Plate implant

Abstract

The present invention relates to a plate implant for bridging a fracture gap to fix a fracture. The plate implant (1a) comprises a longitudinal axis (LA) in the direction of maximum extent of the plate implant (1a), a number of holes (4) arranged at a distance from each other in the direction of the longitudinal axis (LA), and an elastic longitudinal expansion element (2) provided between at least two holes (4). The longitudinal expansion element (2) is designed so that the plate implant (1a) has an improved expandability in the direction of the longitudinal axis (LA) and at the same time a high bending and torsional stiffness.

Description

[Technical field]

[0001] The present invention relates to a plate implant for fixation of bone fractures. [Background technology]

[0002] To fix fractures while the bone is healing, implants in the form of plates are often used (so-called plate implants or osteosynthesis plates). These flat, generally elongated plate implants are provided with a number of holes for, for example, bone screws, by means of which they are screwed into the bone. They are used to stabilize the fracture gap while the bone is healing, and are removed after the effective healing process, generally by surgery.

[0003] In fact, it has been observed that bone healing is delayed or incomplete when plate implants are provided. This is a consequence of the fact that a certain amount of movement is necessary in the bone gap to stimulate bone healing. The medical literature in this regard refers to axial movements in the range of tens of millimeters, while simultaneously suppressing shear and torsional movements.

[0004] US Patent No. 5,399,933 describes a plate implant with a notch in the region of the fracture gap that allows a limited amount of mobility. The notch reduces the load-bearing cross-section of the plate implant in the region of the fracture gap to a thin leaf spring, whose bending and longitudinal expansion are limited by stops. For design reasons, the implant allows limited pivoting of the fixed bone but does not allow longitudinal-axial movement of the fixed bone.

[0005] US Patent No. 5,399,633 discloses a spinal implant having leaf springs used to reduce the bending stiffness of the implant, the enhanced longitudinal expansion of the implant not being supported by the leaf springs. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2021 / 102591 [Patent Document 2] European Patent Application Publication No. 1221308 Summary of the Invention [Problem to be solved by the invention]

[0007] It is therefore an object of the present invention to design a plate implant that bridges and stabilizes the fracture gap, but still allows limited movement in the direction of the (bone) longitudinal axis. [Means for solving the problem]

[0008] The present invention provides a plate implant as claimed in claim 1. The concept forming the basis of the plate implant according to the invention is to provide an elastic longitudinal expansion device arranged between two or more holes, which is configured such that the plate implant has an improved expandability in the direction of the longitudinal axis, but at the same time has high bending and torsional stiffness.

[0009] This allows for an amount of longitudinal movement in the fracture gap to stimulate bone healing. According to a preferred development, the longitudinal expansion device has elastic elements which are integrated into the plate implant.

[0010] According to a further preferred development, the elastic element is formed by an elastomeric insert. According to a further preferred development, the holes are arranged along the longitudinal axis, the elastic element extends parallel to the first holes in a first linear portion offset towards the left edge of the plate implant relative to the first plurality of holes, and the elastic element extends parallel to the second holes in a second linear portion offset towards the right edge of the plate implant relative to the second plurality of holes, the first and second portions being connected to each other by a third linear portion of the elastic element, said third portion extending between the two holes.

[0011] According to a further preferred development, the longitudinal expansion device comprises one or more leaf springs which are formed by one or more notches in the plate implant. According to a further preferred development, the leaf springs are formed by u-shaped notches in the plate implant surrounding the respective holes.

[0012] According to a further preferred development, the first plurality of notches is configured such that the U-shape opens towards the left edge of the plate implant, and the second plurality of notches is configured such that the U-shape opens towards the right edge of the plate implant.

[0013] According to a further preferred development, the notches overlap in the lateral direction. According to a further preferred development, the leaf spring is configured to be formed by respective first, second and third notches, the first and second notches at least partially surrounding the respective holes in a U-shape, the first U-shape opening towards the left edge of the plate implant and the second U-shape opening towards the right edge of the plate implant, the third notches being each arranged perpendicular to the longitudinal axis and being arranged between the respective pairs of first and second notches and spaced apart from the respective pairs of first and second notches.

