Bone anchors and methods for their manufacture

Abstract

Method for manufacturing a bone dowel (1) for attaching an endogenous or exogenous object to a bone structure of a living being, wherein the bone dowel (1) is predominantly or entirely formed from cortical bone material of a living being, wherein the bone dowel (1) has a base body (2) which is essentially cylindrical, wherein the bone dowel (1) is designed as a fastening system for attaching the endogenous or exogenous object to the bone structure of the living being, characterized in that, from a provided starting body which is predominantly or entirely formed from cortical bone material of a living being, in at least one processing step which is carried out under sterile conditions,Material is removed by water jet cutting, thereby producing the bone dowel (1) with its essentially cylindrical base body, which serves as a fastening system for attaching the body's own or foreign object to the bone structure of the living being.

Description

[0001] The invention relates to a bone anchor for attaching an object, whether from the body or from another body, to a bone structure of a living being. The invention also relates to a method for manufacturing such a bone anchor.

[0002] In orthopedics and trauma surgery, for example, metal plates and screws are used for the surgical fixation of objects. There are also proposals for bioresorbable screws, such as those made of magnesium. The products formed during bioresorption can have negative effects in the body. Bone graft screws, made from bone material from a living organism, are also now in use. This achieves optimal biocompatibility. The mechanical durability of such bone graft screws is lower than that of metal screws. Furthermore, threads must first be created in the patient's bone at the site where the bone graft screw is to be attached. This places additional stress on the patient's bone. Creating an internal thread in the bone can also increase the tendency for bone fractures.

[0003] Products made from bone material, such as the Tutofix® interference screw, are known from the company Tutogen Medical GmbH.

[0004] The invention is based on the objective of providing improved possibilities for attaching an object to a bone of a living being.

[0005] This problem is solved by a bone dowel for attaching an object, whether from the body or from another source, to the bone structure of a living being, wherein the bone dowel is predominantly or entirely formed from cortical bone material of a living being. According to the invention, a fastening system for attaching the object to the bone structure of the living being is thus proposed, which is designed as a dowel. As is known, a dowel can be inserted directly into a bore without the need for threads. In this way, the burden on the patient can be minimized, since only a bore needs to be drilled into their bone structure, and no additional thread needs to be cut.

[0006] Another advantage of the invention is that the mechanical stresses on the bone structure when inserting the bone dowel are considerably lower compared to a screw, especially in a direction transverse to the longitudinal extension direction, in which bone structures are particularly sensitive due to their structure.

[0007] The bone dowel is suitable, for example, for attaching an object from the body to the bone structure of the same organism, such as a tendon. It is also possible to attach a foreign object to the bone structure using the bone dowel, for example, a plate.

[0008] Advantageously, the bone anchor is predominantly or entirely composed of cortical bone material from a living organism. Cortical bone material is relatively stable and has high compressive strength. Therefore, such bone material is particularly suitable for fastening objects. The cortical bone material can be the organism's own bone material into which the bone anchor is to be inserted. Alternatively, the cortical bone material can be donor material, i.e., from another living organism. In the case of donor material, it can be sterilized to prevent a rejection reaction in the organism's body. Sterilization can be achieved, for example, using a peracetic acid-ethanol process.

[0009] The bone dowel can be designed as a rotationally symmetrical body.

[0010] According to an advantageous embodiment of the invention, the bone dowel is made of a compression-resistant material having a compressive strength of at least 20 N / mm². 2 exhibits, in particular at least 50 N / mm 2 This has the advantage that the bone dowel can be used in many applications and has sufficient stability for attaching various types of objects to the bone structure of the living being.

[0011] According to an advantageous embodiment of the invention, the bone dowel is machined, at least on its outer circumference, using a subtractive and / or additive manufacturing process. Accordingly, the bone dowel is machined, at least on its outer circumference, using such a manufacturing process after its initial production. The manufacturing process allows the external shape of the bone dowel to be adapted as desired, for example, with a specific texture. A clamping manufacturing process can be used as a subtractive manufacturing process, and it is advantageous to use a process that does not generate excessive heat, particularly when working with living bone tissue. For example, the bone dowel can be machined using a waterjet cutting process.

