AXIALLY PRECISE SCREWDRIVER

Abstract

An implantation set for implanting a screw in a human or animal body includes a tool and a screw designed to receive the tool. The screw has a tool receiving region into which or onto which a torque transmission region of the tool can be or is inserted or placed to transmit torque. At least one inclined insertion region is formed on the tool receiving region to guide the tool during insertion of the screw. The tool forms at least one centering surface that is matched to the inclined insertion region such that when the centering surface comes into contact with the inclined insertion region, a form fit and force fit is created.

Claims

1. An implantation set for implanting a screw in a human or animal body, the implantation set comprising: a tool having a tool shank; and a screw designed to receive the tool, for which the screw comprises a tool mount in the form of a blind hole comprising a torque introduction portion into which or onto which a torque transmission region on the distal end region of the tool shank can be or is inserted or placed to transmit torque, wherein the tool mount of the screw proximal relative to the torque introduction portion forms an inclined insertion region for guiding and/or centering the tool shank during inserting it in/placing it on the screw, characterized in wherein the tool shank forms a centering surface which is proximal relative to the torque transmission portion and matched to the inclined insertion region such that when the centering surface comes into contact with the inclined insertion region, a form fit and preferably a force fit is created in circumferential direction in addition or as an alternative to the form fit between the torque transmission portion and the torque introduction portion.

2. The implantation set according to claim 1, wherein the torque transmission portion on the tool shank of the tool and the torque introduction portion on/in the tool mount of the screw each have at least one or more axially extending ribs or webs which are equally spaced in the circumferential direction and at least one or more axially extending grooves which are equally spaced in the circumferential direction.

3. The implantation set according to claim 1, wherein the tool shank forms or has a radially protruding shaft/shank ring or shoulder which delimits the torque transmission portion proximally in axial direction and on the distal side of which the centering surface is formed in which a number of protrusions is formed, and the inclined insertion region, arranged on the proximal end of the torque introduction portion, forms a number of indentations or grooves which protrude in an axial and also in a radial direction and further are of concave design, which can be brought into form-fitting engagement with the protrusions on the centering surface.

4. The implantation according to claim 1, wherein the ribs or webs which extend axially and protrude radially outward on a cylindrical outer surface of a distal shank portion of the tool, forming the torque transmission portion, extend beyond a distal frustoconical outer surface of a tip of the tool in a distal direction.

5. The implantation set according to claim 1, wherein a sleeve-shaped threaded part is placed on the tool shank so as to be movable relative thereto, said threaded part having an external thread at its distal end and a body or tulip being movably supported on the screw, which encompasses a screw head and forms an internal thread at its proximal end portion provided with longitudinal slits, which can be brought into engagement with the external thread of the sleeve-shaped threaded part.

6. The implantation set according to claim 5, wherein a ring-shaped or shaft shoulder type counterholder is formed or fixed on the tool shank and configured and/or adapted to be axially inserted into longitudinal slits in the body/tulip, in order to apply a torque, in particular a restraining torque onto the body/tulip, wherein the sleeve-shaped threaded part is arranged proximal relative to the counterholder such that its external thread is situated on the side of the counterholder and the sleeve-shaped threaded part can be axially moved into contact with the counterholder in a distal direction, if the sleeve-shaped threaded part is screwed into the body/tulip while being restrained by means of the counterholder.

7. A medical tool for screwing in a screw in a human or animal body, the medical tool comprising a torque transmission portion which is formed on the distal end region of a tool shank and configured and/or adapted to be inserted in/placed on a torque introduction portion of a tool mount of the screw, wherein a radially protruding shaft/shank ring or shoulder is formed or arranged on the tool shank, so as to be positioned proximal relative to the torque transmission portion, and delimits the torque transmission portion in a proximal direction, wherein a centering surface is formed on the distal side of the shaft/shank shoulder and comprises or forms a number of protrusions.

8. The tool according to claim 7, wherein the torque transmission portion comprises a number of ribs/webs which are arranged in axial extension relative to the protrusions formed in the centering surface, such that the protrusions formed in the centering surface extend radially beyond the respectively assigned ribs/webs.

9. The tool according to claim 7 further comprising a sleeve-shaped threaded part which is pushed onto the tool shank so as to be rotatable and axially shiftable and can be brought into axial abutment on an annular counterholder which is formed or fixed on the tool shank and has an oval or elliptic cross-section.

