30 lies in the horizontal frontal plane. An antetorsion angle is not provided in this symmetrical monoblock shaft 21, which is why this one-piece shaft model can be used equally well for the reconstruction of both a right and a left hip joint. Antetorsionspositionen can be achieved by using this Monoblockschaftes 21 only by a slight twist during implantation in the femoral tube.

FIG. 3A illustrates a second embodiment of a monobloc anatomically shaped monoblock shaft 22 in a frontal plane view. In this monoblock anatomically shaped shaft 21, the prosthetic stem 20 and prosthesis neck 30 are integrally connected at a predetermined anti-torsion angle. At the free end 33 of the prosthesis neck 30, an unillustrated inventive navigation ball head can be inserted intraoperatively.

Fig. 3B illustrates the one-piece anatomically shaped monoblock shaft 22 shown in Fig. 3A in a transverse plane view. The axis 32 of the prosthetic neck 30 is here by a predetermined Antetorsionswinkel 70, for example, an antetorsion angle 70 of 5 ° to 15 ° opposite pivoted the horizontal frontal plane. Thus, this one-piece monoblock shaft 22 is intended for either the reconstruction of a right or a left hip joint.

Fig. 4A shows a multi-part module shaft 23 in a frontal plane view. Prosthesis shaft 20 and prosthesis neck 30 form here two separate, modularly exchangeable prosthesis components of the module shaft 23, which can be connected to one another in different positions or with different antetorsion angle.

FIG. 4B illustrates the multi-part module shaft 23 shown in FIG. 4A in a transversal plane view. The axis 32 of the prosthesis neck 30 is adjustable here in different antetorsion angles 70 and can optionally be used in antetorsion angles 70.1, 70.2, 70.3, 70.4, etc. with respect to FIG Prosthesis shaft 20 are fixed. The possibilities of variation usually extend for antetorsion angle 70 from -5 ° to + 30 °. Such a multi-part module shaft 23 therefore offers a very high degree of flexibility intraoperatively to individually adapt a joint endoprosthesis to the anatomical conditions of the patient and thus to achieve maximum mobility. Also in this multi-part module shaft 23, a navigation ball head according to the invention can be attached to the free end 33 of the exchangeable prosthesis neck 30.

The two drawings Fig. 5 and Fig. 6 are essentially the representation of the angular positions of the individual prosthesis components to each other and thus to illustrate the calculation parameters for the mathematical determination of the «safe zone».

Fig. 5 shows in a greatly simplified exploded view of a hip joint endoprosthesis in frontal plane view with an anatomically shaped one-piece Monoblockschaft 22, in the prosthesis stem 20 and prosthesis neck 30 are integrally connected to one another in an integrated Antetorsionswinkel. Denture stem 20 and prosthesis neck 30 are further in a certain CCD angle 50 to each other. The CCD angle depends on the one hand on the design of the prosthesis stem, on the other hand on the sex and age of the patient. Usually, CCD angles 50 are usually realized from 120 ° to 140 °. At the free end of the prosthesis neck 30, instead of a navigation ball head according to the invention, a joint head 19 shown in section is attached, as it remains in the body of the patient after the positioning of the prosthesis components. In contrast to the navigation ball head according to the invention, the joint head 19 has no measuring markings on its surface. The inclination angle 80 of the joint socket 40 is determined in frontal plane view as an angle between the horizontal and the plane 42 of the edge 41 of the joint socket 40. Usually, inclination angles 80 from 40 ° to 55 ° are desired. The inner diameter 43 of the joint socket 40, which also defines the radius of curvature of the joint socket 40, corresponds to the outer diameter of the joint head 19 or of the navigation ball head, not shown.

Fig. 6 shows an exploded view in transverse plan view of the hip joint endoprosthesis shown in Fig. 5 with shown in sectional view, plugged joint head 19. The antetorsion angle 70 of the one-piece anatomically shaped Monoblockschaftes 22, which is selected here, for example, as an angle of 12 °, as well the antetorsion angle 60 of the joint cup 40 can be clearly seen in this view.

FIG. 7 shows an exploded view in frontal plane view of a hip joint endoprosthesis with a navigation ball head 10 according to the invention that can be fixed against rotation on the neck of the prosthesis. The recess 11 for rotationally fixed attachment to the free end 33 of the prosthesis neck 30 of a symmetrically shaped one-piece monoblock shaft 21 shown here For example, provided with a tongue and groove. On the surface of the navigation ball head 10, three measuring markings 12 are provided here in each case as circumferential lines. The individual measuring markings 12 are each located in mutually parallel marking planes ε1, ε2, ε3, which are uniformly spaced from one another. In this case, the marking planes ε1, ε2, ε3 form a frontal plane angle 90 in frontal plane view with the axis 32 of the prosthesis neck 30.

