MONOLITHIC CERVICAL OR LUMBAR IMPLANT BODY

Description

[0001] The invention relates to a monolithic cervical or lumbar implant body for fusing spinal segments, having an upper and a lower side spaced apart from one another while maintaining an intermediate space, wherein the upper and lower sides are connected by webs, furthermore the upper and lower sides, with the exception of shaping and structure-reinforcing edge regions, are designed as a surface with openings and enclose an angle, at least one completely or partially open side surface for introducing bone material or bone substitute material and a further side surface with a stabilization region and a recess for temporarily receiving a surgical instrument in the stabilization region, according to the preamble of claim 1.

[0002] From US 2019 / 000636 A1, a spinal implant with a unitary structure produced using a 3D printer is already known.

[0003] US 2008 / 249627 A1 concerns threaded intervertebral implants for use in the human spine. These implants feature functional threads that serve to secure them in the vertebrae.

[0004] From the generic DE 10 2009 014 184 A1, an implant for fusing spinal segments is already known, which has a monolithic structure. At least parts of the surface of the implant have structure-forming porosity. The volume of the implant has a high density. Furthermore, the volume comprises a number of directionally oriented and / or randomly arranged passages pointing in different directions. The passages are surrounded, limited, or interrupted by stabilizing surfaces that increase the strength of the implant.

[0005] Preferably, the passages according to DE 10 2009 014 184 A1 are formed as a honeycomb structure. Such hexagonal cavities represent a good ratio of the area of ​​the passage created to the strength of the structure delimiting the cavity.

[0006] Starting from the largest surface of the monolithic implant, as previously known, the passages run vertically. In a preferred design, the passages are interrupted in their directional course by at least one free space.

[0007] In a further embodiment, the passages run in one or more directions deviating from the vertical, which improves the sinking behavior.

[0008] In a further development, the monolithic implant has a slightly indicated wedge-shaped profile in order to facilitate the implantation process and to correspond to the anatomical shape of the spine.

[0009] The previously known implant has a bore for temporarily accommodating surgical instruments to facilitate the placement of the implant.

[0010] In addition, the implant contains at least one opening for the application of bone replacement material. The previously known implant can be manufactured using a sintering process and / or electron beam melting.

[0011] Additive processes for the production of implants are also known in principle. Selective laser melting is also used here.

[0012] In such a process, the material to be processed is applied in powder form in a thin layer on a base plate.

[0013] This material is then completely remelted locally using laser beams, forming a solid layer of material after restoration. This allows for the creation of customized three-dimensional bodies, including those with undercuts and cavities.

[0014] If threaded holes are required for implants manufactured using additive processes, for example, to secure surgical instruments, it has previously been necessary to either create the threads by machining, i.e., cutting, or to re-cut or re-groove additively produced threads to ensure the required precision. However, thread cutting or re-cutting requires the use of lubricants and subsequent complex cleaning to remove the lubricants or cutting chips, thus requiring additional work steps. Especially with miniaturized implant bodies, this is often associated with considerable effort, difficulty, and expense.

[0015] It has also been shown that previously known implant bodies with a honeycomb structure of the type described above lead to subsidence, i.e. to the implant sinking into the vertebral bodies due to excessive surface pressure.

[0016] Based on the above, it is therefore an object of the invention to provide a further developed, monolithic cervical or lumbar implant body for the fusion of spinal segments, which, by utilizing the inherently advantageous honeycomb structure, avoids undesired sinking into adjacent vertebral bodies or vertebral body segments, is nevertheless securely fixed and, moreover, is structurally implemented in such a way that production using purely additive processes is possible without any reworking.

[0017] The object of the invention is achieved by an implant body according to the combination of features according to patent claim 1, wherein the subclaims represent at least expedient embodiments and further developments.

[0018] It is therefore assumed that there is a monolithic, cervical or lumbar implant body, which serves to fuse spinal segments.

[0019] This implant body has upper and lower surfaces that are spaced accordingly, while maintaining a gap.

[0020] The top and bottom sides are connected by webs. With the exception of the shaping and structurally reinforcing edge areas, the top and bottom sides are designed as a surface, e.g., a honeycomb surface, with perforations and can include a wedge-forming angle.

[0021] At least one side surface is completely or partially open and serves to insert bone replacement material or bone chips.

[0022] Another side surface features a stabilizing area. This stabilizing area is represented by a reinforced bar connecting the top and bottom surfaces of the implant body. The side surface can be beveled at the transition to the bottom.

[0023] There is a recess in the stabilization area. This recess serves to accommodate a surgical instrument during implant placement.

[0024] Several pin-shaped or thorn-shaped projections with rounded tips extend from the surfaces of the shaping and structurally reinforcing edge regions toward adjacent spinal implants. In other words, these projections extend essentially perpendicularly from the corresponding surface of the structurally reinforcing edge region.

[0025] According to the invention, the recess for receiving a surgical instrument is designed as a continuous or interrupted round thread. This is preferably a round thread consisting of two radii that merge tangentially into one another. This prevents sharp edges, corners, or overhangs due to the flank shape on both the implant and the associated instrument.

