FI69403B - OSTEOSYNTESANORDNING FOER IMMOBILISERING AV BENFRAKTUREN - Google Patents

Description

69403

Osteosynthesis device for fixation of fracture - Osteosynthesis-anordning för immobilisering av benfrakturen

The invention relates to an osteosynthesis device as further defined in the preamble of claim 1.

In traumatology, there is a generally accepted method of using plate-like, rigid, bone-to-bone osteosynthesis plates for fixation of fractures, by means of which the fractured bone is fixed during the healing period.

The material of the osteosynthesis device is subject to very high requirements in terms of mechanical properties, tissue adaptability and effects on bone growth. Most commonly, these are made of austenitic steel, titanium or the like metals or alloys that meet the requirements of the fabric environment. Normally, such a traditional biostable osteosynthesis device is removed when fracture healing has progressed through bone tissue growth long enough.

However, there are a variety of problems with the use of metallic osteosynthesis devices. Many metals and alloys corrode in the tissue environment, causing tissue irritation and infection. Infections associated with metal osteosynthesis are often problematic and only resolve after removal of the metallic osteosynthesis device. Corrosion is particularly common at the contact points between the plate and the fastening screws.

Because the elastic modulus of metals (typically 100-200 GPa) is significantly higher than the modulus of bone (typically 25 6-20 GPa), the metallic osteosynthesis device significantly reduces stresses and deformations on the bone. Such stress protection causes disorders in the behavior of bone tissue, manifested as osteoporosis (increased porosity) and thinning of the bone beneath the disc. In severe cases, the development described above may lead to re-fracture of the fragile bone after removal of the osteosynthesis device.

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69403

In order to eliminate the disadvantages of using metallic osteosynthesis devices, intensive efforts have been made in recent years to develop osteosynthesis devices from polymeric materials.

Polymers and composites useful as surgical implant materials can be classified as biostable and fully or partially resorbable. Similarly, osteosynthesis devices can be classified as biostable, fully resorbable, and partially resorbable.

The response of biosablets to osteosynthesis devices made of polymers to the host tissue is minimal and the implant retains its shape and properties approximately unchanged even over long periods of time (years). Such an osteosynthesis device is disclosed, for example, in Swiss Patent 618,866.

Fully resorbable and partially resorbable osteosynthesis devices retain their tissue-supporting properties over a period of time (typically weeks or months), gradually degrading to non-toxic, non-tissue-irritating, small-molecule implants that leave the tissues via normal me-tabol. In the case of a partially resorbable osteosynthesis device, a non-harmful residue is left in the tissue which no longer supports the tissue.

The use of osteosynthesis devices made of biostable polymers, the modulus of which can be adjusted in the same order of magnitude as the modulus of bone, can significantly reduce osteoporosis and metal corrosion reactions. However, in several cases, they still require 30 removal surgeries. When using fully or partially resorbable polymers, it is possible to avoid removal cutting. Thus, at least partially resorbable osteosynthesis device 69403 (implants) made of resorbable polymers or composites thereof provide the best overall choice for the use of an osteosynthesis device for the following reasons: (1) At a later stage, the implant gradually disintegrates and thus the tensions are gradually transferred to the healing bone, preventing osteoporosis.

(2) The mechanical properties of an implant made of an organic material or a composite can be adjusted closer to the corresponding properties of a bone than the properties of a conventional metallic implant.

(3) At least the completely resorbable osteosynthesis device does not need to be removed, which eliminates the risks and costs of removal surgery 15. This reduces the financial loss to the patient and society.

