Spinal milling cutter, spinal milling cutter system, and method for working on bone structures in the region of the vertebral column

Abstract

The invention relates to a spinal milling cutter for working on bone structures in the region of the vertebral column, the distal end face of which spinal milling cutter is provided with a milling cutter toothing having a tooth profile with at least two teeth. The spinal milling cutter has an axial passage for receiving a further spinal milling cutter. The invention further relates to a vertebral column system having the spinal milling cutter according to the invention and having a further spinal milling cutter, and to a method for working on bone structures in the region of the vertebral column by means of the spinal milling cutter according to the invention.

Description

[0001]Spinal reamer, spinal reamer system, and method for machining bone structures in the spinal region. The invention relates to a spinal reamer, a spinal reamer system with the spinal reamer, and a method for machining bone structures in the spinal region at a site of use using the spinal reamer. Spinal reamers are known from the prior art that have a distal end face with a cutting edge for machining bone structures in the spinal region, thus creating access through the bone structure of a vertebra to an intervertebral disc space. However, with the known spinal reamers, bone structures in the spinal region can only be machined with a constant diameter, which usually corresponds to the outer diameter of the spinal reamer. If a change in the machining diameter, in particular an increase in it, is desired,The spinal reamer initially used must be laboriously removed from the site of use and replaced with another spinal reamer with a larger machining diameter. @T15aA@ This considerably lengthens the procedure time and significantly increases the risk of complications. Therefore, the object of the invention is to propose a spinal reamer that enables more flexible, safer, and faster machining of the bone structures in the spinal region. The object of the invention is achieved by a spinal reamer with the features of claim 1. This comprises a spinal reamer for machining bone structures in the spinal region, with a distal end face provided with a milling cutter toothing with a toothing profile with at least two teeth.wherein the spinal reamer has an axial opening for receiving a further spinal reamer. The object of the invention is further achieved by a spinal reamer system according to claim 16. The spinal reamer system according to the invention has a first spinal reamer according to the invention and a second spinal reamer, which can be received as a further spinal reamer in the axial opening of the first spinal reamer and which has a distal end face with a reamer toothing with a toothing profile. Furthermore, the object of the invention is achieved by a method according to claim 26. This method is a method for machining bone structures in the region of the spine at a site of use using a first spinal reamer according to the invention, in particular using the spinal reamer system according to the invention.and comprises the following steps: − Inserting the first spinal reamer with a further spinal reamer received in the axial opening of the first spinal reamer along a guide means to the site of use, wherein the guide means is arranged within the axial opening of the first spinal reamer, in particular within the axial opening of the further spinal reamer, − Rotating the first spinal reamer together with the further spinal reamer such that the bone structure at the site of use is machined along a predefined path, − Removing the further spinal reamer from the site of use, − Rotating the first spinal reamer such thatthat the desired processing of the bone structure takes place at the site of use and − removing the first spinal reamer from the site of use. In the sense of the invention, a distal direction points to the site of use and a proximal direction to the surgeon or user of the spinal reamer according to the invention. Based on a three-dimensional cylindrical coordinate system, an axial direction parallel to the direction of extension of the spinal reamer and a radial direction from the axis of extension of the spinal reamer perpendicular to this outwards or from the outside perpendicular to this. A direction along the circumference is oriented perpendicular to an axial and a radial direction. The invention is based on the fundamental idea that the axial breakthrough of the spinal reamer creates a structurally particularly simple possibility,to accommodate an additional spinal reamer. Particularly during a procedure, the additional spinal reamer can be guided through the axial opening of the outer spinal reamer according to the invention, so that, due to the comparatively smaller outer diameter of the additional spinal reamer, further, particularly more precise, processing of the bone structure in the spinal region can be carried out almost seamlessly, at least without the external spinal reamer according to the invention having to be laboriously removed from the site of use. This simplifies and accelerates the procedure, reduces the risk of complications, and also allows for greater flexibility in processing the bone structure. The invention also makes it possible to initially perform an initial processing of the bone structure in the spinal region using the additional spinal reamer.which is at least partially received in the axial opening of the spinal reamer according to the invention and which has a comparatively smaller machining diameter, thus reducing the risk of unwanted tissue damage. The additional spinal reamer is securely guided by the surrounding spinal reamer according to the invention. Simultaneously with the use of the additional spinal reamer or immediately thereafter, the bone structure can be machined using the first spinal reamer according to the invention with a comparatively larger machining diameter.without the additional spinal reamer having to be removed from the site of use, which is laborious and fraught with complications. The invention therefore enables, in particular, a safer enlargement of the machining diameter during the procedure. Due to the milling cutter teeth formed on the distal end face of the spinal reamer, the machining of the bone structure is carried out in a controlled and safe manner, essentially via the distal end face. The spinal reamer according to the invention is particularly designed to machine bone structures,so that the spinal reamer can mill axially into the bone structure at the site of use. The spinal reamer according to the invention can remain in a user-defined position on the bone structure after machining, thus providing a certain degree of support. The additional bone reamer can then be pushed through the axial opening of the spinal reamer according to the invention and subsequently inserted as intended, such that the additional spinal reamer, at least partially within the spinal reamer according to the invention, continues machining the bone structure, with this subsequent machining taking place with a smaller machining diameter due to its design. In this way, the spinal reamer according to the invention serves as a kind of protective cover and guide for the additional spinal reamer.so that the risk of injury to nerves and soft tissue structures