MEDICAL IMPLANT FOR OSTEOSYNTHESIS

Description

[0001] The invention relates to a medical implant for the osteosynthesis of symphysis ruptures in the human pelvis, comprising a cranial plate designed to be attached from a cranial side to a first pubic bone and a second pubic bone of a patient to be treated, in order to connect the pubic bones. The invention further relates to a method for the osteosynthesis of a symphysis rupture in a training body for training purposes.

[0002] In recent decades, the development of various surgical techniques and the treatment of bone fractures using implants, such as intramedullary nails or osteosynthesis procedures using plates, has progressed steadily. Nevertheless, there are areas where further development has stagnated.

[0003] The injury patterns of polytrauma patients, and especially fractures of the pelvic ring, continue to pose significant challenges for trauma surgery. Although treatment has steadily improved in recent decades, many strategies remain insufficiently validated or have stagnated in their further development. Due to their high mortality rate, pelvic ring fractures are of paramount importance with regard to stabilization and treatment.

[0004] For osteosynthesis, that is, the surgical joining of two bones, a simple plate implant is often used to treat pelvic ring fractures. This implant is placed cranially, or on the head side, on the iliac crest. Ruptures of the pubic symphysis (symphysis joint) of the human pelvis are also treated today with simple plate implants. In this case, the plate implant is attached from a cranial side to the first and second pubic bones of the patient being treated, thus connecting the two hemispheres of the pelvis. Due to the high physiological stress, implant failure, such as deformation or loosening of the implant, is common with these simple plate implants.

[0005] Furthermore, it is also known to use implants for the treatment of pelvic ring fractures that are more complex in design than simple plates. RU 2 739 692 discloses a plate system for the reconstruction of old pelvic ring fractures in male patients. The disclosed implant has a cranial plate connected to a U-shaped second plate. The second plate is designed to be applied externally to the pelvic bones to be joined. A disadvantage of the disclosed implant is that it is intended only for the treatment of male patients and that the second plate must be attached to the pelvis externally. When treating symphysis pubis ruptures, the abdominal muscles attached to the outside of the pelvis can cause significant discomfort for the patient.Furthermore, the externally attached plate obstructs the surgeon's view of the symphysis, thereby increasing the risk of incorrect implant placement. Osteosynthesis with the proposed implant can only be performed by highly experienced surgeons.

[0006] Furthermore, plate systems for the treatment of pelvic ring fractures are known from CN 205126393 U and CN 204995566 U, but these are not suitable for the treatment of symphysis ruptures. The implant disclosed in CN 205126393 U is intended for the osteosynthesis of fractures of the acetabulum, while the plate disclosed in CN 204995566 U is intended for the osteosynthesis of fractures of the sacroiliac joint. Typical problems associated with the osteosynthesis of symphysis ruptures, such as the correct adjustment of the symphyseal distance between the pubic bones, do not need to be considered in fractures of the acetabulum and the sacroiliac joint, since the bones to be fused can simply be aligned. Implantation is hardly, if at all, hindered by any visual obstruction to the surgeon.

[0007] The "PRO Pelvis and Acetabulum System" is a well-known product from the company Stryker. For the treatment of acetabular fractures, the system includes "PRO quadilateral surface plates" that are applied to the acetabulum from within the pelvic ring. Unlike the pubic symphysis, for which the PRO Pelvis and Acetabulum System only offers simple plates, the acetabulum is considerably more accessible and visible during surgical treatment, especially since the approach is usually from the patient's abdomen, allowing an oblique view of the acetabulum.

[0008] RU 14 498 U1 discloses an implant for the osteosynthesis of symphyseal ruptures comprising two plate-like elements connected to each other via right-angled sections.

[0009] The object of the present invention is to provide a medical implant for the osteosynthesis of symphyseal ruptures in the human pelvis, which, compared to the prior art, has improved reliability against implant failure and can be used in a more patient-friendly manner, as well as enabling simplified implantation.

[0010] The invention solves the problem in a medical implant of the type mentioned above by means of a posterior plate designed to be attached from a posterior side to the first and second pubic bones of the patient in order to connect the pubic bones, wherein the cranial plate and the posterior plate are connected to each other by at least one first connecting arm. The posterior side is the side of the pubic bones facing the inner surface of the pelvic ring. In the region of the pubic symphysis, the posterior side of the pubic bones faces the sacrum of the patient. The cranial side is the side facing the patient's head. The implant according to the invention can therefore be applied to the pubic bones of the patient being treated from the inside and above during the osteosynthesis of a symphysis rupture.The inventors have discovered that it is possible to apply a posterior plate from the posterior side of the pubic bones. This prevents any impairment of the patient's abdominal muscles that attach to the pubic bones from the outside. Furthermore, common problems associated with implant failure, such as the fracture of a simple plate implant, are overcome. This is achieved through a more even distribution of forces by the plates connected via the connecting arm. This allows for optimal transfer of forces and torque to the screws, preventing loosening of the implant. Additionally, the connecting arm ensures optimal alignment of the posterior and cranial plates relative to each other. The medical implant can therefore be applied particularly easily and safely, enabling a gentler treatment for the patient.Preferably, the posterior plate and / or the cranial plate are designed to lie substantially flat (over the entire surface of the plates) against the patient's pubic bones. It should be understood that the plates maintain full contact even when the symphysis is bridged. Preferably, the posterior plate and / or the cranial plate are adapted to the general geometry of the human pubic bones. During osteosynthesis, a plate applied from the posterior side allows the surgeon an unobstructed view of the symphysis. The implantation of the device according to the invention is thus considerably simplified.

[0011] The connecting arm joins the cranial plate and the posterior plate. Preferably, the cross-section of the connecting arm differs from, and is in particular smaller than, the cross-section of the posterior plate and / or the cranial plate. Preferably, the medical implant is L-shaped in a sagittal plane. The connecting arm is more preferably fully or partially flexible. However, it is also possible for the connecting arm to be fully or partially rigid. A connecting arm is rigid if it is not significantly deformed during normal handling in the context of osteosynthesis. A flexible connecting arm is reversibly deformable, in particular by forces caused by the implant's own weight. The connecting arm can preferably be arc-shaped, in particular circular arc-shaped, and / or (multi-)angular.The medical implant can be used for both partial and complete symphysis ruptures.

