Template for making separating cuts in bones during surgical procedures and method for production thereof

Abstract

The invention relates to a template (2) for making separating cuts by means of a disc-shaped cutting tool in bones during surgical procedures, in particular for femur and tibia resection, having a main body (4) and a slot-like opening (6) formed therein through which the disc-shaped cutting tool engages, wherein the slot-like opening (6) guides the disc-shaped cutting tool while it is engaging through the slot-like opening (6) in that the slot-like opening (6) is delimited by wall sections (16, 18) which are opposite one another and are preferably parallel to one another, wherein at least one of the wall portions (16, 18) and preferably both wall portions (16, 18) have elevations (20, 24, 32, 38, 42) which project into the slot-like opening (6), can be brought into sliding contact with the cutting tool and guide the cutting tool through the slot-like opening, and have depressions (22, 26, 34, 40, 44) which are set back with respect to the elevations (20, 24, 32, 38, 42) and which as a result of their being set back do not come into sliding contact with the cutting tool.

Description

[0001] Title: Template for making bone cuts during surgical interventions and method for its manufacture

[0002] Description

[0003] The invention relates to a template for making separating cuts in bones using a disc-shaped separating tool during surgical interventions, in particular for femoral and tibial resection, comprising a base body and a slot-shaped opening formed therein for the disc-shaped separating tool to pass through, wherein the slot-shaped opening guides the disc-shaped separating tool when passing through the slot-shaped opening, in that the slot-shaped opening is delimited by opposing and preferably parallel wall sections. A disc-shaped separating tool is also understood to mean a plate-shaped or blade-shaped separating tool, so that this term particularly includes a saw blade that is conventional per se for the purposes intended here.

[0004] Such templates are often also referred to as cutting templates or sawing templates or saw blocks and are typically used in the preparation of the tibia bone and / or the femur bone for the implantation of knee endoprostheses. The template is typically precisely positioned and fixed to the bone in question by means of a screw connection or a plug connection before one or more separating cuts are made. The minimum width of the slot-shaped opening essentially corresponds to the thickness of the disc-shaped separating tool, so that the disc-shaped separating tool is guided with little play and therefore very precisely when it is immersed in the slot-shaped opening to make the separating cut and slides against the wall sections. In this way, a precise separating cut can be made in the bone.

[0005] EP 2 624 764 B1 has already proposed providing a template made of ceramic material in order to reduce the amount of metallic abrasion on the template side as a result of the friction that always occurs between the separating tool and the template. Such metallic abrasion can only be inadequately removed from the surgical field and can cause or intensify allergic reactions in the patient. The formation of a wider slit-shaped opening in the template in order to reduce the friction that occurs when the separating cut is made is, in turn, problematic because it is accompanied by less precise guidance of the separating tool during the separating cut, so that the inaccuracy would result in larger gaps between the bone tissue and the implant part, which would have to be filled with larger quantities of bone cement.This in turn can have an adverse effect on the fixation and service life of the implant.

[0006] The object of the present invention is to further develop a stencil of the type mentioned at the outset in such a way that the abrasion occurring when the separating cut is carried out, in particular when stencils made of metallic material are used.

[0007] This object is achieved according to the invention in a template of the type mentioned in that at least one of the wall sections and preferably both wall sections have elevations which project into the slot-shaped opening and can be brought into sliding contact with the cutting tool and thereby guide the cutting tool, and depressions which are set back from the elevations and which, due to their setting back, cannot form sliding contact with the cutting tool.

[0008] According to the invention, it is therefore proposed to form at least one wall section which delimits the slot-shaped opening with elevations and depressions in such a way that an only partially load-bearing sliding surface is formed. A respective total surface area of ​​the respective wall sections which can be brought into sliding contact with the cutting tool, i.e. a total contact surface with the cutting tool, is thus smaller than a projected surface area of ​​the relevant wall section which delimits the slot-shaped opening. In this way, the total contact surface between template and cutting tool is reduced. As has been found according to the invention, this makes it possible to reduce abrasion occurring during operation in the cutting tool and / or in the wall section.A further very important advantage of a template designed according to the invention in the surgical situation is that less frictional heat is generated when making the separating cut, which previously sometimes had to be dissipated by adding fluid.

