DE102004052143A1 - Joint prosthesis used as a hip prosthesis comprises an aligning part fixed to a fixing part and separating the fixing part and a hinged part - Google Patents

Abstract

Joint prosthesis comprises an aligning part (15) fixed to a fixing part (1) and separating the fixing part and a hinged part (6). The hinged part is placed on the aligning part and locked in only one position. The hinged part can be brought into different positions together with the aligning part opposite the fixing part. An independent claim is also included for a process for assembling the joint prosthesis. Preferred Features: The aligning part is formed as an annular body or sleeve body which is fixed on a protrusion (3) of the fixing part in different rotating positions using a fixing arrangement (10, 14, 16).

Description

The The invention relates to a joint prosthesis with a fixing part and a fixed thereto in a predetermined position joint part, in particular Hip prosthesis.

Joint prostheses of this type, which are formed of two main parts, namely from the fixing part, which is insertable into a medullary cavity of a bone, in particular a femur, and an attachable thereto hinge part, which in the case of a hip carries a spherical head and the head of a femur to is damaged, for example, by illness or accident, are known for example from WO 95/13757 or the EP 0 681 816 A2 known.

According to the WO 95/13757 known joint prosthesis, the joint part on the fixing part are fixed in different positions, namely the hinge part is pivotable about the hinge axis of the fixing part. To attach the joint part to the fixing part is a conical Recess of the joint part, which is based on a projecting cone of the Fixing parts can be placed. To secure the position of the joint part on the fixing part is still a screw that the hinge part penetrated and screwed into the projecting cone.

One Assembly of this known joint prosthesis is difficult insofar as an exact alignment to the ideal position is only possible if the hinge part is slightly raised from the cone, as in composite Position a rotation of the joint part relative to the fixing part is no longer possible. Has the surgeon by trying the ideal position of the joint part across from determined the fixing part, he must assemble the joint prosthesis and screw the two parts together. This can happen to deviate from the previously determined ideal situation. Is working one with a trial joint part, after determining the ideal position it has to be exchanged for the correct hinge part necessary, a marking of the determined ideal position on the fixing part to serve as an aid in inserting the joint part Has. This is awkward inaccurate and can also be grosser Give rise to mistakes.

According to the EP 0 681 816 A2 the joint part on the fixing part is also fastened with a cone, wherein a shoulder on the cone prevents rotation of the joint part relative to the fixing part. According to this embodiment, the joint part can be fastened with respect to the fixing part in only one single layer. This is disadvantageous, especially since the fixing part has to be inserted into the medullary cavity of a bone and in this case the correct position of the joint part can not yet be predicted. Thus, it may be necessary, for example, to have to accommodate the fixing part in the medullary cavity in an orientation that is not ideal for him, only so that the joint part can later assume its ideal position.

The The invention aims to avoid the disadvantages described above and difficulties and sets itself the task of a joint prosthesis to create the type described above, in which the fixing part in an ideal position in a medullary cavity a bone can be used and the hinge part on the Fixing part can be fixed in an ideal position, even after one if necessary, multiple trials of the correct position of trial joint parts with e.g. different neck lengths, Angular positions etc. In particular, it should be possible the ideal position of Joint part opposite the fixation after trial with a trial joint part, with the The ideal situation has been determined, in turn, so that a Misorientation of the joint part with respect to the fixing part with absolute Safety is avoidable.

• – eine am Fixierteil in unterschiedlichen Lagen fixierbare und vom Fixierteil und Gelenkteil getrennte Ausrichteinrichtung, auf die der Gelenkteil in nur einer Lage einrastbar aufsetzbar ist, und
• – wobei der Gelenkteil mitsamt der Ausrichteinrichtung gegenüber dem Fixierteil unter Mitbewegen der Ausrichteinrichtung in unterschiedliche Lagen bringbar ist.