FIG. 8 shows in an exploded view the hip joint endoprosthesis shown in FIG. 7 in transverse plane view with the navigation ball head 10 according to the invention rotatably attached to the prosthesis neck 30. The marking planes ε1, ε2, ε3 form a transverse plane view with the axis 32 of the prosthesis neck 30 one at a time Transversal plane angle 100.

[0070] List of Item Numbers: <Tb> 10 <September> Navigation Ball Head <Tb> 11 <September> recess <Tb> 12 <September> measurement markings <tb> ε1, ε2 <SEP> Marking Levels <tb> 13 <SEP> Outer diameter of the navigation ball head <T b> 14 <September> Nut <Tb> 19 <September> condyle <Tb> 20 <September> prosthesis shaft <tb> 21 <SEP> symmetric monoblock shaft <tb> 22 <SEP> anatomical monoblock shaft <tb> 23 <SEP> multi-part module shaft <tb> 24 <SEP> Axis of the prosthetic stem <Tb> 30 <September> prosthesis neck <tb> 31 <SEP> Diameter of the neck of the prosthesis <tb> 32 <SEP> Axis of the neck of the prosthesis <tb> 33 <SEP> free end of the neck of the prosthesis <Tb> 40 <September> acetabulum <tb> 41 <SEP> Edge of joint socket <tb> 42 <SEP> Level of the edge of the socket <tb> 43 <SEP> Inner diameter of the joint socket <Tb> 50 <September> prosthetic CCD angle <tb> 60 <SEP> Anteversion angle of the joint socket <tb> 70 <SEP> Antetorsion angle of the prosthetic stem <tb> 80 <SEP> Inclusion angle of the joint socket <tb> 90 <SEP> Frontal plane angle of the marker planes with the axis of the prosthetic shaft <tb> 100 <SEP> Transverse plane angle of the marker planes with the axis of the prosthetic shaft

Claims (15)

