RU2765329C1 - Bone fixation system - Google Patents

Abstract

FIELD: medicine; veterinary medicine.

SUBSTANCE: invention relates to medicine and veterinary medicine and can be used for fixing bone fragments in the treatment of bone fractures. The system for fixing the bones includes a plate with threaded holes and a cap screw. A threaded section is located on the cylindrical rod, the length of which corresponds to the length of the thread in the hole of the plate. The cap screw has a smooth cylindrical shank. The system is completed with headless screws and a transosseous element. Each headless screw has a smooth cylindrical shaft and is equipped with a device for limiting the axial movement of the screw in the hole of the reconstruction plate. One of the headless screws contains two cylindrical sections of different diameters. The distal portion has a smaller diameter. The transosseous element, made in the form of a cylindrical rod with a pointed end, has a threaded section mating with the thread in the hole of the plate. The headless screw is provided with a slot or a seat recess for the tool at the end of the screw. At the end of the headless screw, stop protrusions are made or the end of the headless screw is flared.

EFFECT: increasing the efficiency of fracture treatment, in the ability to easily adapt the configuration of the structure to the corresponding anatomy of the patient's bones, simplifying the process of removing structural elements, simplicity of design, and low cost of manufacturing.

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Description

The invention relates to veterinary medicine and medicine, more specifically to traumatology and orthopedics, namely to devices for fixing bone fragments in the treatment of bone fractures.

Known Compression mini-plate for osteosynthesis of the lower jaw, the method of its installation and a set of tools for installation (US Pat. them. The mini-plates presented in the invention have a different configuration, which allows you to choose the most optimal option depending on the location of the fracture. The disadvantage is that the application is possible only in maxillofacial surgery.

A known method of osteosynthesis using the components of the D-RAD SMART PACK system for osteosynthesis of the distal radius with accessories [https://www.smith-nephew.com/pagefiles/179781/instr2/%D0%9A%D0%BE%D0% BC%D0%BF%D 0%BE%D0%BD%D0%B5%D0%BD%D1%82%D1%8B%20%D1%81%D0%B8%D1%81%D1%82%D0 %B5%D0%BC%D1%8B%20drad%20smart%20pack%20%D0%B4%D0%BB%D1%8F%20%D0%BE%D1%81%D1%82%D0%B5%D0 %BE%D1%81%D0%B8%D0%BD%D1%82%D0%B5% D0%B7%D0%B0%20%D0%B4%D0%B8%D1%81%D1%82%D0 %B0%D0%BB %D1%8C%D0%BD%D0%BE%D0%B3%D0%BE%20%D0%BE%D1%82%D0%B4%D0%B5%D0%BB%D0 %B0%20%D0%BB%D1%83%D1%87%D0%B5%D0%B2%D0%BE%D0%B9%20%D0%BA%D0%BE%D1%81%D1%82 %D0%B 8%20%D1%81%20%D0%BF%D1%80%D0%B8%D0%BD%D0%B0%D0%B4% D0%BB%D0%B5%D0%B6% D0%BD%D0%BE%D1%81%D1%82%D1%8F%D 0%BC%D0%B8.pdf - 08/06/2021]. The components of the D-RAD SMART PACK system are represented by implants in the form of plates, screws, pins and instruments for the treatment of fractures of the distal radius. Fixation of the D-RAD plate is provided by the use of screws and lockable pins, made in the form of screws with a countersunk threaded head of a conical shape and a smooth screw body. The head of the screw of a conical shape is rigidly fixed in the hole of the plate by means of a thread. The disadvantage of the known system lies in the high cost, in the limitations on the strength of the implant due to the fact that the load in the early stages of healing significantly increases the risk of weakening, bending or breakage of the device, so full load is contraindicated until the bone is completely healed. In addition, there are no transosseous elements in the system, which limits the possibility of using the system, for example, for the treatment of unstable comminuted fractures.