[0009] It is conceivable that the elevations are delimited by the depressions, i.e. in particular are designed in the shape of islands, or that the depressions are delimited by the elevations so that the elevations surround the depressions in question. Elevations and depressions can also adjoin one another alternately, in particular in the form of a pattern, in particular in the manner of wavy lines, with advantageous designs being explained below. The elevations and depressions can also be designed and provided irregularly. In any case, the elevations form contact or guide points or surfaces for the cutting tool, whereas this is not the case in the region of the depressions. In this way, the total guide surface or total contact surface is reduced, and according to the invention the wear and abrasion due to the relative movement between the cutting tool and the wall sections of the template is reduced.

[0010] According to one embodiment of the invention, the wall section or sections with their elevations and depressions are formed integrally from the material of the base body, in particular by 3D printing the base body. 3D printing allows complex structures to be easily produced, even using metallic materials, with virtually any geometry. It is also readily possible for the elevations to transition into depressions in a rounded manner, so that discontinuous edges can be avoided at the contact transition between the template and the cutting tool.

[0011] However, it is also conceivable and advantageous if the wall section or sections, with their elevations and depressions, is / are formed by at least one insert that is joined to the base body. In this case, it is possible to separately manufacture an insert that has or delimits the slot-shaped opening and subsequently complete it with the base body of the template.

[0012] However, it may also prove advantageous for the elevations and depressions of the wall section or sections to be produced by surface treatment of the wall section or sections.

[0013] It may also prove advantageous for the elevations and depressions of the wall section or sections or the entire slot-shaped opening to be produced by material-removing machining, in particular by cutting or grinding, or by drilling or by wire erosion processes.

[0014] It may prove advantageous that the elevations and the depressions in the wall section or the wall sections of the base body are formed by first producing a slot-shaped opening with substantially flat wall sections, and then reworking the wall section or the wall sections, or by producing the slot-shaped opening and the wall sections having elevations and depressions in one step.

[0015] However, it may also prove advantageous for the elevations and depressions to be formed in the wall section or wall sections of the base body by drilling holes extending side by side into the base body in the depth direction or in the longitudinal direction of the slot-shaped opening to be produced or obliquely to the depth direction or to the longitudinal direction.

[0016] In further development of this idea, it may prove advantageous for the holes to be positioned in such a way that each hole engages with the two holes formed next to it, so that a continuous slot-shaped opening is formed.

[0017] However, it may also prove advantageous to position the holes in the base body in such a way that they are inserted next to each other and spaced apart from each other, and to connect the holes to form the slot-shaped opening by a further material-removing step. Wire erosion processes can be used for this purpose, in particular and by way of example.

[0018] As already indicated at the beginning, the elevations and depressions can be provided in the form of a pattern; for example, they can form a wave pattern or a waffle pattern.

[0019] It is also advantageous that the elevations form flat, essentially flat plateaus that can be brought into sliding contact with the cutting tool. It is advantageous if the surface of a plateau is 0.5 - 20 mm 2 , especially 0.5 to 16 mm 2 , especially 0.5 to 10 mm2 amounts.

[0020] It is further proposed to design the template such that the total contact area between the elevations of the wall sections and the cutting tool amounts to at most 50%, in particular at most 40%, in particular at most 30%, in particular at most 20%, in particular at most 10%, in particular at most 5% of the projected area of ​​the opposing wall sections. When this patent application refers to a projected area of ​​the wall sections, this refers to the planar surface of the respective wall section viewed orthogonally to its planar extent.

[0021] As already indicated at the beginning, it may prove advantageous for the wall section or the wall sections to be made of metal alloy, in particular cobalt chromium alloy, T16A14V alloy, chromium-nickel stainless steel alloy, in particular 17-4PH1.4542 alloy.