[0012] According to a first preferred embodiment, the first connecting arm is an eccentric connecting arm with respect to the posterior and cranial plates; that is, it is preferably arranged eccentrically along the longest extent of the cranial and / or posterior plates. For optimal force distribution, implants used in osteosynthesis are generally aligned symmetrically to the symphysis pubis. An eccentric connecting arm ensures optimal accessibility to the symphysis pubis, or rather, does not impede access, since the connecting arm is offset when the implant is largely symmetrically aligned to the symphysis pubis. This can prevent complications.

[0013] Preferably, the medical implant has a second connecting arm, wherein the second connecting arm is, particularly preferably, an eccentric connecting arm with respect to the posterior and cranial plates. The second connecting arm can preferably be substantially identical to the first connecting arm. However, it can, for example, and preferably, be provided that the second connecting arm has a different cross-section than the first connecting arm. Preferably, the first connecting arm and / or the second connecting arm are connected substantially perpendicularly to the posterior and / or cranial plates. Connecting arms connected at right angles to the plates then extend substantially transversely to a pelvic ring direction. The pelvic ring direction is defined by the shape of the human pelvis in a transverse plane, i.e., when viewed in a superior-inferior direction.The pelvic ring direction approximately corresponds to the circumferential direction of a circle or an ellipse. However, the first connecting arm and / or the second connecting arm can also extend both transversely and along the pelvic ring direction, for example, obliquely to the pelvic ring direction.

[0014] According to the invention, the medical implant further comprises a positioning projection for at least partial engagement with the symphysis pubis of the patient's pelvis. During osteosynthesis, the positioning projection can engage with the symphysis and thus be positioned along the pelvic ring against the side of a pubic bone facing the symphysis. The positioning projection significantly facilitates the correct alignment of the medical implant with the first pubic bone. In this way, the implant can be correctly aligned with the first pubic bone before the two pubic bones, or the two hip hemispheres of the patient, are aligned relative to each other. The second hemisphere can then be guided precisely along the plate and secured. The two plates allow the hemispheres to be connected horizontally and vertically.With the implant according to the invention, it is no longer necessary to ensure the correct alignment of the pubic bones beforehand, before the plates are attached to the two pubic bones. Misalignment errors are effectively prevented, thus sparing patients. Preferably, the first connecting arm can also be designed as a positioning projection for at least partial engagement with the pubic symphysis. The medical implant can also have a second positioning projection or more than two positioning projections.

[0015] Preferably, the positioning projection is arranged between the first and second connecting arms. Preferably, at least one connecting arm is assigned to each pubic bone of the patient, thereby improving the stability of the implant. Furthermore, the insertion of the positioning projection into the patient's pubic symphysis is not obstructed by the connecting arms. Preferably, the positioning projection is arranged centrally between the connecting arms, i.e., it is positioned at a substantially equal distance from both the first and second connecting arms. The connecting arm is preferably formed integrally with the posterior plate and / or the cranial plate.

[0016] In a preferred embodiment, the positioning projection is arranged centrally on the implant, preferably in a plane of symmetry of the implant. The central arrangement of the positioning projection is considered in the direction of the pelvic ring. The positioning projection is preferably arranged centrally between a first end of the medical implant, which, when the positioning projection is positioned in the symphysis, is furthest from the symphysis in the direction of the pelvic ring, and an opposite second end of the medical implant, which, when the positioning projection is positioned in the symphysis in the direction of the pelvic ring, is furthest from the symphysis. Preferably, the positioning projection is arranged in a plane of symmetry of the implant that is perpendicular to the direction of the pelvic ring.

[0017] Preferably, the positioning projection has a blunt front face. The front face is preferably rounded and most preferably has no edges. A blunt front face prevents injury to the pubic symphysis and / or the sides of the pubic bones facing the symphysis. Preferably, the front face of the positioning projection is dome-shaped. However, it is also possible for the front face to be flat and have rounded transitions to the side walls of the projection. In a preferred embodiment, the positioning projection is an elongated ridge extending transversely to a projection height. An elongated ridge provides a particularly large contact surface and thus allows for secure positioning. The projection height is determined in the direction in which the positioning projection engages the pubic symphysis during intended use of the implant.If the positioning protrusion extends from the cranial plate, then the protrusion height is determined in a superior-inferior direction. If, however, the positioning protrusion extends from the posterior plate, then the protrusion height is determined in a posterior-anterior direction.

[0018] In a preferred embodiment, the positioning projection extends essentially perpendicularly from a contact surface on the cranial plate and / or the posterior plate of the medical implant. This effectively prevents the positioning projection from slipping. However, it is also possible for the positioning projection to extend at an angle from the contact surface. For example, the positioning projection can be wedge-shaped. A wedge-shaped positioning projection facilitates insertion into the pubic symphysis.

[0019] Preferably, the positioning projection is located on the posterior plate. Positioning the projection on the posterior plate allows for easy verification of correct implant placement during osteosynthesis. This reduces the risk of incorrect positioning and / or complications. However, the positioning projection can also be located on the cranial plate. Preferably, the positioning projection extends transversely to its height, completely from an inferior side of the posterior plate to a superior side. This provides a particularly large contact area.

[0020] Preferably, the positioning projection has a height in the range of 0.5 mm to 20 mm, preferably 0.5 mm to 15 mm, preferably 0.5 mm to 12 mm, preferably 1 mm to 12 mm, preferably 1 mm to 10 mm, preferably 1 mm to 8 mm, preferably 2 mm to 8 mm, preferably 2 mm to 6 mm, preferably 2 mm to 5 mm, and particularly preferably 3 mm to 5 mm. The boundary values ​​of the ranges are also preferred. A projection height in the stressed area enables secure placement and simultaneously does not impede the healing process of the pubic symphysis.

