DE4313201A1 - Prosthetic socket set - Google Patents

Description

The invention relates to the preamble of the claim 1 a Prosthetic socket set for cementing the Prosthesis stem in bone, especially for Hip arthroplasty.

An example of such a prosthesis socket set is from EP-B1 0331 623 became known. To the surgeon Work when inserting and cementing the stem into to facilitate a central location, that the length of the cement rod is at least double, length of the shaft measured in the longitudinal axis is and that the centering rod detachably at one end Medullary block can be attached. Regardless of whether the Shank before or after the bone cement in the bones is introduced, the surgeon should in this way shaft centered on the whole at the distal end Keep length centered or centered in the bone cement can press in.

DE 33 04 476 A1 also shows a hip joint prosthesis. This is for connection to a hollow bone nail provided and has a continuous in the longitudinal direction Cutout for passing a guide mandrel through. in the installed state, this prosthesis is at its distal End surrounded by the bone nail while its proximal End extends through the medullary canal.  

An anchoring shaft is already known from EP 434 604 A1 for a femoral head prosthesis (thigh prosthesis) has become known which is a central feed channel for has viscous bone cement. The shaft in its distal end region has lateral outlet openings for the bone cement while the distal end of the Bone cement supply channel through one with elastic Centering flap plug closed is.

EP A2 0129 531 also shows one at the lower end a prosthesis shaft with a centering plug. This Prosthetic socket should be made in impression technique and thus fit into the bone.

Another example of one in a proximal The prosthesis to be cemented shows the US 4,274,163. In this the prosthesis body is on the side with a detachably screwed connection coupling for provided and has a supply hose for bone cement inside a system of distribution channels for the bone cement, some of it on the side Exit openings and also a distal exit opening have above a medullary barrier.

To hold the prosthesis body in the Anchoring process serves according to this state of the art a screw clamp to be attached to the bone Centering device for the prosthesis.

Despite intensive work on the area of operational Bone prostheses are lighter Manageability during surgery and security and Durability of anchoring the prosthesis socket by means of the bone cement still room for improvement.

The present invention is based on the object inexpensive cementing of the prosthesis socket with even distribution of the bone cement in the To allow insertion process.

Starting from a prosthesis socket set as known presupposed genus is the solution to this Task characterized in claim 1.

Such a design allows a simple particularly even cement distribution, without that Special attention to the surgeon To require cement distribution and it results in a reliable and permanent fit of the prosthesis socket.

Claim 2 indicates a particularly advantageous Further training in that the distal end of the Prosthesis shaft and the proximal end of the medullary Plug to mediate a swirl movement for the ascending bone cement are designed.

Preferably, according to claim 3 (according to 2) Proximal medullary plug with spiral guides for the the prosthetic stem distally emerging bone cement designed.

The subclaims characterize advantageous configurations and Developments of the invention.

An exemplary description of the invention follows based on drawings.

FIG. 1 a shows schematically a femur (thigh bone) freed from the medulla with a prosthesis shaft pre-positioned by means of a guide rod (without a joint ball);

FIG. 1b shows the assembly of Figure 1 after removal of the guide mandrel during filling of cement, the proximal uniformly increases from distal to.

Fig. 1c shows the cemented prosthesis stem;

FIG. 2 shows the outer side view of a medullary plug which can be used in the arrangement according to FIGS. 1a-1c and which can be anchored in the bone with an expansion effect;

FIG. 3 shows the inside view of the medullary canal plug with a central threaded hole for the centering mandrel and spiral guides for communicating a swirl to the filled cement;

Fig. 4 shows schematically the guide mandrel with screwed medullary plug and screwed handle (outside the bone);

Fig. 5, the anatomical shape of the prosthesis stem illustrated with attached adapter for Zementeinfüllung and cone approach for installing a joint ball and a einzuschlagenden above into the bone positioning claw;

Fig. 6 shows the positioning claw with through holes for the conical attachment and the cement adapter in a view from above;

Fig. 7 shows in detail the adapter for cement filling;

Fig. 8a shows, facing Ventral-dorsal schematically the anatomical femur cavity adapted prosthesis stem with indicated Zementeinfüllung central to the medullary cavity stopper;

FIG. 8b shows the arrangement according to FIG. 8a with a lateral viewing direction.

In the following description, the prosthesis socket set according to the present invention is described with regard to the attachment of an artificial hip joint ball, for the anchoring of which the prosthesis socket shown is used. The hip joint ball itself can be placed separately on a conical shoulder 1 ( FIG. 5) of the prosthesis socket 3 .

Fig. 1a-1c illustrate schematically and also without showing a hip joint ball (and also not the cone approach) the pre-positioning of the prosthesis stem by means of a centering and guide mandrel 5 (screwed into a medullary plug 7 ), as well as the filling of cement and its steady ascent from distal (away from the patient's body) to proximal (towards the patient's body).