[0026] Due to the fact that a round thread does not have any delicate flanks and has a large increase, such a thread is very robust, which is a significant advantage when placing the corresponding implant and handling the instruments.

[0027] Furthermore, the honeycomb wall thickness of the honeycomb structure is only a fraction of the honeycomb size. The honeycomb size is defined here as the distance between opposing honeycomb walls of a given honeycomb.

[0028] The preferred ratio between honeycomb wall thickness and honeycomb size is 1:10.

[0029] The thickness of the honeycomb walls can be varied to suit the loads acting on the implant. The honeycomb direction can be vertical or at a different angle. Likewise, some honeycomb walls can be deliberately omitted to create a partial passage corresponding to the area of ​​two or more honeycombs.

[0030] In a further development of the invention, the upper side has a spherical, essentially convex surface shape. The underside, however, is designed as an inclined surface.

[0031] The bevel angle here is essentially in the range of 0 to 15 degrees.

[0032] In one possible design of the implant body, the surface area of ​​the upper side is smaller than that of the lower side.

[0033] The stabilization area with recess and round thread is located essentially in the middle of the further side surface.

[0034] At least one of the bars connecting the top and bottom surfaces has a recess or recess for instrument guidance. Another, additional recess is positioned off-center and asymmetrically and, together with a correspondingly designed instrument, ensures the correct fixation of the implant on the instrument.

[0035] The aforementioned projections, which are preferably pin-shaped or thorn-shaped, are located in the corner areas of the implant body.

[0036] The processes are rounded at their free ends. This creates a rounded, non-wedge shape rather than a wedge-shaped point, but rather a spine or truncated cone with a rounded upper end. This design of the processes ensures that the implant is securely held in the adjacent vertebral body without creating a punctiform wedging effect that could potentially cause lasting damage to the corresponding vertebra.

[0037] At least one of the side surfaces, particularly the one opposite the side surface with the recess, is solid and forms a product identification area. This identification area serves to accommodate information about the manufacturer, the lot, and other details.

[0038] According to the invention, the monolithic cervical implant body, including the round thread, is additively manufactured solely by selective laser melting, without any subsequent machining processes or process steps. No rework, especially in the thread area, is required.

[0039] The invention will be explained in more detail below using exemplary embodiments and with the aid of figures.

[0040] Here we show: Fig. 1 a top view of the top side of an exemplary implant body; Fig. 2 a view of the further side surface with stabilization area and threaded recess; Fig. 3 a sectional view along the lines AA according to Fig. 2 with visible round thread; Fig. 4 a detailed view of the thread according to Fig. 3 (Detail A); Fig. 5 a side view of the implant body with an open surface for the insertion of bone replacement material, including recognizable projections on the top and bottom, as well as the spherical, convex surface shape of the top and the design of the bottom as a wedge or inclined surface; Fig. 6 a representation of the closed implant rear surface with the possibility provided there for product labeling; Fig. 7 a sectional view along the line BB according to Fig. 2also with recognizable round thread and extensions; Fig. 8 and 9 perspective representations of the implant body in different views; Fig. 10 exemplary representations of different bevel angles in the range of 4.2 to 12 degrees; Fig. 11 and 12 perspective representations in different views of a further embodiment of the implant body according to the invention with a smaller height extension compared to the embodiment according to the Fig. 1 to 9 ; Fig. 13Examples of round thread designs 1 to 5; and Fig. 14a, bRepresentations of an exemplary interrupted round thread.

[0041] Any dimensions given in the figurative representations are merely exemplary and should not be understood as limiting or restricting the scope of the invention. The same applies to scale information in the figurative representations.

[0042] The monolithic implant body 1 has a top side 2 and a bottom side 3.

[0043] The top and bottom sides are connected by webs 31.

[0044] With the exception of edge areas 4, which are shaping and structurally reinforcing, the upper side 2 and the lower side 3 are designed as a honeycomb surface, as is particularly the case with Figures 1, 3 , 8, 9 as well as 11 and 12.

[0045] The upper side 2 has, for example, a spherical shape 2 and the lower side 3 an inclined surface, wherein the different angles of the inclined surfaces, as in the Figure 10 shown, can be selected depending on the anatomical conditions. For example, angles from 4.2 to 12 degrees are possible.

[0046] Opposite side surfaces 5 are largely open so that replacement material or bone cement can be introduced into the inner space of the implant body.

[0047] Another side surface 6 has a stabilization area 7.

[0048] In the stabilization area 7 there is a recess, designed as a round thread 8. See the illustration according to Figure 3 with detail A to Figure 4 .

[0049] Starting from the surfaces of the shaping and structure-reinforcing edge regions 4, several pin-shaped projections 9 are present, oriented in the direction of adjacent spinal segments.

[0050] The honeycomb wall thickness 10 is only a fraction of the honeycomb size 11, which is defined as the distance between opposite honeycomb walls.

[0051] Preferably, for example, the honeycomb thickness is 0.15 mm and the honeycomb size is 1.5 mm, resulting in an exemplary ratio of 1:10.

