IMPACT INSTRUMENT

Abstract

Impact instrument for joining prosthetic implants, comprising a housing which accommodates a striker pin, a first spring element associated with the striker pin, a release device and, at least in part, a striking piece, wherein the striking piece projects from the housing at an end face, wherein the release device is movable between a fixing position and a release position, wherein the striker pin is spaced apart from the striking piece the fixing position, wherein the release device moves automatically from the fixing position to the release position when the striking piece moves axially into the housing, in order to release the striker pin once the release position has been reached, so that the latter moves in the direction of the striking piece, accelerated by the first spring element.

Claims

1. An impact instrument for joining prosthetic implants, comprising a housing which accommodates a striker pin, a first spring element associated with the striker pin, a release device and, at least in part, a striking piece, wherein the striking piece projects from the housing at an end face, wherein the release device is movable between a fixing position and a release position, wherein the striker pin is spaced apart from the striking piece in the fixing position, wherein the release device moves automatically from the fixing position to the release position when the striking piece moves axially into the housing, in order to release the striker pin once the release position has been reached, so that the latter moves in the direction of the striking piece, accelerated by the first spring element.

2. The impact instrument according to claim 1, wherein when the impact instrument is placed on an implant to be joined, the housing moves in the axial direction towards the implant, wherein the striking piece moves into the housing and from the fixing position into the release position, wherein the striker pin is released as soon as the striking piece reaches the release position and the striking pin, accelerated by the first spring element, moves towards the striking piece to introduce an impulse into the striking piece.

3. The impact instrument according to claim 1, wherein the release device has a first sleeve, which is arranged in the housing in an axially movable manner, and which accommodates the striker pin, wherein the first sleeve has at least one opening on the circumference, wherein at least one locking body is arranged in the opening.

4. The impact instrument according to claim 3, wherein in the striking pin, at least one recess is provided, which accommodates the locking body in the fixing position.

5. The impact instrument according to claim 4, wherein the recess is designed in the form of a circumferential groove which is introduced into the circumference of the striking pin.

6. The impact instrument according to claim 4, wherein the locking body abuts against the inner wall of the housing in the fixing position, wherein the inner diameter of the housing is selected such that the locking body is held in the opening of the first sleeve and in the recess of the striker pin and thereby the striker pin is locked relative to the first sleeve.

7. The impact instrument according to claim 6, wherein the striking piece axially moves the first sleeve and the striker pin locked with the first sleeve in the housing when the striking piece axially moves into the housing.

8. The impact instrument according to claim 3, wherein the housing is provided with a cross-section expansion, wherein the inner diameter of the housing increases in the region of the cross-section expansion, wherein the cross-section expansion is designed to partially accommodate the locking body in the release position.

9. The impact instrument according to claim 8, wherein the locking body, in the release position, slides out of the recess of the striker pin and into the opening of the first sleeve and the cross-section expansion of the housing, so that the striker pin is released.

10. The impact instrument according to claim 3, wherein the first sleeve has, on one end face, a receiving part for the striking piece, wherein the receiving part is designed in such a way that the striking pin directly contacts the striking piece in the release position.

11. The impact instrument according to claim 1, wherein the striking pin is provided with a circumferential collar, wherein the first spring element bears against the collar and against the housing.

12. The impact instrument according to claim 3, wherein a second sleeve is arranged between the first sleeve and the housing, wherein the inner wall of the second sleeve forms a sliding surface for the locking body and wherein the cross-section expansion is introduced into the second sleeve.

13. The impact instrument according to claim 12, wherein the second sleeve is accommodated in the housing in an axially movable manner and a second spring element is provided, which positions the second sleeve relative to the housing.

14. The impact instrument according to claim 3, wherein a third spring element is provided, which is arranged on the end face side between the first sleeve and the housing.

15. The impact instrument according to claim 1, wherein the housing is provided with a handpiece.

Description

[0027] Some embodiments of the impact instrument according to the invention are explained in more detail below with reference the figures. These show, in each case schematically:

[0028] FIG. 1 a cross-section view of the impact instrument in the fixing position;

[0029] FIG. 2 a cross-section view of the impact instrument in the release position.

