DE10308141B4 - Extension sleeve for a modular joint prosthesis - Google Patents

Abstract

Extension sleeve for a modular design, in a tubular bone usable joint prosthesis with a plug-in pin for connection with a first adjacent module of the joint prosthesis and with a adjoining the plug-in sleeve-shaped receiving part with a Receiving channel for receiving a spigot of a second, the first opposite Module of the joint prosthesis whose outer contour for filling the Markraumquerschnittes of the joint prosthesis receiving tubular bone is formed, wherein the flexural rigidity of the wall of the extension sleeve relative to a massive, made of the material of the extension sleeve existing wall is, characterized in that the Wall (11) is formed at least two layers with an inner Layer (15) of a rigid material and with an outer layer (19) made of a less rigid material.

Description

The The invention relates to an extension sleeve for a modular built in a tubular bone usable joint prosthesis with a plug-in pin for connection with a first adjacent module of the joint prosthesis and with a adjoining the plug-in sleeve-shaped receiving part with a Receiving channel for receiving a spigot of a second, the first opposite Module of the joint prosthesis whose outer contour for filling the Markraumquerschnittes of the joint prosthesis receiving tubular bone is formed, wherein the flexural rigidity of the wall of the extension sleeve relative to a massive, made of the material of the extension sleeve wall is reduced.

at The implantation of joint prostheses, it is beneficial if the shafts of such Joint prostheses as possible exactly match the medullary canal geometry of the long bone, in which they are to be used. Especially after the exchange loosened implants arise due to the individual defect situation often intramedullary geometries that are difficult with standard revision implants be supplied. Here it is known to choose an implant system that consists of individual modules, selected intraoperatively by the surgeon, assembled and implanted.

to optimal adaptation of the implant to the bone or for compensation intraoperatively occurring leg length changes, For modular implants, extension sleeves are used. These will installed between proximal and distal implant components.

The Extension sleeves are usually conical Spigot connected to the adjacent modules. In this connection area one observes a micro-abrasion of the prosthesis material by Relative displacement of the two assembled parts of the prosthesis arises and the disturbing is.

In WO 97/18776 A1 describes a generic modular endoprosthesis, wherein the flexural rigidity of the wall of the extension sleeve is reduced by a circumferential groove is so by that a better adaptation of the extension sleeve to the Spigot possible This results in a lower micro-abrasion.

outgoing The invention is based on the object of the prior art in a structurally simple way on the one hand, the bending stiffness of the connecting sleeve in the mating area reduce and on the other hand, an optimal completion of the Cross section of the medullary cavity to allow.

These Task is with an extension sleeve of The type described above achieved according to the invention that the wall the extension sleeve at least two layers is formed with an inner layer of a rigid Material and with an outer layer from a less rigid material.

Thereby On the one hand, the bending stiffness of the extension sleeve is reduced overall, On the other hand, the total cross section is retained.

Especially can the inner layer in one piece formed with the plug of the extension sleeve be, that is, it is essentially an extension sleeve with a small outer diameter used, and this extension sleeve is in the region of the receiving part of a second layer with less Surrounded by bending stiffness.

The outer situation can be made of any biocompatible material, for example Metal, in particular of titanium, wherein it is favorable when the outer layer reticulated or perforated sheet metal is trained. Another possibility This is the outer layer from a frothed Material to manufacture, for example, a metal foam, in particular a titanium foam.

at a further preferred embodiment is provided that the Cross section of the inner layer is weakened by depressions. you receives so that an inner layer with reduced bending stiffness and an outer layer, which fills the medullary canal and which contributes only slightly to the flexural rigidity.

For example can in the inner layer outside Be arranged grooves.

at a preferred embodiment wears the inner layer outside at least one outer circumferential groove, preferably, when using multiple circumferential grooves, these are evenly over the Length of the Shooting part distributed.

The grooves may also extend in a different direction, for example, the direction of the grooves may have an axially parallel component, in particular, the grooves in axis-parallel rich tion. It is also possible to provide such, running in the axis-parallel direction grooves and circumferential grooves together, with these grooves then intersect.

The outer situation can be designed as an outer sleeve be the outside of the inner situation surrounds. The sleeve can close to the outside lie the inner layer, in particular, the outer sleeve in the outboard Immerse grooves of the inner layer, for example by screwing in the Area of the grooves.

It but it is also possible that the outer sleeve of the outside the inner layer except a connection with the receiving part keeps a distance. The resulting distance between the outer sleeve and the inner layer can the shape of an annular space arranged concentrically to the receiving part have, preferably to the insertion side of the receiving channel is open.