located near the site of use by the additional spinal reamer, primarily due to its teeth, which may in particular have a sharp cutting edge, is eliminated. On the other hand, as already described, the bone structure in the spinal region can first be machined using the additional spinal reamer, which is accommodated within the axial opening of the first spinal reamer; the first spinal reamer serves as a guide for the additional spinal reamer. After machining the bone structure using the additional spinal reamer, further machining of the bone structure can be performed using the first spinal reamer, which, along the additional spinal reamer,can be pushed to the site of use. This allows for a safer increase in the machining diameter. Furthermore, the risk of injury to nerves and soft tissue structures located near the site of use due to the first spinal reamer slipping is reduced. The spinal reamer according to the invention is preferably designed so that the machining of the bone structure takes place when the spinal reamer rotates about its axis of extension. The axis of extension of the spinal reamer is preferably arranged within the axial opening. The axial opening can extend over the entire length of the spinal reamer.The axial opening can also be referred to as a lumen or cannulation. In an advantageous embodiment of the invention, the spinal reamer is essentially cylindrical. The spinal reamer according to the invention can have an outer diameter between 4 mm and 9 mm, preferably between 7 mm and 8 mm, for example, approximately 7.3 mm. The spinal reamer according to the invention can have a working length between 150 mm and 350 mm, preferably between 220 mm and 250 mm, for example, approximately 235 mm. Preferably, the tooth profile of the spinal reamer is designed, at least in sections, as a cutting edge in order to improve the processing of the bone structure. Preferred developments of the spinal reamer providethat outer edges of the at least one tooth lie on an outer diameter of the distal end face of the spinal reamer and / or that one edge of the at least one tooth tapers axially parallel to the distal end face of the spinal reamer. Preferably, the distal end face of the spinal reamer has a rounded portion, in particular a convex portion, to avoid injury to nerves and soft tissue structures located in the vicinity of the site of use. In this respect, the rounded portion can be designed to be atraumatic. Further developments of the invention provide for the distal end face to have a concave rounded portion to ensure the cutting ability of the spinal reamer, in particular across its entire distal end face. In this way, the additional spinal reamer, which can be accommodated in the axial opening of the spinal reamer according to the invention, can alsoPreferably, at least one tooth of the toothing profile is oriented distally and / or radially. Particularly preferably, all teeth of the toothing profile are oriented distally and / or radially. Radially oriented teeth, when using the spinal reamer, primarily result in machining of the bone structure via the outer surface of the spinal reamer, whereas with distally oriented teeth, machining is more likely to occur via the distal end face of the spinal reamer. Further developments of the invention can provide for the spinal reamer to have two toothing profiles, with a first toothing profile having radially oriented teeth and a second toothing profile having distally oriented teeth, in order to combine both of the aforementioned advantages. The toothing profiles can be arranged axially offset from one another. At least one tooth of the toothing profile can be non-mirror-symmetrical.wherein the tooth can in particular have two radial elevations with different radial heights. In particular, it is provided that a stepped transition is formed between the radial elevations of a tooth. In the case of several radial elevations of a tooth, the profile of the tooth can have several steps, thus being designed in a stepped manner. The stepped transition between the radial elevations, in particular in the case of a stepped profile, can improve machining due to the sharp edges of the tooth thus formed. It can be provided that all teeth are not mirror-symmetrical, in particular that all teeth each have two radial elevations with different radial heights. Preferably, it is provided that at least one tooth of the tooth profile has a first flank and a second flank.wherein the pitch of the first flank is greater than the pitch of the second flank. The pitches of the flanks can relate in particular to the axial direction and / or the radial direction. The first flank can thus be arranged in front of or behind the second flank relative to the direction of rotation of the spinal reamer during its intended use. Preferably, two adjacent teeth of the toothing profile are separated from each other by a parabolic recess, so that the reception of machined bone structure and ultimately its removal from the site of use can take place via the recesses of the toothing profile. In an advantageous development of the invention, it can be provided that the spinal reamer has a threaded section proximal to the cutter toothing,to advantageously enable machining of the bone structure via the outer surface of the spinal reamer. Furthermore, drilling of the bone structure can be performed in this way, so that the spinal reamer is also designed as a spinal drill. This provides the further advantage that after the machining process, the spinal drill can be screwed into the bone structure, thus preventing unintentional removal due to proximal tensile forces. Furthermore, the threads of the threaded section allow removal of the machined bone structure. Preferably, the thread of the threaded section is at least partially designed as a cutting thread. The tooth profile preferably extends proximally in such a way thatthat the threaded section is thereby formed. Due to the resulting continuous transition between the tooth profile and the threaded section, both the machining properties of the spinal reamer and the removal of the machined bone structure are improved. The threaded section preferably has an axial length between 10 mm and 90 mm, preferably between 20 mm and 75 mm, most preferably of approximately 60 mm. The threaded section preferably has a thread pitch between 60° and 85°, in particular between 70° and 85°, most preferably between 75° and 80°, for example 75° or 80°. In an advantageous development of the invention, it can be provided that the tooth profile has at least one tooth with a triangular basic shape,The corners can be rounded. The at least one tooth of the toothing profile can be designed with mirror symmetry. In a further development of the invention, it can be provided that the preferably distally pointing tip of the tooth is inclined in and / or against the direction of rotation of the spinal reamer. Advantageously, all teeth of the tooth profile can point distally. Preferably, the distal end face of the spinal reamer has a distal projection, wherein the projection is in particular provided with a further toothing profile in order to improve the machining properties of the spinal reamer in the distal direction by means of its distal end face. The projection can have an axial length of 1 mm to 5 mm, preferably 3 mm. The projection can be arranged radially centered relative to the