A bone fixation system is known (US Pat. No. 2605497, RU, IPC A61B 17/80, 2013). The system is designed for external fixation of bone fragments and contains a base plate, a cantilever reconstructive attachment, cylindrical spokes and connecting elements in the form of screws with a conical thread. The support plate is stepped with uniformly spaced shaped holes, which are a combination of an oval-shaped hole with a hole with a conical thread. The free ends of the pins inserted into the bone fragments are fixed with a washer to the base plate or cantilevered reconstructive plate, for which the free end of each pin is placed in one of the grooves of the washer, which can be from one to four. The disadvantages of the system are that, despite the use of pins, it is used only as a bone system and is not provided with the necessary rigidity of fixation. In addition, after the fracture is healed during dismantling of a system using conical threaded screws, the thread is often stripped and the screw head is jammed in the plate hole, so there is a problem of removing such metal structures.

Known System for external osteosynthesis (US Pat. No. 2674932, RU, IPC A61V 17/80, 2017), consisting of a plate with threaded holes mating with the screw thread of the head screw, which has a thread-free section between the head and the screw thread, length which corresponds to the length of the screw thread of the threaded hole of the plate. Additionally, a threaded section is made between the screw head and the thread-free section, the length of which corresponds to the length of the screw thread in the plate hole, and the diameter of the thread-free section is equal to the inner diameter of the screw thread. The efficiency of using the system lies in the fact that the section of the screw without a thread makes it possible to correct possible errors when inserting the screw, for example, the angle of the screw in relation to the surface of the plate. The disadvantage of the system is that the rigidity of fixation is provided only by screws, as well as the existing problem of dismantling the system.

The objective of the invention is to achieve strength and stability of the installed structure and to ensure rigid fixation of bone fragments in the optimal position.

The technical result of the invention consists in increasing the efficiency of fracture treatment, in the ability to easily adapt the configuration of the structure to the corresponding anatomy of the patient's bones, simplifying the process of removing structural elements, simple design, and low cost of manufacture.

The claimed technical result is achieved by the fact that in a system for fixing bones, including a plate with threaded holes, as well as a screw with a head and a cylindrical rod, on which a threaded section is located, the length of which corresponds to the length of the thread in the plate hole, a number of changes and additions are made. The cap screw has a smooth cylindrical shaft. The system is supplemented with headless screws and a transosseous element. Each headless screw has a smooth cylindrical shaft and is provided with a device to limit the axial movement of the screw in the hole of the reconstruction plate. One of the headless screws contains two cylindrical sections of different diameters, while the distal section has a smaller diameter. The transosseous element, made in the form of a cylindrical rod with a pointed end, has a threaded section mating with the thread in the plate hole. In addition, a headless screw is provided at the end of the screw with a slot or a recess for the tool.

Distinctive features of the proposed system from the prototype are as follows.

The execution of screws with a smooth cylindrical rod ensures the strength of the system, because a smooth screw, due to its relative flexibility, easily withstands lateral loads and, when bone fragments are displaced, it bends (within the allowable range). A smooth screw provides simplified dismantling, which is useful when erecting temporary structures in order to accurately match bone fragments. A smooth screw is easy to manufacture and does not differ in high cost.

Making headless screws minimizes soft tissue irritation and simplifies manufacturing.

Making a screw without a head with two cylindrical sections of different diameters makes it possible to use it to stabilize the plate against separation, for which a thinner section of the screw is bent at an angle of 90° after the screw is inserted into the bone.

Adding a transosseous element to the system makes it possible to add an external fixation device and increase the stability and rigidity of the system.

A patent search for the subclass IPC A61B 17/80, as well as an analysis of the available scientific and technical information reflecting the current level of technology for metal structures for osteosynthesis, did not reveal identical developments. These allow us to conclude that there is novelty in the proposed technical solution. The presented distinguishing features provide the achievement of a technical result in solving the problem. Thus, the proposed technical solution has an inventive step. The components of the claimed system can be reproduced repeatedly and do not require the use of exclusive means for implementation, which indicates industrial applicability.