10. A pedicle screw comprising a bone screw and a body/tulip encompassing a screw head, in which a blind hole type tool mount is formed, consisting of a torque introduction portion and an inclined insertion region proximally adjoining it in the form of a chamfer circumferentially surrounding the torque introduction portion, wherein a number of indentations is formed in the inclined insertion region which extend outward in axial and radial direction.

11. The pedicle screw according to claim 10, wherein the torque introduction portion comprises a number of axially extending and radially recessed grooves which are and arranged in axial extension relative to the indentations formed in the inclined insertion region, such that the indentations formed in the inclined insertion region extend radially beyond the respectively associated grooves.

12. The pedicle screw according to claim 11, wherein the indentations formed in the inclined insertion region surround the respectively associated grooves in the torque introduction portion in the radial direction of the blind-hole type tool mount forming a funnel.

13. The pedicle screw according to claim 11, wherein the indentations formed in the inclined insertion region have a uniform outer radius which is curved towards outside, which is dimensioned such that these outer radii of the indentations adjoining in the circumferential direction intersect each other.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0041] The invention is explained in more detail below using a preferred exemplary embodiment with reference to the accompanying Figures wherein:

[0042] FIG. 1 shows the components of an implantation set according to the invention in engagement with each other;

[0043] FIG. 2 shows a tool head of a tool according to the present invention;

[0044] FIG. 3 shows a threaded part arranged on the tool, in the present case in the form of a screwdriver;

[0045] FIG. 4 shows a body/a tulip attached to a screw, in the present case a pedicle screw;

[0046] FIG. 5 shows an insert arranged in the body/the tulip;

[0047] FIG. 6 shows a screw head of the screw/pedicle screw to be implanted, in the present case with a polyaxial design;

[0048] FIG. 7 shows the screw head of FIG. 6 in a detailed view; and

[0049] FIG. 8 is a side view of the tool in the state when clamped in the screw, arranged in the insert and the body.

DETAILED DESCRIPTION

[0050] In FIG. 1, the components of an implantation set are shown in engagement with each other according to the preferred exemplary embodiment of the present invention. A screw, in the present case a pedicle screw 1, is in engagement with a (screw-in) tool/screwdriver 2. A movable body (tulip) 4 is placed axially over the screw 1 at its proximal screw head, which optionally has an insert/inlay 6 which is held so as to be axially movable relative to the body 4.

[0051] Radially above the tool 2 or its tool shank 12, a threaded part/threaded sleeve 8 is placed from the proximal side in the direction towards the distal tool tip/shank tip of the tool 2, which rests axially on a counterholder (approximately oval/elliptical shaft ring) 10 which is arranged/formed on the screwdriver/tool shank at a specific/determinable axial position (axially fixed).

[0052] FIG. 2 shows the head/tip portion/tool head of the tool 2 in a detailed illustration.

[0053] The tool head is formed on the preferably cylindrical screwdriver shank 12, which extends from a handle (not shown) to the counterholder 10. The counterholder 10 has a preferably hammer-shaped (oval/elliptical) cross-section or the design of a wing nut, with two diametrically opposite sides/wings projecting radially beyond the circumference of the cylindrical shank 12 extending above the counterholder 10 (proximally to it). A shaft portion 14 below/distally relative to the counterholder 10 and extending the tool shaft 12 in distal direction is smaller in diameter than the shaft 12 above (proximal to) the counterholder 10. The shaft portion 14 below (distal to) the counterholder 10 merges distally into a centering surface portion 16 or shaft/shank shoulder for centering the tool shaft 14 with respect to the screw 1, for additional torsion transmission and for sealing. The centering surface portion 16 merges distally into a multi-lobe profile/torque transmission portion 18 having axially extending, radially projecting and circumferentially spaced ribs/webs/teeth 20 on its cylindrical outer surface. The transition between the centering surface portion 16 and the multi-lobe portion 18 is preferably formed by rounded geometries (centering surfaces/protrusions 17) arranged in series in the circumferential direction.

[0054] In other words, a number of circumferentially spaced projections 17 are formed on the shaft/shank shoulder 16, each extending axially and radially and forming circumferentially spaced grooves/depressions in the axial and radial directions between them. The projections 17 and grooves on the shaft/shank shoulder 16 are arranged in axial extension to the ribs/webs 20 and grooves in the torque transmission portion 18.

