CH660955A5

CH660955A5 - Hip joint prosthesis

Info

Publication number: CH660955A5
Application number: CH445883A
Authority: CH
Inventors: Maurice E Prof Dr Med Mueller
Original assignee: Protek Ag
Priority date: 1983-08-16
Filing date: 1983-08-16
Publication date: 1987-06-30

Abstract

For fixing and securing articular heads (9), which are only pushed onto the pin (8) during the implantation, against rotation the pin (8) comprises a longitudinal groove (12); during the implantation, a fixation pin (14) fixed in the articular head (9) and projecting into its bore (11) is pushed into the groove from the front side. <IMAGE>

Description

       

  
 

**WARNUNG** Anfang DESC Feld konnte Ende CLMS uberlappen **.

 



   PATENTANSPRUCH
Hüftgelenkprothese mit einem blattartigen Schaft, der einen unter einem Winkel dazu angeordneter Prothesenhals trägt, der seinerseits in einem konischen   Zapfen    endet, auf den ein Gelenkkopf aufsteckbar ist, wobei die Achse einer den Zapfen aufnehmenden Bohrung des Gelenkkopfes radial zum Mittelpunkt des Gelenkkopfes verläuft oder gegen einen solchen Radius versetzt sein kann, dadurch gekennzeichnet, dass in den Zapfen (8) eine stirnseitig offene Längsnut (12) eingelassen ist, in die zumindest bei   Gelenkköpfen    (9) mit versetzter Bohrung (11) ein in diese Gelenkköpfe (9) einsetzbarer, in die Bohrung (11) hineinragender Fixierstift (14) eingreift.



   Die Erfindung betrifft eine Hüftgelenkprothese mit einem blattartigen Schaft, der einen unter einem Winkel dazu angeordneten Prothesenhals trägt, der seinerseits in einem konischen Zapfen endet, auf den ein Gelenkkopf aufsteckbar ist, wobei die Achse einer den Zapfen aufnehmenden Bohrung des Gelenkkopfes radial zum Mittelpunkt des Gelenkkopfes verläuft oder gegen einen solchen Radius versetzt sein kann.



   Hüftgelenkprothese der vorstehend genannten Art sind bekannt aus CH-A 507 704 und 552 383. Eine der Aufgaben, die mit einer solchen Prothese gelöst werden, besteht darin, noch während der Operation die Möglichkeit zu haben, die Lage des Gelenkkopfes relativ zu einem bereits implantierten Schaft - durch Wahl eines Gelenkkopfes, dessen den Zapfen aufnehmende Bohrung gegenüber derjenigen eines  normalen  Gelenkkopfes mit radial auf seinen Mittelpunkt gerichteter Bohrung versetzt ist - zu ändern, um so unter Umständen den individuellen anatomischen Gegebenenheiten besser entsprechen zu können.



   Eines der Probleme bei derartigen Prothesen mit verschiedenen   Gelenkköpfen    ist die Fixierung des Kopfes und seiner Sicherung gegen unerwünschte Rotationen auf dem Schaft; denn diese Fixierung muss während der Implantationsoperation erfolgen. Bei den bekannten Konstruktionen wird diese Schwierigkeit dadurch gelöst, dass an der Basis des Schaftes bzw. auf der  Stirn -fläche des Prothesenhalses Rippen, Nocken oder Nasen vorgesehen sind, die in entsprechende Vertiefungen in der Bohrung des Gelenkkopfes bzw. im, den Zapfen von dem Schaft der Prothese trennenden Bund einrasten.

  Diese Art der Rotationssicherung hat zur Folge, dass der Prothesenhals relativ dick ausgeführt werden muss, wodurch die Beweglichkeit des   Hüftgelenks¯    besonders für Extensions-/Flexionsbewegungen bei Patienten mit angeboren oder erworben krankhaft deformierten   Hüftgelenken - beeinträchtigt    wird.



   Aufgabe der Erfindung ist es daher, die Beweglichkeit derartiger Prothesen mit erst während der Operation ausgewähltem und fixiertem Gelenkkopf gegenüber den bekannten Konstruktionen zu verbessern, ohne die Fixierung und Rotationssicherung zu beeinträchtigen.



