olecranon bone plate

Description

[0001] The invention relates to a bone plate suitable for the treatment of fractures, non-unions and for osteotomies of the olecranon and the proximal ulna according to the preamble of claim 1,

[0002] Proximal ulna / olecranon fractures are relatively common injuries in adults and can lead to severe functional impairment resulting from post-traumatic instability, impingement, soft tissue contractures, malunion, or nonunion. High-energy injuries can result in associated distal injuries, such as forearm and distal radius fractures, fractures involving the intraosseous membrane, or disruption of the distal radioulnar joint. Monteggia fractures are fractures of the proximal third of the ulna with associated radial head dislocation.

[0003] The bone plate according to the invention is intended for use in open reduction and internal fixation (ORIF) of the olecranon and proximal ulna. It is indicated for fractures, osteotomies, and nonunions of the olecranon and proximal ulna.

[0004] From US 8,182,517 a bone plate for the internal fixation of a fracture of the proximal ulna is known, which has a narrow, proximal head part which is bent relative to the wider, distal shaft part and has one or two bore(s) arranged on the longitudinal central axis of the bone plate.

[0005] However, this known bone plate has the disadvantage that the curved head portion is short and narrow relative to the shaft portion, so it cannot be used to treat all intra-articular fractures. Furthermore, it is difficult to properly fixate the fragments in the event of a fracture using just one screw (or two longitudinally arranged screws).

[0006] A bone plate having the features of the preamble of claim 1 is known from EP 3 808 295 A1.

[0007] This invention aims to remedy this situation. The invention is based on the objective of creating a bone plate for the olecranon that allows the treatment of any type of fracture.

[0008] The invention solves the stated problem with a bone plate having the features according to claim 1; and a combination of a bone plate according to the invention with at least one polyaxial bone screw having the features according to claim 14.

[0009] The advantages achieved by the invention are essentially that, thanks to the inventive bone plate with a widened head section equipped with three screw holes, a fractured olecranon can be optimally supported. The two screw holes located to the left and right of the central axis allow two screws to be placed almost parallel to the shaft section, ensuring optimal engagement of all intermediate fragments and achieving optimal mechanical stability.

[0010] Further advantageous embodiments of the invention can be commented on as follows: In a particular embodiment of the bone plate according to the invention, the proximal head portion has a third bore with a bore axis that is centered on the central axis. This additional third bore allows the bone plate to treat virtually all possible fractures. For example, this third, most proximally located bore can also be used to treat a simple intra-articular olecranon fracture. In this case, rarely are all three proximal bores equipped with bone screws, as otherwise the space would be too tight. However, depending on the fracture, the surgeon has a choice as to where to place a screw in the head portion.

[0011] The length LK of the proximal head portion, which is bent relative to the shaft portion, is at least 20%, preferably at least 25%, of the length Ls of the shaft portion. The relatively long head portion allows for support of the entire proximal olecranon.

[0012] In a further embodiment, the free proximal end of the head part is bent relative to the distal shaft part by at least 70°, preferably by at least 80°.

[0013] In a special design, the two bore axes converge distally, and the angle a is greater than 1°, preferably greater than 4°. This ensures that the polyaxial screws, when inserted at a zero-degree angle to the bore axis, cannot be shot into the joint.

[0014] In a non-claimed embodiment, the centers of all plate holes in the distal shaft part are at most 2 mm away from the central axis.

[0015] In a particular embodiment, at least one of the holes or plate holes has an inner wall made of a material with a hardness of HP. Furthermore, a hollow cylindrical or hollow conical insert is mounted in the plate hole, which at least partially rests against the inner wall and is suitable for receiving the head of a bone screw. The insert is arranged in the plate hole in a rotationally secured manner and is made of a material with a hardness of HE < HP. This allows the insertion of a locking screw into the circular plate holes.

[0016] In a non-claimed embodiment, the distal shaft part has an elongated hole for exerting axial or interfragmentary compression.

[0017] In a non-claimed embodiment, the distal shaft portion has a thread hole with a smaller diameter than the diameter of the bores, which is suitable for securing surrounding soft tissue to the bone plate. The thread hole is expediently located between the elongated hole and the proximally closest plate hole.

[0018] In a particular embodiment, the average thickness of the bone plate in the transition zone between the distal shaft part and the proximal head part is smaller than the average thickness of the distal shaft part, preferably 10% smaller.

