Appliance set and its tulip

Abstract

The present invention relates to an instrument set. The instrument set includes a tulip (10), a spinal implant, and a holding device (200). The tulip (10) extends along its longitudinal axis (X). The spinal implant includes pedicle screws and serves to couple a connecting rod along the transverse axis (Q) of the tulip. The holding device (200) temporarily holds the tulip (10) in a held state of the instrument set during an implant insertion procedure. The tulip and the holding device involve a rotational movement about an axis (A) during a transition from the held state to a released state and a transition from the released state to the held state. The axis (A) mainly has a direction component that is lateral to the longitudinal axis of the tulip and parallel to the transverse axis of the tulip.

Description

Technical Field

[0001] The present invention relates to the field of spinal implants, and more particularly to an implant system including pedicle screws, some of which are interconnected via connecting rods or fixation rods to stabilize the spine. In particular, the present invention relates to an instrument set. The instrument set includes a tulip and a holding device, the tulip extends along its longitudinal axis and forms part of a spinal implant, the spinal implant includes pedicle screws, and serves to connect a connecting rod along the transverse axis of the tulip. The holding device temporarily holds the tulip during the implantation process in the held state of the instrument set. The tulip and the holding device involve rotational movement about an axis during the transition from the held state to the released state and from the released state to the held state.

Background Art

[0002] Of course, such implant systems are well known to those skilled in the art. See, for example, US2012 / 0041490A1 or EP2376005B1. Since then, in these techniques and many other techniques, a holding system has been developed that does not rotatably screw the holding device about the longitudinal axis of the tulip but slides it tangentially, depending on a straight (purely tangential) groove on the outer surface of the tulip wall. This means that the holding state between the holding device and the tulip is achieved by rotating the holding device about the longitudinal axis of the tulip. This is disclosed, for example, in US9050148B2, which describes a groove that follows the circumferential direction on the cylindrical outer wall of the tulip and opens on the side surface.

Summary of the Invention

[0003] The present invention is based on the purpose of further improving the above-mentioned instrument set, against the background of the combination of ease of operation and a reliable transition from the released state to the held state.

[0004] This object is achieved by the present invention through the development of the instrument set mentioned above, which is substantially characterized in that the axis extends mainly in a direction transverse to the longitudinal axis of the tulip and parallel to the transverse axis of the tulip. In spherical coordinates, since the longitudinal axis of the tulip is the z-axis and the transverse axis of the tulip is the x-axis, it corresponds to θ > 45° and φ < 45°. However, these angles are preferably closer to 90° (θ) and 0° (φ), preferably deviating not more than 30° from these values, more preferably not more than 20°, and in particular not more than 10°. In a preferred embodiment, the axis of the rotational movement extends substantially parallel to the transverse axis when the tulip and the holding instrument are in the holding state. The axis of the rotational movement is a defined axis defined by the holding instrument and fixed within the system of the holding instrument.

[0005] The solution according to the present invention eliminates the need for the holding instrument and the tulip to be rotatable about the longitudinal axis of the tulip, and ensures a reliable azimuthal alignment between the holding instrument and the tulip during the transition.

[0006] Further advantageous embodiments are specified in the dependent claims.

[0007] Therefore, preferably, during the transition of the instrument set, a shift occurs between an anti-rotation lock that acts radially on the tulip with respect to the longitudinal axis of the tulip and prevents the rotation of the holding device with respect to the tulip about the longitudinal axis, and a rotation lock that blocks the radial outward rotational movement with respect to the longitudinal axis of the tulip. Therefore, the anti-rotation lock against rotation about the longitudinal axis of the tulip exists not only in the final holding state but also already in an intermediate holding state during the transition from the release state to the holding state. Due to the rotational movement, most of the forces acting on the tulip during the closing movement are balanced with respect to their tangential components, where effectively radially inward directed forces are used.

[0008] More preferably, the transition of the instrument set includes a translational axial movement between the tulip and the holding device along the longitudinal axis of the tulip, at least near the holding state. Thereby, the axial depth of the rotary lock is increased.

[0009] Also preferably, in the instrument set, the rotational movement and the axial movement at least temporarily overlap during the transition. For this purpose, preferably, a guide is provided which is achieved through supplementary shapes such as suitable slopes or bends of each coupling region, for example, the underside of the radially protruding part of the instrument and the upward-facing surface on the radially inner side of the tulip.

[0010] A tulip for an instrument set according to one of the foregoing aspects is also provided.