longitudinal axis of the spinal reamer and / or have an opening.which is designed as part of the axial opening of the spinal reamer. The distal projection can have an elliptical, in particular circular, cross-section, wherein the cross-section of the distal projection is smaller than the outer diameter of the spinal reamer. In particular, if the projection has the further toothing profile, the risk of injury to nerves and surrounding soft tissue that is not to be machined is reduced. The toothing profile of the projection can be designed to be mirror-symmetrical, wherein it is particularly provided that the toothing profile of the projection has teeth each with a triangular basic shape. In a further embodiment, the toothing profile can have non-mirror-symmetrical teeth, wherein it is preferably provided that the teeth have two radial elevations with different radial elevations.between which a stepped transition is formed. Preferably, a proximal end section of the spinal reamer has a connecting piece, which is designed in particular to receive the additional spinal reamer. The connecting piece of the spinal reamer can be designed in particular for a rotationally fixed and / or detachable connection to the additional spinal reamer. Due to the detachable connection, the additional spinal reamer can be easily removed from the spinal reamer according to the invention, for example, as soon as the spinal reamer according to the invention has a secure hold in the bone structure to be treated. In particular, with distally oriented teeth on the distal end face of the additional spinal reamer, the risk of injury to nerves and soft tissue structures located in the vicinity of the site of use is thereby eliminated. In one embodiment of the invention, it can be providedthat the connecting piece serves as a driver for driving the spinal reamer. Preferably, the connecting piece has a triangular basic shape in cross-section. For better connectivity of the spinal reamer according to the invention with the additional spinal reamer, it can be provided that the connecting piece of the spinal reamer according to the invention has an interior space that is designed to complement a connecting piece of the additional spinal reamer.so that a positive connection is achieved between the spinal reamer according to the invention and the further spinal reamer. An inner contour of the connecting piece of the spinal reamer according to the invention can be designed to complement an outer contour of a connecting piece of the further spinal reamer. The spinal reamer system according to the invention can comprise, in addition to the spinal reamer according to the invention and the second spinal reamer, further instruments for machining the spine. Within the meaning of the invention, the second spinal reamer of the spinal reamer system can correspond to the further spinal reamer. The second spinal reamer can have at least one feature,which is mentioned above in connection with the spinal reamer according to the invention. The second spinal reamer can be designed as a spinal reamer according to the invention. The spinal reamer system can comprise at least one of the following instruments: guide wire, guide rod, guide sleeve, awl, dilator, working cannula, protective sleeve, trocar, needle, hollow needle, Jamshidi needle. The spinal reamer system according to the invention can providethat the second spinal reamer is detachably connectable to the first spinal reamer. Preferably, the second spinal reamer is connected to the first spinal reamer, in particular in a rotationally fixed manner. The second spinal reamer can be detachably received in the first spinal reamer. Preferably, the second spinal reamer is received in the axial opening of the first spinal reamer and / or connected to the first spinal reamer. In a further embodiment of the invention, it can be provided that the second spinal reamer can be axially secured to the first spinal reamer. Preferably, the second spinal reamer can be removed proximally from the first spinal reamer. Preferably, the second spinal reamer can be connected to the first spinal reamer in a rotationally fixed manner. The second spinal reamer can be axially secured to the first spinal reamer in a defined position relative to the first spinal reamer.so that the second spinal reamer cannot be accidentally removed from the first spinal reamer. The connection between the first spinal reamer and the second spinal reamer can be designed as an axial lock and / or as a rotation lock. Preferably, the second spinal reamer is designed as a further spinal reamer according to the invention, so that the second spinal reamer also has, in particular, an axial opening for receiving an additional, third spinal reamer. The axial opening of the second spinal reamer can be designed to receive a guide means so that the second spinal reamer can reach the site of use along the guide means. The guide means can be designed as an awl and / or a guide rod and / or a guide wire. In particular, it can be providedthat the distal end face of the second spinal reamer has a rounded portion. In an advantageous development of the invention, it is provided that the rounded portion is concave in order to ensure, particularly in combination with distally oriented teeth of the second spinal reamer, its cutting ability over the entire distal end face. Preferably, the second spinal reamer has a proximal connecting piece, the outer contour of which is designed to be particularly complementary to the inner contour of the connecting piece of the first spinal reamer. A development provides that the connecting piece of the second spinal reamer has a distal connecting piece part,whose outer contour is designed to correspond to the inner contour of the connecting piece of the first spinal reamer. In this way, a structurally simple connection option is provided between the first spinal reamer and the second spinal reamer. In a further embodiment of the invention, it can be provided that the second spinal reamer can be driven in rotation, wherein the first spinal reamer can be rotated in particular synchronously with the second spinal reamer due to a positive connection with the latter. Preferably, a drive unit is provided which is designed to drive the first spinal reamer and / or the second spinal reamer in rotation in order to thereby carry out the desired processing of the bone structure at the site of use. In a further embodiment of the invention,that the spinal reamers are independently rotatable. This is particularly advantageous when the first spinal reamer is primarily used to machine the bone structure at the site of use over a user-defined distance and is then to remain in place with a form-fitting connection to the remaining bone structure. Afterward, the second spinal reamer can be used, with the first spinal reamer not rotating, for further machining of the bone structure, thus avoiding damage to nerve cells and surrounding soft tissue. Preferably, the second spinal reamer has an axial opening, which, in particular, when connected to the first spinal reamer,is arranged concentrically to the axial opening of the first spinal reamer. The diameter of the axial opening of the second spinal reamer can be matched, in particular, with respect to the outer diameter of a guide means, such as an awl, a particularly blunt guide rod, or a guide wire, so that the second