[0055] The circumferential surface of the frustoconical tool end portion 22, or centering tip, also forms a multi-lobe geometry (in extension to the multi-lobe geometry in torque transmission portion 18). The primary torque transmission region/portion 18 is formed by the (axially extending) ribs 20 of the multi-lobe unit. The ribs 20 thus extend from the cylindrical peripheral surface of the multi-lobe unit across the peripheral surface of the shaft truncated cone 22 distally adjacent to the torque transmission region 18 to the tool shank tip which is flattened at the end face.

[0056] From FIG. 2 it can also be seen that the centering surfaces/protrusions in the area of the shaft/shank shoulder 16 and the ribs 20 align axially with one another (in extension), the individual centering surfaces/protrusions 17 in the shaft/shank shoulder 16 each being formed as semi-conical axial-radial projections above the ribs 20 and being spaced apart in the circumferential direction by cup-shaped/calotte-shaped recesses/grooves which are formed in the shaft/shank shoulder 16 and which are also arranged in extension to the grooves in the torque transmission portion 18.

[0057] FIG. 3 shows the sleeve-shaped threaded part 8 in detail, which can be/is arranged on the screwdriver 2, i.e. on the tool shank 12, according to the invention so as to be relatively movable thereto. The threaded part 8 has a continuous hole (axial through-hole) 24 for rotationally and axially displaceably receiving the screwdriver shank 12, whereby the hole diameter is complementary to the outside diameter of the shank 12 above the counterholder 10 for an essentially backlash-free support. The threaded part 8 rests axially on the counterholder 10 of the tool 2. On the axial end side of the threaded part 8 facing the counterholder 10, i.e. the distal end of the threaded part 8, an external thread 28 is formed underneath a preferably externally smooth sleeve portion 26. In addition, an axial prong-type profile is worked out at the upper, proximal end of threaded part 8 in order to be able to apply a torque to the threaded part 8 using an appropriate tool (e.g. a wrench, not shown).

[0058] FIG. 4 shows the body (tulip) 4 which can be or is articulated to the screw (pedicle screw) 1. The sleeve-shaped body 4 has a U-shape in side view, i.e. an essentially sleeve-shaped shape with two diametrically opposite longitudinal slots at the proximal sleeve portion and a radial constriction at the distal sleeve end. An internal thread 30 is formed on the side of body 4 facing the tool 2 (in the region of the longitudinally slotted sleeve portion), which is complementary to the external thread 28 of the tool-side threaded part 8, i.e. can receive/accommodate it.

[0059] On the distal side of the body 4, i.e. the side facing the screw 1, an internal dome 32 is formed, i.e. a bulbous through-bore. When the body 4 is put over the distal tip of the screw 1 and pushed proximal towards the screw head 36, the internal dome 32 of the body 4 encompasses/grasps the screw 1 at its upper end (spherical screw head 36). Thus, the body 4 is movably held at the upper end (screw head 36) of the screw 1. In the clamped state, i.e. when the external thread 28 of the threaded part 8 is completely screwed into the internal thread 30 of the body 4, the threaded part 8 presses the tool 2 or the tool shank 12 by an axial force against the counterholder 10 into the screw 1 (its blind hole on the screw head side). The abutment is established by the body 4, which is in contact with screw 1 or its screw head.

[0060] FIG. 5 shows the insert 6, which can optionally be arranged in the body 4. The insert 6 has an axial projection with an internal bore 34, which fits exactly with the shank portion 14 below the counterholder 10 of the tool 2, but can also be larger, and which can be or is inserted into the internal dome 32 of the body 4 to press against the screw head 36. The counterholder 10 of tool 2 does not touch the insert 6 even when the threaded part 8 is completely screwed in place in the body 4. The insert 6 therefore remains movable in the body 4 even when tool 2 is clamped with the body 4. Therefore, the insert 6 is not in a clamped state with the body 4 when the tool 2 is clamped with the screw 1, if the threaded part 8 is screwed in the body 4, and is therefore movable.

[0061] FIG. 6 shows the ball-shaped/spherical screw head 36 of the screw 1 to be implanted. A blind hole is formed in the ball-shaped screw head 36 which extends axially to the screw axis A and opens on the proximal side of the screw head 36. In a distal torque introduction portion 42, the blind hole has at least one radially outwardly projecting indentation/groove 44 and at least one radially inwardly projecting prong/rib/web 46. At the edge of the blind hole, there is a (funnel/cup-shaped) inclined insertion region (chamfer) 41, in which bowl/calotte-shaped indentations/grooves 40 are formed, which preferably line up at the same distance from one another in the circumferential direction. In this way, preferably each indentation/groove 40 in the inclined insertion region 41 represents an individual/separate zone of the inclined insertion region in addition to the at least one groove 44 in the torque introduction portion 42 of the blind hole. In the case of a large number of inclined insertion region areas (indentations) 40, an inclined insertion region area 40 adjoins the respective adjacent one in the circumferential direction, or the inclined insertion region areas 40 are intersected with one another and form a common intersection edge. The intersection edge extends into the interior of a tool receiving area 42 of the blind hole.