[0011] Preferably, the tulip includes at least four coupling regions which are arranged azimuthally spaced from each other on the tulip side for coupling the holding device in the holding state. Preferably, these coupling regions are designed to be axially symmetric with respect to the transverse axis, and as a preferred variant, the foregoing force distribution and supplementation are achieved.

[0012] More preferably, the coupling region of the tulip has a notch having a base which is particularly concave and forms the anti-rotation lock to prevent rotation of the instrument about the longitudinal axis. In this context, "concave" or "the shape of the concave base" does not mean a completely mathematical concave surface, and is distinguished from a purely straight (tangential) contour and the shape of a convex base curved in the opposite direction. For example, when defining the curvature sign around a chord in a circle, the concave surface here means the opposite curvature averaged over the course of the notch base.

[0013] Also preferably, the coupling region of the tulip includes a lower (proximal) axial passage adjacent to the azimuthal notch, and the lower (proximal) axial passage forms the rotation lock region of the rotation lock on the tulip side.

[0014] Preferably, the tulip includes a plurality of upper axial passage portions that open on the upper distal axial side of the side wall of the tulip, and the plurality of upper axial passage portions communicate with and are aligned with the lower passage portion. The upper axial passage portion represents an essentially undesirable material weakening of the wall of the tulip, yet is preferred for manufacturing reasons.

[0015] In one embodiment, the axial passage portion extends linearly in cross-section when viewed perpendicular to the longitudinal axis and is preferably tangential to the longitudinal axis. However, in another embodiment, these passage portions may extend polygonally in this cross-section. A variant is also preferred in which this curved track preferably has a center of curvature located substantially at the center of the tulip (i.e., at the point where the longitudinal axis intersects the cross-section). This applies to both the lower and / or upper axial passage portions.

[0016] Furthermore, preferably, the tulip has side walls of the azimuthal notch facing the distal axial end of the tulip, and the side walls are in or completely within a radial plane and in particular include a planar portion located at the same axial height. Preferably, one side wall of the tulip has at least two such azimuthal notches.

[0017] Even more preferably, the tulip has side walls of the azimuthal notch facing the proximal axial end of the tulip, and the side walls are formed as inclined surfaces. The design of the inclined surface facilitates the transition between rotational and translational movements and provides the necessary spacing for introducing the components of the rotational lock to the holding device side. In one embodiment, the opposing planar portions at the base of each of the two azimuthal notches arranged on the same side wall form an angle different from zero, preferably at least 20°, with respect to each other.

[0018] In a more preferred embodiment, the tulip has a web region formed in the azimuthal direction between two azimuthal notches located on one side wall of the tulip, and in particular has an azimuthal dimension that decreases radially outward. The ratio of the axial passage portion when viewed in the circumferential direction is preferably 70% or less, preferably 65% or less, and particularly 60% or less of the azimuthal region of the side wall. The azimuthal dimension of the web region at the web base, i.e., the radial height of the notch base and the axial height of the proximal notch side surface, is preferably at least 12°, more preferably at least 18°, and particularly at least 24°.

[0019] The two azimuthal notches arranged on different side walls may each have a planar portion extending parallel to each other. Preferably, the azimuthal notch on one side wall is arranged directly opposite the azimuthal notch on the other side wall.

[0020] Preferably, the axial length of the axial end portion of the tulip arranged distally with respect to the azimuthal notch and / or the axial length of the axial passage do not exceed 1.6 times, more preferably do not exceed 1.3 times, and particularly do not exceed 1.1 times the axial dimension of the notch base at the radially innermost point of the notch base. Thereby, the tulip is designed to be axially compact. Regarding the latter two values, this ratio preferably also applies to the axial dimension of the notch at the radially outermost point of the notch.

[0021] A method for manufacturing a tulip is also provided. The lower axial passage portion is formed after the upper passage portion is formed, and the lower passage portion is formed, in particular, before the azimuthal notch is formed. This sequence reduces the risk of damage to the often brittle side walls of the tulip. Preferably, the holding fixture has two legs that can pivot by rotation about the axis of the rotational movement, and the number of the coupling regions of the holding fixture formed radially inside each leg matches the number of the coupling regions on the tulip. Preferably, these coupling regions are formed by a radially protruding portion with a flange on the axial protruding portion. The radially protruding portion engages with the azimuthal notch of the tulip, while the axial protruding portion engages with the lower axial passage.