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

1 a side view of a modular hip prosthesis in a partially broken view;

2 an extension sleeve having a plurality of circumferential grooves;

3 : a view similar 2 with intersecting longitudinal and transverse grooves;

4 : a view of the extension sleeve of the 3 in the direction of arrow A;

5 : a view similar 2 an extension sleeve with axially parallel grooves;

6 a longitudinal sectional view of an embodiment of an extension sleeve with a surrounding spacer ring;

7 : a view similar 6 in an embodiment with an annular space in the wall of the receiving part;

8th : a view similar 7 a two-piece extension sleeve;

9 : a view similar 7 an extension sleeve having a profiled inner surface of the annulus;

10 : a view similar 9 a two-piece extension sleeve;

11 : similar to a longitudinal sectional view of a connecting sleeve 2 with pushed on outer sleeve, and

12 : a view similar 11 with a deferred outer sleeve which is deformed in circumferential grooves.

The invention will be discussed using the example of a hip joint prosthesis intended for insertion into the femur. The embodiments according to 1 to 5 are for general explanation, but the embodiments illustrated there are not part of the protected invention. Embodiments of the invention are described by the embodiments of the 6 to 12 played.

A joint prosthesis 1 includes a shaft 2 , which at its top, so at its proximal end, a conical plug 3 wearing. The joint prosthesis 1 further comprises a head part 4 , facing the shaft 2 extended on one side and an obliquely protruding, conical socket 5 carries for a joint ball, not shown in the drawing. The plug-in pin 5 is at the proximal end of the head part 4 arranged, at the distal end takes the headboard 4 a conical receiving opening 6 in, for example, the spigot 3 of the shaft 2 can be inserted. The taper of the plug and the receiving opening is so small that occurs when firmly inserted self-locking. This gives a firm connection between the shaft 2 and the headboard 4 ,

A joint prosthesis constructed in this way 1 consists essentially of only three parts, namely the shaft 2 , the headboard 4 and the ball joint, not shown in the drawing.

In the embodiment of the 1 There are also three extension sleeves 7 provided, which are the same structure, therefore, below only one of these extension sleeves 7 described in more detail. Each extension sleeve 7 has at its proximal end a conical spigot 8th on that completely the pin 3 of the shaft 2 equivalent. This plug pin 8th is connected to a sleeve-shaped receiving part 9 in which there is a conical receiving channel open in the distal direction 10 located for a pin. This recording channel 10 completely corresponds to the receiving opening 6 in the headboard 4 in the case of a two-part joint prosthesis 1 the spigot 3 of the shaft 2 receives.

The extension sleeves 7 So that's how it is formed that her plug 8th can be inserted into the receiving opening or the receiving channel of the proximal adjacent part, conversely, in each extension sleeve 7 at its distal end a plug-in pin of a distal adjacent prosthesis part are inserted.

Between headboard 4 and shaft 2 a different number of extension sleeves can be used, thereby increasing the overall length of the joint prosthesis 1 can be varied, the extension sleeves 7 can be formed differently long in their longitudinal direction, but they could also be the same length.

In the in the 1 and 2 illustrated embodiment are in the receiving channel 10 surrounding wall 11 of the recording part 9 a plurality of circumferentially spaced circumferential grooves 12 incorporated through which the cross section of the wall 11 is weakened. The outer diameter of the wall 11 corresponds to the outer diameter of the shaft 2 on the one hand and the headboard 4 on the other hand in the connection area, and this outer diameter is chosen so that the medullary cavity of the long bone into which the joint prosthesis 1 is to be used, is essentially completed completely. To achieve this, will be a relatively large strength of the wall 11 needed, and this strength of the wall would in massive design to a very large bending stiffness of the extension sleeve 7 to lead.

Through the circumferential grooves 12 However, the flexural rigidity of the extension sleeve 7 reduced compared to a massive design and this leads to the fact that the micro-abrasion is reduced to a minimum in the connecting region between plug-in pin and receiving sleeve.

In the embodiment of the 2 is the reduction of the bending stiffness by the circumferential grooves 12 achieved, in the embodiment of the 3 are in addition to the circumferential grooves 12 still axially parallel longitudinal grooves 13 provided, the the circumferential grooves 12 cross.

The embodiment of 5 has only longitudinal grooves 13 and no circumferential grooves 12 On, in all cases, a reduction of the flexural rigidity is achieved by these grooves.

