DE202009012964U1 - Casting mold for a cement large head for total hip arthroplasty - Google Patents

Abstract

A multi-part mold for producing a temporary joint prosthesis, the mold having an inner surface (5, 6, 6a, 6b) comprising at least a portion of the outer surface of a condyle, characterized in that the mold consists of a first mold half (1), a second mold half (2) and a conical former (4) which can be arranged through an insertion opening (3) into the inner volume comprised by the first and second mold halves (1, 2), wherein the mold encompassed by the inner volume of the mold mold consists of a section of the outer surface of a condyle consists.

Description

The The invention relates to a casting mold for a cement large head, as a temporary spacer in revision surgery in hip endoprosthesis is usable. In particular, it concerns the invention is a mold for making a temporary Joint prosthesis, as well as those produced with the mold temporary joint prosthesis.

The Mold according to the invention is particular suitable for the production of a joint prosthesis suitable for the temporary implantation is used and only one Condyle includes, d. H. z. For example for a hip joint, and consists of a temporarily usable condyle, does not have a shaft portion, as he z. For example, permanent Prostheses is present and when implanted in a femur is plugged. Therefore, the invention is suitable Casting mold, in particular for producing a temporary Joint prosthesis, which has only one condyle, also known as Big head is called, at the temporary Explantation of a hip prosthesis is used when namely, the shaft portion of an existing hip joint prosthesis remains in the femur while its condyle to remove.

The Temporary joint prosthesis produced according to the invention has a recess for receiving a with the shaft portion of a implanted residual prosthesis associated cone. This recess will Also called cone holder. Therefore, with the inventive Mold made prosthesis suitable on a cone of a in one Thigh bone already implanted shaft portion of a Prosthesis to be plugged and then serves as a temporary Replacement for the condyle. It is therefore in use the temporary produced according to the invention Joint prosthesis not required in the context of revision endosurgery also explantieren the shaft portion of a prosthesis, since the inventive temporary joint prosthesis as a spacer between the femur, or in it remaining shaft portion of a joint prosthesis, and the acetabulum serves.

State of the art

The US 2007/0222114 A1 describes a mold for the production of temporary implants of bone cement, which can be adapted by joining several moldings to the desired size of the casting. It is preferred to provide reinforcement in the manner of a reinforcement. The moldings are preferably transparent, at least elastic, and show for temporary hip joint prosthesis exclusively molds and castings, which have both a shaft for insertion into the femur, and a molded thereto ball head for complete replacement of the permanent, to be explanted joint prosthesis.

The US 6,361,731 B1 describes a method of making a temporary prosthesis for the femoral joint part of a hip joint by pouring cement paste into an elastic mold. It is described for hip joint prostheses that they each have a shaft for insertion into the femur, and the condyle. As a particular advantage it is stated that the mold can be easily separated by tearing from the molded prosthesis part after curing of the cement.

The EP 1274374 B1 describes prefabricated joints for temporary implantation, which have the mutually movable joint surfaces in two matched parts.

The WO 2006/090226 A1 describes prefabricated bone nails of porous material or sleeves of porous material for use around a bone nail.

Of the On the one hand, prior art is disadvantageous in that it used Molds are elastic, because on the one hand no exact reproducibility of the produced casting, but subject to elastic deformation, and on the other hand because of the limited pressure resistance not for use with viscous or pasty Cement composition are suitable, but rather for low viscosity Masses.

Farther The prior art shows that the manufactured temporary Implants regularly insert both the shaft in the femur and the ball joint, in particular made in one piece.

Object of the invention

Across from It is an object of the invention to provide a mold for the manufacture of a temporary implant for the use is suitable in such cases where the Shank portion of a prosthesis is not removed, for example because the shaft section fused firmly with the femur is while the joint ball is explanted.

Temporary implants known in the art are not suitable for use in those instances where the stem portion of an implant is not explanted. Because these temporary implants also regularly have a shaft portion which is fixedly connected to the ball joint, for example in a one-piece casting. Also, the molds used for the production of temporary prostheses regularly have a mold section, which leads to the production of a temporary prosthesis having a shaft portion.