The invention is explained by the description, examples of use and illustrations, where:

Fig. 1 - screw for osteosynthesis;

Fig. 2 - countersunk head screw;

Fig. 3 - screw with a countersunk head under a bend;

Fig. 4 - transosseous element;

Fig. 5 - diagram of the assembly of the system;

Fig. 6 - variant of the assembly of fractures with complex bone relief;

Fig. 7 - a variant of the assembly of the system during reconstructive operations.

The system for osteosynthesis includes screws, transosseous elements and reconstruction plates with holes. The holes for the screws are made cylindrical with a thread identical to the threads on the screws and the transosseous element.

The screw 1 (Fig. 1) has a head 2 and a threaded section 3 adjacent to the head 2, placed on a cylindrical rod 4, which is made smooth, without thread. A smooth screw, due to its relative flexibility, easily withstands lateral loads and, when bone fragments are displaced, it bends. A smooth screw provides simplified dismantling, which is useful when erecting temporary structures. The threaded section 3 mates with the threads in the hole of the reconstruction plate, which provides pressing pressure on the surface of the bones. The screw 1 for osteosynthesis has a pointed shank 5 for entry into the bone. To facilitate screwing, the head 2 has a tool slot at the end, for example, a hexagonal recess, a cross-shaped one, etc. The head 2 can be made in the form of a square, a circle, etc.

Screw 6 (Fig. 2) has no head and is completely recessed into the surface of the reconstruction plate, which minimizes soft tissue irritation, simplifies the manufacture of screws, and also provides simplified assembly and disassembly. The countersunk screw 6 contains a threaded section 3 for mating with the reconstruction plate, made on a smooth cylindrical rod 4, as well as a pointed shank 5. At the end of the screw 6 there is a slot or a recess for a polyhedral key. To limit the axial movement of the screw 6 in the hole of the reconstruction plate at the end of the screw 6, an extension is created, providing with thrust ledges 7 in the amount of 2-3, or the end of the screw is flared.

Screw 8 (Fig. 3) is also a countersunk screw with a smooth cylindrical rod, and contains a threaded section 3 for mating with the reconstruction plate, as well as a pointed shank 5. At the end of the screw 6 there is a slot or a recess for the tool, as well as stop ledges 7. The smooth shaft of the screw 8 contains two cylindrical sections of different diameters, while the distal section has a smaller diameter compared to the proximal one. This design of the screw 8 allows you to install it in the holes of the plate, for example, located at the edges of the plate, and, after passing through the bone, bent at an angle of 90° to stabilize the plate for separation. The length of the screws depends on the thickness of the reconstructed bone fragment, so it can be different. The screws are made from durable medical alloys.

The transosseous element 9 (Fig. 4) installed in the threaded holes of the reconstruction plate is designed to connect the bone system with the external fixation device. The transosseous element 9 in the form of a cylindrical rod with a pointed end has a threaded section 10 mating with the thread in the hole of the plate. The distance from the threaded section 10 to the pointed end 11 should be sufficient for installation in the bone, depending on the thickness of the bone in which it will be installed, therefore it is advisable to make a set of transosseous elements with different lengths from the pointed end to the threaded section.

The inventive system is used as follows. In FIG. 5 shows a variant of a possible scheme of a bone structure. Stabilizing screws 8 are inserted along the edges of the plate. Fixing screws 1 are installed in the center of the plate. Screws 6 are inserted for additional fixation. A transosseous element 9 is installed in one of the holes in the plate, on which an external fixation device is mounted. Transosseous element 9 and screws 1, 6, 8 are inserted into the bone in pre-prepared channels. Bone anatomy imposes restrictions on the size and thickness of the used bone screws or plates, and therefore the stability and rigidity of implants is limited, and to increase the stability of the bone structure, it is optimal to supplement it with an external fixation device. When using relatively thin and flexible plates for osteosynthesis, having a thickness of 1 to 2 mm, the assembled bone structures play the role of intermediate, stabilizing and auxiliary. But in combination with external fixation devices, which provide structural rigidity, such osseous systems, by reducing the displacement of bone fragments in the fracture area, significantly increase the stability of the entire structure.