Another way to reduce the bending stiffness of the relatively thick wall 11 is in the embodiment of the 7 achieved by that in the wall 11 an annular space open to the distal side 14 is incorporated. The partition 15 between this annulus 14 and the receiving channel 10 receives thereby a relatively small wall thickness, which is sufficient for reasons of stability, but which would not be sufficient to fill the medullary canal of the long bone. This filling is through the annulus 14 and the adjoining outer wall 16 performed. The relatively thin partition 15 can optimally fit the pin 15 adapt, even in deformations, so that the abrasion in the connection area is largely avoided.

In the embodiment of the 7 is selected an overall one-piece design, in the embodiment of the 8th becomes the outer wall 16 formed as a separate sleeve, which has an annular flange 17 with the partition 15 connected is. The connection can be made in various ways, for example by welding, soldering, gluing, screwing, shrinking or pinning.

In the 9 respectively. 10 are shown similar configurations as in the 7 and 8th , they differ only by the embodiments of the 7 and 8th in that the dividing wall 15 has a greater wall thickness and outside with circumferential grooves 12 is provided, which is substantially the circumferential grooves 12 of the embodiment of 1 and 2 correspond.

In the embodiment of the 11 is via an extension sleeve 7 , which according to the embodiment of the 2 is formed, outside a thin sleeve 18 deferred, which the circumferential grooves 12 closes on the outside and which in a suitable manner with the extension sleeve 7 is connected. In the embodiment of the 12 will this sleeve 18 in the area of the circumferential grooves 12 bent inwardly, thereby defining the sleeve 18 can be done in the axial direction, also results in a structured and thus enlarged outer surface, which favors the connection of the joint prosthesis with the bone.

In the embodiment of the 6 an embodiment is selected that of the extension sleeve of the 7 largely corresponds. However, the outer wall is eliminated 16 and the ring flange 17 , Instead, it's on the partition wall 15 a sleeve 19 pushed on the one hand, the extension sleeve 7 on the other hand brings less rigid than a solid wall with the same outer diameter. This sleeve 19 can be made of any biocompatible material, such as metal, especially titanium. By suitable shaping can be achieved here a relatively low bending stiffness, for example, the sleeve 19 have the shape of a network or a perforated plate or made of foamed material. This results in a two-layer construction with a through the partition 15 formed inner layer whose flexural rigidity is chosen so that a sufficient stability is given, the bending stiffness due to the use of less rigid sleeve 19 Total is reduced so far that micro-abrasion can be avoided.

Claims (12)

Extension sleeve for a modular prosthesis insertable into a tubular bone with a plug-in pin for connection to a first adjacent module of the joint prosthesis and with a sleeve-shaped receiving part adjoining the plug-in pin with a receiving channel for receiving a plug-in pin of a second, the first opposing module of the joint prosthesis, the outer contour of which is formed to fill the medullary cross-section of the tubular bone receiving the joint prosthesis, the flexural rigidity of the wall of the extension sleeve being reduced relative to a solid wall consisting of the material of the extension sleeve, characterized in that the wall ( 11 ) is formed at least two layers with an inner layer ( 15 ) made of a rigid material and with an outer layer ( 19 ) made of a less rigid material. Extension sleeve according to claim 1, characterized in that the inner layer ( 15 ) integral with the spigot ( 8th ) of the extension sleeve ( 7 ) is trained. Extension sleeve according to claim 1 or 2, characterized in that the outer layer ( 19 ) is formed net-shaped. Extension sleeve according to claim 1 or 2, characterized in that the outer layer ( 19 ) is formed perforated plate-shaped. Extension sleeve according to claim 1 or 2, characterized in that the outer layer ( 19 ) consists of foamed material. Extension sleeve according to one of claims 1 or 2, characterized in that the cross section of the inner layer ( 15 ) by depressions ( 12 . 13 ) is weakened. Extension sleeve according to claim 6, characterized in that in the inner layer ( 15 ) outside grooves ( 12 . 13 ) are arranged. Extension sleeve according to claim 7, characterized in that in the inner layer ( 15 ) at least one outer circumferential groove ( 12 ) is arranged. Extension sleeve according to one of claims 6 to 8, characterized in that the inner layer ( 15 ) on the outside of an outer sleeve ( 16 . 18 ) is surrounded. Extension sleeve according to claim 9, characterized in that the outer sleeve ( 18 ) close to the outside of the inner layer ( 15 ) of the receiving part ( 9 ) is present. Extension sleeve according to claim 10, characterized in that the outer sleeve ( 18 ) in the outside grooves ( 12 ) of the inner sleeve ( 15 immersed). Extension sleeve according to claim 9, characterized in that the outer sleeve ( 16 ) from the outside of the inner layer ( 15 ) with the exception of one compound ( 17 ) with the receiving part ( 9 ) maintains a distance.