[0014] According to a further preferred development, the second notch is spaced apart from the first notch and is opposite the first notch, and the third notch is arranged perpendicular to the longitudinal axis and is located between the respective pair of the first and second notches and spaced apart from the respective pair of the first and second notches so that a leaf spring is formed.

[0015] According to a further preferred development, the plate implant has a body region with a substantially constant first width and a head region which widens continuously from the first width. The invention is explained in more detail below using preferred embodiments and with reference to the drawings. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 shows a plate implant according to a first embodiment of the present invention. [Diagram 2] FIG. 4 shows a plate implant according to a second embodiment of the present invention. [Diagram 3] FIG. 13 shows a plate implant according to a third embodiment of the present invention. [Figure 4] FIG. 13 shows a plate implant according to a fourth embodiment of the present invention. [Diagram 5] FIG. 13 shows a plate implant according to a fifth embodiment of the present invention. [Figure 6] FIG. 13 shows a plate implant according to a sixth embodiment of the present invention. [Figure 7] FIG. 13 shows a plate implant according to a seventh embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] In the following, like or functionally identical elements will be referred to as like reference numbers. FIG. 1 shows a plate implant according to a first embodiment of the invention. The elongated plate implant 1a has a first partial plate 11a and a second partial plate 12a connected to each other via a longitudinal expansion device in the form of an elastic element 2. A plurality of ten holes 4 extend along a central longitudinal axis LA of the plate implant 1a, with respect to a central transverse axis M of the plate implant, five first holes 41a being arranged on a first side S1 of the central transverse axis M and five second holes 42a being arranged on the other second side S2 of the central transverse axis M. The elastic element 2 extends parallel to the first holes 41a in a first linear portion 21 on the first side S1 offset from the first holes 41a towards the left edge LR of the plate implant 1a, and parallel to the second holes 42a in a second linear portion 22 on the second side S2 offset from the second holes 42a towards the right edge RR of the plate implant 1a. The first portion 21 and the second portion 22 are connected to each other by a third linear portion 20 of the elastic element 2 along the central transverse axis M.

[0018] During surgery, the fracture gap is positioned along the central transverse axis M and the two partial plates 11a, 12a are attached by fixation elements (not shown), e.g. screws, to the two bone fragments separated by the fracture gap. The decision of which holes 4 to use for the fixation elements depends on the type and trajectory of the fracture gap.

[0019] When the fracture gap is subjected to compression or tension, the plate implant 1a can elastically deform in the direction of the central longitudinal axis LA without substantial loss of stiffness in bending and torsion. The elastic element 2 can for example be configured as an elastomeric insert that does not allow any bending or torsional movements but does allow longitudinal deformation.

[0020] FIG. 2 shows a plate implant according to a second embodiment of the invention. The elongated plate implant 1b according to Fig. 2 has a first and a second partial plate 11b, 12b arranged to the left and right of a central longitudinal axis LA of the plate implant 1b. The first partial plate 11b and the second partial plate 12b have longitudinal expansion devices in the form of a number of leaf springs 3.

[0021] A plurality of ten holes 4 extend along a central longitudinal axis LA of the plate implant 1b, with five first holes 41b arranged on a first side S1 of the central transverse axis M of the plate implant, and five second holes 42b arranged on the other second side S2 of the central transverse axis M.

[0022] The leaf spring 3 extends perpendicular to the central longitudinal axis LA of the plate implant 1b. The leaf spring 3 allows elastic deflection in the direction of the central longitudinal axis LA.

[0023] The leaf springs 3 are formed by u-shaped notches 5 of the plate implant 1b surrounding the respective holes 4. In particular, the notches 5 are provided on a first side S1 of the central transverse axis M such that the U-shape opens towards the left edge LR, and the notches 5 are provided on a second side S2 of the central transverse axis M such that the U-shape opens towards the right edge RR.

[0024] Thus, the partial plates 11b, 12b and the leaf spring 3 form a ladder structure which can be sheared into a parallelogram due to the elasticity of the leaf spring and thus can be expanded longitudinally.