The most widely studied and resorbable polymers suitable for surgical applications are polyglycolide, polylactide and their copolymers, the preparation and applications of which in the form of su-20 tubes and others have been described e.g. U.S. Patents Pat. 2,668,162 to U.S. Pat. Pat. 2,676,945 to U.S. Pat. Pat. 3,297,033, U.S. Pat. Pat. 3,463,158, U.S. Pat. Pat. 3,636,956, Can. Pat. 808,731. U.S. Pat. Pat 3,297,033 discloses the possibility of combining polyglycolide fiber and other structures. This principle has been used in French Patent Application 78 29878, which describes a resorbable osteosynthesis device with resorbable fibers as a reinforcement. Em. the osteosynthesis plates according to the French patent application are provided with holes for screw fastening. Thus, the conventional technique known from the use of metal sheets has been followed in the fastening of the plates (P. Christel et al., Biomaterials 1980, p. 271).

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Figure 1 is a schematic top view of a conventional osteosynthesis device attached to a bone. According to Figure 1, a bone 1 with a fracture 2 is immobilized by means of an osteosynthesis plate 3 extending over the fracture, which is fixed to the bone 5 by nails or screws 4. The number of screws typically varies between 6-8.

Screw fastening is suitable for metals, because the compressive stresses formed in the screw around the hole in the plate usually do not exceed the yield strength of the metal, so that the metallic materials are elastically filled in this situation.

Due to their viscoelastic nature, osteosynthetic materials made from polymers and polymer composites do not have a clear range of elastic behavior. Therefore, the stress caused by the screw attachment around the attachment hole causes a continuous deformation (creep) in the polymer-based osteosynthesis plate, which results in the attachment loosening and / or the formation of fractures around the hole in the osteosynthesis plate. In addition, polymeric materials are typically notch-sensitive materials, so those holes 20 adversely act as concentrators of stress concentrations, which also promotes the formation of fractures around the holes (P. Christel et al., Biomaterials 1980, p. 271).

In addition, the screw attachment of the osteosynthesis device causes high local torsional stresses at the screw-bone interface, as a result of which this interface is the weakest point in question. in construction.

Finnish patent application 83 3351 discloses at least a partially resorbable osteosynthesis device, by means of which the problems caused by known osteosynthesis devices, in particular due to their attachment technique, and the need for removal surgery can be eliminated.

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The osteosynthesis device according to the above-mentioned applications is mainly characterized in that the osteosynthesis device comprises a combination of (a) at least one, at least immediately after the operation 5 substantially rigid, at least partially resorbable osteosynthesis plate placed over or through the fracture site; ) at least one at least in the operative step, a flexible fastener attached to the bone and / or tightened) to pass over or through the fracture site of the bone and / or to pass over the osteosynthesis plate, wherein the osteosynthesis plate, the fastener and the fracture-containing area of the fracture a rigid and robust assembly for healing, wherein the stiffness and strength of the osteosynthesis device through resorption are preferably reduced as the healing progresses so that the need to perform removal of the device is eliminated.

Further, said osteosynthesis means may be located in a groove or channel or the like formed at least in part in the bone, the osteosynthesis plate being shaped to fit the groove and / or channel at least in part and comprising e.g. a groove or cross section .

Figure 2 shows three typical embodiments of the invention according to patent application FI 83 3351. In the case of Figure 2a, the at least partially resorbable osteosynthesis plate 7 extending beyond the fracture 6 in the bone 5 is mechanically pressed against the bone by means of fasteners 8 'threaded through the holes 10 and tightened into annular structures. The osteosynthesis plate 7 is at least partially embedded in the transverse groove 6 69403 9 made in the bone. Further, in this construction, transverse fasteners 8 are used to press the fracture surfaces of the bone directly against each other. Many different solutions can be applied to the placement of the fasteners 8 and 8 ', some of which preferred embodiments are described in more detail in the application FI 83 3351.

According to the embodiment shown in Figure 2b, the osteosynthesis plate 7 is placed completely inside the bone to be fixed, in a channel 11 drilled through the fracture site. The osteosynthesis plate then gives the construction the necessary lateral rigidity. The longitudinal rigidity of the fracture-10 parts thereof is ensured by means of fasteners which are tightened and knotted into annular structures 8 through wire channels 10 drilled above and below the fracture plane. If strong torsional stresses are applied to the fracture area, it is possible to use, for example, two plates placed in channels drilled through the fracture site. In other cases, if necessary, two or more osteosynthesis plates placed on different sides of the bone may be used.