Main problems in cement processing for Attachment of hip prosthesis stems and their Cementing are laminations, folds, blood Cement mixes (PMMA bone cement) and Air pockets. As a result of faulty cementing technology can drastically reduce mechanical Strength of the bond between the bone and cement prosthesis socket the endoprosthesis. The usually processed PMMA bone cement is therefore of relatively high viscosity the one pressed into the femur (thigh bone) Prosthesis, if possible, no longer his position changed, and at the same time the transfer of polymers into the blood circulation is reduced.

To achieve the desired steady ascent of the bone cement ( Fig. 1b-1c), the port shaft 3 , guide pin 5 and medullary plug 7 are coordinated as a prosthesis shaft set, this also a positioning claw 9 ( Fig. 5) and expediently a cement filler adapter 11 has.

In detail, the elements of the prosthesis socket set following configuration on:

The prosthesis stem illustrated in FIG. 5 is adapted as shown in FIG. 8a and FIG. 8b illustrated manner to the anatomical shape of the proximal femoral medullary cavity. On the basis of a larger number of measured femoral medullary spaces, an optimized shaft design was designed for different sizes, which is used for the purposes of the present invention. Such profile prosthesis stems are available from DePuy in 5 different sizes, each for right use and left use. They are designed for a gap of about 2 mm between the prosthesis socket and the rasped bone wall, which is then filled by the cement.

In the exemplary embodiment shown, the profile prosthesis socket is now provided with a through hole 13 of 4 mm diameter, which on the one hand can accommodate the guide and centering mandrel 5 , but also serves as a cement supply channel.

The through hole 13 of 4 mm inner diameter is provided at the end with a threaded hole for a 6 mm thread (M6), and has a length of about 6 mm. The threaded hole serves to screw in the corresponding M6 thread of the cement filling adapter shown in FIG. 7. Like the prosthesis socket, the adapter has a 4 mm through hole for centering the guide mandrel 5 . The positioning claw 11 , which has a centering hole 21 , ensures the position on the bone in a manner to be described in more detail.

Instead of the cement filling adapter 11 , an instrument for pulling out the prosthesis socket can also be screwed into the M6 thread.

The distal end 15 of the prosthesis socket has a rounded design that fits at a distance into the cavity of the medullary plug and acts in a flow-favorable manner with the design of the medullary plug 7 to be explained in more detail in the sense of the steady ascent of the cement illustrated in FIG. 1b from distal to proximal together.

The through hole 5 can also serve to pass a blood suction tube, not shown in detail. The graphic representation would correspond schematically to that of the centering and guide mandrel 5 .

The medullary plug 7 has claw-like engagement grooves on the outside, which secure it with a wedge effect in the bone.

The distal end of the prosthesis shaft and the medullary plug 7 are matched to one another in the sense of a swirl design in order to give the cement emerging from the distal end of the prosthesis shaft a swirl which allows it to rise as evenly as possible around the prosthesis shaft, as in FIG. 1b -1c illustrates.

FIG. 3 illustrates the interior design of the medullary plug 7 with turbine blade-like spiral grooves or guides 15 . In Fig. 4 we see the cup-shaped design of the medullary-plug 7. The arrangement advantageously comprises 6 or 9 spiral grooves. The number, depth and slope of the spiral grooves can be matched to the viscosity of the cement used, which is chosen to be low-viscosity. The entry plane of the medullary plug and the distal end of the prosthesis stem are positioned approximately 5 mm apart for a favorable cement injection process. A raised base 17 is provided in the central area of the medullary plug, which has a central M3 threaded hole for screwing in a threaded end of the centering and guide mandrel 5 .

At the opposite end of the centering and guide mandrel 5 , an opposing M4 thread is provided, onto which a handle 19 can be screwed, which allows the mandrel 5 to be unscrewed after the medullary plug 7 has been inserted into the bone.

The distal section of the prosthesis shaft, which forms the outlet end of the bone cement towards the medullary plug 7 , can also be expanded and equipped with spiral-shaped spiral guides, for example 9 mm high, to communicate a swirl to the outflowing bone cement.

However, a smooth design also proves its worth of the outflow end of the prosthetic socket, and it is one such a smooth design also advantageous in terms of cost because the prosthesis socket generally made of metallic Alloy material must be worked.

The medullary plug, however, can be produced as a simple plastic pressed part, and therefore the spiral guides 15 are preferably provided in the medullary plug 7 in the manner illustrated in FIG. 3. Depending on the application, the pot part of the medullary plug can have a diameter of about 12-22 mm and, for example, without the thread, can be 12 mm deep.

In conjunction with a low-viscosity bone cement itself through the described design of prosthetic socket and medullary plug a smooth rise of the Reach cement, so that the previously problematic Laminations, folds, blood-cement mixes and  Air pockets can be avoided. The cement injection can be done in less than 60 seconds.

For the positioning process, the prosthesis shaft 3 is to be secured in its position on the femur by means of the positioning claw 9 shown in FIGS. 5 and 6. Such positioning claws 9 are expediently manufactured in dimensions corresponding to three different shaft sizes. At 19 the claw tips intended to be driven into the femur can be seen.

The positioning claw 9 has a bore 21 which is used for centering the cement filling adapter 11 and thus also centers the guide mandrel 5 .

Through the through hole of the cement filling adapter can also insert a plastic tube over which required rinses can be made.