[0030] The figures show an impact instrument 1 for joining prosthetic implants. The impact instrument 1 is used in particular for joining tapered interference fits, which are frequently used in endoprosthetics in general. In the present embodiment, the impact instrument 1 is used for joining joint balls to a conical clamping pin of a hip implant. However, it is also conceivable that the impact instrument 1 is used for joining knee prostheses, shoulder prostheses or the like.

[0031] The impact instrument 1 comprises a housing 2 made of metallic material, wherein the housing 2 is provided with a through bore 22. The housing 2 accommodates a striker pin 3, a first spring element 4 assigned to the striker pin 3, a release device 5 and, in part, a striking piece 6. The striking piece 6 protrudes from the housing 2 at one end face of the housing 2.

[0032] The striker pin 3, the first spring element 4 and the striking piece 6 are also made of metallic material.

[0033] The release device 5 is movable between a fixing position 8 and a release position 9, wherein the striker pin 3 is spaced apart from the striking piece 6 in the fixing position 8. When the striking piece 6 is moved axially into the housing 2, the release device 5 moves automatically from the fixing position 8 to the release position 9.

[0034] After reaching the release position 9, the striker pin 3 is released so that it moves accelerated by the first spring element 4 towards the striking piece 6.

[0035] The release device 5 has a first sleeve 10, which is arranged in the bore 22 of the housing 2 in an axially movable manner, wherein the first sleeve 10 accommodates the striker pin 3, wherein the first sleeve 10 has three openings 11 distributed over the circumference. A locking body 12 in the form of a metal ball is arranged in each of the openings 11. The first sleeve 10 is also made of metallic material.

[0036] A recess 13 in the form of a circumferential groove is formed in the striker pin 3, wherein the locking bodies 12 are locked in the recess 13 in the fixing position 8.

[0037] A second sleeve 17 is arranged between the first sleeve 10 and the housing 2, wherein the inner wall 26 of the second sleeve 17 forms a sliding surface for the locking bodies 12. In the fixing position 8, the locking bodies 12 abut against the inner wall 26 of the second sleeve 17. In this case, the inner diameter of the second sleeve 17 is selected such that the locking bodies 12 are held in the openings 11 of the first sleeve 10 and in the recess 13 of the striker pin 3, so that the striker pin 3 is locked relative to the first sleeve 10.

[0038] When the impact instrument 1 is placed on an implant to be joined and a force is exerted onto the impact instrument 1, the striking piece 6 moves the first sleeve 10 and the striker pin 3 that is locked to the first sleeve 10 relative to the housing 2 in the axial direction. The striking piece 6 thereby moves in axial direction into the housing 2.

[0039] The second sleeve 17 is provided with a cross-section expansion 14, wherein the inner diameter of the second sleeve 17 increases in the area of the cross-section expansion 14, wherein the cross-section expansion 14 is configured to partially accommodate the locking bodies 12 in the release position 9.

[0040] If the striking piece 6 is axially moved this far into the housing 2, the locking bodies 12 reach the area of the cross-section expansion 14 in the release position 9. Thereby, the locking bodies 12 slide out of the recess 13 of the striker pin 3 and into the opening 11 of the first sleeve 10 and the cross-section expansion 14 of the second sleeve 17. This causes the striker pin 3 to be released abruptly and accelerated by the first spring element 4 in the direction of the striking piece 6.

[0041] The first sleeve 10 has a receiving part 15 for the striking piece 6 on one end face, wherein the receiving part 15 is designed such that the striker pin 3 directly contacts the striking piece 6 in the release position 9. For this purpose, the first sleeve 10 has an opening 25 on the end face.

[0042] The striker pin 3 is provided with a circumferential collar 16, wherein the first spring element 4 bears against the collar 16 and against the housing 2.

[0043] The second sleeve 17 is accommodated in the housing 2 in an axially movable manner. A second spring element 18 positions the second sleeve 17 relative to the housing 2.

