Surgical Instrument

Abstract

Surgical instrument (2) with a tulip (10) for receiving a pedicle screw (7), wherein the tulip has a pressure ring (19, 22, 28) and / or at least a guide element, a tulip extension (9) and an extension stem (8) wherein the pressure ring (19, 22, 28) and / or the at least one guide element is arranged on the tulip (10) in a replaceable and / or rotatable and / or displaceable and / or modifiable manner, wherein the tulip extension (9) is connected to the tulip (10) via a predetermined breaking point (13), wherein the tulip extension (9) has a connecting thread (14) on an outer side at a rear area and includes an internal thread (15) on its inner side, and wherein the extension shaft (8) has at least partially an extension thread in its front area, wherein the connecting thread (14) is suitable to enter into operative connection with the extension thread, characterized by the fact that The connecting thread (14) is a left-hand thread and the internal thread (15) is a right-hand thread.

Description

TECHNICAL AREA

[0001] The invention relates to a surgical instrument according to the features of the preamble of claim 1. STATE OF THE ART

[0002] The indications for spinal fusion (fusion) of the entire spine or adjacent vertebrae are very diverse. Stabilization procedures are performed, for example, in cases of degenerative spinal changes, after tumor removal, infections, or trauma.

[0003] To stabilize the spine, combinations of dorsal systems (e.g. rod-pedicle screw systems) are often used in combination with one or more cages for ventral support.

[0004] The following are known as prior art in this regard: US 2008 / 0 082 103 A1, US 2007 / 0 161 996 A1, US 2009 / 0 299 415 A1, WO 2006 / 005 198 A1 and US 7 179 261 B2.

[0005] Biomechanics tells us that the spine, as a load-bearing unit, can be compared to the statics of a crane. The anterior column, consisting of vertebral bodies and intervertebral discs, bears approximately 80% of the load, while the dorsal structures bear approximately 20%. From this, it can be deduced that in the lumbar spine, the anterior portion is primarily subjected to compressive forces, and the dorsal portion primarily to tensile forces. In addition, shear, torsional, and flexion forces act on both columns.

[0006] While the aforementioned screw / rod systems can be used in the dorsal area, a cage or an implant is used for ventral support.

[0007] The goal of stabilizing the vertebral bodies is rapid ossification of the intervertebral space in order to achieve lasting pain relief for the patient.

[0008] Examples of indications for spinal fusion include: unstable vertebral fractures, degenerative instabilities, fractures with sufficient anterior support, dislocations, spinal tumors (without anterior defects), and failed previous fusion (pseudoarthrosis).

[0009] Depending on the indication, surgical techniques are performed either as open or minimally invasive procedures. These methods are generally distinguished by the size and type of access point(s).

[0010] Access to the affected region can be achieved through a combination of ventral and dorsal approaches (in the cervical spine, sometimes purely ventral) or via a dorsal, dorsolateral, or lateral approach.

[0011] Depending on the existing structures and their dimensions, an implant of the correct size is selected. Generally, the size is chosen so that the screw extends into the anterior third of the vertebral body.

[0012] Pedicle screws are screwed through the pedicle into the vertebral body. For safe navigation and guidance, some screws are cannulated and can therefore be inserted using a guide wire. Some have additional transverse holes in the threaded portion for subsequent cementation.

[0013] A rod is inserted into the head of the screw, also called the "tulip," which connects two or more pedicle screws. The tulip can be rigid or movable in one or more directions to facilitate the subsequent insertion of the rod.

[0014] After the rod is inserted on both sides, the vertebral bodies to be fixed are pushed apart using different spreading systems, usually via the pedicle screws, in order to achieve the optimal distance between the vertebral bodies.

[0015] Multidirectional mobility of the tulip can be a hindrance when it comes to straightening vertebrae or reconstructing physiological alignment (mainly in trauma surgery).

[0016] Minimally invasive procedures require an extension of the tulip to allow for the extracorporeal, percutaneous insertion of the rod.

[0017] Depending on the surgical technique, different screw shapes and the corresponding instrument sets from one manufacturer are used.