The centering and guide mandrel is provided with a length marking (not shown in more detail) in order to be able to exactly determine the position of the medullary plug in the femoral canal. The positioning claw 9 , together with the cement filling adapter temporarily screwed to it, ensures that the prosthesis shaft maintains its centered position in the femur, as it results after threading the prosthesis shaft on the mandrel 5 screwed to the medullary plug 7 . Moreover, after setting the optimal position of the prosthesis socket, the adapter 11 and the claw 9 at the proximal end of the prosthesis socket provide the necessary fixation.

The positioning claw 9 also seals against the leakage of bone cement and ensures compression of the cement, for example, introduced at 8 bar. When the cement has hardened, the positioning claw is also removed.

The cement guide adapter can be manufactured as a sterile single-use product made of polyurethane and can be added to the prosthesis socket set together with the medullary plug 7 and a positioning claw 9 . The centering and guide mandrel can also be included in a uniform set or used several times.

Depending on requirements, the components explained in detail above can be supplied individually or in groups of several or all together as a set. What is essential is the coordination that takes place for cheap handling and a good cement flow. The described swirl design in the area of the medullary plug 7 and possibly the distal end of the shaft prosthesis is designed in accordance with the flow behavior of the bone cement selected in each case. Depending on the flow behavior of the selected bone cement, the desired uniform circumferential distribution of the bone cement emerging distally from the prosthesis socket can also be achieved without spiral guides, if such spiral guides, as shown in FIG. 3 at 15, have also proven to be particularly effective.

Claims (16)

1. prosthesis socket set for cementing the prosthesis socket into bone, in particular for hip endoprostheses, with a through hole running longitudinally in the shaft for inserting a removable guide mandrel, which can be detachably fastened in a medullary plug to be anchored in the bone for positioning the prosthesis socket, characterized in that
that the through bore ( 13 ) for the centering mandrel ( 5 ) is at the same time designed as a feed channel for viscous bone cement which is known per se,
that the cement outlet opening, as is also known per se, is arranged at the lower end of the cement supply channel, and
that the distal end of the prosthesis shaft ( 3 ) with the cement outlet opening and the opposite proximal end of the medullary plug ( 7 ) are matched for a uniform all-round distribution of the emerging cement and its uniform rise from distal to proximal. 2. prosthesis socket set according to claim 1, characterized in that the distal end of the prosthesis socket and the proximal end of the medullary plug ( 7 ) are designed to impart a swirl movement for the ascending bone cement. 3. prosthesis socket set according to claim 2, characterized in that the medullary plug is designed proximally with spiral guides ( 15 ) for the bone cement emerging distally from the prosthesis socket. 4. prosthesis socket set according to claim 3, characterized in that the area surrounding the cement outlet opening of the prosthesis socket has a design coordinated with the spiral guides ( 15 ) of the medullary canal plug to promote the swirl movement of the bone cement. 5. prosthesis socket set according to claim 4, characterized in that the medullary plug is preferably designed as a proximally enlarged hollow cup with inside spiral guides ( 15 ). 6. prosthesis socket set according to claim 5, characterized in that the distal end of the prosthesis socket is rounded all around and fits with the surrounding distance in the hollow bowl of the medullary plug ( 7 ). 7. prosthesis socket set according to claim 5 or 6, characterized by a raised in the central region bottom ( 17 ) of the hollow cup of the medullary plug and a central screw hole (M3) for screwing in the distal end of the guide mandrel. 8. prosthesis socket set according to claim 7, characterized in that the proximal end of the guide mandrel ( 5 ) has an opposite thread (M4) for a handle ( 19 ) for the screwing and unscrewing movement of the guide mandrel. 9. prosthesis socket set according to one or more of the preceding claims, characterized in that the proximal end of the through hole ( 13 ) serving as a cement supply channel ( 13 ) has a screw thread (M6) for temporarily connecting an adapter ( 11 ) for a cement gun or the like . having. 10. prosthesis socket set according to one or more of the preceding claims, characterized by a detachable positioning claw ( 9 ) for driving in at the proximal end of the bone, and provided with a centering through opening ( 21 ) for the adapter ( 11 ) for the cement supply, and a centering lateral passage opening for a proximal prosthesis socket attachment ( 1 ), which is used to place a joint ball or the like. 11. Prosthetic stem set according to one or more of the preceding claims, marked by anatomical shaft shaping according to an average Femur for different femur size ranges. 12. prosthetic stem set according to claim 9 and 10, characterized in that the Bore of the cement feed adapter also as a guide for the guiding mandrel is designed.   13. prosthesis socket for a prosthesis socket set according to the characteristics of the prosthesis socket ( 3 ) according to one or more of the preceding claims. 14. medullary plug for a prosthesis socket set according to the characteristics of the medullary plug ( 7 ) according to one or more of the preceding claims. 15. positioning claw for a prosthesis socket set according to the characteristics of the positioning claw ( 9 ) according to claims 10 and 12. 16. Centering and guiding mandrel for a prosthesis socket set according to the characteristics of the centering and guiding mandrel ( 5 ) according to one or more of the preceding claims.