   Diese Aufgabe wird nach der Erfindung dadurch gelöst dass in den Zapfen eine stirnseitig offene Längsnut eingelassen ist, in die zumindest bei Gelenkköpfen mit versetzter Bohrung ein in diese Gelenkköpfe einsetzbarer, in die Bohrung hineinragender Fixierstift eingreift.



   Längsnut des Zapfens und der in die Bohrung des Gelenkkopfes hineinragende Stift sind in Form und Abmessungen so aufeinander abgestimmt, dass nach Aufsetzen und Aufpressen des - bereits mit einem eingesetzten Fixierstift   angelieferten - Gelenkkopfes    der Fixierstift möglichst spielfrei in der Längsnut sitzt oder sich   sogar - gegebenenfalls    unter plastischer Verformung - darin verklemmt.



   Die neue Prothesenkonstruktion ist neben einer Verwendung als Dauerimplantat als sogenannte Manipulierprothese geeignet; eine solche dient dem Operateur dazu, während der Operation aus einem Bausatz von verschiedenen Grössen und Halslängen die für den individuellen Fall richtige Auswahl zu treffen.



   Als Materialien für die neue Prothese dienen vor allem in der Implantat-Technik üblichen Metalle und Metall-Legierungen. Um die erwähnte plastische Verformung des Fixierstiftes zu erreichen, ist es unter Umständen vorteilhaft, dafür ein relativ weiches Material, z.B. Protasul 10, zu verwenden.



   Im folgenden wird die Erfindung anhand eines Ausführungsbeispiels im Zusammenhang mit der Zeichnung näher erläutert.



   Fig. 1 ist eine Aufsicht auf die neue Prothese, wobei der mit einer versetzten Bohrung versehene Gelenkkopf im Schnitt dargestellt ist;
Fig. 2 ist ein Schnitt II-II von Fig. 1.



   Die gezeigte Prothese hat einen geraden, blattartigen Schaft 1, in dessen Blattseiten 2 Längsnuten 3 vorgesehen sind. Proximal endet der Schaft 1 in einer Schulter 4, die in einen Prothesenhals 5 übergeht. Dieser ist von den Blattseiten 2 durch einen stufenförmigen Absatz   (Kragen) 6    getrennt.



   Der Prothesenhals 5, in dem eine Ausschlagvertiefung 7 vorgesehen ist, um ein Ausschlagen des Schaftes 1, beispielsweise bei Reoperationen, zu erleichtern, trägt an seinem freien Ende einen konischen Zapfen 8. Auf diesen wird der Gelenkkopf 9 aufgesetzt, dessen Kugelform zum Prothesenhals 5 hin in einen unsymmetrischen Kegelstumpf 10 übergeht.



   Die den Zapfen 8 aufnehmende Bohrung 11 des Gelenkkopfes ist gegenüber seinem Zentrum nach lateral versetzt.



   Nach der vorliegenden Erfindung ist in den Zapfen 8 in dem gezeigten Beispiel nach medial gelegen - eine Längsnut 12 eingelassen, die sich vom Fuss des Zapfens 8 aus zu seiner Stirnseite gegen die Prothesenhalsachse 13 erweitert und stirnseitig offen ist. In diese Längsnut greift ein Fixierstift 14 ein, der in den Gelenkkopf 9 im Pass-Sitz eingesetzt ist, in die Bohrung 11 hineinragt.



   Wie Fig. 2 zeigt, ist das freie Ende des Fixierstiftes 14 an die Form und Abmessungen der Längsnut 12 angepasst, so dass er ohne Spiel in dieser sitzt.



   Der Gelenkkopf 9 wird mit bereits eingesetztem Fixierstift 14 geliefert und während der Implantation von oben auf den Zapfen 8 aufgeschoben, wobei der Fixierstift 14 von der Stirnseite her in die Längsnut 12 hineingleiten kann. 



  
 

** WARNING ** beginning of DESC field could overlap end of CLMS **.

 



   PATENT CLAIM
A hip joint prosthesis with a blade-like shaft that carries a prosthetic neck arranged at an angle to it, which in turn ends in a conical pin onto which a joint head can be plugged, the axis of a bore of the joint head receiving the pin running radially to the center of the joint head or against one Such a radius can be offset, characterized in that a longitudinal groove (12) which is open at the end is inserted into the pin (8) and into which, at least in the case of joint heads (9) with an offset bore (11), an insert can be inserted into these joint heads (9) the fixing pin (14) protruding into the bore (11).