[0018] Unfortunately, these consist of a variety of instruments, meaning that only experienced surgeons and surgical assistants can use this instrument set without the help of product managers from the manufacturers. TASK OF INVENTION

[0019] The object of the invention is to provide an improved surgical instrument that eliminates the aforementioned disadvantages. SOLUTION TO THE TASK

[0020] The features of claim 1 lead to the solution of the problem.

[0021] A surgical instrument comprises a tulip-shaped head, the tulip having a pressure ring and / or a guide element for receiving a pedicle screw. Preferably, the pressure ring is arranged on the tulip in a replaceable manner.

[0022] In typical embodiments, the guide element(s) is / are formed in one piece on the pressure ring.

[0023] In typical embodiments, the guide element(s) is / are a separate component. Advantageously, one or more pressure rings are used in combination with one or more guide elements, which are / are a separate component.

[0024] Preferably, the pressure ring and / or the guide element are each formed as a single piece. This means that the pressure ring is designed as one component and / or the guide element is also designed as one component.

[0025] In alternative embodiments, the pressure ring and / or the guide element is multi-part. This means that the pressure ring is composed of several individual parts and / or the guide element is also composed of several individual parts. This offers the advantage that the guide elements or the pressure ring can be inserted through recesses / holes in the tulip. This allows the pressure ring and / or the guide element to be easily installed and replaced. For example, the pressure ring may have an inner and / or an outer ring.

[0026] In typical embodiments, the pressure ring and / or the guide element is rotatable and / or displaceable. Preferably, the pressure ring is designed such that its guiding properties are changed by altering its position. Particularly preferably, the pressure ring has one or more guide elements that can engage with a screw head depending on the position of the pressure ring. This allows for different movements of the screw head or screw depending on the position of the pressure ring.

[0027] Advantageously, the pressure ring and / or the guide element has a shaft. Preferably, the shaft is connected to the pressure ring and / or the guide element via a predetermined breaking point, so that the shaft can be broken off. This offers the advantage that the pressure ring and / or the guide element can be easily rotated, moved, and / or replaced.

[0028] Advantageously, the pressure ring has a first guide element, the guide element of which allows a monoaxial relative movement of the pedicle screw to the tulip.

[0029] Preferably, the pressure ring has a second guide element that allows polyaxial relative movement of the pedicle screw to the tulip.

[0030] In typical embodiments, the pressure ring includes a third guide element that rigidly fixes the tulip to the pedicle screw.

[0031] In typical embodiments, the pressure ring and / or the guide element are integrally connected to the tulip. This offers the advantage that no additional components are required.

[0032] Preferably, the guide elements are connected to the tulip and / or the pressure ring via a predetermined breaking point. This offers the advantage that unneeded guide elements can be broken out. This also makes a pressure ring and / or a tulip suitable for rigid, monoaxial, and polyaxial support of the pedicle screw. The unneeded guide elements can then be separated at the predetermined breaking points.

[0033] According to the invention, the surgical instrument has a tulip-shaped extension suitable for connection to the extension shaft. The design of the extension shaft, the tulip extension, and the tulip itself is particularly preferred, as it is always identical. This offers the advantage that the pedicle screw and the tulip, along with its extension shaft, can be easily interchanged. This allows the surgeon to always work with their familiar instrument, extension shaft, and / or handle.

[0034] According to the invention, the tulip extension is connected to the tulip via a predetermined breaking point. This offers the advantage that the tulip can be easily separated from the extension stem via the extension. It is also conceivable to manufacture the tulip, the extension, and the extension stem as a single piece.

[0035] According to the invention, the extension shaft has an extension coil at least partially in its front area.

[0036] According to the invention, the tulip extension comprises a connecting thread, at least in its rear region. According to the invention, the connecting thread is suitable for engaging with the extension thread of the extension shaft. This offers the advantage that the extension shaft and the tulip extension can be easily connected to one another. Advantageously, the connecting or extension thread is preferably designed opposite to the direction of rotation of the pedicle screw thread.