Figure 2c shows an embodiment of an osteosynthesis device in which an at least partially resorbable osteosynthesis plate 20 7 is fixed and tightened in place by means of a clamp 8 "formed by clamping wedges 14 or the like placed between the annular members 13 and the bone 5 and the members 13. The annular member 13 can be (This embodiment can therefore be applied in particular when the ends of the bone 5 are detached at the fracture point 6.) After the members 13 have been placed, they are tightened in place by wedges 14. The annular member 13 may be resorbable in material and / or biostable (e.g., carbon fiber) and wedges or the like can be preferably made of a resorbable material, in which case the osteosynthesis device loses its rigidity as the osteosynthesis plate and wedges resorb as healing progresses and the load is gradually transferred to the bone. pool promotes healing.

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The osteosynthesis device according to the application FI 83 3351 has many advantageous properties compared to conventional osteosynthesis devices. In particular, these devices can effectively immobilize a fracture against deformations caused by different types of external forces without having to resort to unfavorable screw fixation. At the same time, the use of fully or partially resorbable materials avoids the risks and costs of surgical removal of the osteosynthesis device.

However, the osteosynthesis device according to the application FI 83 3351 has some limitations with regard to their use in areas where the bone is subjected to very strong tensile or torsional stresses and / or where, for example due to poor bone circulation, the aim is to minimize operational trauma or maximize fracture surface area. 15 compressive force. The osteosynthesis device according to the application FI 83 3351 immobilizes the fracture against tensile stresses by means of tensioned fasteners 8 and / or by frictional forces between the osteosynthesis plate 7 and the bone 5. In the case of high tensile stresses, this results in the use of thick fasteners 8, which slows down the cutting operation due to the fastening technique of the fasteners. In order to prevent deformations in the immobilized fracture caused by torsional stresses as effectively as possible, the osteosynthesis plate 7 must be placed at least partially in the groove 9 and / or the channel 25 crossing the fracture site 6 and 11. Machining such a groove or channel over or through the fracture site for example, bone in the area of poor blood circulation can be harmful and slow healing. Furthermore, the provision of an effective compressive stress on the fracture surface requires the above-mentioned osteosynthesis means to compress the bone parts against each other in the direction of the longitudinal axis of the bone, which in practice may require special equipment and unnecessary exposure of the bone surface.

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The present invention provides an at least partially resorbable osteosynthesis device which, for structural reasons, does not have the above drawbacks. The osteosynthesis device according to the invention is mainly characterized in that it comprises a combination of an at least partially resorbable osteosynthesis plate partially embedded in at least one bone groove or channel or hole or the like not exceeding a fracture, the osteosynthesis plate being or partially suitable for a duct or hole or the like.

The invention and its functionality are further illustrated in the following description with reference to Figures 3-7.

Figure 3a shows a view from above of a fracture of a preferred embodiment of the invention, in which the bone is provided with fracture-elongate grooves 9 on both sides, which do not extend to the fracture 6. The osteosynthesis plate 7 has beams 7 'corresponding to the shape of the grooves 9, which are tightly pressed into the grooves 9. The depth of the groove 9 can vary so that, for example in the tubular bone, it can extend to the bone marrow canal (e.g. Figure 3c). In the case of Figure 3, the fasteners 8 'are annular in structure and can rotate around the entire bone, tightening and knotting in place to press the osteosynthesis plate against the bone to be immobilized. The fastener 8 'may preferably be a bundle or yarn assembled from resorbable and / or biostable fibers or a structure woven or knitted from yarns or constructed by some other similar method. The fibrous structure in question may also be impregnated with a monomer or polymer, which may also polymerize or cure at or after the end of the operation. Figure 3b shows a longitudinal section of the osteosynthesis plate and Figure 3c shows a longitudinal section of the system formed by the osteosynthesis device and the immobilized bone. The osteosynthesis device of Figure 3 effectively prevents the fracture-opening effect of tensile stresses acting in the longitudinal direction of the bone. Likewise, it effectively prevents the deformations that torsional stresses tend to cause in the fracture region. Furthermore, the installation of the osteosynthesis device shown in Figure 3 does not immediately cause operational trauma to the fracture area.