[0022] The invention also relates to a method for producing the stencil according to the invention according to claims 15-17.

[0023] Further features, details and advantages of the invention emerge from the appended patent claims and from the drawings and subsequent description of preferred embodiments of the template according to the invention.

[0024] The drawing shows:

[0025] Figures 1a-c show various views of a schematic representation of a first embodiment of a template according to the invention;

[0026] Figures 2a-c show views of a second embodiment of a template according to the invention corresponding to Figure 1;

[0027] Figures 3a-d show various views of a third embodiment of a template according to the invention;

[0028] Figures 4a-d show various views of a fourth embodiment of a template according to the invention; and

[0029] Figure 5 is a schematic representation of a wall section defining a slot-shaped opening with elevations having a planar plateau and depressions surrounding these.

[0030] Figures 1a to 1c show a perspective view, a top view and a partially sectioned view along line AA of a first embodiment of a template according to the invention for making a separating cut in the bone during surgical interventions using a disk-shaped separating tool (not shown), which is known per se and therefore not shown. The template 2 is shown schematically with a three-dimensional base body 4 with, for example, flat boundary surfaces that are inclined towards one another in a wedge shape. A slit-shaped opening 6 is formed in the base body 4 and extends through the entire thickness of the base body 4, so that the disk-shaped separating tool (not shown) can be immersed in the slit-shaped opening 6 and, guided through the slit-shaped opening 6 in a predetermined plane, can emerge on the opposite side and cut into the bone to be treated.In this way, with prior exact alignment of the template 2 relative to the bone, a defined separating cut can be made in the bone during the surgical procedure.

[0031] The slot-shaped opening 6 has a clear opening surface 8 with a longitudinal extent 10 and, in comparison, a much smaller transverse extent 12. It also has a depth or depth extension 14 as indicated in Figure 1c. The slot-shaped opening 6 is delimited in width by opposing and parallel wall sections 16 and 18. These wall sections 16, 18 face a disk plane of the disk-shaped cutting tool when the cutting tool is inserted into the slot-shaped opening 6. The transverse extent 12 of the slot-shaped opening 6 essentially corresponds to the disk thickness of the disk-shaped cutting tool so that the latter is guided essentially free of play and thus with high precision when inserted into the slot-shaped opening 6.

[0032] According to the present invention, it is provided that at least one and preferably both wall sections 16, 18 are formed with elevations 20 and depressions 22, which is only indicated schematically and graphically in Figures 1a to 1c. The elevations 20 protrude slightly into the slot-shaped opening 6 and can therefore be brought into sliding contact with the separating tool. This means that the separating tool only touches the wall sections 16, 18 in the region of their elevations 20, but not in the region of the depressions 22 set back from the elevations 20. Thus, according to the invention, the total contact area between the separating tool and the two opposite wall sections is reduced compared to a design in which the wall sections 16, 18 would be exactly flat.According to the invention it was found that the abrasion occurring during operation between the cutting tool and the stencil material can be reduced.

[0033] The elevations 20 and depressions 22 can be designed and manufactured as described in the introduction to the description. They are shown in Figure 1c purely by way of example in the form of a waffle pattern with diamond-shaped elevations 20 and the linear depressions 22 bordering them.

[0034] Figures 2a-c show corresponding views of a further embodiment of a template 2 according to the invention with a merely schematically indicated base body 4 and a slot-shaped opening 6. Figures 2a-c show elevations 24 and depressions 26 arranged next to one another, for example, in a wave-like pattern or in a wave-like manner. These elevations 24 and depressions 26 can be produced, for example, by material-removing processes, in particular by machining or grinding, or by drilling or by wire erosion processes.In the example shown, they can be formed by arranging bores extending in the depth direction of the slot-shaped opening 6 to be produced next to one another along the longitudinal extent 10 of the slot-shaped opening 6, the bores 28 being positioned such that a respective bore engages with the two bores 28 formed next to it, so that a continuous slot-shaped opening 6 extending in the longitudinal direction 10 is formed. Finally, the transitions between each two bores 28 have been rounded so that sharp edges are avoided in the region of the elevations 24 formed by the transitions.