spinal reamer, in particular in combination with the first spinal reamer, is provided with safe and reliable guidance to the site of use via the already positioned guide means. The inner diameter of the axial opening of the first spinal reamer can essentially correspond to the outer diameter of the second spinal reamer.so that the machined bone structure is transported out of the application site via the outer surface of the outer spinal reamer, if possible, and in particular does not enter a gap between the first spinal reamer and the second spinal reamer and become lodged there. This reduces the risk of jamming of the spinal reamers. The axial opening of the second spinal reamer can extend over the entire axial length of the second spinal reamer. Preferably, the second spinal reamer has an outer diameter of between 3 mm and 7 mm, in particular approximately 4 mm. The diameter of the axial opening of the second spinal reamer can be between 1 mm and 4 mm, preferably approximately 2.4 mm. The second spinal reamer can have a working length of between 160 mm and 360 mm, in particular between 230 mm and 280 mm.preferably approximately 256 mm. The axial length of the spinal milling cutter system can correspond to the axial length of the second spinal milling cutter. Preferably, at least one tooth of the toothing profile of the second spinal milling cutter has a triangular basic shape, wherein a flank of the tooth can have a pitch of approximately 90°. In a further development of the invention, the tooth of the toothing profile has an undercut. In particular, it is provided that the at least one tooth is inclined in the direction of or counter to the direction of rotation of the spinal milling cutter. Preferably, the toothing profile of the second spinal milling cutter extends proximally in such a way that a threaded portion of the second spinal milling cutter is formed, for example, bythat the tooth profile extends proximally in rotation around the extension axis of the spinal reamer. The threaded portion of the second spinal reamer can have an axial length between 10 mm and 40 mm, in particular approximately 20 mm. In particular, the threaded portion of the second spinal reamer has the same pitch and / or the same direction of rotation as the threaded portion of the first spinal reamer. This allows for a largely seamless transition between the threaded portion of the second spinal reamer and the threaded portion of the first spinal reamer, which in particular facilitates the removal of the machined bone structure, or bony structure or bone material. Preferably, the second spinal reamer is spaced apart from the first spinal reamer, in particular its distal end face, by an axial length between 0.5 mm and 10 mm, in particular between 1.5 mm and 6 mm.preferably approximately 4 mm. The spinal reamer according to the invention can be designed for machining bone structures in the region of a spinal joint, in particular in the region of an articular process (processus articulares). The spinal reamer according to the invention is preferably designed for machining the upwardly directed articular process (processus articularis superior). The method according to the invention can provide for the further spinal reamer to be removed from the site of use when the first spinal reamer is positively connected to the bone structure to be machined and thus has sufficient hold for further machining of the same. The spinal reamer is preferably introduced to the site of use along an awl, a guide wire, and / or a guide sleeve. In a further development of the method according to the invention,that the arrangement of the guide means at the site of use takes place via an access to the site of use, wherein the access is created by means of an access means. An awl or a needle, in particular a Jamshidi needle, is used as the access means, for example. The creation of the access can be X-ray-based and / or navigated, i.e. with the aid of a navigation means, and / or robotically. The site of use can be arranged in the region of the articular process (processus articulares) of a vertebra, in particular in the region of the upwardly directed articular process (processus articularis superior) of a vertebra. The needle can be cannulated, i.e., have an internal cavity in which the guide means can be arranged at the site of use, in particular can be connected to the bone structure at the site of use. During processing of the bone structure at the site of use, the spinal reamer,in particular its distal end face and / or its threaded portion, are surrounded by a protective working sleeve. Preferably, the guide means is connected to the bone structure before the spinal reamer is introduced to the site of use, in particular anchored to the bone structure, in order to ensure improved guidance of the spinal reamer to the site of use. Preferably, before the spinal reamer is introduced to the site of use, in particular after the guide means has been connected to the bone structure, a protective sleeve, also referred to as a working sleeve, is pushed over the guide means, in particular over the first spinal reamer, to the site of use in order to protect sensitive tissue at the site of use, in particular nerve structures. Preferably, the processing of the bone structure by the first spinal reamer takes place essentially through its lateral surface, so that the bone structure is thus primarily laterally,i.e., along the circumference of the spinal reamer, in order to protect sensitive structures, such as nerves. In particular, sensitive nerve structures distal to the spinal reamer can be better protected. Access to the site of application is preferably via an articular process of a vertebral body, in particular via an upwardly directed articular process of the vertebral body. The method is particularly designed such that, by processing the bone structure, in particular in the area of ​​the articular process of a vertebral body, access to the spinal canal, or further into the intervertebral disc space of the spine, in particular to its nucleus pulposus, is created. After the spinal reamer is removed from the site of application, in a further development of the method, a working sleeve can be introduced into the intervertebral disc space via the access created by the spinal reamer.The nucleus pulposus of the intervertebral disc space can then be removed, particularly under endoscopic vision. In this respect, the method can be used in the context of an intervertebral implant implant, also referred to as an intervertebral basket or intervertebral cage. Further advantages and features of the invention emerge from the claims and the following description, in which exemplary embodiments of the invention are explained in detail with reference to the drawings. In the drawings: Fig. 1 shows a spinal reamer according to the invention in a perspective view. Fig. 2 shows the spinal reamer according to Fig. 1 in a side view. Fig. 3 shows another spinal reamer, particularly as part of a spinal reamer system according to the invention, in a perspective view. Fig. 4 shows an enlarged view of detail G of Fig. 3. Fig. 5 shows the spinal reamer according to Fig. 3 in a side view.Fig. 6 shows a spinal reamer system in a perspective view, Fig. 7 shows an enlarged view of detail C of Fig. 6, Fig. 8 shows the spinal reamer system of Fig. 6 in another perspective view, Fig. 9 shows an