[0021] In a further preferred embodiment, the posterior plate has first mounting holes for receiving first fasteners, the cranial plate has second mounting holes for receiving second fasteners, and the first or second mounting holes are oval-shaped. Preferably, the first mounting holes are oval-shaped. Oval holes have a greater extent in a first direction transverse to a direction of passage through which fasteners extend than in a second direction. Oval holes have a cross-section other than a circle. For example, oval holes can be oval or elliptical. Preferably, however, oval holes can also be elongated with parallel sides or rectangular transverse to the direction of passage.It should be understood that oval holes are not limited to an oval cross-section. Oval holes allow drilling with the drill's main axis inclined relative to the direction of passage through the oval hole. Thus, during osteosynthesis, fixation holes often need to be drilled into the patient's bone to anchor the fixation devices. Surgical access is limited. Oval holes allow the drill to be held at an angle to the bone, simplifying patient care. Injuries to surrounding tissue are minimized, errors are prevented, and the patient is spared unnecessary discomfort. Alternatively, both the initial and subsequent fixation holes can be designed as oval holes.

[0022] Preferably, one longitudinal axis of the oval holes is oriented essentially along a basin ring direction. The longitudinal axis defines the largest clear width of the oval holes perpendicular to the direction of passage. The inventor has found that by orienting the longitudinal axis of the oval holes in the basin ring direction, drilling can be further simplified.

[0023] In a preferred embodiment, the connecting arm exhibits lower stiffness than the posterior and cranial plates, allowing the alignment of the posterior plate relative to the cranial plate to be adjusted by plastically deforming the connecting arm. If the medical implant has multiple connecting arms, the overall stiffness of the connecting arms is preferably lower than the stiffness of the posterior and cranial plates. This lower stiffness allows the connecting arm to be deformed, while the posterior and cranial plates do not deform, or only minimally. Plastically deforming the connecting arm allows the medical implant to be adapted to the specific characteristics of the patient being treated. This preferably allows for variation of the angle enclosed by the plates.The relevant stiffness is preferably a stiffness against deformation in a plane transverse to the pelvic ring direction (e.g., a sagittal plane passing through the symphysis). Preferably, the connecting arm has a length of approximately 25 mm and a width of approximately 10 mm.

[0024] Preferably, the cranial plate is convex in a transverse plane and / or the posterior plate is convex in the transverse plane. Within the scope of the invention, a convex plate is curved towards the patient's abdomen or outwards. A convex posterior plate is particularly well adapted to the natural shape of the pelvic ring. A convex cranial plate provides a particularly large contact surface. Convex plates also prevent the implant from protruding after implantation, thus preventing injury to the surrounding tissue.

[0025] In one embodiment, a first implant section for attachment to the first pubic bone and a second implant section for attachment to the second pubic bone are essentially mirror-symmetrical to each other. The first implant section comprises those portions of the posterior plate and the cranial plate intended for attachment to the first pubic bone, and the second implant section similarly comprises the portions of the posterior plate and the cranial plate intended for attachment to the second pubic bone. A mirror-symmetrical design allows for a symmetrical distribution of forces and thus prevents loosening and / or damage to the implant. It should be understood that implant sections located between the first and second implant sections need not be mirror-symmetrical, but may be.

[0026] Preferably, the cranial plate, the posterior plate, and / or the connecting arm, or the entire implant, is made of steel, titanium, a powder-coated metal, and / or a medical-grade plastic, preferably PEEK. Preferably, the cranial plate, the posterior plate, the connecting arm, and / or the positioning projection may also have surface textures. The medical implant is particularly preferably manufactured using 3D printing (additive manufacturing).

[0027] Preferably, the length of the posterior plate and the length of the cranial plate are essentially identical. The length of the plates is determined in the direction of the pelvic ring. By designing the plates with the same length, optimal force distribution can be achieved and implant failure prevented.

[0028] In a preferred embodiment, the at least one connecting arm is spaced apart in a pelvic ring direction from the ends of the posterior plate and / or the end of the cranial plate. The connecting arm is therefore not located at the ends of the posterior plate and / or the cranial plate that lie in the pelvic ring direction. If the implant has multiple connecting arms, preferably all connecting arms are spaced apart from the ends of the plates.

[0029] Furthermore, the invention solves the aforementioned problem by means of a method for osteosynthesis of an artificial symphysis rupture on a training body for training purposes by means of a medical implant according to the invention described above, comprising the steps of: applying a cranial plate of the medical implant to a first pubic bone of the training body from a cranial side; applying a posterior plate of the medical implant to a first pubic bone of the training body from a posterior side; attaching the cranial plate to the first pubic bone; attaching the posterior plate to the first pubic bone; adjusting a symphysis distance between the first pubic bone and the second pubic bone; attaching the cranial plate to the second pubic bone and attaching the posterior plate to the second pubic bone after adjusting the symphysis distance.The training body is not a living human or animal body. The method according to the invention allows for effective training of osteosynthesis of a symphysis rupture. The steps of applying the cranial plate to the first pubic bone and applying the posterior plate to the first pubic bone can be performed in any order, preferably simultaneously. Similarly, the fastening of the cranial plate and the fastening of the posterior plate to the first pubic bone can also be performed in any order, preferably simultaneously. Adjustment of the symphyseal distance is preferably carried out after fastening the posterior plate and / or the cranial plate to the first pubic bone of the training body.

[0030] In a first preferred embodiment, the method further comprises: attaching a positioning projection of the medical implant to the first pubic bone from a side facing the symphysis of the body being trained, wherein the positioning projection is attached before the cranial plate and / or the posterior plate are fastened to the first pubic bone. Preferably, in the method according to the invention, the medical implant is first fastened to the first pubic bone, with correct positioning of the implant being ensured by the positioning projection attached to the first pubic bone. Thus, the implant can first be correctly positioned and fastened to the first pubic bone before the symphyseal distance is adjusted and the implant or the posterior plate and the cranial plate are also fastened to the second pubic bone. The method is significantly easier to learn compared to conventional training methods.