[0022] Preferably, the legs of the holding device are biased, for example by an elastic device, to reach the release position. Further preferably, the holding device has a locking mechanism which can lock the device in a closed state corresponding to its holding state against the bias. It is clear that this locking mechanism also forms a (primary) rotational lock for preventing the relative pivoting of the legs away from each other. However, based on the findings of the present invention, this rotational lock alone may not always be sufficient in certain cases, which means that an additional rotational lock provided by the coupling region between the holding device and the tulip provides additional safety against the opening relative movement of such legs.

Brief Description of the Drawings

[0023] Further details, features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings.

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0025] The basic functions of the spinal implant 100 shown in FIG. 1 will be well known to those skilled in the art. The spinal implant 100 includes a bone anchor in the form of a pedicle screw 30, which is attached to the head of the spinal implant 100, generally called the tulip 10, in a pivotal manner with respect to the longitudinal axis X of the tulip 10, in particular in a multi-axial pivotal manner. The basic structure of the tulip 10 is also typical and is well understood by those skilled in the art. In addition to the receiving area at the bottom for accommodating the (hidden) head of the pedicle screw 30, the tulip forms a receiving groove extending in the transverse direction Q for accommodating a connecting rod (not shown) used to connect one pedicle screw to another pedicle screw, and has an upper cylindrical peripheral region from the basic outer shape.

[0026] Thus, at the top, two side walls 11a, 11b of the tulip 10 remain, and inside the side walls, there are threads (not shown), for example, threads for receiving a set screw, such as a female set screw, by which the connecting rod can be fixed to the tulip 10. Tightening the set screw also fixes the position of the pedicle screw 30 relative to the tulip 10 not by direct force transmission from the connecting rod onto the screw head, but generally by indirect force transmission by an intermediate component generally called the saddle 20. The saddle 20 is shaped to at least partially accommodate the screw head at its lower part and its upper side fits onto the connecting rod extending along the transverse direction Q.

[0027] It is understood that the present invention is not limited with respect to a number of design possibilities of the basic functionality described so far, such as the specific design of the saddle 20, the internal structure of the tulip 10, uniaxiality or multiaxiality, symmetry or asymmetry of the angular range available for pivoting with respect to the longitudinal axis (axial axis) X, the material selection of the implant, the thread design of the pedicle screw 30, and / or any additional functionality.

[0028] During the implantation of the spinal implant 100, in particular in minimally invasive surgery, a holding device 200 is provided to hold the tulip 10. To be more clearly visible in the holding state shown on the right side of FIG. 2 between the device 200 and the tulip 10, the holding device 200 has two legs 211a and 211b, and the legs 211a and 211b are each coupled to one of the side walls 11a and 11b. The transition from the release state to this holding state involves a rotational movement about an axis, which does not correspond to the conventional axis of rotation that is aligned with the longitudinal axis X of the tulip in the prior art. Instead, the axis A of the rotational movement extends in the transverse direction Q. Thus, the device does not rotate relative to the tulip about the axial axis X, and instead, the coupling movement involves a pivoting movement of the legs 211a and 211b towards each other induced by the rotational movement, and accordingly, approaches the tulip 10 mainly in the radial direction with respect to the axial axis X and orthogonal to the axis A of the rotational movement fixed in the coordinate system of the device.

[0029] In this exemplary embodiment, the tulip-side coupling regions 12a and 12b on the side walls 11a and 11b are designed identically on both sides, which means that the following description focuses only on one side. As can be seen most clearly in FIG. 3, the tulip 10 has a recessed cut 12a shaped to function as a coupling region near its upper axial end. These cuts do not follow the circumferential direction of the convex substantially cylindrical side wall 11a, but instead act as a rotational lock for the opposing coupling parts on the device side, preventing the device 200 from rotating relative to the tulip 10 about the longitudinal axis X of the tulip 10. Thereby, even in an intermediate holding state before reaching the final holding state, entry and exit of the opposing object on the device into the concave notch-shaped coupling region 12a due to rotational forces are prevented. This is best seen in the radial cross-sectional view A-A of FIG. 4.

[0030] The concave notch-shaped coupling region 12a (hereinafter simply referred to as notch 12a) includes a base surface 120, a first side surface 121, and a second side surface 122 in terms of terms related to the radial direction of the axial axis X. The first side surface 121 follows the course of the base surface 120 on its adjacent side and transitions to the convex side wall 11a at the opposite edge. However, although the first side surface 121 is not located within the radial plane, the normal vector of the first side surface 121, which is not necessarily constant along the course of the first side surface 121, exhibits a direction component that points radially outward, particularly near the base surface 120.