enlarged view of detail H of Fig. 8, Fig. 10 shows the spinal reamer system of Fig. 6 in a side view, Fig. 11 shows the spinal reamer system of Fig. 6 with a further spinal reamer fully inserted in a perspective view, Fig. 12 shows an enlarged view of detail B of Fig. 11, Fig. 13 shows an enlarged view of detail A of Fig. 11, Fig. 14 shows the distal end face according to Fig. 13 in a side view, Fig. 15 shows a further embodiment of the distal end face according to detail A of Fig. 11, Fig. 16 shows the distal end face according to Fig. 15 in a side view, Fig. 17 shows a further embodiment of the distal end face according to detail A of Fig. 11,Fig. 18 shows the distal end face according to Fig. 17 in a side view. Fig. 19 shows the spinal reamer system according to Fig. 11 in a side view. Figs. 20-33 show an exemplary sequence of a method according to the invention. Fig. 34-45 show an exemplary sequence of a further method according to the invention. Fig. 1 shows a spinal reamer 10 according to the invention for machining bone structures in the region of the spine at a site of use in a perspective view. The spinal reamer 10 has a working length of 235 mm and an outer diameter of approximately 7.3 mm. On its distal end face 11, the spinal reamer 10 has a convex rounding 12, which is also referred to as an atraumatic rounding.This avoids the risk of unwanted damage to nerves or soft tissue structures located around the site of use when machining the bone structure. An axial and radially centered opening 14 extends from the distal end face 11 to the proximal end face 13 of the spinal reamer 10, thus over its entire axial length of approximately 278 mm. This opening 14 is designed to accommodate a further spinal reamer 15, not shown in Fig. 1. The opening 14 is circular in cross-section and has a diameter of approximately 4.1 mm. For machining the bone structure, the distal end face 11 of the spinal reamer 10 has a reamer toothing 16 with a toothing profile 17, wherein the toothing profile 17 in the embodiment shown in Fig. 1 has several radially outward-facing,on the radial outer side of the distal end face 11 and distributed over its circumference, teeth 18. As can be seen in particular from the enlarged view of Fig. 13, each tooth 18 of the toothing profile 17 has two radial elevations 19, 20 with different radial heights, with a stepped transition 21 being formed between the radial elevations 19, 20. In a view from distally onto the distal end face 11, the first radial elevation 19 of a tooth 18 in the circumferential direction has a greater radial height than the second radial elevation 20 of the same tooth 18. The left flank 22 of the tooth 18, which is associated with the first radial elevation 19, has a larger pitch angle than the right flank 23 of the same tooth 18, which is associated with the second radial elevation 20. The radial outer profiles of the teeth 18, which correspond to the tooth profile 17,are designed as cutting edges. Between each two adjacent teeth 18, a circumferentially parabolic recess 24 is formed, which seamlessly connects the right flank 23 of one tooth 18 with the left flank 22 of the next tooth 18. The tooth profile 17 of the distal end face 11 extends proximally such that the lateral surface 25 proximal to the distal end face 11 of the spinal reamer 10, as shown in Fig. 1, is provided with a threaded portion 26. As a result, the outer contour 27 of a cross-section through the threaded portion 26 corresponds at a specific axial height to the tooth profile 17 of the distal end face 11 and, in particular, is rotated relative to the latter by a specific angle around the extension axis of the spinal reamer 10. The threaded portion 26 has an axial length of approximately 60 mm and a pitch angle of 80°.wherein the threaded portion 26 transitions seamlessly at its proximal end 28 into the substantially smooth outer surface 25 there. Proximal to the threaded portion 26, the spinal reamer 10 has, at a proximal end portion 31, a connecting piece 32 which is designed to receive a further spinal reamer 15, in particular for a detachable and positive connection to the further spinal reamer 15, as described further below. The connecting piece 32 has a triangular basic shape with rounded corners 33 and, in the present embodiment, serves as a driver for rotating the spinal reamer 10 according to the invention synchronously with the further spinal reamer 15. Fig. 2 shows the spinal reamer according to the invention according to Fig. 1 in a side view, from which in particular the axial length of the spinal reamer 10 as a whole as well as of the threaded portion 26 can be seen. Fig. 3 shows the further spinal cutter 15,which, together with the spinal reamer 10 according to the invention, for example in the embodiment according to Fig. 1, forms a spinal reamer system 34 according to the invention, which is shown in Fig. 6. The further spinal reamer 15 has a total length of approximately 278 mm, a working length of approximately 255 mm and an outer diameter of approximately 4 mm, so that the outer diameter essentially corresponds to the inner diameter of the axial opening 14 of the spinal reamer 10 according to the invention, wherein to ensure the mobility of the further spinal reamer 15 within the axial opening 14 of the spinal reamer 10 according to the invention, at most a comparatively small gap is formed. The further, second spinal reamer 15 is thus in the axial opening 14 of the first,The distal end face 35 of the second spinal reamer 15 has, according to the enlarged view in Fig. 4, a concave rounding 36, in contrast to the convex rounding 12 of the first spinal reamer 10 according to Fig. 1. A milling cutter toothing 38 with a toothing profile comprising five teeth 40 is arranged on the circumferential contour 37 of the distal end face 35. The teeth 40 each point axially distally and radially outward. From the enlarged view of the toothing profile 39 according to Fig. 4, it is evident that the teeth 40 are not mirror-symmetrical. The teeth 40 each have two radial elevations 41, 42 with different radial heights, wherein in contrast to the tooth profile 17 of the first spine milling cutter 10 according to Fig. 1, the first, left flank 43 of a tooth 40 has a pitch of approximately 90°, while the second,The right flank 44 of the tooth 40 has a pitch of approximately 40°. A substantially continuous transition 45 is formed between the radial elevations of a tooth, as is the case between two adjacent teeth 40. Similar to the first spinal cutter 10, the tooth profile 39 of the second spinal cutter 15 extends proximally such that the lateral surface 46 of the second spinal cutter 15 is provided with a threaded portion 47. The threaded portion 47 of the second spinal cutter 15 has an axial length of 20 mm and a thread pitch of 80°.This is also evident in the side view of the second spinal reamer 15 according to Fig. 5. The axial length of the threaded portion 47 of the second spinal reamer 15 is less than the axial length of the threaded portion 26 of the first spinal reamer 10. In a proximal end portion 49, the second spinal reamer 15 has a connector 50 with a proximal connector part 51 and a distal connector part 52. The distal connector part 52 is designed with its outer contour 53 corresponding to the inner contour 54 of the connector 32 of the first spinal reamer 10 shown in Figs. 8 and 9, so that