[0035] Figures 3a-d show a further embodiment of the template 2 according to the invention. To form the slot-shaped opening 6, bores 30 extending through the base body 4 in the direction of the longitudinal extent 10 of the slot-shaped opening 6 to be produced are first provided. They are therefore introduced into the base body 4 from the side. These bores 30 are slightly spaced from one another in the direction of the depth 14 of the slot-shaped opening 6. They are only connected to one another by subsequently forming a cut extending in the direction of the depth 14, in particular by means of the methods mentioned at the outset, so that the slot-shaped opening 6 is formed in this way.In this way, elevations 32 are formed in the area of ​​the transitions between the bores 30 and depressions 34 are formed by the bores 30 themselves, so that a cutting tool entering the slot-shaped opening 6 can only come into sliding contact with the elevations 32.

[0036] Figures 4a-d show a fourth embodiment of the template 2 according to the invention, again with a base body 4 with a slot-shaped opening 6, which is again only schematically indicated. This embodiment is similar to the embodiment of Figures 3a-d, wherein the plurality of bores 36 extending in the direction of the longitudinal extent 10 merge into one another in the direction of the depth extent 14, whereby a wave-like pattern of elevations 38 and depressions 40 is formed, similar to Figures 2a-c, but oriented orthogonally thereto. Again, the elevations 38 are rounded. Finally, Figure 5 indicates a perspective view of a partial area of ​​a wall section 16 with elevations 42 and depressions 44, wherein the pattern-like arrangement of the elevations 42 and depressions 40 could be described as waffle-shaped.

[0037] Elevations 42 have essentially flat plateaus 46, which are, for example, rectangular in shape and rounded on all sides into the recessed depressions 44. In this way, only the essentially flat plateaus 46 of the elevations 42 contribute to the overall surface, which can be brought into sliding contact with a cutting tool (not shown) when the cutting tool is immersed in the slot-shaped opening 6 delimited by the wall sections 16.

Claims

Patent claims 1. Template (2) for making separating cuts by means of a disc-shaped separating tool in bones during surgical interventions, in particular for femoral and tibial resection, with a base body (4) and a slot-shaped opening (6) formed therein for the disc-shaped separating tool to reach through, wherein the slot-shaped opening (6) guides the disc-shaped separating tool when reaching through the slot-shaped opening (6), in that the slot-shaped opening (6) is delimited by opposing and preferably parallel wall sections (16, 18), characterized in that at least one of the wall sections (16, 18) and preferably both wall sections (16, 18) have elevations (20, 24, 32, 38, 42) projecting into the slot-shaped opening (6), can be brought into sliding contact with the separating tool and thereby guide the separating tool, and opposite the elevations (20, 24, 32, 38, 42) recessed recesses (22, 26,34, 40, 44) which, due to their recessed position, cannot form sliding contact with the cutting tool.

2. Template (2) according to claim 1, characterized in that the wall section (16, 18) or the Wall sections (16, 18) with their elevations (20, 24, 32, 38, 42) and depressions (22, 26, 34, 40, 44) are formed in one piece from material of the base body (4), in particular are produced by 3D printing of the base body (4).

3. Template (2) according to claim 1 or 2, characterized in that the wall section (16, 18) or the wall sections (16, 18) with their elevations (20, 24, 32, 38, 42) and depressions (22, 26, 34, 40, 44) is / are formed by at least one insert part which is joined to the base body (4).

4. Template (2) according to one or more of the preceding claims, characterized in that the elevations (20, 24, 32, 38, 42) and the depressions (22, 26, 34, 40, 44) of the wall section or the wall sections are produced by surface machining of the wall section or the wall sections.