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Figure 4a is a top view of a preferred embodiment in which fracture holes 9 'are drilled in the bone on both sides of the fracture. The number of holes can vary, being typically between 1 and 4 on each side of the fracture. The osteosyn-5 tea plate 7 then has cylindrical beams (pins) 7 'corresponding to the holes, which are pressed tightly into the holes. Figure 4b shows a longitudinal section of such an osteosynthesis plate mounted in place in Figure 4a. Again, the osteosynthesis means effectively prevents the effects of tensile and torsional stresses 10 in the fracture region, and the installation of the osteosynthesis means does not cause operational trauma to the fracture.

In a preferred embodiment, the beams 7 'of the osteosynthesis plate 7 and the grooves 9 made in the bone are shaped relative to each other so that pressing the osteosynthesis plate 7 and the beams 7 * into the grooves 9 causes compression stress between the fractured parts, effectively immobilizing the fracture. Such a situation is created e.g. by making fracture-shaped grooves 9 on both sides of the bone which do not extend to the fracture 6 and the osteosynthesis plate 7 has wedge-shaped beams 7 'with a cross-sectional shape of grooves 9 which are pressed into the grooves 9. Figure 5 presents such an embodiment. Figure 5a shows, seen from above the fracture 6, elongate grooves 9 made in the bone 5 with a distance between them. Figure 5b shows a longitudinal section of an osteosynthesis plate 7 containing wedge-shaped beams 7 '. The distance between the base parts of the wedge-shaped beams is B. the distance between the grooves 9 and the distance between the grooves 9 are proportional so that A is slightly larger than B, when the osteosynthesis plate is pressed into place, a favorable compressive force F 30 is generated, which presses the broken bone parts together. This situation is illustrated in Figure 5c, which shows a longitudinal section of the system formed by the osteosynthesis device and bone in the vicinity of the fracture. Compression force ____ ____: ·. ... The retention of the osteosynthesis plate 7 which maintains the position of the osteosynthesis plate 7 is achieved, for example, by tightening the fasteners 8 'to pass over the osteosynthesis plate, as has been done in the case of Fig. 5c. The compression effect on the fracture can also be achieved by making the grooves 9 5 conical at the surfaces closest to the fracture and the beams 7 'of the osteosynthesis plate, which can be straight (such as in Fig. 3b) or wedge-shaped (such as in Fig. 5b) pressed into the grooves. Figure 6 shows a longitudinal section of this type of embodiment.

Fasteners for holding the osteosynthesis plate in place and / or reinforcing fracture immobilization can be placed on the osteosynthesis plate and the fracture in a number of preferred ways, some typical solutions of which are shown in Figure 7. Figure 7 shows the whole formed by the osteosynthesis device and the bone from above the fracture.

In the case of Figure 7a, the fasteners 8 extend over the fracture and are positioned by threading the fastener braid on both sides through the holes 10 drilled in the fracture and tightening and joining the braids into annular structures. When using, for example, fasteners braided or woven from strong resorbable fibers, the fixing effect of the osteosynthesis device is strongest immediately after installation, whereby the healing fracture is weakest. The effect of the osteosynthesis means preferably diminishes as a function of time as a result of the resorption of the osteo-25 synthesis plate and possibly also of the fixatives, while the bone fracture site strengthens as healing progresses. In the case of rigid fasteners, a technique may be used in which the holes do not necessarily extend through the bone but form notches into which the rigid fasteners are pressed.