[0037] The tulip extension and the extension shaft are not part of the invention and are formed in one piece. According to the invention, the tulip extension is connected via a predetermined breaking point.

[0038] The tulip, the tulip extension, and the extension shaft are not part of the invention and are formed in one piece. Preferably, the tulip, the tulip extension, and the extension shaft are connected via predetermined breaking points.

[0039] In alternative components, the tulip, the tulip extension and the extension shaft are individual parts that are connected to each other via threads, plugging, snapping and / or gluing.

[0040] In the typical embodiment, the extension shaft is hollow. This offers the advantage that the extension shaft is suitable for inserting the rod, a screwdriver, an initiator, a guide wire, and for introducing cement.

[0041] Preferably, the screwdriver and / or the pedicle screw is cannulated. This offers the advantage that the components are suitable for inserting the guide wire and / or cement. Additionally, the cannulation of the pedicle screw can incorporate, for example, an internal thread or a coupling-like device suitable for attaching an instrument or cartridge for cementation.

[0042] The pedicle screw can also be tightened using the extension shaft and, for example, a counter-holder, thus eliminating the need for a screwdriver. For this, the pedicle screw only needs to be clamped in, for example, the tulip-shaped socket; this can be done with a simpler, less expensive instrument such as a cannulated screwdriver.

[0043] According to the invention, the tulip extension has an internal thread. In typical embodiments, the surgical instrument includes an Ini. Preferably, the Ini has a large adjustment range. This offers the advantage that adjustment is possible via only one Ini drive and / or a T-handle without additional instruments.

[0044] Advantageously, the extension shaft and / or the tulip extension includes an outer cone. Preferably, the snap-off tool includes an inner ring. Particularly preferably, the inner ring is designed as a cone. This offers the advantage that the extension shaft can also be used for the "snap-off" operation. When a snap-off tool is placed on the extension shaft and pressed down, for example, by a lever (not shown), the extension shaft snaps inwards at the predetermined breaking point on the tulip. Snapping can also occur laterally or outwards.

[0045] Separately, protection is claimed for a pedicle screw for a surgical instrument, wherein the pedicle screw has a single screw head which can be brought into operative contact with a first guide element and / or the second guide element and / or the third guide element of the pressure rings.

[0046] This offers the advantage that the same instrumentation set can be used to select whether no movement, monoaxial movement, or polyaxial movement should be permitted between the tulip and the pedicle screw; only the pressure ring needs to be changed accordingly. The pressure ring is replaceable on the tulip.

[0047] Preferably, the pedicle screw is cannulated. Particularly preferably, the pedicle screw includes a self-drilling tip suitable for opening the pedicle. Particularly preferably, the pedicle screw has a self-tapping thread. Even more preferably, the pedicle screw has a partially cylindrical and / or partially conical threaded section, so that several thread diameters can be achieved, which are connected to each other, for example, via conical transitions.

[0048] The invention is particularly advantageous in that all pedicle screws have a characteristic multifunctional extension shaft with the same tulip design, tulip extensions and extension shafts.

[0049] Preferably, pedicle screws are manufactured in various diameters of approximately 5 mm, 6 mm, and 7 mm, with lengths ranging from 30 mm to 70 mm. Tulips in polyaxial, monoaxial, or rigid configurations can be combined with the pedicle screws. Preferably, all pedicle screws are cannulated, self-tapping, and / or, in the 6 mm and 7 mm diameters, cementable.

[0050] Preferably, the extension shaft serves as a guide for the rod and rod insertion, and at the same time holds the closure (Ini) for the rod pre-assembled.

[0051] All work steps, such as screwing in the pedicle screws, measuring the rod length, cementing if necessary, inserting the rod, distraction and compression, straightening the vertebral bodies to reconstruct the physiological alignment and fixing the rod with the Ini, take place via the extension shaft.

[0052] Once all rods are fixed in the tulip, the rod inserter is decoupled from the rod; now the extension shaft can be separated from the tulip extracorporeally using the SnapOff technique, i.e., the tulip extension, with an instrument, without burrs.