[0012] According to an advantageous embodiment of the invention, the bone dowel has one or more radially projecting retaining structures distributed around its outer circumference. This has the advantage that the bone dowel can be anchored particularly securely in the bone structure of the living being, even without a thread. A retaining structure can, for example, have a wedge-shaped geometry in cross-section, similar to a barb.

[0013] According to an advantageous embodiment of the invention, one, several, or all of the retaining structures are designed as circumferential structures. Such a retaining structure can, for example, be ring-shaped, surrounding a base body of the bone dowel around its longitudinal axis.

[0014] According to an advantageous embodiment of the invention, one, several, or all of the retaining structures are asymmetrically shaped in a longitudinal section through the bone dowel. This ensures secure fixation of the bone dowel in a bore in the bone structure. In particular, it prevents the bone dowel from slipping out of the bore. The bone dowel can, for example, have a front end face with which it is inserted into the bore. When the bone dowel is inserted into the bore, a rear end face, facing away from the front end face, can also be visible. In longitudinal section, a retaining structure can then, for example, be wedge-shaped, with the wedge tip pointing towards the front end face of the bone dowel.

[0015] According to an advantageous embodiment of the invention, the bone dowel has a base body that is essentially cylindrical, with one, several, or all retaining structures projecting radially from the base body by an amount that is at least 5% of the diameter of the base body. In this way, the retaining structures are larger than a simple surface roughness on the outer surface of the bone dowel. The retaining structures can also project radially from the base body by an amount that is at least 10%, at least 15%, or at least 20% of the diameter of the base body.

[0016] According to an advantageous embodiment of the invention, the bone dowel is designed as an expansion dowel. This expansion function allows the bone dowel to be anchored particularly firmly in a borehole in the bone structure of the living being. Such an expansion dowel can be expanded, at least partially, in a radial direction to ensure particularly secure fixation in a borehole.

[0017] According to an advantageous embodiment of the invention, the bone anchor has an internal cavity for receiving an expansion element. By inserting the expansion element into the internal cavity, the bone anchor can be expanded to securely anchor it in the borehole. The expansion element can be, for example, a screw, particularly a setscrew, or a wedge. The internal cavity can extend, for example, from one end face of the bone anchor longitudinally towards an opposite end face. The length of the internal cavity in the longitudinal direction of the bone anchor can be, for example, at least 40%, at least 50%, at least 60%, or at least 70%, but at least 80% of the length of the bone anchor.

[0018] According to an advantageous embodiment of the invention, at least one section of the inner cavity extends completely transversely through the bone dowel. In this way, the bone dowel is divided by the inner cavity into several lamellae that can be easily spread apart.

[0019] According to an advantageous embodiment of the invention, at least one section of the inner cavity is designed as a slot-shaped cavity, which has a single slot or several slots, in particular several intersecting slots and / or several star-shaped slots. This allows for multiple adaptations of the bone dowel to the respective fastening task. Such a slot-shaped cavity can, in particular, extend completely transversely through the bone dowel.

[0020] According to an advantageous embodiment of the invention, a first inner cavity extends from a first end face of the bone dowel towards a second end face of the bone dowel, and a second inner cavity extends from a second end face of the bone dowel towards the first end face of the bone dowel. This has the advantage that an expansion element can be inserted from each of the two end faces of the bone dowel. This allows for particularly secure fixation of the bone dowel in the bore. The second end face can be the end face of the bone dowel facing away from the first end face. The first inner cavity and the second inner cavity thus converge longitudinally along the bone dowel. The first cavity can meet the second cavity, resulting in an open inner region of the bone dowel in which the first cavity transitions into the second cavity.The first and second cavities can also be formed without such a transition area, i.e., they do not meet.

[0021] According to an advantageous embodiment of the invention, the bone anchor has a base body that is essentially cylindrical, wherein the inner cavity has a maximum dimension of diameter or width that is less than 40% of the diameter or width of the base body. This maximum dimension thus extends perpendicular to the longitudinal direction of the bone anchor. The maximum dimension can also be less than 30%, 20%, or 15% of the diameter of the base body.

[0022] The aforementioned problem is also solved by a method for manufacturing a bone dowel of the type described above, in which a starting material is provided from cortical bone material of a living being, and material is removed from the starting material in at least one processing step, in particular by waterjet cutting. This allows for a particularly efficient manufacturing process for the bone dowel. The bone dowel can also be manufactured to measure for the individual patient shortly before its use, for example, in a hospital.