the second spinal reamer 15 can be pushed from the proximal side through the axial opening 14 of the first spinal reamer.until the distal connecting piece part 52 of the second spinal reamer 15 is completely received by the connecting piece 32 of the first spinal reamer 10. Thus, the second spinal reamer 15 can be positively connected to the first spinal reamer 10, whereby in this state, the positive connection thus established allows the first spinal reamer 10 to rotate synchronously with the second spinal reamer 15 when the latter is driven in rotation. Due to the aforementioned design of the outer contour 53 of the distal connecting piece part 52 corresponding to the inner contour 54 of the connecting piece 32 of the first spinal reamer 10, a continuous transition is formed between the proximal connecting piece part 51 of the second spinal reamer 15 and the connecting piece 32 of the first spinal reamer 10 when the spinal reamers 10, 15 are connected to one another.which is also shown in Figs. 11 and 12. To drive the second spinal reamer 15, a drive device (not shown) can be connected to the proximal connecting piece part 51 and set it in rotation. Due to the positive connection with the first spinal reamer 10, the latter is then also set in rotation synchronously with the second spinal reamer 15. To release the connection, the second spinal reamer 15 can be moved proximally relative to the first spinal reamer 10 and pushed out of it. According to Figs. 3 and 4, the second spinal reamer 15 has an axial opening 55 with a diameter of approximately 2.4 mm, which is designed to accommodate a guide wire 69.an awl 64 or a guide rod 70 is designed as a guide means 65 to the site of use. Fig. 6 shows a spinal reamer system 34 according to the invention with the first spinal reamer 10 and the second spinal reamer 15 in a perspective view obliquely from the distal direction, wherein the second spinal reamer 15 is only partially inserted into the axial opening 14 of the first spinal reamer 10, coming from the proximal direction. In this position, the distal end face 35 of the second, inner spinal reamer 15 does not protrude beyond the distal end face 11 of the first, outer spinal reamer, but is rather covered by the first spinal reamer 10 and is therefore not shown in Fig. 6. According to Fig. 7, which shows an enlargement of detail C of Fig. 6,The proximal connecting piece 32 of the first spinal reamer 10 is designed to receive the distal connecting piece part 52 of the connecting piece 50 of the second spinal reamer 15. Fig. 8 shows the spinal reamer system 34 according to Fig. 6 in another perspective view, namely from an oblique proximal perspective, which particularly shows the axial opening 14 and the inner contour 54 of the connecting piece 32 of the first spinal reamer 10, which, as already mentioned, is designed to positively receive the distal connecting piece part 52 of the second spinal reamer 15. In addition, the axial opening 55 of the second spinal reamer 15 is visible.which is arranged concentrically to the axial opening of the first spinal reamer 10. This is also evident from the enlarged view of detail H of Fig. 8 in Fig. 9. Fig. 10 shows the spinal reamer system 34 according to Figs. 6 and 8 in a side view. Fig. 11 shows the spinal reamer system 34 with a second spinal reamer 15 fully inserted into the first spinal reamer 10 in a perspective view obliquely from the distal side. The second spinal reamer 15, in particular its distal end face 35, protrudes from the distal end face 11 of the first spinal reamer 10 by approximately 4 mm, so that the reamer teeth 38 and the threaded section 47 of the second spinal reamer 15 are visible. Fig. 12 shows the proximal end sections 31, 49 of both spinal reamers 10,15 of Fig. 11 in an enlarged view. The distal connecting piece part 52 of the connecting piece 50 of the second spinal reamer 15 is completely accommodated within the connecting piece 32 of the first spinal reamer 10 and is therefore concealed in Fig. 12. A flush transition is formed between the proximal connecting piece part 51 of the second spinal reamer 15 and the connecting piece 32 of the first spinal reamer 10. As soon as the second spinal reamer 15 is set in rotation by a drive means (not shown), the first spinal reamer 10 rotates synchronously with it; the connecting piece 32 of the first spinal reamer 10 thus acts as a driver to ensure synchronization of the rotational movements of the spinal reamers 10.15. The total length of the spinal milling cutter system 34, at 278 mm, essentially corresponds to the axial length of the second spinal milling cutter 15. Fig. 13 shows, in an enlarged view of detail A of Fig. 11, the distal end faces 11, 35 of the two spinal milling cutters 10, 15 and their threaded sections 26, 47. As already described, the second spinal milling cutter 15 protrudes axially from the distal end face 11 of the first spinal milling cutter 10 by a length of approximately 4 mm. The roundings 12, 36 of the end faces 11, 35 of both spinal milling cutters 10, 15 are clearly visible, as are their tooth profiles 17, 39 and threaded sections 26, 47. Since the outer diameter of the lateral surface 46 of the second spinal milling cutter 15 essentially corresponds to the diameter of the axial opening 14 of the first spinal milling cutter 10,15 only a comparatively narrow gap is formed. Fig. 14 shows the representation of Fig. 13 in a side view, from which it can be seen in particular that the pitch angle and the direction of rotation of the threaded section 47 of the second spinal milling cutter 15 essentially correspond to the pitch angle and the direction of rotation of the threaded section 26 of the first spinal milling cutter 10. Fig. 15 shows in particular the distal end face 11 and the threaded section 26 of the first spinal milling cutter 10 in a further embodiment, in which the toothing profile 17 of the distal end face 11 also has teeth 18 distributed over the circumference of the distal end face 11 on the radial outer side of the distal end face 11; however, the teeth 18 now point distally, so that the cutting properties of the distal end face 11 of the first spinal milling cutter 10 are improved. The teeth 18 of the tooth profile 17, viewed from distal and clockwise,a left, almost right-angled flank 22 and a right flank 23 with a pitch angle of approximately 40°, with a continuous transition to a recess 24 between two adjacent teeth 18. The toothing profile 17 extends proximally such that in the embodiment of Fig. 15, the threaded portion 26 is also formed according to the embodiment of Fig. 13, whereby this occurs over an axially longer, continuous transition region 56. This is also evident from the side view of Fig. 16. The spinal reamer system 34 shown there has the same second spinal reamer 15 as in Fig. 13; this also protrudes over an axial length of approximately 4 mm beyond the distal end face 11 of the first spinal reamer 10. Fig. 17 shows a further embodiment of the distal end face 11 of the first spinal reamer 10, which, similar to the embodiment of Fig. 13,a toothing profile 17 with radially outwardly pointing teeth 18, which, as already described, extend proximally into the threaded section 16. In contrast to the design of Fig. 13, the distal end face 11 has a distal projection 57, which is provided with a further toothing profile 58, which essentially corresponds to