[0031] Embodiments of the invention are now described below with reference to the drawings. These drawings are not necessarily intended to represent the embodiments to scale; rather, where this is helpful for clarification, the drawings are presented in a schematic and / or slightly distorted form. With regard to additions to the teachings directly apparent from the drawings, reference is made to the relevant prior art. It should be noted that numerous modifications and changes concerning the form and detail of an embodiment can be made without deviating from the general idea of ​​the invention. The features of the invention disclosed in the description, the drawings, and the claims can be essential for the further development of the invention, both individually and in any combination.Furthermore, the invention encompasses all combinations of at least two of the features disclosed in the description, the drawings, and / or the claims. The general idea of ​​the invention is not limited to the exact shape or detail of the preferred embodiments shown and described below, nor is it limited to an object that would be restricted compared to the object claimed in the claims. Where specified dimensioning ranges are given, values ​​lying within the stated limits are also disclosed as limit values ​​and may be used and claimed as desired. For the sake of simplicity, identical or similar parts, or parts with identical or similar functions, are used below as reference numerals.

[0032] Further advantages, features and details of the invention will become apparent from the following description of the preferred embodiment and from the drawings, which show: Figure 1 shows a medical implant in a first embodiment; Figure 2 shows the medical implant according to the first embodiment, attached to a model of a human hip bone; Figure 3 shows a medical implant in a second embodiment; and Figure 4 shows an illustrative representation of the method according to the invention.

[0033] Figure 1Figure 1 shows a medical implant 1 for the osteosynthesis of symphysis ruptures in the human pelvis, comprising a cranial plate 2 and a posterior plate 4. The cranial plate 2 and the posterior plate 4 are connected by a first connecting arm 6 and a second connecting arm 8. For application to a first pubic bone 20 and a second pubic bone 24 of a patient to be treated (not shown), the cranial plate 2 has a cranial contact surface 10. Similarly, the posterior plate 4 has a posterior contact surface 12 for application to the pubic bones 20 and 24.

[0034] The connecting arms 6, 8 are angled so that the cranial contact surface 10 of the cranial plate 2 and the posterior contact surface 12 of the posterior plate 4 are arranged at an angle to each other. In this embodiment, the posterior contact surface 12 and the cranial contact surface 10 form an angle of approximately 90°. However, an angled arrangement of the contact surfaces 10, 12 can also be achieved by arcuate, multiaxially curved, or multiply bent connecting arms 6, 8. The first connecting arm 6 extends from a side surface 14a of the cranial plate 2 facing the posterior plate 4 to a side surface 14b of the posterior plate 4 facing the cranial plate 2. The second connecting arm 8 extends analogously between the side surface 14a of the cranial plate 2 and the side surface 14b of the posterior plate 12.The first connecting arm 6 is angled, such that a first arm section 6a is essentially perpendicular to a second arm section 6b, with the first arm section 6a being connected to the cranial plate 10 and the second arm section 6b to the posterior plate 12. Sections 6a and 6b merge into each other at right angles. Similarly, a first arm section 8a and a second arm section 8b of the second connecting arm 8 are also connected to the cranial plate 10 and the posterior plate 12, respectively.

[0035] The first connecting arm 6 and the second connecting arm 8 are essentially symmetrical. Connecting arms 6 and 8 have a substantially rectangular cross-section with rounded corners perpendicular to a connection direction RV. Due to the right-angled arrangement of the arm sections 6a, 6b, 8a, and 8b, the connection direction is curved or angled and runs along connecting arms 6 and 8. Connecting arms 6 and 8 extend laterally from the cranial plate 10 and the posterior plate 12, with a longitudinal axis AV1 of the first connecting arm 6 being perpendicular to a longitudinal axis AK of the cranial plate 2. Furthermore, the longitudinal axis AV1 of the first connecting arm 6 is essentially perpendicular to a longitudinal axis AP of the posterior plate 4. Similarly, a longitudinal axis AV2 of the second connecting arm 8 is also essentially perpendicular to the longitudinal axis AK of the cranial plate 2 and to the longitudinal axis AP of the posterior plate 4.The longitudinal axes AV1, AV2, AK, AP denote the respective greatest geometric extent of the connecting arms 6, 8, the cranial plate 2 and the posterior plate 4.

[0036] The connecting arms 6 and 8 are designed as off-center connecting arms 6 and 8. The first connecting arm 6 is connected to the cranial plate 2 at a distance from the center M1 of the cranial plate 2 and to the posterior plate 4 at a distance from the center M2 of the posterior plate 4. Similarly, the second connecting arm 8 is connected to the cranial plate 2 and the posterior plate 4 at a distance from the first center M1 of the cranial plate 2 and from the second center M2 of the posterior plate 4. A viewing window 16 is thus formed between the connecting arms 6 and 8, which facilitates the alignment of the medical implant 1 during the osteosynthesis of a symphysis rupture. The symphysis 34 of the patient being treated is not obscured by the connecting arms 6 and 8.In this embodiment, the medical implant 1 is designed to be mirror-symmetrical, with the plane of symmetry (not shown) extending through the center M1 of the cranial plate 2 and the center M2 of the posterior plate 4. A first implant section 18 for attachment to a first pubic bone 20 (. Figure 2 The first implant section 18 and a second implant section 22 for attachment to a second pubic bone 24 are essentially identical in design. However, if, for example, osteosynthesis of multiple fractures (including a symphyseal rupture) is to be performed, the medical implant 1 can also be asymmetrically designed. For example, the first implant section 18 in the direction of the pelvic ring RB can be longer than the second implant section 22 to allow for the fusion of fragments of the first pubic bone 20.