[0023] In principle, any type of waterjet cutting can be used, both with and without abrasives. Either injection waterjet cutting or suspension waterjet cutting can be used, even in combination, when manufacturing the same bone anchor.

[0024] According to an advantageous embodiment of the invention, at least one processing step is carried out under sterile conditions. Accordingly, the bone anchor can already be provided as a sterile product, for example in sterile packaging.

[0025] The insertion of a bone anchor in a patient can be performed as follows. First, a hole is drilled into the bone structure where the bone anchor is to be placed, creating a clearance fit with the anchor. The bone anchor, along with the object to be secured, is then attached to the bone structure, possibly with an additional fastening element such as an expansion wedge or a screw.

[0026] For the purposes of the present invention, the indefinite term "a" is not to be understood as a numeral. Therefore, when, for example, a component is mentioned, this is to be interpreted as "at least one component". Where angles are specified in degrees, these refer to a circle of 360 degrees (360°).

[0027] The invention is explained in more detail below with reference to exemplary embodiments and drawings.

[0028] They show Fig. 1 to Fig. 2 a first embodiment of a bone dowel and Fig. 3 to Fig. 4 a second embodiment of a bone dowel and Fig. 5 to Fig. 6 a third embodiment of a bone dowel and Fig. 7 a cross-sectional view of another embodiment of a bone dowel.

[0029] The Fig. 1 to Fig. Figure 6 shows different perspective views of the bone dowel.

[0030] The Fig. 1 and Fig. Figure 2 shows a bone dowel 1, which has a substantially cylindrical base body 2 from which several longitudinally L arranged ring-shaped retaining structures 3 project radially. The bone dowel 1 has a first end face 4, which can also be referred to as the front end face, and a second end face 5 facing away from it, which can also be referred to as the rear end face. The bone dowel 1 is designed to be inserted into a bore in a bone structure of a living being with the first end face 4 facing forward. The retaining structures 3 are designed such that they have a shallower slope in the insertion direction, i.e., towards the first end face 4, than in the opposite direction. This ensures good retention of the bone dowel 1 in the bore.

[0031] The in the Fig. 1 and Fig. The embodiment of the bone anchor 1 shown in Figure 2 has a solid base body 2, meaning that the base body 2 has no internal cavity. Accordingly, the bone anchor 1 is not designed as an expansion anchor. The four holding structures 3 shown as examples are only one possible embodiment; depending on the application, more or fewer holding structures 3 may be present. The holding structures 3 may also have other profile shapes, in particular rounded contours.

[0032] The Fig. 3 to Fig. Figure 4 shows an embodiment of a bone anchor 1 designed as an expansion anchor. By way of example, a first inner cavity 7 is shown, extending from the first end face 4 into the interior of the base body 2. Additionally, a second inner cavity 6 is shown, extending from the second end face 5 into the interior of the base body 2. In this embodiment, both the first inner cavity 7 and the second inner cavity 6 are designed as slot-shaped cavities, extending completely through the base body 2 and the retaining structures 3 in the transverse direction. The second inner cavity 6 is arranged at an angular offset from the first inner cavity 7, for example, rotated by 90 degrees.

[0033] In this case, both the first inner cavity 7 and the second inner cavity 6 have a longitudinal extension in the longitudinal direction L of the bone dowel 1 that is more than half the length of the bone dowel 1. The inner cavities 6, 7 therefore meet in a certain area and merge into one another, so that a common cavity results in this area.

[0034] The Fig. 5 and Fig. Figure 6 shows an embodiment of a bone dowel 1, which is also designed as an expansion dowel. In this case, in addition to the second inner cavity 6, which can be configured as described above, a third inner cavity 8 is present, which also extends into the base body 2 from the second end face 5. The third inner cavity 8 is also slot-shaped. The third inner cavity 8 extends completely through the base body 2 and also through the retaining structures 3 in the transverse direction. The third inner cavity 8 has an angular offset from the second inner cavity 6, for example by 90 degrees. In this way, a bone dowel 1 with a cross slot is realized.

[0035] As one can imagine, the inner cavities 6, 7, 8 can also be shaped differently, for example arranged in a star shape from only one end face or from both end faces.