[0025] During the operation, the fracture gap can be positioned along the central transverse axis M and the two partial plates 11b, 12b are attached by fixation elements (not shown), e.g. screws, to the two bone fragments separated by the fracture gap. However, due to symmetry in this second embodiment, it is possible to position the fracture gap offset relative to the central transverse axis M in the region of the leaf springs. The holes 4 of the partial plates 11b, 12b are assigned to the partial plate 11b or the partial plate 12b, respectively, depending on the position of the fracture gap.

[0026] As a result, when the fracture gap is subjected to compression or tension, the plate implant 1b can elastically deform in the direction of the central longitudinal axis LA without substantial loss of stiffness in bending and torsion. The sum of the bending stiffnesses of the leaf springs 3 produces the overall stiffness of the plate implant 1b for the desired movement. The maximum force transverse to the leaf spring plane is expected in the vicinity of the location of the fracture gap. It is therefore advantageous to make the thickness of the leaf spring 3 thicker or wider in the vicinity of the location of the fracture gap.

[0027] The notch 5 can be manufactured by methods such as laser beam cutting, water jet cutting or erosion. The cutting width can be appropriately selected to limit the movement in the direction of the central longitudinal axis LA. Alternatively, the plate implant 1b can also be manufactured additively, for example by laser sintering. In this case, not only the bone topology but also the position of the fracture gap can be better taken into account. The material for the plate implant can be a typical corrosion-resistant steel or titanium or titanium alloy.

[0028] In particular, in the case of an individual manufacture of such a plate implant 1b, it is possible to alternatively reorient the leaf spring so that the movement occurring during loading occurs approximately perpendicular to the surface of the fracture gap, in this regard the surface of the leaf spring preferably extends approximately parallel to the fracture gap.

[0029] FIG. 3 shows a plate implant according to a third embodiment of the invention. 3 shows an alternative plate implant 1c with a first partial plate 11c and a second partial plate 12c and a number of third partial plates 13c. As in the previous embodiment, the location of the fracture gap is bridged by the partial plates 11c, 12c, 13c, for example in the region of the central transverse axis or, as shown, along an axis M' displaced relative to the central transverse axis. Thus, an advantage in this embodiment is that the location of the fracture gap relative to the plate implant 1c is not narrowly defined.

[0030] With respect to the displaced axis M' of the plate implant 1c, the five first holes 41c are arranged on a first side S1 of the axis M', and the six second holes 42c are arranged on the other second side S2 of the axis M'.

[0031] The partial plates 13c are connected along a central longitudinal axis LA to leaf springs 3' as longitudinal expansion devices, which are each formed in a pair and hold the other partial plates 11c, 12c. The third partial plates 13c each have a hole 4 along the central longitudinal axis LA.

[0032] The leaf spring 3' is configured to be formed by respective first, second and third notches 5', 5'', 5''', the first notches 5' defining the third partial plate 13c on the first partial plate 11c in a u-shape and partially surrounding the respective hole 4. The second notches 5'' defining the third partial plate 13c on the second partial plate 12c in a u-shape and partially surrounding the respective hole 4 and spaced apart from the first notches 5'.

[0033] The third notches 5''' are each disposed perpendicular to the central longitudinal axis LA and are between and spaced apart from a respective pair of first notches 5' and second notches 5''.

[0034] Thereby, the partial plate 13c is flexible in the direction of its longitudinal axis but is rigidly mounted in the direction of the bore axis and transversely to the longitudinal axis LA. It is not necessary for all holes 4 to be elastically mounted. Such an implant is suitable for example for treating juxta-articular or compound fractures.

[0035] FIG. 4 shows a plate implant according to a fourth embodiment of the present invention. The elongated plate implant 1d according to Fig. 4 can be used, for example, to treat distal tibia fractures. The elongated plate implant 1d has a body region R having a substantially constant first width and a head region K that expands continuously from the first width (imaginary separation line T).

[0036] The partial plates 11d, 12d each extend over the entire length of the plate implant 1d. As in the second embodiment, the first and second partial plates 11d, 12d have longitudinal expansion devices in the form of a number of leaf springs 3. The plate implant 1d is provided with a number of holes 13.