In the constructions according to Figures 7b and 7c, at least one osteosynthesis plate 7 is pressed against the bone to be mechanically immobilized by means of at least one fastener 8 '. The rigid and flexible - il '-' - - · 69403 fasteners may be annular in structure and may rotate around the entire bone as shown in Figure 7b. Flexible fasteners can be threaded through holes drilled through the bone as shown in Figure 7c. The rigid fasteners can also be pushed from the top-5 into place in the holes 10 in the case of Fig. 7c. Due to the compression applied to the osteosynthesis plate 7 through the fasteners, the osteosynthesis plate 7, the fasteners 8 'and the bone 5 containing the fracture 6 form an assembly effectively carrying different stresses at least immediately after the installation surgery. The strength and stiffness of the osteosynthesis device preferably decrease as a function of time as the healing progresses as a result of the resorption of the osteosynthesis plate or the osteosynthesis plate and the fixative.

If the fracture is subjected to very strong different types of stresses (as is the case, for example, in the case of a tubular bone), the construction according to Figure 7d can be used. In this case too, the at least partially resorbable osteosynthesis plate 7 is pressed against the bone to be mechanically immobilized by means of fasteners 8 'extending around the bone. Furthermore, in the construction according to Fig. 7d, fracture-extending fasteners 8 are used to press the fracture surfaces of the bone directly against each other. The fasteners 8 can be positioned as described in the description of Figure 7a.

Fasteners 8 and 8 'can also be constructed of a uniform resorbable and / or biostable fastener braid or strip 25 which is threaded through holes drilled in the bone (flexible fastener) or inserted into the bones. holes (rigid fastener), as made in Fig. 7e, whereby the fastener structure provides a pressure acting directly on both the osteosynthesis plate 7 and the fracture surface 6 of the bone. The degree of compression and thus the rigidity of the osteo-30 synthesis device preferably decreases as the osteosynthesis plate or the osteosynthesis plate and the fastener resorb as a function of time as the fracture heals.

Figure 7f shows an embodiment of the osteosynthesis device in which the at least partially resorbable osteosynthesis plate ____ L · 12 69403 7 is fixed and tightened in place by means of a fastener 13 "formed by tension wedges 14 or the like arranged between the annular members 13 and the bone 5 and the members 13. can be placed as shown in the figure, in a substantially fracture position around the bone through the fracture 6. (Thus, this embodiment can be applied especially when the ends of the bone 5 are detached at the fracture point 6.) After placing the members 13, they are tightened with wedges 14. Annular member 13 the material may be re-sorbable and / or biostable (e.g. carbon fiber) and the wedges or the like may be preferably made of a resorbable material, in which case the osteosynthesis means loses its rigidity as the osteosynthesis plate and wedges resorb and the load gradually shifts. which 15 contributes to healing.

In the embodiments 7a-7f of Figure 7, the fasteners are positioned to pass over the osteosynthesis plate. In order to prevent the fasteners from moving along the longitudinal axis of the osteosynthesis plate, special grooves can be made in the surface of the osteosynthesis plate in which the fasteners are placed. Likewise, there may be special protrusions on the surface of the osteosynthesis plate between which the fasteners are placed. The fastener can also be placed to pass through holes or channels made in the osteosynthesis plate, which, while weakening the strength of the osteosynthesis plate, on the other hand effectively ensure the movement of the fasteners in the direction of the longitudinal axis of the osteosynthesis plate. These embodiments are illustrated by way of example in Figures 7g-7i, which consider some longitudinal sections of the osteosynthesis device and the system formed by the bone to be immobilized. Figure 7g shows the fasteners 8 'in the grooves 15, 7h in the grooves 16 made in the osteosynthesis plate 7 and in the channels 17 made in the osteosynthesis plate 7i.

In connection with the fastener techniques shown in Figure 7, the techniques shown in Figures 3-6 may be applied to place the osteosynthesis plate 13 69403 in a groove, channel, hole, or the like partially made in the bone. It is also natural that numerous other types of osteosynthesis plate and fastener placement options than those shown in Figures 3-7 are possible.