the design according to Fig. 15, in particular has distally pointing teeth 59. By forming two tooth profiles 17, 58, the design of Fig. 17 therefore combines the cutting ability of the radially outwardly facing teeth 18 according to the design of Fig. 13 with the cutting ability of the distally facing teeth 18 according to the design of Fig. 15. As in the design of Fig. 15, the second spinal cutter 15 protrudes distally over a length of 4 mm from the distal end face 11 of the first spinal cutter 10,which is also evident from the side view of Fig. 18. Fig. 19 shows the spinal reamer system 34 of Fig. 11 in a side view, with the detail B shown therein being shown in the three already described embodiments by Figs. 14, 16, and 18. Figs. 20 to 33 illustrate the sequence of a method according to the invention, in which bone structures 29 in the region of the spinal column 30 are machined at a location 48, in particular by means of the spinal reamer 10 according to the invention. Fig. 20 shows an overview of the essentially horizontally oriented spinal column 30 with upwardly oriented articular processes 60 of the vertebral bodies 61,whose bone structures 29 correspond to the insertion site 48. Fig. 21 shows the insertion site 29 in an enlarged view of detail A of Fig. 20. First, a Jamshidi needle 62 shown in Figs. 20 and 21 is driven into the insertion site 48, the upwardly directed articular process 60 (processus articulares superior), via a trocar 63 guided within the Jamshidi needle 62. In the transition from Fig. 20 to Fig. 22, the trocar 63 guided within the Jamshidi needle 62 is pulled proximally out of the Jamshidi needle 62. The Jamshidi needle 62 remains at the insertion site 48. Fig. 23 shows an enlarged view of detail G of Fig. 22, the insertion site 48 with the Jamshidi needle 62 arranged there. In the sense of the invention, the Jamshidi needle 62 serves in the present method as an access means,since it provides access to the insertion site 48 for further instruments for processing the bone structure 29. In the transition from Fig. 22 to Fig. 24, an awl 64 is guided from distal to proximal through the cavity of the Jamshidi needle 62 to the insertion site 48. The awl 64 is then driven into the upwardly directed articular process 60 so that the awl 64 is connected to it. This is also illustrated in Fig. 25 by the enlarged view of detail B of Fig. 24 shown there. The awl 64 serves for the present method as a guide means 65 for the insertion of the spinal reamer 10 according to the invention, as described below. In the transition from Fig. 24 to Fig. 26, the Jamshidi needle 62, as an access means, is removed proximally from the insertion site 48.while the awl 64 remains as a guide means 65 at the insertion site 48 and is connected there to the articular process 60. Fig. 27 illustrates detail C of Fig. 26 in an enlarged view. In the transition from Fig. 26 to Fig. 28, a working sleeve 66 with a long lip 67, arranged on the right in Fig. 28, as well as a spinal reamer 10 according to the invention and a further spinal reamer 15 are pushed over the awl 64 distally to the insertion site 48. These components are part of the spinal reamer system 34. The working sleeve 66 radially surrounds the first spinal reamer 10 according to the invention, which in turn radially surrounds the further, second spinal reamer 15. Based on the positions of the connecting piece 32 of the first spinal reamer 10 and the handpiece 50 of the second spinal reamer 15 in Fig. 28, it can be seen that the spinal reamers 10, 15 are connected to each other in a rotationally fixed manner. The spinal reamers 10, 15 are, together,driven in rotation, so that processing of the bone structure 29 at the site of application 48 takes place in such a way that it is first processed by the second spinal milling cutter 15, which projects distally beyond the first spinal milling cutter 10, until finally the bone structure 29 is also processed by the first spinal milling cutter 10. During this processing, the awl 64 is still connected to the articular process 60. This is also evident from the enlarged view of detail D of Fig. 28 in Fig. 29. After the first spinal milling cutter 10 has a sufficiently strong hold in the bone structure 29, the awl 64 is removed proximally from the site of application 48 in the transition from Fig. 28 to Fig. 30. The working sleeve 66 remains at the site of application together with the spinal milling cutters 10, 15, which is also illustrated by the enlarged view of detail E of Fig. 30 in Fig. 31. In an optional step, a blunt awl,A guide wire or guide rod can be moved distally within the axial opening 55 of the second spinal reamer 15 to the insertion site 48, and then further processing of the bone structure 29 can be performed by the two spinal reamers 10, 15, which is not shown in the figures. In the transition from Fig. 30 to Fig. 32, the second spinal reamer 15 is moved proximally relative to the first spinal reamer 10, initially out of the insertion site 48 and finally removed from the first spinal reamer 10, so that only the first spinal reamer 10, still housed in the working sleeve 66, remains at the insertion site 48. Thereafter, the bone structure 29 is processed only by the first spinal reamer 10, which is protected by the surrounding working sleeve 66. This is also evident from Fig. 33.which shows an enlarged view of detail F of Fig. 32. Figs. 34 to 45 illustrate a further embodiment of the method according to the invention. Fig. 34 shows the insertion site 48 similar to Fig. 20. Here, a hollow needle 68, which can also be referred to as an access needle in the sense of an access means, is in contact with the bone structure 29 at the insertion site 48. The hollow needle 68 was previously introduced into the insertion site 48 using a stylet (not shown in Fig. 34). Fig. 35 shows an enlarged view of detail H of Fig. 34.from which the arrangement of the hollow needle 68 on the bone structure 29 can be seen. In the transition from Fig. 34 to Fig. 36, after removal of the stylet, a guide wire 69 is brought from proximal to distal through the hollow needle 68 to the bone structure 29 at the insertion site 48. This can also be seen from the enlarged view of detail I of Fig. 36 in Fig. 37. In the transition from Fig. 36 to Fig. 38, the hollow needle 68 is removed proximally from the insertion site 48, so that only the guide wire 69 remains there, which is also shown in the enlarged view of detail J of Fig. 38 in Fig. 39. Then, in the transition from Fig. 38 to Fig. 40, a guide rod 70 is moved over the guide wire 69 distally to the insertion site 48. Fig. 41 shows an enlarged view of detail K of Fig. 40. In the transition from Fig. 40 to Fig. 42, similar to Fig. 28,the working sleeve 66 including its extended lip 67 and together with the spinal reamers 10, 15 accommodated therein is pushed distally over the guide rod 70 to the insertion site 48. Fig. 41 shows an enlarged view of detail L of Fig. 40. In the transition from Fig. 42 to Fig. 44, as already described in connection with the first embodiment of the method according to the invention, the two spinal reamers 10, 15 are driven in rotation and process the bone structure 29 at the insertion site 48 until the first spinal reamer 10 has sufficient hold in the bone structure 29. Fig. 45 shows an enlarged view of detail M of Fig. 44. After the first spinal reamer 10 has a,