[0053] All pedicle screws can preferably be offered with integrated initiator and drill wire, and especially preferably individually and sterilely packaged.

[0054] Preferably, a small, clearly arranged instrument set according to the invention, which is the same for all surgical techniques, comprises a drill wire, measuring instruments for the screw length via the drill wire, a combination instrument tap / pedicle opener, a screwdriver / drive for the initial insertion, a screwdriver / drive for the pedicle screw, a T-handle with ratchet and integrated torque limiter, a tulip / extension shaft snap-off tool, a counterholder and / or an instrument for distraction and compression with rod length measurement.

[0055] In typical embodiments, the predetermined breaking point is designed as a ring, in two parts, or in multiple parts. A multi-part predetermined breaking point typically results from interruptions, for example, by openings for inserting or removing the rod. A multi-part design of the predetermined breaking point can also make it easier to separate.

[0056] Titanium Grade 5 is the preferred material for the pedicle screw, pressure ring, tulip, tulip extension and the Ini.

[0057] The preferred material for the extension shaft is stainless steel tubing. According to the invention, the extension shaft can be screwed to the tulip extension via a left-hand thread, providing a positive connection. Other connection methods include soldering, gluing, welding, and push-fit fitting.

[0058] The use of the surgical instrument according to the invention offers the surgeon significant advantages: pre-assembled implants with Ini can be used, the extension shaft is multifunctional as all work steps are performed via it, and the system can be cemented for open and minimally invasive surgical techniques. A single, streamlined instrument is provided for all surgical methods. All products look and operate identically for monoaxial, polyaxial, and rigid pedicle screws. This minimizes potential errors, and even inexperienced surgeons can achieve a rapid learning curve with this surgical instrument.

[0059] Preferably, the surgical instrument is offered in sterile individual packaging. The thread of the pedicle screw is particularly preferred, designed to achieve maximum compression.

[0060] In typical embodiments not shown in detail, the tulip includes molded pockets or the screw head, so that the pressure rings can be switched or rotated, moved and inserted from the outside and inside, so that the desired permissible relative movement between the tulip and the screw head can be set with a pressure ring before sterile packaging, before or during the operation.

[0061] All possible elements that offer the degrees of freedom for rigid, monoaxially movable or polyaxially movable are permissible as guide elements between the pressure ring and the screw head.

[0062] A compression ring can, for example, consist of a combination of two compression rings, or a compression ring or compression rings with another part, whereby the inner or outer compression ring can be exchanged or selected as needed before sterile packaging, before or during surgery to achieve a different screw axiality.

[0063] The guide elements and pressure rings can also be equipped with a breakable shaft with a snap-off break-off point, like the tulip, for easy changing, twisting, moving, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The invention is briefly described below with reference to the accompanying figures, which show: Fig. Figure 1 shows a schematic representation of a set with a surgical instrument according to the invention in an implantation situation; Fig. Figure 2 shows a cross-sectional view of a surgical instrument according to the invention; Fig. Figure 3 shows a side view of the surgical instrument according to the invention, in which the instrument is separated at the predetermined breaking point; Fig. Figure 4 shows a schematic representation of an enlarged, cut section of the instrument according to the invention; The Fig. Figures 5 to 7 show different embodiments of a pressure ring for a surgical instrument according to the invention; Fig. Figure 8 shows a schematic representation of a perspective view of a pedicle screw for a surgical instrument according to the invention; Fig. Figure 9 shows an enlarged perspective view of a pedicle screw head; Fig. Figure 10 shows an enlarged, sectioned view of a surgical instrument according to the invention. Fig. 1. EXAMPLE OF EXECUTION

[0065] Fig. Figure 1 shows a rod-pedicle screw system for stabilizing the spine. This system comprises a rod 1, three screw units 2 as a surgical instrument according to the invention, a screwdriver 3 for insertion, a collet 4, a T-handle 5 with torque limiter, and a snap-off sleeve 6, which is only partially shown.

[0066] In Fig. Figure 1 also shows a screwdriver 3.1 for a pedicle screw.