Examples of using.

Example 1 Use for transverse diaphyseal fractures.

An incision was made in the skin and muscles in the area of the fracture and the fragments were repositioned. Then a plate was applied to hold the contact point of the fragments in a natural position. The plate can be a straight or shaped plate of various widths and thicknesses and a different number of holes. The plate was fixed with screws 1, 6, 8. Then the wound was closed and an external fixation device was applied.

Example 2 Use for oblique fractures.

Initially, surgical access was made to bone fragments, then the fragments were compared and fixed, for which a thin flexible and narrow reconstruction plate with a large number of holes was used, one end of which was fixed with screw 1 to the bone, then the plate was passed under the bone, brought to the fixation point of the first end of the plate and pulled, tightly pressing the fragments to each other. The stretched end of the plate was slightly displaced relative to the initial fixation to the side and fixed with screw 6. If necessary, the second and third cerclages were applied. Next, the wound was sutured and an external fixation device was applied.

Example 3. Use of the system for intra-articular fractures with complex bone relief.

After access to the fragments, the fragments were given a natural anatomical position. Then a plate was attached to one of the fragments with one or two screws 1 or 6 (Fig. 6). A thin narrow plate with a straight thread and a large number of holes was used. Then the plate was tightly pressed to the bone and clearly bent along the relief, additionally fastening the fragments. After fixing all the fragments in the original configuration, the wound was sutured and an external fixation device was applied to two adjacent bones in order to neutralize the fracture area.

Example 4. Use of the system in reconstructive operations.

After osteotomy and giving the required position to the fragments, the plate curvature was changed in accordance with the anatomical contour of the bone, then the plate was applied, fixed with screws 1, 6, 8, and after the wound was sutured, an external fixation device was applied (Fig. 7).

Example 5 System Use in Osteoporosis

Initially, a skin incision was made in the proximal part of the bone, as far as possible from the fracture area. Then, a plate was attached to the bone on one central screw 1. Straight plates of sufficient thickness with 3-5-7 holes were used. Then, at different distances from the central screw, preliminary channels were drilled through the free holes of the plate on the right and left, and the wound was closed. After that, screws 1, 6 are drilled percutaneously into the prepared holes until they lock in the plate. A similar procedure was performed in the distal part, below the fracture area. After that, an external fixation device was applied to the rods.

Thus, the claimed system increases the effectiveness of treatment:

- when used in conditions of osteoporotic bone, as well as in cases of expected excessive mechanical stress for rigid retention of screws in the bone, where the plate with screws is used as an auxiliary fixing component;

- when used as a cerclage in the treatment of oblique fractures;

- when repositioning small-comminuted fractures to connect the fragments and the main bone fragments;

- for precise fixation of small fragments in case of intra-articular fractures;

- during reconstructive operations in order to fix a given position of bone fragments.

Claims (4)

1. A system for fixing bones, including a plate with threaded holes, as well as a screw with a head and a cylindrical rod, on which a threaded section is located adjacent to the head, and the length of the threaded section corresponds to the length of the thread in the hole of the plate, characterized in that the screw with a head has a smooth cylindrical shaft, and the system is supplemented with headless screws and a transosseous element, and each headless screw has a smooth cylindrical shaft and is equipped with a device to limit the axial movement of the screw in the plate hole, in addition, one of the headless screws consists of two cylindrical sections of different diameter, while the distal section has a smaller diameter, and the transosseous element, made in the form of a cylindrical rod with a pointed end, has a threaded section mating with the thread in the hole of the plate, located at a distance from the pointed end. 2. The system according to claim 1, characterized in that the screws at the end are provided with a tool slot. 3. The system according to claim. 1, characterized in that at the end of the headless screw, stop protrusions are made. 4. The system according to claim 1, characterized in that the end of the screw without a head is flared.

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