[0036] The expansion of the respective expansion anchors according to the Fig. 3 to Fig. 6 can be achieved, for example, by inserting an expanding element such as a screw or an expanding wedge into the respective inner cavity 6, 7, 8, thereby widening the respective slot-shaped cavities slightly.

[0037] The Fig. Figure 7 shows, using the example of the bone dowel 1, according to the Fig. 1 to Fig. 2 a cross-sectional view in which further features are illustrated by means of dimensions.

[0038] The base body 2 has a diameter d, which can also be referred to as the inner diameter of the bone dowel 1. The retaining structures 3 project from this base body 2, or from the inner diameter d, by a certain amount, so that they form an outer diameter D. The respective retaining structures 3 can, for example, project from the base body 2 by a distance D / 2, which is at least 5% of the diameter d, or at least 10%, or at least 15%, or at least 20%.

[0039] In an exemplary implementation, the outer diameter D can be, for example, 3 mm. The distance between adjacent retaining structures 3 can be, for example, 1.5 mm. With the wedge-shaped designs of the retaining structures 3 shown, the engagement angle α can be, for example, in the range of 2 degrees to 30 degrees, and the flank angle β, for example, in the range of 2 degrees to 65 degrees.

[0040] To attach the bone dowel 1, for example, with a clearance fit in a bore of the bone structure, the bore can be produced with an interference of 20 µm, that is, D Bohrung = D + 20 µm.

Claims

[1] Bone dowel (1) for fastening an object of the body or of a foreign origin to a bone structure of a living being, wherein the bone dowel (1) is formed predominantly or entirely from cortical bone material of a living being. [2] Bone dowel according to claim 1, characterized by , that the bone dowel (1) is made of a compression-resistant material having a compressive strength of at least 20 N / mm² 2 exhibits. [3] Bone dowel according to any one of the preceding claims, characterized by , that the bone dowel (1) is machined at least on its outer circumference using a subtractive and / or additive manufacturing process. [4] Bone dowel according to any one of the preceding claims, characterized by that the bone dowel (1) has one or more radially projecting retaining structures (3) distributed around its outer circumference. [5] Bone dowel according to claim 4, characterized by, that one, several or all of the holding structures (3) are designed as structures that completely circumferentially. [6] Bone dowel according to one of claims 4 to 5, characterized by , that one, several or all of the holding structures (3) are asymmetrically formed in a longitudinal section through the bone dowel (1). [7] Bone dowel according to any one of claims 4 to 6, characterized by , that the bone dowel (1) has a base body (2) which is essentially cylindrical, wherein one, several or all retaining structures (3) project from the base body (2) in a radial direction by a distance (D / 2) which is at least 5% of the diameter (d) of the base body (2). [8] Bone dowel according to any one of the preceding claims, characterized by , that the bone dowel (1) is designed as an expansion dowel. [9] Bone dowel according to claim 8, characterized by, that the bone dowel (1) has an internal cavity (6, 7, 8) for receiving an expansion element. [10] Bone dowel according to claim 9, characterized by , that at least one section of the inner cavity (6, 7, 8) extends completely through the bone dowel (1). [11] Bone dowel according to one of claims 9 to 10, characterized by , that at least one section of the inner cavity (6, 7, 8) is designed as a slot-shaped cavity having a single slot or several slots, in particular several intersecting slots and / or several star-shaped slots. [12] Bone dowel according to any one of claims 9 to 11, characterized by, that a first inner cavity (7) extends from a first end face (4) of the bone dowel (1) towards a second end face (5) of the bone dowel (1) and a second inner cavity (6) extends from a second end face (5) of the bone dowel (1) towards the first end face (4) of the bone dowel (1). [13] Bone dowel according to any one of claims 9 to 12, characterized by , that the bone dowel (1) has a base body (2) which is substantially cylindrical, wherein the inner cavity (6, 7, 8) has a maximum dimension of diameter or width which is less than 40% of the diameter (d) or width of the base body (2). [14] Method for manufacturing a bone dowel (1) according to any one of the preceding claims, characterized by, that a starting body is provided from cortical bone material of a living being and that material is removed from the starting body in at least one processing step, in particular by water jet cutting. [15] Method according to claim 14, characterized by that at least one processing step is carried out under sterile conditions.

Images