[0067] Fig. Figure 2 shows an enlarged sectional view of the screw unit 2. The screw unit 2 comprises a pedicle screw 7 and an extension shaft 8, a tulip extension 9 and a tulip 10.

[0068] The extension shaft 8, the tulip extension 9, the tulip 10, and the pedicle screw 7 are cannulated. A guide wire 11 is integrated into the components. In its upper region, the extension shaft 8 includes an opening 12, particularly suitable for counter-holding.

[0069] The tulip extension 9 and the tulip 10 are connected via a predetermined breaking point 13. Fig. Figure 3 shows the screw unit 2, in which the tulip extension 9 and the tulip 10 are separated at the predetermined breaking point 13.

[0070] Fig. Figure 4 shows an enlarged sectional view of the tulip extension 9 with the tulip 10, which are connected at the predetermined breaking point 13. The tulip extension 9 has a connecting thread 14 on one outer side at a rear area. Furthermore, the tulip extension 9 has an internal thread 15 on its inner side. The connecting thread 14 is a left-hand thread. The internal thread 15 is a right-hand thread.

[0071] The internal thread 15 extends to an upper area of ​​the inside of the tulip 10.

[0072] The tulip 10 has two retaining lugs 16 and 17 on each inner side, approximately at mid-height. An elongated hole 18 is provided in the tulip extension 9 and the tulip 10, suitable for receiving the rod 1.

[0073] Fig. Figure 5 shows a first embodiment of a pressure ring 18. The pressure ring 18 has a hemispherical inner surface with an opening 20. The pressure ring 18 is suitable for rigidly holding one of the pedicle screws 7. For this purpose, the pressure ring 18 has a circumferential groove 20 on its inner surface as a guide element. To secure the pressure ring 18 in the tulip 10, the pressure ring 18 includes a recess 21 into which the retaining lug 16 of the tulip 10 fits as shown in Figure 5. Fig. 4 shown, can be grasped. Opposite the recess 21, the pressure ring 19 includes another recess, not shown, which can be brought into operative contact with the retaining lug 17.

[0074] Fig. Figure 6 shows a further embodiment of a pressure ring 22, suitable for monoaxially holding the pedicle screw 7. The pressure ring 22 is essentially analogous to the pressure ring 19. The pressure ring 19 has a hemispherical inner surface with an opening 20. The pressure ring 22 differs from the pressure ring 19 in the design of the guide element. As a guide element, the pressure ring 22 has a first web 23 and a second web 24. The webs 23 and 24 are arranged essentially symmetrically to each other. The web 23 has a semicircular arc shape. The web 23 is attached to an inner surface of the pressure ring such that the ends of the semicircular arc 26 and 27 terminate at an edge 25 of the pressure ring. This edge 25 is the edge that faces the pedicle screw 7 when the screw unit 2 is mounted.

[0075] Fig. Figure 7 shows a further embodiment of a pressure ring 28. The pressure ring 28 is essentially designed analogously to the pressure rings of the preceding embodiments and differs in its guide element. The pressure ring 28 allows polyaxial relative movement of the pedicle screw 7 to the tulip 10. For this purpose, an inner surface 29 of the pressure ring 28 is designed as a half-shell 29. An upwardly directed opening 30 is provided in the half-shell 29.

[0076] The opening 30 in the half-shell 29 serves to provide an internal polygon 31 for a screw head 32 of the pedicle screw 7, as shown in Fig. 9 shown.

[0077] As shown in the enlarged view in Fig. As can be seen from the screw head 32, the screw head 32 also has guide elements that interact with the pressure rings 19, 22 and 28.

[0078] A pedicle screw 7 with a screw head 32 of the same design can be used for all pressure rings 19, 22 and 28. The screw head 32 is spherically shaped so that it can interact with the hemispherical inner surface 29 of the pressure rings 19, 22 or 28 in the manner of a ball joint.