This object is achieved in a joint prosthesis according to the invention by:

• - One on the fixing in different positions fixable and separate from the fixing part and hinge part alignment, to which the hinge part is latched in only one position, and
• - Wherein the hinge part together with the alignment device relative to the fixing part while moving the alignment device can be brought into different positions.

Of the The core of the invention is therefore the provision of the alignment device, So an additional Part of the fixing part and joint part, which, as it were, has a "memory function" for the fixing part.

A first advantageous embodiment is characterized in that the alignment device as a ring body or Sleeve body is formed, the on an extension of the fixing part in different rotational positions can be fixed by means of a fixing device, and that the alignment device and the hinge part with a form-locking connection in the circumferential direction are provided, which is a putting on and latching of the joint part in only a single angular position across from allow the alignment device wherein advantageously the alignment device and the extension of the fixing part with in different angular positions of the alignment over the Extension form-fitting engageable elevations and depressions, for example with a toothing and counter toothing, are provided.

Appropriately access the alignment and the hinge part only in the circumferential direction form-fitting in one another and are in the axial direction of the fixing but at loosened or remote fixation against each other at least as far movable until the positive connection between the alignment and your fixing part except Intervention passes, wherein advantageously the positive connection between the hinge part and alignment device formed as a tongue and groove connection with limited length in the axial direction is.

Prefers come the alignment device, and possibly also the fixing device, in a cavity of the joint part, with which the joint part of the extension encloses the fixing part, with assembled joint prosthesis to lie.

A further preferred embodiment is characterized in that the configured as a sleeve alignment device in an assembled joint prosthesis from a cavity, with the the hinge part surrounds the extension of the fixing part, after Outside Tagt and the fixing device protrudes through the sleeve. According to this Embodiment is the alignment device from the fully assembled joint prosthesis away. Here the alignment device serves only during the Phase of assembly to, the position of the joint part against the Secure the fixing part.

According to one preferred variant has a toothing in the alignment an uneven number of teeth on, like teeth a provided on the extension of the fixing counter teeth are present, being provided between each adjacent teeth voids.

Preferably is a toothing acting between the hinge part and the fixing part designed in an analogous manner as that between the extension of the fixing part and the alignment device acting toothing, wherein the toothing between the joint part and the fixing part expedient teeth, extending in the radial direction of the fixing part, and the teeth between the extension of the fixing part and the alignment device Has teeth, which extend in the axial direction of the fixing part. An unambiguous position assurance is then given, if with each toothing and counter toothing several teeth with differently directed flanks are engaged.

A preferred variant, which can also be produced by means of a milling process, is characterized in that a row of teeth of the teeth teeth at a uniform distance has, wherein the distance of the teeth an integer multiple of a Tooth width is and the further tooth row engageable with this tooth friction the counter teeth also teeth evenly spaced, where the distance is also an integer multiple of one Tooth width, but different multiples of the other row of teeth, corresponds, wherein advantageously a row of teeth at a distance of three tooth widths and the other teeth teeth at a distance of two tooth widths.

For an individual Adaptation of a joint prosthesis are preferably two or more with each other differently designed sample joint parts present, of which each in only one position on the alignment device latched placed is.

• – Anbringen einer an dem Fixierteil in unterschiedlichen Lagen fixierbaren Ausrichteinrichtung am Fixierteil vor oder nach Fixieren des Fixierteils am Knochen,
• – Aufsetzen eines an der Ausrichteinrichtung in nur einer einzigen Lage einrastbaren Gelenkteiles auf den Fixierteil,
• – Ausrichten des Gelenkteils gegenüber dem Fixierteil in eine ausgewählte Lage unter Mitbewegen der vorher entfixierten Ausrichteinrichtung,
• – Fixieren der Ausrichteinrichtung gegenüber dem Fixierteil in der ausgewählten Lage.