[0037] At the beginning of the upper proximal body region R and the lower distal head region K, nine holes 4 are arranged along the central longitudinal axis LA. As the lower distal head region K continues, two holes 4 are assigned to each of the left and right partial plates 11d, 12d, at which point they are offset toward the right edge RR or the left edge LR.

[0038] The leaf springs 3 allow elastic deflection in the direction of the central longitudinal axis LA and are formed by u-shaped notches 5 in the plate implant 1d surrounding respective holes 4 in the body region R along the central longitudinal axis LA. As the upper proximal head region K continues, two holes 4 are assigned to each of the left and right partial plates 11d, 12d, and the leaf springs 3 are offset towards the left edge LR and have an asymmetric u-shape.

[0039] In particular, the first six notches 5 and the eighth notch 5 in the body region R are u-shaped opening toward the left edge LR, while the eighth notch 5 in the body region R is u-shaped opening toward the right edge RR. The notches 5 in the head region K are also u-shaped opening toward the right edge RR.

[0040] The partial plates 11b, 12b and the leaf spring 3 therefore form a ladder structure which, due to the elasticity of the leaf spring 3, forms a longitudinal expansion device which can be sheared into a parallelogram.

[0041] The alternating arrangement of the leaf springs 3 allows the location of one or more fracture gaps to be taken into account by selecting the screw connections in the holes 4. It is precisely the central screw connection that is of considerable importance for stabilizing the fracture against bending loads and therefore it is important to be able to insert the screw exactly in this area.

[0042] The location of the fracture gap is indicated by alternative locations A, B, or C. For example, if the fracture gap location is A, a screw is inserted into hole 4a while hole 4b remains open. For example, if the fracture gap location is B, a screw is not inserted into either hole 4a or hole 4b. For example, if the fracture gap location is C, a screw is inserted into hole 4b while hole 4a remains open.

[0043] As can further be seen in Fig. 4, the leaf spring 3 has at its ends a gentle transition to the partial plates 11d, 12d. Thanks to the reduced notch effect, this improves the fatigue behavior of the plate implant 1d, which is important in this respect since typical materials for implants have a certain notch sensitivity. It can also be seen that the resulting width of the partial plates in the area surrounding the location of the fracture gap increases to accommodate the larger bending moments likely to occur in this region.

[0044] FIG. 5 illustrates a plate implant according to a fifth embodiment of the present invention, such as may be used to treat distal tibia fractures. The plate implant 1e having first and second partial plates 11e, 12e and multiple third partial plates 13e differs from the plate implant 1d of the fourth embodiment in that the leaf springs 3' around the sixth to eighth holes 4 are formed in the same manner as the leaf springs 3' of the third embodiment.

[0045] In particular, these leaf springs 3' are configured to be formed by respective first, second and third notches 5e', 5e'', 5e''', the first notches 5e' defining the third partial plate 13e in a u-shape on the first side S1 and partially surrounding the respective hole 4. The second notches 5e'' defining the third partial plate 13c in a u-shape on the second side S2 and partially surrounding the respective hole 4 and spaced apart from the first notches 5e'. The third notches 5e'' are each arranged perpendicular to the central longitudinal axis LA and are located between and spaced apart from the respective pair of first and second notches 5e' and 5e''.

[0046] Thereby, the partial plate 13e is flexible in the direction of its longitudinal axis but is rigidly mounted in the direction of the bore axis and transversely to the longitudinal axis LA. This arrangement likewise allows the screws to be placed close to the fracture gap along positions A, B, C, regardless of the location of the fracture gap, thereby not limiting the movement in the fracture gap. Thus, holes 4a, 4b, 4c can be provided with fixation elements according to the fracture gap. Thus, this variant is likewise advantageous when fixing fragments.

[0047] FIG. 6 shows a plate implant according to a sixth embodiment of the present invention. The plate implant 1f having first and second partial plates 11f, 12f and a number of third partial plates 13f differs from the leaf springs of the plate implant 1d of the fourth embodiment in that the leaf springs 3f around the sixth to eighth holes 4 are formed such that the attachment parts of the partial plates 13f are formed only by two notches 5f', 5f'' of increased length that are spaced apart so as to overlap, thereby improving flexibility.