[0019] In a further embodiment, a constriction is provided at least between two plate bores of the distal shaft portion, so that the width is preferably reduced by at least 20%, which facilitates bending of the bone plate by the surgeon. The area moment of inertia of the plate cross-section at the narrowest point of the constriction advantageously essentially corresponds to the area moment of inertia of the plate cross-section in the area of ​​the largest diameter of the adjacent plate bore. The bone plate can thus be bent equally well throughout, and no weak points develop under continuous loading.

[0020] In a further embodiment of the bone plate according to the invention, the proximal head portion has a through hole for receiving a Kirschner wire, the hole axis of which preferably runs parallel to one of the bore axes. This allows the fracture to be reduced and held, and the optimal screw alignment to be defined.

[0021] Advantageously, the distal shaft part is free of lateral wings running transversely to the central axis, in particular those with a screw hole.

[0022] In a non-claimed embodiment of the bone plate according to the invention, the length LK of the proximal head part bent relative to the shaft part is in the range of 16 - 24 mm, preferably in the range of 17 - 23 mm.

[0023] The bone plate according to the invention can also be made mirror-inverted.

[0024] The bone plate according to the invention can be provided both as such and in combination with at least one polyaxial bone screw, e.g. in the form of a sterile kit.

[0025] The bone plate according to the invention is particularly suitable for the treatment of fractures, non-unions and for osteotomies of the olecranon and the proximal ulna.

[0026] The invention and further developments of the invention are explained in more detail below with reference to the partially schematic representations of an embodiment.

[0027] They show: Fig. 1 a side perspective view of an embodiment of the bone plate according to the invention; Fig. 2 a frontal perspective view of the Fig. 1 illustrated embodiment; Fig. 3 another perspective view from above of the Fig. 1 illustrated embodiment; and Fig. 4 a side view of the Fig. 1 illustrated embodiment,

[0028] The Fig. 1 bis 4 The embodiment shown shows a bone plate 1 for the treatment of fractures, non-unions and for osteotomies of the olecranon and the proximal ulna.

[0029] As in Fig.1 As shown, the bone plate 1 consists of a distal longitudinal shaft part 2 and an adjoining proximal head part 4. The length of the proximal head part 4, which is bent relative to the shaft part 2, is approximately 20 mm, which corresponds to approximately 30% of the length of the shaft part 2.

[0030] The distal shaft part 2 has four plate holes 11 and a slotted hole 9 arranged along the central axis 3. The bone plate 1 has a longitudinal central axis 3.

[0031] The centers of all plate holes 11 and the elongated hole 9 in the distal shaft part 2 are located on the central axis 3. The distal shaft part 2 also has a thread hole 10 for receiving a thread with which surrounding soft tissue can be fixed to the bone plate 1.

[0032] The suture hole 10 is located between the elongated hole 9 and the proximally closest plate hole 11. The elongated hole 9 is located between the three proximal plate holes 11 and the fourth distal plate hole 11. The most distal region of the shaft part 2 is beveled and has a through hole 13 for receiving a Kirschner wire.

[0033] Between two plate holes 11 of the distal shaft part 2, which has a width of 10.4 mm, there is a constriction 12 which reduces the shaft width in this area to 7.5 mm.

[0034] The head part 4 is bent relative to the distal shaft part 2. Fig. 4 It can be seen that the most proximal area of ​​the head part 4 has an angle of approximately 90° to the shaft part 2. The head part 4 is also wider than the shaft part 2.

[0035] The thickness of the bone plate 1 in the transition zone between the distal shaft part 2 and the proximal head part 4 is smaller than the average thickness of the distal shaft part 2 of 3.2 mm and varies between 2.5 - 2.8 mm.

[0036] The proximal head part 4 has a total of three bores 5, 6 and 14, with two of the three bores 5, 6 being arranged on opposite sides of the central axis 3 and the third bore 14 being arranged on the central axis 3. The bores 5, 6 located on opposite sides of the central axis 3 have bore axes 7, 8 that converge distally and enclose an angle α of 7°. The two bores 5, 6 are designed such that they are suitable for accommodating both (i) polyaxial locking screws at an angle of ±15° to their respective bore axes 7; 8, and (ii) non-locking standard screws.