[0037] The cranial plate 2 is designed as a flat plate, with its longitudinal axis AK being straight. The longitudinal axis AK defines a longitudinal direction for the cranial plate 2. Two ends 26a, 26b of the cranial plate 2, which bound the cranial plate 2 in this longitudinal direction, are rounded. The cranial contact surface 10 of the cranial plate 2 is essentially rectangular with two semicircular sections at the ends 26a and 26b.

[0038] The posterior plate 4 also has a straight longitudinal axis AP, which defines a longitudinal direction of the posterior plate 4. The contact surface 12 of the posterior plate 4 is essentially rectangular, with the posterior plate 4 having rounded corners 30 at its longitudinally bounding ends 28a, 28b. Between the corners 30, the posterior contact surface 12 is bounded by straight lines. In contrast to the cranial plate 2, the ends 28a, 28b of the posterior plate 4 are therefore not semicircular in this embodiment.

[0039] The ends 26a, 26b of the cranial plate 2 project longitudinally from the connecting arms 6, 8. Since the longitudinal axis AK of the cranial plate 2 extends essentially along a pelvic ring direction RB, the ends 26a, 26b also project longitudinally from the connecting arms 6, 8. The connecting arms 6, 8 are not connected to the ends 26a, 26b, but rather terminate in the cranial plate 2 between the center M1 and the ends 26a, 26b.

[0040] The ends 28a, 28b of the posterior plate 4 project from the connecting arms 6, 8 in the longitudinal direction of the posterior plate 4, such that the connecting arms 6, 8 merge into the posterior plate 4 between the center M2 and the ends 28a, 28b of the posterior plate 4. The longitudinal axis AP of the posterior plate 4 also extends essentially in the direction of the pelvic ring RB, so that the ends 28a, 28b of the posterior plate 28a, 28b likewise project from the connecting arms 6, 8 in the direction of the pelvic ring RB.

[0041] However, it is also possible for connecting arms 6, 8 to terminate at the ends 26a, 26b of the cranial plate 2 and / or the ends 28a, 28b of the posterior plate 4. Furthermore, the connecting arms 6, 8 can form an angle other than 90° with the longitudinal axis AK of the cranial plate 2 and / or the longitudinal axis AP of the posterior plate 4. For example, the connecting arms 6, 8 can also be arranged in a V-shape.

[0042] The length L1 of the cranial plate 2 is determined along the longitudinal axis AK, and the length L2 of the posterior plate 4 is determined along the longitudinal axis AP. The length L1 of the cranial plate 2 is essentially identical to the length L2 of the posterior plate 4. The width B1 of the cranial plate 2 is determined transversely to the longitudinal axis AK. Similarly, the width B2 of the posterior plate 4 is determined transversely to the longitudinal axis AP of the posterior plate 4. In this embodiment, the width B1 of the cranial plate 2 is less than the width B2 of the posterior plate 4. Thus, the cranial contact area 10 of the cranial plate 2 is smaller than the posterior contact area 12 of the posterior plate 4.A thickness D1 of the cranial plate 2, determined transversely to the cranial contact surface 10 and transversely to the longitudinal axis AK of the cranial plate 2, is essentially identical to a thickness D2 of the posterior plate 4, measured transversely to the posterior contact surface 12 and transversely to the longitudinal axis AP of the posterior plate 4. However, it is also possible for the thicknesses D1 and D2 of the cranial plate 2 and the posterior plate 4 to differ. For example, the stiffness of the plates 2 and 4 against deformation can be adjusted to accommodate loads occurring after implantation, thus preventing implant failure.

[0043] A positioning projection 32 is formed on the posterior plate 4, extending from the posterior plate 4 transversely to the pelvic ring direction RB. The positioning projection 32 is for engaging with the symphysis 34 ( Figure 2) formed. Here, the positioning projection 32 extends essentially perpendicularly from the posterior plate 4, such that side walls 46a, 46b of the positioning projection 32 are arranged essentially perpendicular to the posterior contact surface 12. The positioning projection 32 is designed as an elongated web 38 that extends over the entire width B2 of the posterior plate 4. Alternatively, the positioning projection can preferably also be designed as a cylinder, cone, or wedge extending from a contact surface 10, 12.

[0044] The positioning projection 32 is located centrally on the posterior plate 4 and extends from its second center point M2. One end face 40 of the positioning projection 32 is blunt, meaning it has no sharp edges. Transitions 42a, 42b of the end face 40 into the side walls 46a, 46b of the positioning projection 32 are rounded, thus minimizing the risk of injuring surrounding tissue when inserting the positioning projection into the pubic symphysis 34. Here, the end face 40 is essentially parallel to the posterior contact surface 12. However, it is also possible for the end face 40 to form a (preferably rounded) point or to be dome-shaped or arc-shaped. Alternatively or additionally, a positioning projection 32 can also be provided on the cranial plate 2.

[0045] The projection height H of the positioning projection 32 is determined transversely to the contact surface 12. If the cranial plate 2 rests against the first pubic bone 20 and the second pubic bone 24 from a cranial side 44, and the posterior plate 4 rests against the first and second pubic bones 20 and 24 from a posterior side 46, the projection height H is a measure of how far the positioning projection 32 engages the symphysis 34. Preferably, the projection width B3 of the positioning projection 32, which is determined in the pelvic ring direction RB, is adapted to the width of a human symphysis. During osteosynthesis of a symphysis rupture, the correct positioning of the medical implant 1 and the adjustment of the symphyseal distance between the first pubic bone 20 and the second pubic bone 24 are considerably facilitated.The first implant section 18 can thus be initially positioned against the first pubic bone 20, with the positioning projection 32, which engages in the symphysis 34, ensuring an optimal position of the medical implant 1 in the pelvic ring direction RB. The first implant section 18 can then be attached to the first pubic bone 20. The medical implant 1 is then firmly connected to the first pubic bone 20. The symphyseal gap between the first pubic bone 20 and the second pubic bone 24 can then be adjusted by bringing the second pubic bone 24 into contact with the positioning projection 32 on the side opposite the first pubic bone 20. To connect the two pubic bones 20 and 24, the second implant section 22 is then connected to the second pubic bone 24.