[0079] Furthermore, the screw head 32 comprises two grooves 33 and 34. The grooves 33 and 34 are formed as recesses on the screw head 32. The grooves 33 and 34 are essentially symmetrical to each other. The grooves 33 and 34 extend as semicircular arcs in the lateral regions of the spherical screw head 32. The grooves 33 and 34 are arranged such that they run on the webs 23 and 24 of the pressure ring 22, thereby allowing uniaxial movement.

[0080] The pedicle screw 7 has a thread on its pedicle screw shaft 35. The thread is preferably double-start, self-drilling and / or self-tapping.

[0081] In particular, a tip 36 of the pedicle screw shank 35 is designed to be self-tapping and self-drilling. Furthermore, the pedicle screw shank 35 is preferably conical, such that the pedicle screw shank 35 has a smaller diameter in a front region of the tip 36 than in a rear region near the screw head 32.

[0082] Preferably, the pedicle screw 7 is cantilevered, as for example in Fig. 2. This offers the advantage that, for example, the guide wire 11 can be inserted through the pedicle screw 7, and the pedicle screw 7 is also suitable for the injection of cement. Preferably, the pedicle screw 7 comprises through-holes in its pedicle screw shaft 35, through which the cement injected into the cannula of the pedicle screw 7 can flow outwards into the vertebral body and bond with it.

[0083] The Fig. Figure 10 shows a cutaway and enlarged view of the screw unit 2 with a part of the rod 1 after the Fig. 1. It can be seen that the pedicle screw 7 with the pedicle screw head 32 is received in the tulip 10. One of the pressure rings 19, 22 or 28 is inserted into the tulip 10 and allows the desired movement of the pedicle screw 7.

[0084] The functioning of the present invention is as follows: Depending on the indication, the screw elements 2 can be inserted using open or minimally invasive techniques. After determining the implant dimensions, the correct position for the pedicle screw 7 is determined, preferably under radiographic guidance, using a Jamshidi needle or the guide wire 11.

[0085] The guide wire 11 and / or a gantry are then inserted. To check the pedicle screw length, the screw length can be determined or compared using other measuring instruments (not shown) via the drill wire 11.

[0086] The opening of the pedicle and the thread cutting are preferably carried out directly with the self-tapping thread of the pedicle screw 7 on the pedicle screw shaft 35. The cannulated pedicle screw 7 has the internal polygon 31 in the screw head 32, preferably Torx-like, and is securely guided through the pedicle into the vertebral body via the guide wire 11 and screwed in.

[0087] In cases of brittle, hard bones or osteogenesis imperfecta, opening the pedicle and cutting the threads should be performed using a combination instrument. It is preferable to use different types of taps.

[0088] In cases of insufficient compression or osteoporotic vertebral bodies, cement can be injected through the cannulated pedicle screw 7 after insertion.

[0089] During percutaneous insertion of the rod 1, the rod 1 is inserted from above through the extension shaft 8 and exited from one side through the elongated hole 18 in the tulip extension 9 or the tulip 10, and guided through the vertebral body. This allows two or more vertebral bodies to be connected with a single rod 1 up to a length of approximately 120 mm.

[0090] The necessary distraction or compression, as well as straightening of the vertebral bodies, is now performed extracorporeally via the extension shaft 8 in order to reconstruct a physiological alignment.

[0091] Distraction or compression is achieved via an instrument adjustable along the extension shaft 8. This instrument is also used to determine the length of the rod 1.

[0092] A necessary straightening of vertebral bodies is preferably carried out only via the pre-assembled Ini with large adjustment range and only with an Ini drive 3 and the T-handle 5 without any further additional instruments.

[0093] Once all rods in the tulips 10 of the screw units 2 are fixed and tightened to the specified torque, the extension shaft 8 can be cut off burr-free at the predetermined breaking point 13, the so-called snap-off connection, using an instrument (not shown). Alternatively, the snap-off sleeve 6 can be used.

[0094] In further embodiments, a tulip extension shaft break-off tool is used extracorporeally.

[0095] To tighten the Ini to the required torque, a counterhold (not shown) can be attached to the extension shaft 8 extracorporeally. The extension shaft 8 has the opening 12 for this purpose.