Claims

Patent claims 1. Spinal milling cutter (10) for machining bone structures (29) in the region of the spine (30), with a distal end face (11) provided with a milling cutter toothing (16) with a toothing profile (17) with at least two teeth (18), wherein the spinal milling cutter (10) has an axial opening (14) for receiving a further spinal milling cutter (15).

2. Spinal milling cutter according to claim 1, characterized in that the toothing profile (17) is designed as a cutting edge, at least in sections.

3. Spinal milling cutter according to claim 1 or 2, characterized in that the distal end face (14) of the spinal milling cutter (10) has a rounded portion (12), in particular a convex portion.

4. Spinal reamer according to one of claims 1 to 3, characterized in that at least one tooth (18) of the tooth profile (17) is oriented distally and / or radially. 2024004017 2 5. Spinal milling cutter according to claim 4, characterized in that at least one tooth (18) of the toothing profile (17) is not mirror-symmetrical, wherein the tooth (18) in particular has two radial elevations (19, 20) with different radial heights, wherein it is provided in particular that a step-shaped transition (21) is formed between the radial elevations (19, 20) of a tooth (18).

6. Spinal milling cutter according to one of claims 1 to 5, characterized in that at least one tooth (18) of the toothing profile (17) has a first flank (22) and a second flank (23), wherein the pitch of the first flank (22) is greater than the pitch of the second flank (23).

7. Spinal reamer according to one of claims 1 to 6, characterized in that two adjacent teeth (18) of the tooth profile (17) are separated from each other by a parabolic recess (24).Spinal reamer according to one of claims 1 to 7, characterized in that the spinal reamer (10) has a threaded portion (26) proximal to the reamer toothing (17).

9. Spinal reamer according to claim 8, characterized in that the toothing profile (17) extends proximally in such a way that the threaded portion (26) is formed thereby. 3 10. Spinal reamer according to one of claims 8 or 9, characterized in that the threaded portion (26) has an axial length between 10 mm and 90 mm, preferably between 20 mm and 75 mm, most preferably of approximately 60 mm.

11. Spinal reamer according to one of claims 8 to 10, characterized in that the threaded portion (26) has a thread pitch between 60° and 85°, in particular between 70° and 85°, most preferably between 75° and 80°, for example 75° or 80°.

12. Spinal reamer according to one of claims 1 to 11, characterized in that the toothing profile (17) has at least one tooth (18) with a triangular basic shape.

13. Spinal reamer according to one of claims 1 to 12, characterized in that the distal end face (11) of the spinal reamer (10) has a distal projection (57), wherein the projection (57) is provided in particular with a further tooth profile (58).Spinal reamer according to claim 13, characterized in that the toothing profile (58) of the projection (57) is designed to be mirror-symmetrical, wherein it is particularly provided that the toothing profile (58) of the projection (57) has teeth (59) each with a triangular basic shape. 4 15. Spinal reamer according to one of claims 1 to 14, characterized in that a proximal end section (31) of the spinal reamer (10) has a connecting piece (32) which is designed in particular to receive the further spinal reamer (15).

16. Spinal reamer system (34) with a first spinal reamer (10) according to one of claims 1 to 15 and a second spinal reamer (15) which, as a further spinal reamer (15), can be received in the axial opening (14) of the first spinal reamer (10) and which has a distal end face (35) with a reamer toothing (38) with a toothing profile (39).

17. Spinal reamer system according to claim 16, characterized in that the second spinal reamer (15) is rotatably and / or detachably connectable to the first spinal reamer (10).Spinal milling cutter system according to one of claims 16 or 17, characterized in that the second spinal milling cutter (15) is designed according to one of claims 1 to 15.

19. Spinal milling cutter system according to one of claims 16 to 18, characterized in that the second spinal milling cutter (15) has a proximal connecting piece (50) whose outer contour (53) is designed, at least in sections, to be complementary to the inner contour (54) of the connecting piece (32) of the first spinal milling cutter (10). 5 20. Spinal milling cutter system according to one of claims 16 to 19, characterized in that a drive unit is provided which is designed to drive the first spinal milling cutter (10) and / or the second spinal milling cutter (15) in rotation.

21. Spinal milling cutter system according to one of claims 16 to 20, characterized in that the spinal milling cutters (10, 15) are rotatable independently of one another.

23. Spinal milling cutter system according to one of claims 16 to 21, characterized in that the second spinal milling cutter (15) has an axial opening (55) which, in particular when connected to the first spinal milling cutter (10), is arranged concentrically to the axial opening (14) of the first spinal milling cutter (10). 23.Spinal milling cutter system according to one of claims 16 to 22, characterized in that at least one tooth (40) of the toothing profile (39) of the second spinal milling cutter (15) has a triangular basic shape.

24. Spinal milling cutter system according to one of claims 16 to 23, characterized in that the toothing profile (39) of the second spinal milling cutter (15) extends proximally in such a way that a threaded portion (47) of the second spinal milling cutter is formed.

25. Spinal milling cutter system according to one of claims 16 to 24, characterized in that the second vertebral... 6 column milling cutters (15) are received in the axial opening (14) of the first spinal milling cutter (10) and / or are connected to the first spinal milling cutter (10).

26. A method for machining bone structures (29) in the region of the spine (30) at a site of use (48) by means of a first spinal milling cutter (10) according to one of claims 1 to 15, in particular by means of a spinal milling cutter system (34) according to one of claims 16 to 25, comprising the following steps: − introducing the first spinal milling cutter (10) with a further spinal milling cutter (15) received in the axial opening (14) of the first spinal milling cutter (10) along a guide means (65) to the site of use (48), wherein the guide means (65) is arranged within the axial opening (14) of the first spinal milling cutter (10), in particular within the axial opening (55) of the further spinal milling cutter (15),− Rotating the first spinal cutter (10) together with the further spinal cutter (15) such that the bone structure (29) at the site of use (48) is machined along a predefined path, − Removing the further spinal cutter (15) from the site of use (48), 7 − Rotating the first spinal reamer (10) such that the desired processing of the bone structure (29) takes place at the deployment site (48), and − Removing the first spinal reamer (10) from the deployment site (48).

27. The method according to claim 26, characterized in that the guide means (65) is connected to the bone structure (29) before the spinal reamers (10, 15) are introduced to the deployment site (48).

28. The method according to one of claims 26 or 27, characterized in that before the spinal reamers (10, 15) are introduced to the deployment site (48), in particular after the guide means (35) has been connected to the bone structure (29), a protective sleeve (66) is pushed over the guide means (35), in particular over the first spinal reamer (10), to the deployment site (48). 29.Method according to one of claims 26 to 28, characterized in that the processing of the bone structure (29) by the first spinal milling cutter (10) takes place essentially through its lateral surface (25).

30. Method according to one of claims 26 to 29, characterized in that access to the insertion site (48) takes place via an articular process (60) of a vertebral body (61), in particular via an upwardly directed articular process (60) of the vertebral body (61).

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