DE8400642U1 - Conical connection for a joint prosthesis - Google Patents

Description

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ME34.1 page 4

description

The invention relates to a shaft prosthesis of the type specified in the preamble of claim 1 and a corresponding bin 'or extraction tool.

In the known cone systems, cutouts for receiving a securing element are made in the neck area, which are used to prevent rotation of an in or serve as a deflector for conical shafts.

Such recesses weaken the neck area of the prosthesis and have not previously been used with overall maximum strength to be achieved. Furthermore, there is the disadvantage of the known prostheses that additional tolerances occur due to the spatial distance of the recess from the cone, which lead to it can that, despite the engagement of the securing element in the recess, the mating cone of the insertion or removal tool is not correctly seated on the cone and at the sudden stress, the forces to be transmitted are not evenly distributed over the cone area. In addition, for different neck lengths, because of the from resulting different arrangement of the hole various tools are kept in stock with respect to the cone.

The invention specified in claim 1 has the object

basis, with such prostheses under Erzeilung a increased strength of the prosthetic neck on the one hand

ME34.1 page 5

a more secure transmission of sudden stress to effect when driving in or driving out the prosthesis and, on the other hand, to enable standardization.

The invention is based on the knowledge that because of the in Direction of the cone end of the prosthesis decreasing bending moment under load which is then lowest due to the recess in the neck area below the cone surface, if this is as close as possible to the conical surface.

In this way, the conical connection surface remains unaffected for the tool and is completely available for power transmission. On the other hand, is simultaneous causes the tool to be fitted to the cone to be secured as close as possible to the enlarged end of the cone follows to switch off tolerances here, which one is more possible wise a tilting of the inner cone of the tool in relation to the outer cone of the prosthetic neck result.

In a preferred development of the invention for use in a hip joint prosthesis, the round recess is tion arranged on the inside of the near-joint curvature of the shaft.

It is ensured in an advantageous manner that when If a prosthesis is knocked out, the tensile forces that occur only

a deeper penetration of the fuse element into the corresponding recess (in the transverse direction based on the

Prosthesis neck), so that no Loosening of the seat of the tool on the cone occurs

and in this respect also no impairment of the transmission the sudden tensile forces occur.

ME34.1 page 6

The securing element is preferably located in the area of the enlarged end of the cone from the pivot point Recess pivoted so that the tool can be put on without difficulty and after Put on only the securing element iet to pivot, which is also achieved through suitable lever transmissions by im Handle of the instrument arranged actuating elements can be done, so dad one-handed operation is possible.

The invention also relates to a corresponding insertion or removal tool.

It can be used particularly advantageously in cementless prostheses in which the prosthesis shaft for Achieving a firm fit in the medullary canal must be hammered. It is also advantageous that the design of the Lower neck area can be chosen relatively independently, since there is no recess and the surface design surrounding it need to be taken into account.

A is preferred for knocking in and knocking out the prosthesis only tool used, as both by securing the cone seat by the measures according to the invention Tensile and compressive forces - alternating if necessary - can be safely transmitted.

Advantageous developments of the invention are characterized in the subclaims or are described in more detail in the illustration below together with a preferred embodiment of the invention. Show it:

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ME34.1 page 7

FIG. 1 the neck area of the prosthesis according to the invention with attached insertion or extraction tool, which is marked with de «* Prosthetic cone is engaged, as well

Figure 2 shows a part of the illustration according to Figure 1 with the Securing the tool out of engagement.

In Figure 1, a hip joint prosthesis provided with the measures according to the invention including a tool is shown in side view. The prosthesis shaft 1 carries a neck 2, at the free end of which a cone 3 is arranged, onto which a corresponding mating cone 4 of an inserting and / or a. Extraction tool is attached.

A recess 5 of circular cross-section is located on the neck 2 in the immediate vicinity of the enlarged end of the cone 3. This arrangement acts The systematic weakening of the material affects the transferable bending moment as little as possible the end. The achievable fatigue strength of the prosthesis in the neck area is significantly increased compared to other solutions.