[0046] To connect the medical implant 1 to the first pubic bone 20 and the second pubic bone 24, the posterior plate 4 has first connection holes 48. Furthermore, the cranial plate 2 has second connection holes 50. During osteosynthesis, first connecting elements (not shown) can be inserted through the first connection holes 48 of the posterior plate 4, and second connecting elements (not shown) through the second connection holes 50 of the cranial plate 2. Such connecting elements are typically medical screws, nails, and / or pins. A head portion of the connecting element then rests on a side of the plates 2, 4 opposite the contact surfaces 10, 12 and clamps the posterior plate 4 or the cranial plate 2 against the first pubic bone 20 or the second pubic bone 24.

[0047] In the illustrated embodiments, the posterior plate 4 has two first connecting holes 48, which are designed as oval holes 52. It should be understood that the posterior plate 4 can also have only one first connecting hole 48 or more than two. Furthermore, not all first connecting holes 48 need to be designed as oval holes 52. The longitudinal axes AL of the oval holes 52 lie on the longitudinal axis AP of the posterior plate 4. The longitudinal axis AL of the oval holes 52 defines a maximum clear width of the oval holes 52 transversely to the direction in which the fasteners are guided through the oval holes 52. Here, the oval holes 52 are formed from two semicircular sections connected by sections parallel to the longitudinal axis AL of the oval holes 52. Connecting holes 48 with such a cross-sectional geometry are also frequently referred to as elongated holes.The oval holes 52 lie on the longitudinal axis AP of the posterior plate 4, which extends essentially along the pelvic ring direction RB, so that the longitudinal axis AL of the oval holes 52 also extends essentially along the pelvic ring direction RB. The oval holes 52 facilitate the drilling of fixation holes (not shown) into the first pubic bone 20 and the second pubic bone 24, which must be drilled as part of the osteosynthesis to allow for the fixation of the implant 1. A drill bit (not shown) does not need to be guided perpendicular to the posterior side 46 during drilling, but can also be positioned at an angle.

[0048] The cranial plate 2 has a total of four secondary fixing holes 50, which are designed as round holes. Transverse to the direction in which fasteners are inserted through the holes 50 (direction of passage), the fixing holes 50 have a circular cross-section. However, it is also possible for some or all of the secondary connecting holes 50 to be designed as oval holes 52. During osteosynthesis, access from the cranial side 44 is usually better ensured than access from the posterior side 46, which is why at least the posterior plate 4 preferably has oval holes 52. Round holes, on the other hand, advantageously prevent the fasteners from slipping. Preferably, the first fixing holes 48 and / or the second fixing holes 50 can be conical in the direction of passage.

[0049] The first fixing holes 48 and / or the second fixing holes 50 are preferably arranged in the region of the connecting arms 6, 8. Thus, the longitudinal axis AV1 of the first connecting arm 6 extends on the cranial plate 2 preferably between the fixing holes 50 of the first implant section 18. Similarly, the second longitudinal axis AV2 of the second connecting arm 8 extends on the cranial plate 2 between the fixing holes 50 of the second implant section 20. On the posterior plate 4, the first longitudinal axis AV1 of the first connecting arm 6 and / or the second longitudinal axis AV2 of the second connecting arm 8 extends through the elongated holes 52 on the first implant section 18 and on the second implant section 22, respectively.

[0050] Preferably the first connecting holes 48 and / or the second connecting holes 50 are arranged centrally on the cranial plate 2 and the posterior plate 4 respectively in a lateral direction that runs parallel to the first and second widths B1, B2.

[0051] The cross-section of the connecting arms 6, 8 is chosen such that the connecting arms 6, 8 have a lower stiffness than the cranial plate 2 and the posterior plate 4. This allows the connecting arms 6, 8 to be plastically deformed in order to change the orientation of the cranial contact surface 10 relative to the posterior contact surface 12. Thus, the Figure 1The depicted right-angled arrangement of the cranial contact surface 10 to the posterior contact surface 12 can be modified by bending the connecting arms 6, 8. After bending, the cranial contact surface 10 and the posterior contact surface 12 form an angle greater than 90°. Similarly, the medical implant 1 can also be bent together so that the cranial contact surface 10 and the posterior contact surface 12 form an angle less than 90°. It should be understood that the contact surfaces 10, 12 can also have an angle other than 90° before bending or bending. When one or both connecting arms 6, 8 are plastically deformed, the shape of the longitudinal axis AV1 of the first connecting arm 6 and / or the second connecting axis AV2 of the second connecting arm 8 changes.The cranial plate 2 and the posterior plate 4, whose stiffness in the illustrated one-piece design is essentially determined by the widths B1, B2 and the thicknesses D1, D2, are not deformed and remain flat. The plastically deformable connecting arms 6, 8 thus allow the medical implant 1 to be adapted to the shape of the first pubic bone 20 and the second pubic bone 24. Preferably, the connecting arms 6, 8 are deformable without tools.

[0052] During plastic deformation, the longitudinal axes AV1, AV2 of the connecting arms 6, 8 are curved. However, it can also be provided that transition regions 54 of the connecting arms 6 to the plates 2, 4 are deformed, while the shape of the connecting arms 6, 8 remains essentially constant. A cross-sectional area (not shown) of the connecting arms 6, 8 transverse to their longitudinal axes AV1, AV2 is selected such that the stiffness of the connecting arms 6, 8 is lower than the stiffness of the plates 2, 4. Furthermore, the cross-sectional geometry of the connecting arms 6, 8 influences the stiffness of the connecting arms, with round, oval, rectangular, square, I-shaped, T-shaped, L-shaped and / or ring-shaped cross-sectional forms of the connecting arms being preferred.However, it can also be provided that at least one of the connecting arms 6, 8 has a deformation section (not shown) made of a more easily deformable material than the plates 2, 4. For example, the connecting arms 6, 8 can be made of titanium in sections, while the posterior plate 4 and the cranial plate 2 are made of steel.