When assembling a joint prosthesis according to the invention with a fixing part and a joint part which can be fixed therein in a predetermined position, the procedure is as follows:

• Attaching an aligning device which can be fixed to the fixing part in different positions on the fixing part before or after fixing the fixing part to the bone,
• Placing a hinge part which can be latched on the alignment device in only a single position onto the fixing part,
• Aligning the joint part with respect to the fixing part in a selected position while moving the previously unfixed alignment device,
• - Fixing the alignment with respect to the fixing part in the selected position.

Preferably is by means of a trial joint part orthopedically correct position and / or shape determined by the joint part, using the correct position brought and properly selected Sample-joint part the alignment device fixed to the fixing part and the trial joint part is replaced with an identically designed joint part.

It is useful in a joint prosthesis with an alignment device designed as a sleeve the sleeve removed after fixing the joint part to the fixing part.

The invention is explained in more detail with reference to embodiments shown in the drawing, wherein 1 a longitudinal section through a joint prosthesis, 2 the joint part of the joint prosthesis in oblique and in the axial section, 3 the fixing part of the joint prosthesis in the assembled state and 4 show in exploded view. 2A shows the hinge part of the joint prosthesis in a modified embodiment. In the 5 and 6 Further embodiments are shown, wherein 5 another execution in an oblique position in assembled condition, but without hinge part, and 6 show another embodiment in exploded view. Based on 7 to 11 the teeth are explained below.

The joint prosthesis according to the invention has a fixing part 1 with an anchoring part insertable into the medullary cavity of a bone 2 on, whose design can be designed in terms of cross-section and length corresponding to the medullary cavity, At the insertable into the medullary cavity of the bone anchoring part 2 , includes as a cone 3 formed extension, being between the cone 3 and the anchoring part 2 a gearing 4 with radially aligned teeth 5 , which will be explained later, is provided.

On the cone 3 is a joint part 6 the joint prosthesis by means of a cone 3 adapted conical recess 7 be placed, wherein the recess 7 at the end facing the fixing with one with the teeth 4 interacting counter-toothing 8th Is provided. This counter-toothing 8th whose teeth 5 are also aligned radially, is formed as internal toothing. The conical recess 7 of the joint part 6 goes to the fixing part 1 averted end in a substantially cylindrical recess 9 about, but has some peculiarities, as will be explained later.

The cone 3 has a gearing at its end 10 with axially aligned teeth 11 and one opposite the cone 3 recessed cylindrical extension 12 on, with a thread at its end 13 is equipped, on which a ring nut 14 can be placed. On the cylindrical extension 12 is a trained as a ring body alignment 15 , which - as will be explained - has a "memory function", which can be placed on a plan side with an axially directed toothing 10 corresponding counter-toothing 16 with teeth 11 Is provided. This alignment device 15 can by means of the ring nut on the cylindrical extension 12 be fixed either, with the axially aligned teeth 10 with the counter teeth 16 engages and prevents twisting, or if the ring nut 14 is not completely screwed, be moved in the axial direction by an amount whose size is such that the axially aligned teeth 10 with the counter teeth 16 is disengaged.

Between the hinge part 6 and the alignment device 15 is provided in the circumferential direction a positive connection resulting fixation, for example, a tongue and groove joint 17 (either after 1 and 2 or according to 2a designed), on the one hand, a vertical displacement of the joint part 6 opposite the fixing part 1 allows, on the other hand, however, a rotation of the joint part 6 around the axis 22 of the cone 3 or the alignment device relative to the alignment device 15 prevented.

The function of the joint prosthesis is the following:
First, the fixing part 1 with the anchoring part 2 fixed in the medullary cavity of a bone, in the position in which it fits best in this medullary cavity. For this purpose, the longitudinal shaft of the fixing part may have a cross-section adapted to the medullary cavity and also a longitudinal extent adapted to the medullary cavity of the bone, possibly in curved form.

At the fixing part 1 is the alignment device 15 pushed on and by means of the ring nut 14 fixed such that a vertical displacement of this alignment device 15 is possible between two positions, namely a first position in which the axially aligned toothing 10 with the counter teeth 16 the alignment device 15 is engaged and a second position (see. 3 ), in which the gearing 10 is disengaged, with the counter teeth 16 , so once a twisting of the alignment device 15 opposite the fixing part 1 is prevented and once, in the second position, a rotation of the alignment 15 opposite the fixing part 1 can take place.