[0031] In contrast, the second side surface 122 in this exemplary embodiment is formed substantially planar and thus extends within the radial plane with respect to the axial axis X. Therefore, the axial distance between the second side surface 122 and the first side surface 121 is, in any case, greater at the azimuth midpoint than at the base side in the transition to the convex outer surface of the side wall 11a. In the embodiments shown in FIGS. 1 to 4, it is particularly provided that this axial distance increases in the azimuth direction from the radially inner side to the radially outer side and from the outer edge towards the azimuth midpoint of the notch 12a. In this exemplary embodiment, the notches 12a are arranged at intervals in the azimuth direction such that their azimuth midpoints are separated by approximately 60°.

[0032] In this exemplary embodiment, the two notches 12a are separated by a ridge 14a. Since the base surface 120 of the notch 12a has a concave shape, the ridge 14a has a substantially trapezoidal and approximately triangular shape in the radial cross-section. Therefore, in this exemplary embodiment, it has a significantly larger azimuth dimension on the radially inner side compared to the radially outer side, which is 30°. This shape is intended to provide greater material rigidity in particular to compensate for material weakening in the wall 11a of the tulip within the region of the axial direction X between the notch 12a and the upper axial end of the tulip 10, which is most clearly visible in the radial cross-section B - B of FIGS. 3 and particularly FIG. 4.

[0033] Therefore, the tulip 10 has two holes 18a extending in the axial direction X, which are configured as azimuthal slots within this region 16a. The azimuthal range of the two holes 18a covers only a part, and in this embodiment, it covers approximately half of the azimuthal range of the notch 12a. The inner wall of the radial slot is substantially axially aligned with the base surface 120 of the notch 12a. The axial protrusion 218a is accommodated in the slot 18a in a held state, and since the axial protrusion 218a is concealed by the leg 211a of the instrument, it cannot be seen in FIG. 1 or FIG. 2. However, as can be seen in FIG. 1, the axial protrusion 218b attached to the radial protrusion 212b can be seen in FIG. 7 and is designed to fit into the slot 18b on the opposite side wall 11b. Therefore, the radially outer boundary of the slot 18a (18b) forms a rotational lock in a held state, preventing the leg 211a from pivoting about the axis A of the rotational movement of the instrument 200.

[0034] The slots 18a, 18b are closed on both azimuthal sides. In this embodiment, the ratio of the material region of the tulip that is not occupied by the slots 18a, 18b to the full azimuthal range of the side wall 11a of the tulip within the radial region of the slots 18a, 18b is approximately 50%.

[0035] In the embodiment shown in FIG. 5, the slots 18a, 18b are not concentric as in the embodiment of FIG. 4. Instead, they are in a tangential direction, which means that the slots are designed to be linear. In the embodiment shown in FIG. 6, three slots are provided for each of the side walls 11a, 11b, and in this case, they are arranged concentrically in the same manner as the embodiment of FIG. 4. However, in another embodiment not shown, these slots may be designed to be linear (tangential direction) as in the embodiment of FIG. 5.

[0036] As shown in FIG. 2, the holding state shown on the right side of FIG. 2 is achieved by the leg portions 211a and 211b performing a pivotal movement about the axis A, thereby mainly radially drawing the radially protruding portions 212a and 212b protruding radially inward from the inside of the leg portions 211a and 211b into the notches 12a and 12b facing them. The final holding state is achieved by an axial translational movement between the instrument 200 and the tulip 10, during which the rotational movement about the axis A and this translational movement may already overlap. In the exemplary embodiment shown in the figure, the first side surface 121 and the lower surfaces of the radially protruding portions 212a, b facing this side surface 121 support such a translational axial movement from the rotational movement and form a guide that can also be generated particularly as required. Correspondingly, when releasing the instrument 200 and the tulip 10, an axial translational movement along the longitudinal axis X of the tulip is initiated, and the rotational movement may be guided or initiated by this guide.

[0037] In FIGS. 7 and 8, the entire holding instrument 200 is shown again. In the open state shown in FIG. 7, the leg portions 211a and 211b pivot relative to each other from the base configuration (FIG. 8) that is parallel in the holding state. The sliding switch 230 positioned at the extension of the leg portion 211b beyond the axis A can maintain the holding state (FIG. 8) against the restoring force of the spring mechanism 240. However, in the holding state of the tulip, the locking mechanism of the switch 230 is no longer stressed by the forces acting on the free ends of the leg portions 211a and 211b, particularly the forces directed radially outward, because these forces are absorbed by the rotational lock formed by the coupling region of the tulip 10.