[0053] Figure 2Figure 1 illustrates the arrangement of the medical implant 1 within the framework of osteosynthesis of a symphysis rupture in the human pelvis 3, where, instead of a real human pelvis 3, a training model 64 is shown that faithfully replicates the natural shape of a human pelvis 3. The cranial plate 2 is applied to the first pubic bone 20 and the second pubic bone 24 from the cranial side 44. The cranial plate 2 thus bridges the symphysis 34 from the cranial side 44. Forces applied to the pubic bones 20 and 24 can be transmitted by the cranial plate 2 from the first pubic bone 20 to the second pubic bone 24 and vice versa. The posterior plate 4 is attached to the pubic bones 20, 24 from the posterior side 46 and also bridges the symphysis 34. The positioning projection 32 engages in the symphysis 34 when the medical implant 1 is correctly positioned on the pelvis 3.

[0054] In the Figure 2In the first embodiment shown, the cranial plate 2 and the posterior plate 4 are straight and flat plates. Nevertheless, the posterior plate 4 and the cranial plate 4 extend substantially along the pelvic ring direction RB. The positioning projection 32, designed as a web 38, extends in a vertical direction VR from an inferior side 56 to a superior side 58 of the pelvis 3. Perpendicular to the posterior plate 4, the positioning projection 32 does not extend completely from the posterior contact surface 12 through the symphysis 34.

[0055] Figure 3 Figure 1 illustrates a second embodiment of the medical implant 1. In this second embodiment, the shape of the medical implant 1 is further adapted to the natural shape of the human pelvis 3. In contrast to Figure 1 , which shows a side of the medical implant 1 facing the pubic bones 20, 24, illustrates Figure 3a view of the side of the medical implant 1 facing away from the pubic bones 20, 24.

[0056] The second embodiment according to Figure 3 is essentially analogous to the first embodiment according to the Figure 1 and 2 formed, wherein identical sections and components are provided with the same reference numerals. In contrast to the first embodiment, the cranial plate 2 and the posterior plate 4 according to the second embodiment are not formed as straight plates, but curved. The cranial plate 2 is planar curved and the cranial contact surface 10 is a planar surface. The longitudinal axis AK of the cranial plate 2 lies in a transverse plane that is substantially parallel to the image plane. Figure 3is convexly curved, such that a bulge 60 of the cranial plate 2 faces away from the posterior side 46. Protrusion of the cranial plate 2 beyond the pubic bones 20, 24 after successful osteosynthesis is thus minimized while simultaneously maximizing the contact area.

[0057] The posterior plate 4 is also curved. The longitudinal axis AP of the posterior plate 4 is convex. A bulge 62 of the posterior plate 4 points away from the posterior side 46, i.e., in the same direction as the bulge 60 of the cranial plate 2. In contrast to the first embodiment, the posterior contact surface 12 is not flat, but curved in an arc. Here, the posterior plate 4 is curved only uniaxially (only the longitudinal axis AP of the posterior plate 4 is curved). However, it is also possible for the posterior plate to be curved multiaxially. Due to the curvature, the posterior contact surface 12 is optimally adapted to the shape of the pubic bones 20, 24 of the pelvis 3. As an alternative to the embodiment shown, it can be provided that the posterior mounting surface 12 is curved, while one of the surfaces of the posterior plate 12 opposite the posterior mounting surface 12 is flat.

[0058] Furthermore, the connecting arms 6, 8 of the second embodiment of the medical implant 1 have a larger cross-section compared to the first embodiment. The resistance of the connecting arms 6, 8 to deformation is increased, so that forces applied to the plates 2, 4 can be transmitted more effectively between them. However, a greater force is required to adapt the medical implant 1 to the pelvis 3. The transitions 54 formed between the connecting arms 6, 8 and the plates 2, 4 are rounded, which improves the stability of the medical implant 1 and prevents damage to surrounding tissue.

[0059] Figure 4Figure 100 illustrates a procedure for the osteosynthesis of a symphysis rupture on a training body 64 for training purposes using a medical implant 1. In a first step S1, the cranial plate 2 of the medical implant 1 is applied to the first pubic bone 20 of the training body 64. The application is made from the cranial side 44.

[0060] In a second step S2, the posterior plate 4 of the medical implant 1 is applied to the first pubic bone 20 of the training body 64, with the application being carried out from the posterior side 46. It should be understood that steps S1 and S2 can be performed simultaneously or in reverse order.

[0061] In a third step S3, the positioning projection 32 of the medical implant 1 is applied to the first pubic bone 20 from one side 66 facing the symphysis 34 of the training body 64. This ensures optimal positioning of the first implant section 18 relative to the first pubic bone 20.

[0062] In a fourth step, S4, the cranial plate 2 is then attached to the first pubic bone 20. For this purpose, in a first sub-step, S4.1, fastening holes (not shown) are drilled into the first pubic bone 20 through the second connecting holes 50. Then, in a second sub-step, S4.2, fasteners are inserted through the second connecting holes 50 and into the previously drilled fastening holes, thus attaching the cranial plate 2 to the first pubic bone 18.

[0063] In a fifth step, S5, the posterior plate 4 is attached to the first pubic bone 20. Analogous to the fourth step, S4, in the fifth step, S5, in a first sub-step, S5.1, fastening holes (not shown) can first be drilled into the first pubic bone 20 through the first connecting holes 48. In a second sub-step, S5.2, fasteners (not shown) can then be inserted through the first connecting holes 48 and into the fastening holes to attach the posterior plate 4 to the first pubic bone 20. If necessary, the first sub-step, S5.1, can be omitted, and the fasteners, for example, screws, can be inserted directly. Steps S4 and S5 can be carried out in any order, for example, in parallel or in reverse order. For example, sub-steps S4.1 and S5 can be performed first.1. This procedure is performed before the posterior plate 4 and the cranial plate 2 are attached to the first pubic bone 20 using the fasteners (S 5.2, S 4.2). Alternatively, for example, the posterior plate 4 can be attached to the first pubic bone 20 before the cranial plate 2.