Subsequently, on the fixing part 1 a trial articulated part fitted, reflecting what the interior design of the conical recess 7 and the counter teeth 8th and 16 is concerned, completely the same design as the joint part 6 , The tongue and groove connection 17 between the joint part 6 and the alignment device 15 gets involved in this case. It can now be started with an adaptation of the trial joint part to the given situation by trying in which angular position the trial joint part is best positioned. For this purpose, the trial joint part including the alignment 15 moved in the vertical direction until the alignment device 15 in the in 3 shown position reaches, in which the axially directed toothing 10 with the counter teeth 16 the alignment device 15 has been disengaged. In addition, when the sample joint part is displaced in the axial direction, a toothing provided on the sample joint part also arrives 8th with the fixing part 1 provided toothing 4 disengaged, and it may be the ideal angular position of the trial joint part relative to the fixing part 1 be determined. Once the most favorable position is found, the alignment device 15 by tightening the ring nut 14 so far against the fixing part 1 moved until the axially directed toothing 10 of the fixing part 1 with the countervers perforation 16 the alignment device 15 engaged.

Subsequently, the trial joint part is again from the fixing part 1 removed and against a joint part 6 , which then remains on the joint prosthesis replaced. This joint part 6 has a groove-spring connection analogous to the trial joint part 17 with the alignment device 15 , whereby the hinge part 6 in only one position - that of the now fixed alignment device 15 is determined (hence "memory function") - on the fixing part 1 can be placed, in the same position as the trial joint part.

Fixing the joint part 6 on the cone 3 is caused by pressing or by hitting. The alignment device 15 remains in the joint prosthesis and may be useful in further surgical procedures. The recess 9 is closed by means of a threaded insert, not shown.

The design of the gears and counter teeth 4 . 8th . 10 and 16 between hinge part 6 and fixing part 1 and between fixing part 1 and alignment device 15 may have different embodiments. So it is not absolutely necessary between the hinge part 6 and the fixing part 1 a toothing with radially aligned teeth 5 provided. Here also aligned in the axial direction teeth could vorgese hen as at the alignment 15 , Conversely, the alignment can also 15 be provided with radially directed teeth.

Both gears 4 and 10 and counter teeth 8th and 16 are designed such that the teeth 4 and 10 each an unequal number of teeth 5 respectively. 11 like the teeth 5 respectively. 11 each of the counter teeth 8th and 16 , being between the teeth 5 respectively. 11 each empty space 18 are provided and where the teeth 5 and 11 both of each gearing 4 and 10 as well as every counter toothing 8th and 16 evenly spaced 19 present and the distance 19 between tips of the teeth 5 respectively. 11 an integer multiple of a tooth width 20 is. The distances 19 at the toothing 4 and 10 amount to a different multiple of the distances 19 the teeth 5 and 11 each counter toothing 8th and 16 ,

According to the illustrated embodiment, cf. the 7 to 11 (the 8th and 9 show the teeth in settlement), the distance is 19 the teeth 5 respectively. 11 one row of teeth, ie the teeth, three tooth widths 20 and the distance 19 the counter-toothing, for example, four tooth widths 20 , In particular from 7 can be seen, thereby always get six tooth flanks 5 ' respectively. 11 ' engaged, with three tooth flanks 5 ' . 11 ' acting in one direction and three in the opposite direction. This also provides a fine adjustment of the joint part 6 opposite the fixing part 1 ensures it can namely the hinge part 6 opposite the fixing part 1 or the alignment device 15 opposite the fixing part 1 each one of a tooth width 20 assumed circumferential angle can be adjusted.