A navigation ball head (10) for selecting and positioning a joint endoprosthesis for spherical joints of a human or animal body, in particular a hip joint endoprosthesis, wherein the joint endoprosthesis insertable into a medullary cavity of a bone prosthesis shaft (20) from which extends a prosthesis neck (30) a joint head (19) which can be fastened to the free end (33) of the prosthesis neck (30) and a joint socket (40) which can be inserted into a bone and forms a ball joint together with the joint head (19), the navigation ball head (10) having a to the inner diameter (43) of the Gelenkpan (40) corresponding outer diameter (13) and with a recess (11) for attachment to the free end (33) of the prosthesis neck (30) and provided on its surface, at least partially encircling measuring marks (12) is equipped, characterized in that the measuring marks (12) on the navigation ball head (10) dreidi Mental image of a mathematical calculation model, which indicates an ideal for the mobility of the joint endoprosthesis value range of the relative position of the prosthetic socket (20) and joint socket (40) to each other according to safe zone are, wherein the measuring marks (12) on the surface of the navigation ball head (10) in two or more marking planes (ε1, ε2, ε3) are mounted parallel to one another in such a way that, for an optimal relative position of the components of the joint endoprosthesis, the measuring markings (12) of the navigation ball head (10) in the installed position parallel to the edge (41) of the joint socket 40) are arranged and preferably one of the measuring marks (12) with this in a plane (42). 2. Navigationskugelkopf (10) according to claim 1, characterized in that the navigation ball head (10) in its recess (11) to the free end (33) of the respective prosthesis neck (30) patch state based on its measurement marks (12) a measure of provides the relative position of prosthesis stem (20) and socket (40). 3. navigation ball head (10) according to claim 1 or 2, characterized in that the arrangement of the measuring marks (12) on the navigation ball head (10) according to a calculation of the ideal value range of the relative position of the prosthesis stem (20) and Gelenkpan (40) to each other using a mathematical Function containing at least one of the following calculation parameters: Prosthesis CCD angle (50), Anteversion angle (60) of the joint socket (40), Anti-torsion angle (70) of the prosthesis shaft (20), Inclination angle (80) of the joint socket (40), - Offset distance of the femur to the hip bone, - Diameter of prosthesis neck (30) and joint head (19) is taken. 4. navigation ball head (10) according to one of claims 1 to 3, characterized in that the marking planes (ε1, ε2, ε3) on the surface of the navigation ball head (10) in the mounted state in a frontal plane view with the axis (24) of the prosthesis neck ( 20) include a frontal plane angle (90) of 50 ° to 130 °, preferably 60 ° to 110 °. 5. navigation ball head (10) according to one of claims 1 to 4, characterized in that the marking planes (ε1, ε2, ε3) on the surface of the navigation ball head (10) in the mounted state in a transverse plane view with the axis (24) of the prosthesis neck ( 20) include a transversal plane angle (100) of 70 ° to 150 °, preferably of 80 ° to 120 °. 6. navigation ball head (10) according to one of claims 1 to 5, characterized in that the measuring marks (12) on the surface of the navigation ball head (10) in the mounted state in three marker planes (ε1, ε2, ε3) are provided parallel to each other, wherein the middle marking plane (ε2) in an ideal installation position according to the safe zone is arranged parallel to the edge (41) of the joint socket (40) and preferably lies in a plane (42) therewith. 7. navigation ball head (10) according to claim 6, characterized in that the two edge-side marking levels (ε1, ε3) specify a tolerance interval of +/- 5 ° angular deviation about the central position. 8. navigation ball head (10) according to one of claims 1 to 7, characterized in that the measuring marks (12) on the surface of the navigation ball head (10) as depressions, in particular as notches, or as lines are executed. 9. navigation ball head (10) according to one of claims 1 to 8, characterized in that the measuring marks (12) on the surface of the navigation ball head (10) are designed as contrasting color, circumferential ribbons. 10. navigation ball head (10) according to any one of claims 1 to 9, characterized in that the measuring markings (12) on the surface of the navigation ball head (10) as differently colored ball parts, in particular hemispheres are executed, said in the installation position outside the Gelenkpan ( 40) located ball part of the navigation ball head (10), in particular a hemisphere, in a different color than in the installed position within the Gelenkpan (40) located ball part is designed. 11. navigation ball head (10) according to one of claims 1 to 10, characterized in that the measuring marks (12) on the surface of the navigation ball head (10) are designed as at least one paragraph, wherein in the installed position outside the Gelenkpan (40) lying ball part of the navigation ball head (10), in particular a hemispherical half, has a smaller radius relative to the ball part located in the installed position within the joint cup (40) and thereby settles. 12. navigation ball head (10) according to one of claims 1 to 11, characterized in that the navigation ball head (10) has a recess (11) for attachment to the free end (33) of a prosthesis neck (30), wherein by a corresponding shaping of this Recess (11), preferably by a molding with a groove (14), the rotational position of the navigation ball head (10) relative to the prosthesis neck (20) is fixed. 13. Set with a navigation ball head (10) according to one of claims 1 to 12 and with a Gelenkendoprothese, comprising a prosthesis neck (3) and a symmetrical prosthesis stem (20), characterized in that the navigation ball head (10) with its recess (11 ) on the free end (33) of the respective neck of the prosthesis (30) placed on the basis of its measurement marks (12) a measure of the relative position of Gelenkpan (40) and the symmetrical prosthesis stem (20), which with a prosthesis neck (30) to a symmetrical Monoblockschaft (21) without integrated Antetorsionswinkel (70) is integrally connected provides. 14. Set with a navigation ball head (10) according to one of claims 1 to 12 and with a joint endoprosthesis comprising a modular prosthesis neck (30) and an anatomically shaped prosthesis stem (20), characterized in that the navigation ball head (10) in with its recess ( 11) attached to the free end (33) of the respective prosthesis neck (30) state on the basis of its measurement marks (12) a measure of the relative position of Gelenkpan (40) and the anatomically shaped prosthesis stem (20) which with a prosthesis neck (30) an integral monoblock shaft (22) with integrated anti-torsion angle (70) is integrally connected provides. 15. Set with a navigation ball head (10) according to one of claims 1 to 12 and with a joint endoprosthesis comprising a modular prosthesis neck (30) and a modular prosthesis stem (20), characterized in that the navigation ball head (10) with its recess (11 ) on the free end (33) of the respective prosthesis neck (30) placed state on the basis of its measurement marks (12) a measure of the relative position of Gelenkpan (40) and the modular prosthesis stem (20) which with a modular prosthesis neck (30) to a multi-part module shaft (23) with variably adjustable Antetorsionswinkel (70) is connectable, provides.