[0096] The extension shaft 8 has an outer cone above the predetermined breaking point 13 on the tulip extension 9, and the breaking tool has an inner ring, preferably conical in shape. When the breaking tool is placed on the extension shaft 8 and pressed down, for example, by means of a lever (not shown), the extension shaft 8 breaks off inwards at the predetermined breaking point 13 on the tulip 10. However, the tulip 10 can also break off outwards or laterally. For this purpose, an instrument that partially cuts or slices off at the predetermined breaking point 13 can be used.

[0097] Once the rods 1 are tightened to torque, the rod inserter can also be decoupled from the rod and removed from the body. Reference symbol list 1 rod 2 screw unit 3 screwdrivers 4 collet 5 T-handle 6 Snap-off sleeve 7 Pedicle screw 8 Extension shaft 9 Tulip Extension 10 Tulips 11 Guide wire 12 Opening 13 Breakaway point 14 connecting threads 15 internal threads 16 Retaining nose 17 Retaining nose 18 elongated holes 19 Pressure ring 20 Nut 21 In-depth study 22 Pressure ring 23 First jetty 24 Second Pier 25 edge 26 End of arc 27 End of arc 28 Pressure ring 29 half-shell 30 Opening 31 Internal polygon 32 screw head 33 groove 34 groove 35 Pedicle screw shaft

Claims

[1] Surgical instrument (2) with a tulip (10) for receiving a pedicle screw (7), wherein the tulip has a pressure ring (19, 22, 28) and / or at least a guide element, a tulip extension (9) and an extension stem (8) wherein the pressure ring (19, 22, 28) and / or the at least one guide element is arranged on the tulip (10) in a replaceable and / or rotatable and / or displaceable and / or modifiable manner, wherein the tulip extension (9) is connected to the tulip (10) via a predetermined breaking point (13), wherein the tulip extension (9) has a connecting thread (14) on an outer side at a rear area and includes an internal thread (15) on its inner side, and wherein the extension shaft (8) has at least partially an extension thread in its front area, wherein the connecting thread (14) is suitable to enter into operative connection with the extension thread, characterized by , that The connecting thread (14) is a left-hand thread and the internal thread (15) is a right-hand thread. [2] Surgical instrument according to claim 1, characterized by , that a slot (18) suitable for receiving a rod (1) is provided in the tulip extension (9) and the tulip (10). [3] Surgical instrument according to any of the preceding claims, characterized by , that the pressure ring (19, 22, 28) and / or the guide element is designed in multiple parts. [4] Surgical instrument according to any of the preceding claims, characterized by , that the pedicle screw (7) is interchangeably arranged on the pressure ring (19, 22, 28) and / or the guide element. [5] Surgical instrument according to any one of claims 1 to 4, characterized by, that the pressure ring (19, 22, 28) has a first guide element (23, 24) wherein the guide element (23, 24) allows a monoaxial relative movement of the pedicle screw (7) to the tulip (10). [6] Surgical instrument according to any of the preceding claims, characterized by that the pressure ring (19, 22, 28) has a second guide element (29) which allows a polyaxial relative movement of the pedicle screw (7) to the tulip (10). [7] Surgical instrument according to any of the preceding claims, characterized by , that the pressure ring (19, 22, 28) has a third guide element (20) that rigidly fixes the tulip (10) to the pedicle screw (7). [8] Surgical instrument according to any of the preceding claims, characterized by , that the surgical instrument includes a pedicle screw (7). [9] Surgical instrument according to claim 8, characterized by , that the pedicle screw (7) is cannulated. [10] Surgical instrument according to any of the preceding claims, characterized by , that the extension shaft (8) is hollow. [11] Surgical instrument according to any of the preceding claims characterized by , that the extension shaft (8) is a distraction and / or compression device. [12] Surgical instrument according to any of the preceding claims, characterized by , that an Ini, especially one with a large adjustment range, is pre-assembled. [13] Surgical instrument according to any of the preceding claims, characterized by that the extension shaft and / or the tulip extension has an outer cone and the breaking tool has an inner ring, which is preferably conical in shape.

Images