General description of invention

The Invention solves the above object with the features of the claims and provides a mold for the production a temporary joint prosthesis ready, a method for Production of a temporary joint prosthesis, as well as the temporary joint prosthesis. The mold is drawing It is characterized by the fact that the joint prosthesis produced with it only one Includes condyle having a molded cone seat, the approximately central and particularly preferably rotationally symmetric in a substantially spherical condyle is arranged. Particularly preferred is the condyle of the invention from bone cement mass in sections spherical, where a section of the surface of a surface with less curvature than the curvature of the sphere, or formed by a substantially flat surface is arranged in which rotationally symmetrical a cone receiver is.

The Conical seat, with the mold according to the invention in an at least partially spherical temporary Joint prosthesis head is arranged, allows the plugging on a cone of the shaft portion of a joint prosthesis, which implanted in the bone, and therefore an at least partial mobility or functioning of the joint.

at The development of the invention has been shown that for the at least temporary partial mobility of a joint, part of which is formed by a temporary joint prosthesis is a fit of the cone of the shaft section in the temporary used joint prosthesis head is required. Because without cone recording The cone of a shaft section can not with the temporary Joint prosthesis are connected so that the cone of the shaft portion can slip next to the joint prosthesis and not the joint prosthesis their function as spacers between the other joint elements can perceive. On the other hand, it has been shown that a cone shot without fit a much poorer mobility of the joint with the temporary prosthesis results, including the risk that the cone of the implanted shaft section out the cone seat of the temporary joint prosthesis head slips.

The Casting mold according to the invention consists of two mold halves, which between them a closed inner Surface form, consisting of a section of the outer surface of a Condyle consists, in the one condyle comprehensive inner Surface of the mold molded a cone holder is. For the formation of the cone holder, the inventive Mold on a cone shaper, the z. B. in the form of a cone-shaped pin is formed and in the of the both halves of the form encompassed inner volume protrudes. The cone shaper is through an insertion opening in the internal volume arranged the mold, preferably so that the cone former protrudes from the mold and is rotatable. Because a demolding is when using conventional bone cement because of that strong adhesion to surfaces of a mold difficult so that before demolding a rotation of the cone shaper and / or its removal from the mold is helpful.

The Mold halves can each be adjacent to each other Having surfaces which are perpendicular to the axis of the cone former lie so that the shape in a plane perpendicular to the axis of the cone shaper through Remove the mold halves open from each other can be. Alternatively, the mold halves can each other Contact in a plane that is in the plane of the axis of the cone shaper lies so that the insertion opening through which the Konusformer is arranged, sections in the first and second Mold half is arranged, for example, with a semicircular Cross section of each proportionate insertion opening in each of the two mold halves in a circular Cross section of the cone former.

The Mold halves of the mold according to the invention are sufficiently rigid, so z. B. the filling of Cement paste, in particular from viscous to pasty cement paste, optionally with adjoining Introduction of the cone former through the insertion opening in the inner volume of the mold not to deformation the mold halves leads. It has been found that the structural stability of the mold halves in is provided to a sufficient extent when the mold halves made of solid plastic or metal, preferably with a superficial coating of low adhesion or adhesion-reducing plastic, in particular polytetrafluoroethylene (PTFE), available under the name Teflon. Especially preferred exist the two mold halves and / or the cone former made of PTFE.

Preferably, the mold halves have recesses which are accessible from the plane in which the mold halves are arranged in the closed state against each other to receive a lever tool, with which the separation of the mold halves for demolding is facilitated. alternative or additionally, the mold halves have lugs that assist levers to remove the mold halves from each other during demolding.

The Inner volume of the mold comprises in the closed state, d. H. with suitably aligned arrangement of the first against the second mold half, a mold that is part of the outer surface a condyle consists and the outer surface a condyle comprises at least in sections. This internal volume can assume a spherical shape, which is interrupted only by the cone former is, so that one with the mold according to the invention produced temporary joint prosthesis has a spherical shape, which is only interrupted by the molded cone holder.

In This embodiment, the first mold half a concave dome-shaped inner surface have, without interruption of a likewise concave dome-shaped inner surface of the second mold half continued is, wherein in the second mold half or in a section between the first and second mold half the insertion opening is arranged to receive the Konusformers, and the Konusformer protrudes through this into the internal volume of the mold.