In this recess 5 engages a corresponding securing element 6, which is close to the recess 5 in Prosthetic neck is rotatably mounted about a tangentially directed axis 7. The shank 8 of the tool is in the Drawing shown partially in section, with a handle 9 and a striking area 10 for use Are expediently arranged.

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A pivotably mounted on the shaft 8 operating lever 11 § 's for the S Icher ung linen t 6 is by means of an appropriate' connected i \ force transmission with this in such a way that - by JI a suitable deflection of the movement - in the resting against the shank state, the securing element 6 is located - possibly under pretension - for locking the impact transmission within the recess 5, so that a low-tolerance securing of the conical seat (elements 3 and 4) is guaranteed. ,

This prevents the conical seat from having play despite the securing element 5 being used, so that the sudden stress is not evenly distributed and thus possibly contributes to deformation of the cone which its dimensional accuracy in relation to the later, impair the joint ball to be placed on. Furthermore has the pivotable securing element 6 with respect to the closest support in the area of the outer cone 4 of the tool a short lever arm, so that there occurring bending moments are small and the forces to be transmitted in this area do not require additional reinforcement of the storage etc. of this element.

The lever IX is mounted about an axis 12 and has a Mouth 13, which engages around a pin 14 located at the end of the safety lever 6 and thus in the form of a Control cam forms a mechanical translation.

From Figure 2 it can be seen that when the handle of the lever 11 is pivoted away from the shaft 8, the securing lever 6 is off pivots and releases the prosthetic neck so that the

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ME34.1 page 9

Cone 3 can be pulled out of the corresponding receptacle 4.

Between a stop surface provided below the handle 9 15 and a collar provided above the end of the handle 11 - also serving as a stop surface 16 is an impact mass 17 on the shaft in the longitudinal direction movably arranged, which serves to knock out the prosthesis. However, if the forces required are only small, it can can also be used during the impact process. This is the way the tool is shown in and out universally applicable.

The implementation of the invention is not restricted to the example given above. Rather are one A large number of variants are conceivable, which of the solution shown also with fundamentally different designs Make use.

Claims (8)

new claims page 1 G 84 OO 642.0 April 9, 1984 ME34.G1 claims 1. Cone connection for a joint prosthesis with a recess in the neck area to secure an insertion or extraction tool placed on the cone, with an in the pin engaging the recess, characterized,
10 that the recess (5) is provided in the immediate vicinity of the enlarged end of the cone (3). 2. Cone connection to claim 1, characterized in that with a hip joint prosthesis the recess (5) is provided on the inside of the curvature near the joint. 3. Cone connection according to one of the preceding claims, characterized in that the recess (5) is round. 4. Impact tool for a prosthesis with a cone connection according to one of the preceding Claims, characterized in that the pin (6) is adapted to the recess and that the recess is provided in the immediate vicinity of the enlarged cone end. II IUM II nil 'ι I new claims page 2 G 84 OO 642.0 April 9, 1984 ME34.G1 5. Tool according to claim 4, characterized in that the pin (6) is designed to be pivotable about a tangentially directed axis (7).
5 6. Tool according to one of claims 4 or 5, d a - fi is characterized by the fact that an actuating ¥ lever is provided, which by means of a mechanical 10 niche translation is associated with the pen in such a way that that the lever with the pin engaging in the recess t (6) rests on the tool shank (8). 7. Tool according to one of claims 4 to 6, characterized in that with the Shank (8) both an (impact) head (10) located above a handle and one below the handle located movable (out) striking mass (17> with egg- LO ner stop surface (15) in the area immediately below of the handle is connected. 8. Tool according to claims 6 and 7, characterized
characterized in that a further stop (16) for the (impact) mass (17) is arranged directly above the lever (11) resting on the tool shank (8).