[0048] In particular, these leaf springs 3f are configured to be defined by respective first and second notches 5f', 5ef'', the first notches 5f' defining the third partial plate 13f in a u-shape on the first side S1 and partially surrounding the respective hole 4 in an overlapping manner, and the second notches 5f'' defining the third partial plate 13f in a u-shape on the second side S2 and partially surrounding the respective hole 4 and spaced apart from the first notches 5f'.

[0049] FIG. 7 shows a plate implant according to a seventh embodiment of the invention used for the reconstruction of a mandible 7 from a fragment of the fibula. FIG. 7 shows the use of two plate implants 1g, 1g' with leaf springs 3g and notches 5g', 5g'' similar to the leaf springs 3f and notches 5f', 5f'' according to FIG. 6 in the reconstruction of a mandible from a fibula fragment. Individually configured implant plates 1g, 1g' are used, each bridging the respective fracture gap 6 location.

[0050] Instead of rigidly fixing the fragments, the function consists in generating movements and forces by dynamization with forces F present in the part of the reconstructed mandible 7, said movements and forces contributing to the compression of the fracture gap.

[0051] This is possible because the leaf spring 3g is oriented at a slight angle to the location of the fracture gap. A force component is generated which closes the fracture gap.

Claims

1. A plate implant (1a-1g) for bridging a fracture gap (6), comprising: a longitudinal axis (LA) in the direction of greatest extent of said plate implant (1a-1g); a plurality of holes (4) spaced apart from one another in the direction of the longitudinal axis (LA); and an elastic longitudinal expansion device (2; 3; 3'; 3, 3'; 3, 3f; 3g) provided between at least two holes (4), the longitudinal expansion device (2; 3; 3'; 3, 3'; 3, 3f; 3g) is configured so that the plate implant (1a-1g) has an improved expandability in the direction of the longitudinal axis (LA) but at the same time has high bending and torsional stiffness, The longitudinal expansion device (2; 3; 3'; 3, 3'; 3, 3f; 3g) comprises a plate implant (1a-1g) comprising leaf springs (3; 3'; 3, 3'; 3, 3f; 3g) formed by U-shaped notches (5; 5', 5'', 5''; 5; 5, 5e', 5e'', 5e'''; 5, 5f', 5f''; 5g', 5g'') in the plate implant (1a-1g) surrounding each hole (4).

2. A plate implant (1a-g) for bridging a fracture gap (6) as described in claim 1, wherein the U-shaped notches include a first plurality of U-shaped notches (5f', 5f''; 5g', 5g'') and a second plurality of U-shaped notches (5, 5f', 5f''; 5g', 5g''), the first plurality of U-shaped notches (5f', 5f''; 5g', 5g'') each configured to open towards the left edge (LR) of the plate implant, and the second plurality of U-shaped notches (5, 5f', 5f''; 5g', 5g'') each configured to open towards the right edge (RR) of the plate implant.

3. The plate implant (1a-g) for bridging a fracture gap (6) according to claim 1, wherein said notches (5f', 5f''; 5g', 5g'') overlap laterally.

4. 2. The plate implant for bridging a fracture gap according to claim 1, wherein the leaf springs are formed by respective first notches, second notches, and third notches, the first notches and the second notches at least partially surrounding the respective holes in a U-shape, the U-shape of the first notches opening towards a left edge of the plate implant and the U-shape of the second notches opening towards a right edge of the plate implant, and the third notches are each disposed perpendicular to the longitudinal axis and are disposed between respective pairs of the first and second notches and spaced apart from the respective pairs of the first and second notches.

5. 5. The plate implant (1a-g) for bridging a fracture gap (6) according to claim 4, wherein the second notches (5'') are spaced apart from the first notches (5') and are opposite the first notches (5'), and the third notches (5''') are each disposed perpendicular to the longitudinal axis (LA), and are disposed between respective pairs of the first notch (5') and the second notch (5'') and spaced apart from the respective pairs of the first notch (5') and the second notch (5'') so as to form the leaf springs (3').

6. 6. A plate implant (1a-g) for bridging a fracture gap (6) according to any one of claims 1 to 5, characterized by a body region (R) having a substantially constant first width and a head region (K) which continuously widens from said first width.

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