However, it is essential for all osteosynthesis devices according to the invention (A) to combine the mechanical effects of at least one osteosynthesis plate 7, at least partially resorbable, partially embedded in bone, and at least one fastener 8, 8 ', 8 "according to the invention in order to prevent e.g. It is further essential for the osteosynthesis devices of the invention that (B) their mechanical, fracture-reinforcing and stiffening effect diminishes as a function of time as a result of low resorption of the plate or plate and fastener, that the need for osteosynthesis device removal surgery is eliminated.

The osteosynthesis plate 7 may be made of a resorbable material. It may additionally contain resorbable reinforcing fibers. It may also contain biostable reinforcing fibers, such as carbon-20 fibers, in which case it is a partially resorbable osteosynthetic sheet. In addition, the osteosynthesis plate may contain alloying and / or additives necessary for its manufacturing process or performance.

The fastener 8, 8 ', 8 "may be a bundle or yarn assembled from resorbable and / or biostable fibers or woven or knitted from yarns or a structure constructed by some other similar method. The fibrous structure may also be impregnated with a monomer or polymer which may also polymer. -treat or harden at or after the end of surgery.

Claims (12)

An osteosynthesis device for immobilizing the bone fracture, comprising at least one organ, sorting beyond the fracture (6), which means communicates with the portions of the bone (5) which are located on opposite sides of the fracture (6) and which osteosynthesis device comprises assembly with at least one, substantially at least immediately after the surgical installation operation, substantially rigid, at least partially resorbable osteosynthesis plate (7), which passes past the fracture (6) and - at least one, at least during the installation, flexible fixation elements (8, 8 ', 8 ") which is attached to the bone (5) and / or clamped in place to pass or perforate the fracture (6) of the bone (5) and / or to pass or perforate the osteosynthetic plate (7) in such a manner, the osteosynthesis plate (7), the fixation element (8, 8 ', 8 ") and the region of the immobilized bone (5) where the fracture exists after the clamping of the fixation element (8, 8', 8") forms an aggregate whose stiffness is high enough to cure the healing of the fracture (6), and where the stiffness and pour strength of the osteosynthesis device during healing is advantageously reduced as a consequence of the resorption of the osteosynthesis plate of the osteosynthesis plate and the fixation element in such a way that the need to remove the in a separate operation is excluded, characterized in that the at least partially resorbable osteosynthetic plate (7) is placed partially into the at least one bone or canal or shark or shark or shaft (9, 9 ') which does not pass the fracture. , wherein the osteo-synthesis plate (7) is shaped in such a way that it fits partially within the groove or channel or heel or the like (9, 9 '). 2. An osteosynthesis device according to claim 1, characterized in that the osteosynthesis plate (7) comprises at least one support beam (7 ') which is placed at least partially in the bone shaped groove, slab or the like (9, 9') 'whose shape corresponds to the shape of the support beam or its cross-section. Osteosynthesis device according to claims 1 and 2, characterized in that the support beams (7 ') located in the osteosynthesis plate which are on opposite sides of the fracture are shaped in such a way that when the support beams are placed into the latch ( 9, 9 ') which are formed in the bone, a compressive stress (F) between the portions of the fracture arises. 4. An osteosynthesis device according to claims 1-3, characterized in that at least one of the support beams (71) is wedge-shaped. Osteosynthesis device according to at least one of claims 1-4, characterized in that the fixing element (8, 8 ") is eaten around the bone (5). Osteosynthesis device according to at least one of claims 1-4, characterized in that at least one tail or notch (10) is formed into the leg (5) and the fixing element (8, 8 ') is eaten between the heel or notch ( 10) and the outer surface of the leg (5) and / or between the heel or notch (10). Osteosynthetic device according to at least claim 5, characterized in that the fixing element (8 ") comprises an assembly composed of at least one