   The invention relates to a hip joint prosthesis with a leaf-like shaft which carries a prosthesis neck arranged at an angle thereto, which in turn ends in a conical pin onto which a joint head can be plugged, the axis of a hole of the joint head receiving the pin being radial to the center of the joint head runs or can be offset against such a radius.



   Hip joint prosthesis of the type mentioned above are known from CH-A 507 704 and 552 383. One of the tasks that are solved with such a prosthesis is to be able to position the joint head relative to an already implanted one during the operation To change the shaft - by choosing an articulated head whose bore accommodating the pin is offset from that of a normal articulated head with a bore directed radially towards its center - in order to be able to better meet the individual anatomical circumstances.



   One of the problems with such prostheses with different joint heads is the fixation of the head and its securing against undesired rotation on the shaft; because this fixation must be done during the implantation operation. In the known constructions, this difficulty is solved in that ribs, cams or noses are provided at the base of the shaft or on the end face of the prosthesis neck, which ribs in corresponding recesses in the bore of the joint head or in the pin of the Snap the stem of the prosthesis separating collar into place.

  This type of rotation protection means that the neck of the prosthesis must be made relatively thick, which affects the mobility of the hip joint, particularly for extension / flexion movements in patients with congenital or acquired deformed hip joints.



   It is therefore the object of the invention to improve the mobility of such prostheses with a joint head that has been selected and fixed only during the operation compared to the known constructions without impairing the fixation and rotation lock.



   This object is achieved according to the invention in that a longitudinal groove which is open at the end is inserted into the pin and into which a fixing pin, which can be inserted into these rod ends and protrudes into the hole, engages, at least in the case of rod ends with an offset hole.



   The longitudinal groove of the pin and the pin protruding into the bore of the joint head are matched to one another in terms of shape and dimensions so that after the joint head, which has already been supplied with a fixing pin, is placed and pressed on, the fixing pin sits as free of play in the longitudinal groove as possible or even - if necessary, underneath plastic deformation - jammed in it.



   In addition to being used as a permanent implant, the new prosthesis construction is suitable as a so-called manipulation prosthesis; The surgeon uses this to make the right choice for the individual case from the kit of different sizes and neck lengths.



   The materials used for the new prosthesis are mainly metals and metal alloys that are common in implant technology. In order to achieve the aforementioned plastic deformation of the fixing pin, it may be advantageous to use a relatively soft material, e.g. Protasul 10 to use.



   The invention is explained in more detail below using an exemplary embodiment in conjunction with the drawing.



   Fig. 1 is a plan view of the new prosthesis, with the joint head provided with an offset bore is shown in section;
FIG. 2 is a section II-II of FIG. 1.



   The prosthesis shown has a straight, leaf-like shaft 1, in the leaf sides of which 2 longitudinal grooves 3 are provided. Proximally, the shaft 1 ends in a shoulder 4, which merges into a prosthesis neck 5. This is separated from the leaf sides 2 by a step-shaped shoulder (collar) 6.



   The prosthesis neck 5, in which a deflection recess 7 is provided in order to facilitate knocking out of the shaft 1, for example during reoperations, has a conical pin 8 at its free end merges into an asymmetrical truncated cone 10.



   The bore 11 of the joint head receiving the pin 8 is laterally offset with respect to its center.



   According to the present invention, in the pin 8 in the example shown is located medially - a longitudinal groove 12 is inserted, which widens from the base of the pin 8 to its front side against the prosthesis neck axis 13 and is open on the front side. A fixing pin 14, which is inserted into the joint head 9 in a snug fit, engages in this longitudinal groove and projects into the bore 11.



   As shown in FIG. 2, the free end of the fixing pin 14 is adapted to the shape and dimensions of the longitudinal groove 12, so that it sits in the latter without play.



   The joint head 9 is supplied with the fixing pin 14 already inserted and is pushed onto the pin 8 from above during the implantation, the fixing pin 14 being able to slide into the longitudinal groove 12 from the front side.

Claims

PATENT CLAIM A hip joint prosthesis with a blade-like shaft that carries a prosthetic neck arranged at an angle to it, which in turn ends in a conical pin onto which a joint head can be plugged, the axis of a bore of the joint head receiving the pin running radially to the center of the joint head or against one Such a radius can be offset, characterized in that a longitudinal groove (12) which is open at the end is inserted into the pin (8) and into which, at least in the case of joint heads (9) with an offset bore (11), an insert can be inserted into these joint heads (9) the fixing pin (14) protruding into the bore (11).