In In a preferred embodiment, the internal volume the mold except for that taken by the cone former Volume section be substantially spherical, and optionally in a section perpendicular to the axis of the cone former have a surface portion which is a lesser Curvature as the spherical shape, or a flat surface. Accordingly, the cone former is preferably perpendicular through this surface portion arranged, which is flat or has a lower curvature as the adjacent spherical section. Also in this Execution, the first mold half a concave have dome-shaped portion of the inner volume, and the second mold half to the first mold half adjacent concave dome-shaped section of a section of the inner surface is completed, the has a lower curvature, or is flat, and in which preferably centrally and perpendicular to the cone former is arranged.

to Mounting the first and second mold half against each other when closed, it is preferred that the mold halves to be encompassed by two legs of a bracket facing each other are parallel and arranged at a distance from each other, that they are arranged with clamping action around the two mold halves are. In particular, the parallel legs are at a distance equal to the height of the mold in the closed Condition arranged.

Of the Konusformer preferably has a holding approach, the one larger diameter than the cone former itself, and serves as a handle for the cone shaper, and / or as a stop for the cone former against the outside Surface of the mold so that the cone shaper with the holding approach against the outside of the mold, if he has the desired level in the internal volume the mold protrudes, for example, 50 to 80% of the distance the inner surfaces along the axis of the Konusformers in the Interior volume protrudes.

Of the Konusformer preferably has in a first apical section the desired cone shape, the shaped cone recording should have, for example, over an apical section from 15 to 20 mm a 12/14 cone. The radius dome-shaped Portions of the internal volume of the mold are preferably a radius of 20 to 30 mm, in particular of 25 or 22.5 mm.

Especially Preferably, the two mold halves are locked together and have, for example, mutually aligned Projections and recesses, so that the mold halves can not slip against each other when arranged. at lockable first and second mold halves has been shown that a load of the two mold halves against each other, for example, by two parallel legs of a bracket, a sufficient Closure of the mold results, so at their Use for making a temporary implant first pasty cement paste through the insertion can be introduced into the mold, and then the cone former through the insertion opening in the Inner volume of the mold can be pushed without getting the mold opens or the mold halves be moved against each other. Preferably cement paste is in a volume filled in the closed mold, the equal to the enclosed by the mold halves inner volume minus the volume fraction occupied by the cone former.

Of the Cone shaper can be adjacent to an apical cone-shaped Section have a longitudinal groove, preferably only in the area where he is inside the insertion opening is arranged, optionally by 1 to 10, preferably by 2 to 5 mm in the section of the cone former that is inside the inner volume is arranged. In the preferred fit of cone shaper and Insertion can be such a groove in the cone former serve as a vent and, in the preferred Embodiment for receiving a screw, with a Holding approach to the cone shaper is fixable.

The process of making a tempo The joint casting prosthesis uses the casting mold according to the invention and provides for casting into this casting mold, eg. As viscous to pasty cement paste to fill through the insertion until the inner volume is substantially completely filled, and then inserting the Konusformers through the insertion. In this way, a temporary joint prosthesis according to the invention is provided, which exclusively encloses a condyle, and at least partially has a spherical shape, in which a rotationally symmetrical conical reception is formed. It has been found that, in particular in the case of mold halves, which consist of PTFE, effective curing of conventional cement bone mass, preferably in less time than in a thin-walled shape or when curing without form, and that the casting produced has a precise cone recording, the over a corresponding cone, for example, a shaft portion of a joint prosthesis can be arranged positively and / or non-positively. The joint prosthesis made with the casting mold according to the invention therefore has a cone receptacle for covering the cone of an implanted shaft portion, and moreover, in the implanted state on the cone of the shaft portion, forms an immovable spacer which provides an at least partial joint function in the remaining joint socket.

The Invention will now be described in more detail with reference to the figures, in which

1 shows a plan view of the surface of a first mold half, which can be arranged against the second mold half,

2 a sectional view along CC of 1 shows,

3 shows a plan view of the surface of a second mold half, against which the first mold half is placed,

4 a section along AA 3 shows,

5 a cut accordingly 4 another embodiment of the second mold half shows

6 showing a view of a cone former,

7 shows an overview drawing of a mold according to the invention in the closed state,

8th a plan view of a mold according to the invention in the closed state shows and

9 a holding approach in supervision and in partial section shows.

In the same reference numerals designate functionally identical elements.

1 shows a plan view of a first mold half 1 with an inner surface 5 , which is concave dome-shaped. According to the preferred embodiment, the first mold half 1 as well as the second half of the mold 2 point-symmetrical with arranged inner surface, so that in the arrangement of the first and second mold halves 1 . 2 against each other regardless of their rotation about the axis of the inner surface, the inner surfaces are arranged to fit each other.