[0064] In a subsequent sixth step S6, a symphyseal distance between the first pubic bone 20 and the second pubic bone 24, viewed in the direction of the pelvic ring RB, is set. For this purpose, the second pubic bone 24 is preferably moved towards the first pubic bone 20 until the first pubic bone 24 rests against the positioning projection 32. The positioning projection 32, or rather its width B3, determines the symphyseal distance of the symphysis 34. This facilitates the alignment of the pubic bones 20 and 24 of the training body 64 relative to each other.

[0065] In a seventh sub-step S7, the cranial plate 2 is connected to the second pubic bone 24, whereby the second pubic bone 20 is initially attached to the cranial plate 2. The seventh step S7, analogous to the fourth step S4, can have sub-steps.

[0066] In an eighth step, S8, the second pubic bone 24 is attached to the posterior plate 4, whereby the second pubic bone 24 is first positioned against the posterior plate 4. The eighth step, S8, can, analogous to the fifth step, S5, comprise sub-steps. Furthermore, steps S7 and S8 can be performed in any order.

Claims

1. A medical implant (1) for osteosynthesis of symphysis ruptures on the human pelvis, comprising a cranial plate (2) configured to be attached to a first pubic bone (20) and a second pubic bone (24) of a patient to be treated from a cranial side (44) for connecting the pubic bones (20, 24), a posterior plate (4) configured to be attached to the first pubic bone (20) and the second pubic bone (24) of the patient from a posterior side (46) for connecting the pubic bones (20, 24), wherein the cranial plate (2) and the posterior plate (4) are connected to each other by at least one first connecting arm (6), and wherein the medical implant (1) further comprises a positioning protrusion (32) for at least partially engaging the symphysis (34) of the pelvis of the patient to be treated.

2. The medical implant (1) according to claim 1, wherein the first connecting arm (6) is an off-center connecting arm (6) with respect to the posterior plate (4) and the cranial plate (2).

3. The medical implant (1) according to claim 1 or 2, further comprising a second connecting arm (8), wherein the second connecting arm (8) preferably is an off-center connecting arm (8) with respect to the posterior plate (4) and the cranial plate (2).

4. The medical implant (1) according to claim 3, wherein the positioning protrusion (32) is arranged between the first connecting arm (6) and the second connecting arm (8).

5. The medical implant (1) according to any of the preceding claims, wherein the positioning protrusion (32) is arranged centered on the implant (1), preferably on a symmetry plane of the implant (1), and / or wherein the positioning protrusion (32) has a blunt end face (40), and / or wherein the positioning protrusion (32) is a ridge (38) that is elongated transverse to a protrusion height (H) of the positioning protrusion (32).

6. The medical implant (1) according to any of the preceding claims, wherein the positioning protrusion (32) extends substantially perpendicular from a contact surface (10, 12) on the cranial plate (2) and / or the posterior plate (4) of the medical implant (1).

7. The medical implant (1) according to any of the preceding claims, wherein the positioning protrusion (32) is provided on the posterior plate (4).

8. The medical implant (1) according to any of the preceding claims, wherein the positioning protrusion (32) has a protrusion height (H) in a range from 1 mm to 15 mm, preferably 2 mm to 5 mm.

9. The medical implant (1) according to any of the preceding claims, wherein the posterior plate (4) comprises first mounting holes (48) provided for receiving first connecting means, wherein the cranial plate (2) comprises second mounting holes (50) provided for receiving second connecting means, and wherein the first mounting holes (48) or the second mounting holes (50) are oval holes (52), wherein a longitudinal axis (AL) of the oval holes (52) is preferably oriented substantially along a pelvic ring direction (RB).

10. The medical implant (1) according to any of the preceding claims, wherein the connecting arm (6, 8) has a lower rigidity than the posterior plate (4) and the cranial plate (2), so that an alignment of the posterior plate (4) relative to the cranial plate (2) can be adjusted by plastically deforming the connecting arm (6, 8).

11. The medical implant (1) according to claim 1, wherein the cranial plate (2) is convex in a transversal plane and / or wherein the posterior plate (4) is convex in the transversal plane.

12. The medical implant (1) according to any of the preceding claims, wherein a first implant section (18) for attachment to the first pubic bone (20) and a second implant section (22) for attachment to the second pubic bone (24) are configured substantially mirror-symmetrical to each other, and / or wherein a length (L2) of the posterior plate (4) and a length (L1) of the cranial plate (4) are substantially identical.

13. The medical implant (1) according to any of the preceding claims, wherein the at least one connecting arm (6, 8) is spaced apart in a pelvic ring direction (RB) from ends (28a, 28b) of the posterior plate (4) and / or ends (26a, 26b) of the cranial plate (2).

14. Method (100) for osteosynthesis of a symphysis rupture on a training body (64) for training purposes with a medical implant (1) according to any of the preceding claims 1 to 13, wherein the training body (64) is not a living human or animal body, the method (100) comprising the steps: - placing (S1) a cranial plate (2) of the medical implant (1) to a first pubic bone (20) of the training body (64) from a cranial side (44); - placing (S2) a posterior plate (4) of the medical implant (1) to a first pubic bone (20) of the training body (64) from a posterior side (46); - attaching (S4) the cranial plate (2) to the first pubic bone (20); - attaching (S5) the posterior plate (4) to the first pubic bone (20); - adjusting a symphysis gap (S6) between the first pubic bone (20) and the second pubic bone (24); - attaching (S7) the cranial plate (2) to the second pubic bone (24) and attaching (S8) the posterior plate (4) to the second pubic bone (24) after adjusting the symphysis gap (S6).

15. Method (100) according to claim 14, further comprising the step of: - placing (S3) a positioning protrusion (32) of the medical implant (1) on the first pubic bone (20) from a side (66) facing the symphysis (34) of the training body, wherein placing (S3) of the positioning protrusion (32) is performed before attaching (S4, S5) the cranial plate (2) and / or the posterior plate (4) to the first pubic bone (20).