In the design of the tooth flanks 5 ' respectively. 11 ' is due to easy machinability - the teeth 5 and 11 are very small and housed in a confined space - and to take into account a sufficient transmission of forces during the setting and trial phases. In the 10 and 11 different tooth flank forms are shown, wherein the in 11 shown form has a point symmetry of the edge shape.

According to the in the 5 and 6 The embodiment shown is the alignment device 15 ' formed by an elongated sleeve, which at one end also with a counter-toothing 16 Corresponding to the teeth 10 is provided and which sleeve 15 ' by means of a threaded pin 21 on the fixing part 1 in a position determined by means of the trial joint part on the fixing part 1 can be fixed. After removing the trial joint part and pushing on the joint part 6 on this sleeve 15 ' becomes the hinge part 6 by hitting the cone 3 fixed, in turn, the gearing 4 of the fixing part 1 with the counter teeth 8th of the joint part 6 engaged. Then the sleeve 15 ' removed and the hinge part 6 closed at its end by means of a threaded insert. In this case, the alignment remains 15 ' not on the joint prosthesis and it is reusable.

Claims (17)

Joint prosthesis with a fixing part ( 1 ) and a fixed thereto in a predetermined position joint part ( 6 ), in particular a hip prosthesis, characterized by: - one on the fixing part ( 1 ) fixable in different positions and from the fixing part ( 1 ) and joint part ( 6 ) separate alignment device ( 15 . 15 ' ) to which the joint part ( 6 ) in only one position latchable is settable, and - wherein the hinge part ( 6 ) together with the alignment device ( 15 . 15 ' ) relative to the fixing part ( 1 ) while moving the alignment device ( 15 . 15 ' ) Can be brought into different layers. Joint prosthesis according to claim 1, characterized in that the alignment device as a ring body ( 15 ) or sleeve body ( 15 ' ) formed on an extension ( 3 ) of the fixing part ( 1 ) in different rotational positions by means of a Fixiereinrich tion ( 10 . 14 . 16 . 21 ) is fixable, and that the alignment device ( 15 . 15 ' ) as well as the joint part ( 6 ) with a circumferentially positive connection ( 17 ), which is a placement and locking of the joint part ( 6 ) in only a single angular position relative to the alignment device ( 15 . 15 ' ) enable. Joint prosthesis according to claim 2, characterized in that the alignment device ( 15 . 15 ' ) and the extension ( 3 ) of the fixing part with in different angular positions of the alignment device ( 15 . 15 ' ) opposite the extension ( 3 ) positively engageable elevations and depressions, for example with a toothing ( 10 ) and counter-toothing ( 16 ) are provided. Joint prosthesis according to claim 2 or 3, characterized in that the alignment device ( 15 . 15 ' ) and the joint part ( 1 ) intermesh positively only in the circumferential direction, in the axial direction of the fixing part ( 1 ) but with a loosened or removed fixing device ( 10 . 14 . 16 . 21 ) are at least as far movable against each other until the positive connection between the alignment device ( 15 . 15 ' ) and the fixing part disengaged. Joint prosthesis according to claim 4, characterized in that the positive connection between the hinge part ( 6 ) and alignment device ( 15 . 15 ' ) Is designed as a tongue and groove connection with limited length in the axial direction. Joint prosthesis according to one or more of claims 1 to 5, characterized in that the alignment device ( 15 ) and optionally also the fixing device ( 10 . 14 . 16 ) in a cavity ( 9 ) of the joint part ( 1 ), with which the joint part ( 1 ) the extension ( 3 ) of the fixing part ( 1 ) encloses, come to lie with assembled joint prosthesis. Joint prosthesis according to one or more of claims 1 to 5, characterized in that the sleeve ( 15 ' ) configured alignment device with assembled joint prosthesis from a cavity ( 9 ), with which the joint part ( 6 ) the extension ( 3 ) of the fixing part ( 1 ), protrudes outwards and the fixing device ( 21 ) through the sleeve ( 15 ' ) protrudes. Joint prosthesis according to one or more of claims 3 to 7, characterized in that a toothing ( 10 ) of the alignment device ( 15 . 