[0038] Since the inner passage 250 formed between the legs 211a and 211b extends to the distal end, a stamp (not shown) guided internally can be guided within the instrument to push the connection rod (also called the fixing rod) described above into the tulip. The lateral free space between the legs 211a and 211b of the instrument 200 also has sufficient dimensions for this purpose. The stamp guided internally may also be hollow inside to allow for the axial introduction of additional instrument parts, in which case a set screw (not shown) can be screwed into the internal threads of the side walls 11a and 11b of the tulip. Similarly, a screwing instrument (not shown) can be guided into the instrument 200 to insert the pedicle screw 30 into the vertebra while the tulip 10 is held by the instrument. In the case of the configuration having the saddle 20, the saddle includes an access opening that provides access to the screw head of the pedicle screw 30 for this purpose.

[0039] It is understood that the holding instrument can also perform additional functions well known to those skilled in the art in relation to the insertion of the pedicle screw and the holding of the tulip in such a spinal implant. In this regard, the details of the exemplary embodiments described above should not be considered as limiting the present invention. Instead, the features of the above description and the following claims may be essential, individually or in combination, for implementing the present invention in its various embodiments.

Claims

1. An instrument set (10, 200) including a tulip (10) and a holding device (200), wherein the tulip (10) extends along its longitudinal axis (X) and forms part of a spinal implant (100), the spinal implant (100) includes pedicle screws (30), and the tulip (10) serves to connect a connecting rod along the transverse axis (Q) of the tulip, and the holding device (200) temporarily holds the tulip (10) during an implantation process in a holding state of the instrument set, and a transition of the tulip (10) and the holding device (200) from the holding state to a release state and a transition from the release state to the holding state involve a rotational movement about an axis (A). In the instrument set (10, 200), the axis (A) mainly extends in a direction transverse to the longitudinal axis (X) of the tulip and parallel to the transverse axis (Q) of the tulip, characterized by the instrument set (10, 200).

2. During the transition, there is a shift between an anti-rotation lock (12, 212) that acts radially on the tulip with respect to the longitudinal axis (X) of the tulip and prevents rotation of the holding device (200) with respect to the tulip (10) centered on the longitudinal axis (X), and a rotation lock (18, 218) that blocks the radial outward rotational movement of the tulip with respect to the longitudinal axis of the tulip. The instrument set according to claim 1

3. The transition includes at least near the holding state a translational axial movement between the tulip and the holding device along the longitudinal axis of the tulip. The instrument set according to claim 1 or 2

4. The rotational movement and the axial movement at least temporarily overlap during the transition. The instrument set according to claim 3

5. A tulip for the instrument set according to any one of the preceding claims

6. The tulip according to claim 5, including at least four coupling regions (12, 18) arranged at azimuthal intervals with respect to each other on the tulip side for coupling the holding device in the holding state

7. The coupling region forms the anti-rotation lock and has a notch, particularly a concave base (120), for preventing rotation of the instrument centered on the longitudinal axis. The tulip according to claim 6

8. The coupling region includes a lower axial passage portion (18) adjacent to the azimuth notch, and the lower axial passage portion (18) forms the rotation lock region of the rotation lock on the tulip side. The tulip according to claim 6 or 7.

9. Including a plurality of upper axial passage portions (18) opening on the upper distal axial side of the side wall of the tulip, and the plurality of upper axial passage portions (18) communicate with the lower passage portion, and in particular, it is preferably aligned with the lower passage portion. The tulip according to any one of claims 5 to 8.

10. The side wall (122) of the azimuth notch facing the distal axial end of the tulip is located substantially in a radial plane, and in particular at the same axial height. The tulip according to any one of claims 7 to 9.

11. The side wall (121) of the azimuth notch facing the proximal axial end of the tulip is formed as an inclined surface. The tulip according to any one of claims 7 to 10.

12. Including a raised region formed in the azimuth direction between two azimuth notches formed on one side wall of the tulip, and in particular having an azimuth dimension that decreases radially outward. The tulip according to any one of claims 6 to 11.

13. A manufacturing method of the formed tulip according to any one of claims 5 to 12, wherein the lower axial passage portion is formed after the upper passage portion is formed, and the lower passage portion is in particular before the azimuth notch is formed, and in particular before the side wall of the tulip is formed by removing the material region located between the side walls. A manufacturing method that is preferably formed.

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