[0062] The recesses/grooves 40 in the inclined insertion region 41 form force-fit and force-fit areas for the aforementioned semi-conical axial (and radial) projections on the shaft/shank shoulder 16 of the tool 2 of the invention. According to the invention, the inclined insertion region areas 40 form form-fit areas for the centering surface 16 of the tool 2.

[0063] The screw head 36 represents the abutment, in other words the contact surface, of the body 4 in the clamped state when the threaded part 8 is screwed in place in the body 4. The alignment takes place via a force fit and form fit between the centering surface 16 or the projections 17 formed there and the inclined insertion region 41 or the indentations 40 formed there.

[0064] FIG. 7 shows the ball-shaped/spherical screw head 36 in detail. The tool receiving area/torque introduction portion 42 of the screw head 36 or the blind hole 38 has indentations/grooves 44 extending axially toward the screw 1 and machined radially outwards. The radially outwardly pointing indentations/grooves 44 are separated in the circumferential direction by radially inwardly pointing prongs/ribs/webs 46. At the distal edge of the blind hole 38 on the screw head 36, the inclined insertion region 41 is formed. Whereas in conventional screws the inclined insertion region evenly surrounds the entire hole (in the manner of a single lathed chamfer) and projects into the hole like a funnel, the inclined insertion region 41 is designed, so to speak, individually for each indentation/groove 44 in the screw 1 of the present invention, i.e. by circumferentially spaced as well as overlapping, respectively funnel-shaped inclined insertion region areas/indentations 40. This results approximately in the shape of a multi-leaf cloverleaf in plan view.

[0065] FIG. 8 shows the tool 2 in the clamped condition according to an advantageous embodiment. The tool 2 is in engagement with the screw 1 and the shank portion 14 underneath/distal to the counterholder 10 is arranged in the internal bore 34 in the insert 6, which in turn is arranged in the body 4. It can be seen from FIG. 8 that the insert 6 still has clearance to the body 4 and is thus movably arranged therein, as seen in the longitudinal axis of tool 2.

[0066] The blind hole 38 in the screw 1 or screw head 36 is deeper than the length of the tool portion/torque transmission portion 18 and the adjoining end portion 22 starting from the distal (flattened tool tip) to the shaft/shank portion 16. In other words, the tool 2 in the clamped condition at the flattened tool shaft tip 22 is not in operative engagement/facing abutment with/on the blind hole 38 of the screw 1, whereas the torque transmission region 18 of the tool 2 is in operative engagement with the torque introduction portion 42 of the blind hole 38. This means that the force applied to the screw 1 by the tool 2 is partly (in addition to the torque transmission portion 18) also applied by the projections/centering surfaces 17 in the shaft/shank shoulder 16 to the inclined insertion region 41 or the dome-shaped inclined insertion region areas/indentations 40 formed there.

[0067] The indentations or axial grooves 44 in the torque introduction portion 42 of the blind hole 38 each form form-fit and force-fit regions for the ribs/webs 20 in the torque transmission portion 18 of the tool 2, and the (cup-shaped/calotte-shaped) inclined insertion region areas/indentations 40 form foam-fit and force-fit regions for the centering surfaces/spherical projections 17 of the tool 2. The centering surfaces 17 of the tool 2 are designed analogously to the inclined insertion region areas 40 of the tool 2.

[0068] In summary, the invention relates to an implantation set for implanting a screw 1 in a human or animal body, comprising a tool 2 and a screw 1 designed to receive the tool 2, wherein the screw (1) has a tool-receiving region (42) into which or onto which a torque transmission region (18) of the tool (2) can be or is inserted placed to transmit torque, wherein at least one inclined insertion region (41) is formed on the tool receiving region (42) to guide the tool (2) during insertion of the screw (1), characterized in that the tool (2) forms at least one centering surface (16), which is matched to the inclined insertion region (41) such that when the centering surface (16) comes into contact with the inclined insertion region (41), a form fit and force fit is created.