5. Template (2) according to one or more of the preceding claims, characterized in that the elevations (20, 24, 32, 38, 42) and the depressions (22, 26, 34, 40, 44) of the wall section (16, 18) or the wall sections or the entire slot-shaped opening (6) are formed by material-removing processes, in particular by machining or grinding machining or by drilling or by Wire EDM process.

6. Template (2) according to one or more of the preceding claims, characterized in that the elevations (20, 24, 32, 38, 42) and the depressions (22, 26, 34, 40, 44) in the wall section (16, 18) or the wall sections (16, 18) of the base body (4) are formed by firstly producing a slot-shaped opening (6) with substantially flat wall sections (16, 18), and then reworking the wall section (16, 18) or the wall sections (16, 18), or by producing the slot-shaped opening and the wall sections (16, 18) having elevations (20, 24, 32, 38, 42) and depressions (22, 26, 34, 40, 44) thereof in one step. are.

7. Template (2) according to one or more of the preceding claims, characterized in that the elevations (20, 24, 32, 38, 42) and the depressions (22, 26, 34, 40, 44) in the wall section (16, 18) or the wall sections of the base body (4) are formed by bores (28, 30, 36) extending side by side in the depth direction (14) or in the longitudinal direction (10) of the slot-shaped opening (6) to be produced or obliquely to the depth direction or longitudinal direction being introduced into the base body (4).

8. Template (2) according to claim 7, characterized in that the bores (28, 40) are positioned such that a respective bore (28, 40) engages in the two bores (28, 40) formed next to it, so that a continuous slot-shaped opening (6) is formed.

9. Template (2) according to claim 7, characterized in that the bores (30) are positioned such that they are introduced into the base body (4) next to one another and at a distance from one another, and that the bores (30) are connected to one another by a further material-removing step to form the slot-shaped opening (6).

10. Template (2) according to one or more of the preceding claims, characterized in that the elevations (20, 24, 32, 38, 42) and depressions (22, 26, 34, 40, 44) form a wave pattern or a waffle pattern.

11. Template (2) according to one or more of the preceding claims, characterized in that the elevations (20, 24, 32, 38, 42) form planar plateaus (46) which can be brought into sliding contact with the separating tool.

12. Template (2) according to claim 11, characterized in that the area of ​​a plateau (46) is 0.5 - 20 mm 2 , especially 0.5 to 16 mm 2, especially 0.5 to 10 mm 2 amounts.

13. Template according to one or more of the preceding claims, characterized in that a total contact area between the elevations (20, 24, 32, 38, 42) of the wall sections (16, 18) and the separating tool is at most 50%, in particular at most 40%, in particular at most 30%, in particular at most 20%, in particular at most 10%, in particular at most 5%, of the projected area of ​​the opposite wall sections (16, 18).

14. Template (2) according to one or more of the preceding claims, characterized in that the wall section (16, 18) or the wall sections (16, 18) are formed from metal alloy, in particular cobalt chromium alloy, Ti 6A14V alloy, chromium-nickel stainless steel alloy, in particular 17-4PH1.4542 alloy.

15. A method for producing a template according to one or more of the preceding claims 1-14, characterized in that the elevations (20, 24, 32, 38, 42) and the depressions (22, 26, 34, 40, 44) are formed in the wall section (16, 18) or the wall sections of the base body (4) by drilling holes (28, 30, 36) extending side by side into the base body (4) in the depth direction (14) or in the longitudinal direction (10) of the slot-shaped opening (6) to be produced or obliquely thereto.

16. A method for producing a template according to claim 15, characterized in that the bores (28, 40) are positioned such that a respective bore (28, 40) engages in the two bores (28, 40) formed next to it, so that a continuous slot-shaped opening (6) is formed.

17. A method for producing a template according to claim 15, characterized in that the bores (30) are positioned such that they are introduced into the base body (4) next to one another and spaced from one another, and that the bores (30) are connected to one another by a further material-removing step to form the slot-shaped opening (6).

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