[0052] It can be seen from the figures that the surface area of ​​the upper side 2 can be larger than the surface area of ​​the lower side 3.

[0053] The stabilizing area 7 with recess and round thread 8 is located essentially in the middle of the further side surface 6 as can be seen from the Figures 1 to 3 as well as 8 and 9, but also 11 can be traced.

[0054] In one of the webs 31, which connects the upper side 2 with the lower side 3, a recess or a recess 32 is formed for instrument guidance.

[0055] The projections 9 are preferably located in the corner areas of the respective implant body 1.

[0056] At least one of the side surfaces is closed and forms a product identification surface 13. The closed side surface, i.e. the product identification surface 13, is preferably realized opposite the stabilization area 7 with recess and round thread 8.

[0057] The implant body shown in the exemplary embodiments, including the round thread 8, is additively manufactured using selective laser melting. Machining or other shape-changing processes for machining or post-processing, particularly of the round thread, are not required.

[0058] With the help of the Figure 13 , each of which shows sectional views, an example for round thread designs 1-5 will be explained.

[0059] The sectional view with round thread 1 shows a thread root radius that is equal to the radius at the flank tip. There is a direct transition between the thread root radius and the radius at the flank tip.

[0060] In round threads of type 2, the thread root radius is larger than the radius at the flank crest. The flank is thin. Furthermore, there is a direct transition between the thread root radius and the flank crest radius.

[0061] In round threads of type 3, the thread root radius is larger than the radius at the flank crest. This results in a thin flank. Furthermore, there is a vertical area between the thread root radius and the flank crest radius. The flank angle here is approximately 0 degrees. The flank is perpendicular to the thread's longitudinal axis.

[0062] For round threads 4, the thread root radius is equal to the radius at the flank crest. The flank angle differs from 0 degrees.

[0063] For round threads 5, the thread root radius is equal to the radius at the flank tip. The flank angle deviates from 0 degrees.

[0064] The Figure 14a shows a perspective view of a recess with a round thread, wherein the round thread has interruptions 33. Therefore, this is an interrupted or segmented round thread for easier insertion of the associated instrument.

[0065] The Figure 14brepresents a longitudinal section of the view according to Figure 14a with noticeable interruptions 33.

Claims

1. A monolithic cervical or lumbar implant body (1) for fusing spinal column segments, comprising an upper side (2) and a lower side (3) which are spaced apart from one another while maintaining an intermediate space, wherein the upper side (2) and the lower side (3) are connected by webs (31), furthermore the upper side (2) and the lower side (3), with the exception of shape-defining and structure-reinforcing edge regions (4), are designed as a surface having openings and enclose an angle, at least one completely or partially open side surface (5) for introducing bone substitute material, and a further side surface (6) having a stabilisation region (7) and a recess for temporarily receiving a surgical instrument in the stabilisation region, characterized in that the recess is formed as a continuous or interrupted round thread (8).

2. The monolithic cervical or lumbar implant body according to Claim 1, characterized in that the surface is configured as a honeycomb surface, and the honeycomb wall thickness (10) is a fraction of the honeycomb size (11), defined as the distance between opposite honeycomb walls, preferably in a ratio of substantially 1:10 between the honeycomb wall thickness (10) and the honeycomb size (11).

3. The monolithic cervical or lumbar implant body according to Claim 1 or 2, characterized in that starting from the surfaces of the shape-defining and structure-reinforcing edge regions (4), several pin-shaped or mandrel-shaped protrusions (9) extend in the direction of adjacent spinal column segments.

4. The monolithic cervical or lumbar implant body according to one of the preceding claims, characterized in that the upper side (2) has a spherical, convex surface shape, and the lower side (3) is configured as an inclined surface.

5. The monolithic cervical or lumbar implant body according to Claim 4, characterized in that the inclined surface angle lies in the range between substantially 1 and 15 degrees, preferably between 4 and 12 degrees.

6. The monolithic cervical or lumbar implant body according to one of the preceding claims, characterized in that the surface dimension of the upper side (2) is smaller than the surface dimension of the lower side (3).

7. The monolithic cervical or lumbar implant body according to one of the preceding claims, characterized in that the stabilisation region (7) having the recess and the round thread (8) is located substantially centrally in the further side surface (6).

8. The monolithic cervical or lumbar implant body according to one of Claims 3 to 7, characterized in that in at least one of the webs (31) connecting the upper side and the lower side (2; 3), a recess or a setback (12) is formed for guiding an instrument.

9. The monolithic cervical or lumbar implant body according to one of Claims 3 to 8, characterized in that the protrusions (9) are respectively located in the corner regions of the implant body (1).

10. The monolithic cervical or lumbar implant body according to one of the preceding claims, characterized in that at least one side surface is embodied in a closed manner and forms a product labelling surface (13).

11. The monolithic cervical or lumbar implant body according to Claim 8, characterized in that the closed side surface lies opposite the stabilisation region (7) having the recess and the round thread (8).

12. The monolithic cervical or lumbar implant body according to one or more of the preceding claims, characterized in that it is additively manufactured including the round thread (8) free of machining methods by selective laser melting.