15 ' ) an uneven number of teeth ( 11 ), like teeth ( 11 ) one on the extension ( 3 ) of the fixing device ( 1 ) provided counter-toothing ( 16 ) are present, between each adjacent teeth ( 11 ) White spaces ( 18 ) are provided. Joint prosthesis according to one or more of claims 3 to 8, characterized in that a between the joint part ( 6 ) and the fixing part ( 1 ) acting toothing is designed in an analogous manner as that between the extension ( 3 ) of the fixing part ( 1 ) and the alignment device ( 15 . 15 ' ) acting gearing. Joint prosthesis according to one or more of claims 1 to 9, characterized in that the toothing ( 4 ) between the joint part ( 6 ) and the fixing part ( 1 ) Teeth ( 5 ), which in the radial direction of the fixing part ( 1 ), and the gearing ( 10 ) between the extension ( 3 ) of the fixing part ( 1 ) and the alignment device ( 15 . 1 p ') Teeth ( 11 ), which in the axial direction of the fixing part ( 1 ). Joint prosthesis according to one or more of claims 3 to 10, characterized in that at each toothing ( 4 . 10 ) and counter-toothing ( 8th . 16 ) several teeth ( 5 and 11 ) with differently directed flanks ( 5 ' . 11 ' ) are engaged. Joint prosthesis according to one or more of claims 3 to 11, characterized in that a row of teeth of the toothing ( 4 . 10 ) Teeth ( 5 . 11 ) at regular intervals ( 19 ), wherein the distance ( 19 ) the teeth ( 5 . 11 ) an integer multiple of a tooth width ( 20 ) is and which can be brought into engagement with this row of teeth further tooth row of the counter-toothing ( 8th . 16 ) also teeth ( 5 . 11 ) at regular intervals ( 19 ), wherein the distance is also an integer multiple of a tooth width ( 20 ), but different multiples of the other row of teeth, corresponds. Joint prosthesis according to claim 12, characterized in that a row of teeth ( 5 . 11 ) at a distance ( 19 ) of four tooth widths ( 20 ) between tips and the other teeth teeth ( 5 . 11 ) at a distance ( 19 ) of three tooth widths ( 20 ) between peaks. Joint prosthesis according to one or more of claims 1 to 13, characterized in that two or more mutually differently designed trial joint parts are present, each of which in only one position on the alignment device ( 15 . 1 p ') is latched placed. Method for assembling a joint prosthesis according to one or more of Claims 1 to 14, having a fixing part ( 1 ) and a fixed thereto in a predetermined position joint part ( 6 ), in particular hip prosthesis, characterized by a combination of the following method steps: - attaching a to the fixation part ( 1 ) in difference Lichen fixable alignment device ( 15 . 15 ' ) on the fixing part ( 1 ) before or after fixing the fixing part ( 1 ) on the bone, - placing one on the alignment device ( 15 . 15 ' ) in only one position latchable hinge part ( 6 ) on the fixing part ( 1 ), - Aligning the joint part ( 6 ) against your fixation part ( 1 ) in a selected position while moving the previously unfixed alignment device ( 15 . 15 ' ), - fixing the alignment device ( 15 . 15 ' ) relative to the fixing part ( 1 ) in the selected location. A method according to claim 15, characterized in that using a joint prosthesis according to claim 14 by means of a trial joint part, the orthopedically correct position and / or shape of the joint part ( 6 ) is determined, wherein on the basis of the correctly positioned and correctly selected sample hinge part, the alignment device ( 15 . 1 p ') on the fixing part ( 1 ) and the trial joint part against an identically designed joint part ( 6 ) is exchanged. A method according to claim 15 or 16, characterized in that in a joint prosthesis with a sleeve ( 15 ' ) aligned alignment device the sleeve ( 15 ' ) after fixing the joint part ( 6 ) on the fixing part ( 1 ) Will get removed.