The first half of the mold 1 has according to the preferred embodiment latching elements, which engage with matching latching elements of the second mold half. Here are the Verrastungselemente as Verrastungsvorsprünge 9a shown while the second half of the mold 2 latch recesses 9b having.

The cut of 1 is in 2 and shows that in the preferred embodiment, the first mold half 1 a concave hemispherical inner surface 5 having.

Preferably, the inner surface 5 the first half of the mold 1 and also the inner surface 6 the second half of the mold 2 and the cone former 4 on a common axis 7 arranged.

3 shows the view of a second mold half 2 for latching with the first half of the mold 1 a Verrastungsausnehmung 9b in the form of a peripheral groove arranged along the edges. Particularly preferred are the first mold half 1 and second mold half 2 each have the same outer extent or base perpendicular to the common axis 7 on, so that in the arrangement of the first against the second mold half 1 . 2 the mold halves congruently cover each other, and z. B. the connecting portion of a clip parallel to the edges of the first and second mold halves 1 . 2 are arranged, which lie in a common plane, which facilitates the handling of the mold.

The cross section along AA of 3 is in 4 shows and makes it clear that particularly preferably the second mold half 2 on its inner surface 6 first a dome-shaped section 6a adjacent to the plane in which the inner surface 5 the first half of the mold 1 in the closed state adjacent, and then a section 6b that has a smaller curvature than the dome-shaped section 6a on points, or is essentially flat. In the common axis 7 is the insertion opening 3 arranged to receive the cone former 4 serves.

For locking the second half of the mold 2 in this embodiment Verrastungsausnehmungen 9b on, the z. B. as a circumferential groove accordingly 3 may be formed, and may also latching projections 9a having in correspondingly aligned Verrastungsausnehmungen 9b the first half of the mold 1 can intervene. As shown in the figures, it is generally preferred that the mold halves have a square base approximately perpendicular to the common axis 7 have, more preferably to the common axis 7 point symmetric.

5 shows in cross section AA of 3 an alternative embodiment of the second mold half 2 , namely the inner surface 6 is dome-shaped and only from the insertion opening 3 is interrupted, in the common axis 7 is arranged.

Generally, it is preferable that the inner surface 5 the first half of the mold 1 describes a complete hemisphere and the inner surface 6 the second mold half at least adjacent to the plane in which the first mold half 1 when closed, has the same radius of the dome shape as the inner surface 5 the first half of the mold.

In 6 is a preferred embodiment of a cone former 4 shown, which is round rod-shaped and in an apical section 4a frusto-conical or conical, preferably with a rounded tip. According to the preferred embodiment, the cone former 4 partially a longitudinal groove 4b which extends at least over the region in which the conical fomer 4 in the insertion opening 3 is arranged.

The overview drawing 7 shows the closed state of the mold with the first mold half 1 and second half of the mold 2 that enclose between them an internal volume that exclusively encloses a portion of a condyle and that of the cone former 4 occupied volume excludes.

In 7 is shown schematically as a bracket 10 can be arranged with 2 parallel legs on the mold, so that the two parallel legs are arranged approximately parallel to the plane in which the first and second mold half 1 . 2 lie against each other and the two mold halves 1 . 2 include.

The clip is particularly preferred 10 , such as In 8th represented, in one of its legs on a recess in which a holding lug 11 of the cone former 4 can be arranged when the cone shaper 4 in the insertion opening 3 is arranged. Then the holding approach lies 11 on the outer surface of a mold half 1 . 2 and thus preferably provides the positioning of the cone former 4 along the common axis 7 within the internal volume of the mold.

For demolding it is preferred that the cone former 4 rotatable in the insertion opening 3 is stored so that after curing of the cement paste of the cone former 4 , z. B. by means of the holding approach 11 can be rotated to be released from the casting. Preferably, the mold halves are then separated from each other, and removed the produced casting or molding.

9 shows a particularly preferred embodiment of a holding approach 11 , the one central hole 11a for arrangement around the cone former 4 has, and preferably a thread 11b for arranging a screw, which in the central bore 11a opens, leaving a screw through the thread 11b against the cone former 4 , For example, in the longitudinal groove 4b can be arranged.