[0044] Furthermore, a third spring element 19 is provided, which is arranged on the side of the end face between the first sleeve 10 and the housing 2 and causes the first sleeve 10 and the striking piece 6 to be returned in the release position 9.

[0045] The housing 2 has a handpiece 20 on the end face facing away from the striking piece 6. The handpiece 20 may be formed of plastic or metal.

[0046] A sealing element 21 is provided between the housing 2 and the striking piece 6.

[0047] On the end face facing the striker pin 3, the striking piece 6 has a projection which projects through the opening 25 made in the end face of the first sleeve 10.

[0048] FIG. 1 shows the impact instrument 1 in its initial position. The striking piece 6 and the striker pin 3 are spaced apart from each other. The locking bodies 12 are located in the opening 11 of the first sleeve 10 and in the recess 13 of the striker pin 3. The locking bodies 12 bear against the inner wall 26 of the second sleeve 17. As a result, the first sleeve 10 and the striker pin 3 are locked with each other.

[0049] FIG. 2 shows the impact instrument 1 after it has been placed on an implant component to be joined and a force has been exerted axially onto the impact instrument 1 via the handpiece 20. The exertion of force in the axial direction causes the striking piece 6 to move relative to the housing 2, wherein the striking piece 6 takes along the first sleeve 10 and the locking members 12 disposed therein. As a result of the fact that the striker pin 3 is locked with the first sleeve 10 via the locking bodies 12, the striker pin 3 also moves in the same way.

[0050] In the position shown in FIG. 2, the cross-section expansion 14 of the second sleeve 17 has been reached and the locking bodies 12 slide out of the recess 13 of the striker pin 3 and release the striker pin 3. By moving the striking piece 6, the first sleeve 10 and the striker pin 3, the first spring element 4 has been preloaded so that the striker pin 3, after being released by the locking bodies 12 sliding out of the recess 13, is accelerated towards the striking piece 6.

[0051] After release, the striker pin 3 is accelerated by the spring element 4. The accelerated striker pin 3 contacts the front face of the striking piece 6 directly and at high velocity. Together with the pre-force required to release the release device 5, an impulse is introduced into the striking piece 6, which in turn is introduced into the implant component to be joined via the free end 23. For better contacting of the implant component, the striking piece 6 has a contacting element 24 at the free end 23, which is provided with a conical recess on the side facing the implant component. This ensures at least a ring-shaped contact of the striking piece 6 with the implant component to be joined. Due to the initial force required to release the release device 5, the impact instrument 1 or the contacting element 24 of the striking piece 6 rests with a preload on the implant component to be joined. In this way the impulse introduced into the striking piece 6 via the striker pin 3 can be transferred completely onto the implant component to be joined. This allows a predetermined and reproducible impulse to enter an implant component.

[0052] During the acceleration of the striker pin 3, the striker pin 3 moves in an axial direction relative to the first sleeve 10, the second sleeve 17 and the striking piece 6. In this position, the recess 13 of the striker pin 3 is displaced in the axial direction towards the locking bodies 12. The locking bodies 12 remain in the opening 11 of the first sleeve 10 and in the cross-section expansion 14 of the second sleeve 17.

[0053] If the impact instrument 1 is now unloaded, the striking piece 6 moves out of the housing 2 again. Thereby, the spring elements 18, 19 relax, wherein the third spring element 19 causes the first sleeve 10 to move together with the striking piece 6 in axial direction and, in doing so, the first sleeve 10 to abut against the end face of the striking piece 6. The second spring element 18, in turn, causes the second sleeve 17 to move in the opposite direction until the opening 11, the locking bodies 12 and the recess 13 are aligned, thereby causing the locking bodies 12 to slide back into the recess 13, thereby locking the striker pin 3 with the first sleeve 10.

[0054] Thus, the components of the impact instrument 1 automatically move back to the initial position shown in FIG. 1 after the impact and release. The impact instrument 1 can be used immediately for another impact. It is not necessary to preload the device manually or the like.