The invention relates to a hip joint prosthesis with a leaf-like shaft which carries a prosthesis neck arranged at an angle thereto, which in turn ends in a conical pin onto which a joint head can be plugged, the axis of a hole of the joint head receiving the pin being radial to the center of the joint head runs or can be offset against such a radius.

Hip joint prosthesis of the type mentioned above are known from CH-A 507 704 and 552 383. One of the tasks that are solved with such a prosthesis is to be able to still position the joint head relative to an already implanted head during the operation To change the shaft - by choosing an articulated head whose bore accommodating the pin is offset from that of a normal articulated head with a bore directed radially towards its center - in order to be able to better meet the individual anatomical circumstances.

One of the problems with such prostheses with different joint heads is the fixation of the head and its securing against undesired rotation on the shaft; because this fixation must be done during the implantation operation. In the known constructions, this difficulty is solved in that ribs, cams or noses are provided at the base of the shaft or on the end face of the prosthesis neck, which ribs in corresponding recesses in the bore of the joint head or in the pin of the Snap the stem of the prosthesis separating collar into place.

This type of rotation protection means that the neck of the prosthesis must be made relatively thick, which affects the mobility of the hip joint, particularly for extension / flexion movements in patients with congenital or acquired deformed hip joints.

It is therefore the object of the invention to improve the mobility of such prostheses with a joint head that has been selected and fixed only during the operation compared to the known constructions without impairing the fixation and rotation lock.

This object is achieved according to the invention in that a longitudinal groove which is open at the end is inserted into the pin and into which a fixing pin, which can be inserted into these rod ends and protrudes into the hole, engages, at least in the case of rod ends with an offset hole.

The longitudinal groove of the pin and the pin protruding into the bore of the joint head are matched to one another in terms of shape and dimensions so that after the joint head, which has already been supplied with a fixing pin, is placed and pressed on, the fixing pin sits as free of play in the longitudinal groove as possible or even - if necessary, underneath plastic deformation - jammed in it.

In addition to being used as a permanent implant, the new prosthesis construction is suitable as a so-called manipulation prosthesis; The surgeon uses this to make the right choice for the individual case from the kit of different sizes and neck lengths.

The materials used for the new prosthesis are mainly metals and metal alloys that are common in implant technology. In order to achieve the aforementioned plastic deformation of the fixing pin, it may be advantageous to use a relatively soft material, e.g. Protasul 10 to use.

The invention is explained in more detail below using an exemplary embodiment in conjunction with the drawing.

Fig. 1 is a plan view of the new prosthesis, with the joint head provided with an offset bore is shown in section; FIG. 2 is a section II-II of FIG. 1.

The prosthesis shown has a straight, leaf-like shaft 1, in the leaf sides of which 2 longitudinal grooves 3 are provided. Proximally, the shaft 1 ends in a shoulder 4, which merges into a prosthesis neck 5. This is separated from the leaf sides 2 by a step-shaped shoulder (collar) 6.

The prosthesis neck 5, in which a deflection recess 7 is provided to facilitate knocking out of the shaft 1, for example during reoperations, has a conical pin 8 at its free end. The joint head 9 is placed on this, the spherical shape of the prosthesis neck 5 merges into an asymmetrical truncated cone 10.

The bore 11 of the joint head receiving the pin 8 is laterally offset with respect to its center.

According to the present invention, in the pin 8 in the example shown is located medially - a longitudinal groove 12 is inserted, which widens from the base of the pin 8 to its front side against the prosthesis neck axis 13 and is open on the front side. A fixing pin 14, which is inserted into the joint head 9 in a snug fit, engages in this longitudinal groove and projects into the bore 11.

As shown in FIG. 2, the free end of the fixing pin 14 is adapted to the shape and dimensions of the longitudinal groove 12, so that it sits in the latter without play.

The joint head 9 is supplied with the fixing pin 14 already inserted and is pushed onto the pin 8 from above during the implantation, the fixing pin 14 being able to slide into the longitudinal groove 12 from the front side. ** WARNING ** End of CLMS field could overlap beginning of DESC **.