1

first mold

2

second mold

3

insertion

4

former cone

4a

cone section

4b

longitudinal groove

5

inner Surface of the first half of the mold

6

inner Surface of the second mold half

6a

concave arched dome-shaped section of the inner Surface of the second mold half

6b

section the inner surface of the second mold half with less curvature

7

common axis

8th

axis of the cone former

9a

latch projection

9b

locking recess

10

clip

11

retaining extension

11a

central bore

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• US 2007/0222114 A1 [0004]
• - US 6361731 B1 [0005]
• - EP 1274374 B1 [0006]
• WO 2006/090226 A1 [0007]

Claims (16)

Multi-part casting mold for the production of a temporary joint prosthesis, wherein the casting mold has an inner surface ( 5 . 6 . 6a . 6b ), which comprises at least a portion of the outer surface of a condyle, characterized in that the mold consists of a first mold half ( 1 ), a second mold half ( 2 ) and one through an insertion opening ( 3 ) into that of the first and second mold halves ( 1 . 2 ) comprised internal volume of disposable cone shapers ( 4 ), wherein the shape encompassed by the inner volume of the mold consists of a portion of the outer surface of a condyle. Casting mold according to claim 1, characterized in that the first mold half ( 1 ) a concave dome-shaped inner surface ( 5 ) having. Casting mold according to one of the preceding claims, characterized in that the second mold half ( 2 ) a concave dome-shaped inner surface ( 6 . 6a ) in the closed state of the mold to the inner surface ( 5 ) of the first half of the mold ( 5 ). Casting mold according to one of claims 1 or 2, characterized in that the inner surface ( 6 ) of the second mold half ( 2 ) adjacent to the inner surface ( 5 ) of the first half of the mold ( 5 ) a concave dome-shaped section ( 6a ) and an adjacent planar section (FIG. 6b ), the concave dome-shaped section ( 6a ) and in which the insertion opening ( 3 ) is arranged. Casting mold according to one of the preceding claims, characterized in that the inner surface ( 5 ) of the first half of the mold ( 1 ), the inner surface ( 6 . 6a . 6b ) of the second mold half ( 2 ) and the insertion opening ( 3 ) to a common axis ( 7 ) are rotationally symmetric. Casting mold according to one of the preceding claims, characterized in that the inner surface ( 5 ) of the first half of the mold ( 5 ) the inner surface ( 6 . 6a . 6b ) of the second mold half ( 2 ) in a plane perpendicular to the axis ( 8th ) of the cone former ( 4 ) is arranged. Casting mold according to one of claims 1 to 5, characterized in that the inner surface ( 5 ) of the first half of the mold ( 1 ) the inner surface ( 6 . 6a . 6b ) of the second mold half ( 2 ) in a plane parallel to the axis ( 8th ) of the cone former ( 4 ) is arranged and the insertion opening ( 3 ) in each case half of recesses of the first and second mold half ( 1 . 2 ) is formed. Casting mold according to one of the preceding claims, characterized in that the cone former ( 4 ) extends over 50 to 80% of the diameter of the inner volume. Casting mold according to one of the preceding claims, characterized in that the cone former ( 4 ) has a circular cross section which extends in an end section ( 4a ) conically tapered. Casting mold according to one of the preceding claims, characterized in that the cone former ( 4 ) a longitudinal groove ( 4b ) which extends only over a portion of constant diameter. Casting mold according to one of the preceding claims, characterized in that the cone former ( 4 ) about its axis ( 8th ) rotatable in the insertion opening ( 3 ) is arranged. Casting mold according to one of the preceding claims, characterized in that the cone former ( 4 ) an integrally formed, force or form-fitting fixed holding approach ( 11 ) contacting a mold on a surface opposite to its inner surface. Casting mold according to one of the preceding claims, characterized in that the mold halves ( 1 . 2 ) and the cone former ( 4 ) are structurally stable. Casting mold according to one of the preceding claims, characterized in that the mold halves ( 1 . 2 ) and the cone former ( 4 ) each consist of PTFE. Casting mold according to one of the preceding claims, characterized in that the mold halves ( 1 . 2 ) at least in sections of two parallel legs of a bracket ( 10 ), which are arranged at a distance equal to the height of the mold in the closed state on a support. Casting mold according to one of the preceding claims, characterized in that the mold halves ( 1 . 2 ) are latched together.