[0037] The head part 4 also has two through holes 13 for receiving a Kirschner wire; one through hole 13 is arranged distally to the centrally arranged third bore 14 and the second through hole 13 is located distally between the two bores 5, 6 arranged to the right and left of the central axis 3.

[0038] As a variant to the embodiment according to the Figuren 1 - 4 The distal shaft part 2 can have eight plate holes 11 instead of four, three of which are located proximal to the elongated hole 9 and the remaining five distal to the elongated hole 9. In this bone plate with an extended shaft part 2, the length of the proximal head part 4, which is bent relative to the shaft part 2, is approximately 15% of the length of the shaft part 2.

Claims

1. Bone plate (1) suitable for the treatment of fractures, non-unions and for osteotomies of the olecranon and the proximal ulna, with A) a distal longitudinal shaft part (2), which has a number of plate holes (11); B) a longitudinal central axis (3); C) a proximal head part (4), which is widened relative to the distal shaft part and has two bores (5; 6) arranged on opposite sides of the central axis (3) with the bore axes (7, 8); wherein D) the head part (4) is bent with respect to the shaft part (2); and E) the two bores (5, 6) are suitable for receiving (i) a polyaxial locking screw at an angle of ±15° relative to the respective bore axis (7;8); or (ii) a non-locking standard screw; characterized in that F) the two bore axes (7, 8) converge distally and include an angle α greater than 1°.

2. Bone plate (1) according to claim 1, characterized in that the proximal head part (4) has a third bore (14) with the bore axis (15), which is arranged centrally to the central axis (3).

3. Bone plate (1) according to claim 1 or 2, characterized in that the length LK of the proximal head part (4), which is bent with respect to the shaft part (2), is at least 20%, preferably at least 25%, of the length LS of the shaft part (2).

4. Bone plate (1) according to one of claims 1 to 3, characterized in that the free proximal end of the head part (4) is bent by at least 70°, preferably by at least 80°, with respect to the distal shaft part (2).

5. Bone plate (1) according to one of claims 1 to 4, characterized in that the angle α is greater than 4°.

6. Bone plate (1) according to one of claims 1 to 5, characterized in that at least one of the bores (5, 6) or the plate bores (11) has an inner wall made of a material which has a hardness HP, and in that a hollow cylindrical or hollow conical insert is mounted in the plate bore, which insert at least partially abuts against the inner wall and is suitable for receiving the head of a bone screw, the insert being arranged in the plate bore in a non-rotatable manner and consisting of a material which has a hardness HE < HP.

7. Bone plate (1) according to one of claims 1 to 6, characterized in that the distal shaft part (2) has a thread hole (10) with a smaller diameter compared to the diameter of the bores (5, 6) and which is suitable for fixing surrounding soft parts to the bone plate (1).

8. Bone plate (1) according to one of claims 1 to 7, characterized in that the average thickness of the bone plate (1) in the transition zone between the distal shaft part (2) and the proximal head part (4) is smaller than the average thickness of the distal shaft part (2), preferably 10% smaller.

9. Bone plate (1) according to one of claims 1 to 8, characterized in that a constriction (12) is provided at least between two plate bores (11) of the distal shaft part (2), so that the width of the distal shaft part (2) is preferably reduced by at least 20%.

10. Bone plate (1) according to one of claims 1 to 9, characterized in that the proximal head part (4) has a through hole (13) for receiving a Kirschner wire, the hole axis of which preferably runs parallel to one of the bore axes (7, 8, 15) of the bores (5, 6, 14).

11. Bone plate (1) according to one of claims 1 to 10, characterized in that the distal shaft part (2) is free from lateral wings extending transversely to the central axis (3), in particular from wings with a screw hole.

12. Bone plate (1) according to one of claims 1 to 11, characterized in that its geometry is adapted to the anatomy of the right-sided ulna (1).

13. Bone plate (1) according to claim 12, characterized in that its geometry is adapted to the left-sided ulna (1) in a mirror-inverted manner.

14. Combination of a bone plate (1) according to any one of claims 1 to 13 and at least one polyaxial bone screw.

15. Bone plate (1) according to any one of claims 1 to 13, suitable for the treatment of fractures and non-unions of the olecranon and the proximal ulna as well as osteotomies thereof.