RU173377U1 - BIOACTIVE CELLULAR TRIANGULAR IMPLANT FOR REPLACEMENT OF THE TIBERAID DEFECT - Google Patents

Abstract

The utility model relates to medicine, namely to implantable devices for replacing post-traumatic tibial defects. The implant is made of VT-6 titanium powder fused by selective layer-by-layer laser melting, in the form of a triangular equilateral prism 1, equipped at the ends with supporting rims 2, 3 that perform the supporting function. The rims 2, 3 are equipped with holes 4 for bone screws 5, fixing the implant to bone fragments 7, 8. The geometric shape, dimensions, structure are based on a digital three-dimensional mathematical model. The implant is coated with a bioactive layer 6 of hydroxyapatite. The implant contains a network of similar longitudinal and transverse through channels 9 in the form of cells 10, a network of pores 11, 12. The technical result is to ensure that the implant immediately replaces the tibial diaphysis defect, provides complete implant osseointegration and shortens its life. 4 s.p. f-ly, 5 ill.

Description

The utility model relates to medicine, namely to implantable devices for replacing post-traumatic tibial defects, is installed in the diastasis of the diaphyseal tibia.

A known method of replacing a bone defect ([1], RU 2002113871) using the patient’s own bone. The method [1] includes the formation of a fragment in the form of flakes of bone of an adjacent segment, smaller in magnitude of the length of the defect, and a metered movement of the fragment into inter-fragment diastasis. The selected fragment is sequentially antero-retrograde moved in the defect.

A known method of autocostnoplastic replacement of a post-resection defect in the tubular bone of the hand ([2], RU 2479272), including performing intraosseous resection of the destruction site, corticotomy of the affected tubular bone. After resection of the destruction site, an external fixation mini-apparatus is applied to the tubular bone, a cortical autograft is taken from the tibia, a corticotomy of the affected tubular bone is performed through the destruction site, the autograft is taken into the defect cavity, compressive forces are created at the junction of the bone fragments and the graft the cortical layer of the tubular bone of the hand in the corticotomy zone by dosed movement of the nodes of the mini-apparatus towards each other.

These methods [1, 2] show high results in restoring the integrity of the tubular bone. However, their drawback is the long term of osteosynthesis. The methods [1, 2] suggest a long multi-stage treatment in a hospital with constant medical supervision for the entire treatment period. A long stay in the external fixation apparatus reduces the quality of life of the patient. Method [2] involves the collection of a cortical autograft from the tibia, which is an additional surgical intervention, with all its inherent risks. An autograft weakly sprouts capillaries, to a depth of not more than 5 millimeters. Such an autograft is able to withstand the maximum functional load after organotypic reconstruction, but it occurs slowly up to 8 months, so there is a risk of pathological fractures in the postoperative period. The method [1] does not allow replacing a bone defect at the same time by setting a flap in diastasis.

Known prosthesis of the vertebral body ([3], RU 2204361). The prosthesis is made of a carbon-carbon composite material containing a pyrocarbon matrix, in which a multidirectional reinforcing frame of rods formed from carbon fibers located along the axis of these rods is located. The prosthesis can be made of various shapes, for example in the form of a prism, a rectangular prism with a base having a U-shaped, L-shaped, cross.

This analogue [3] is not applicable for the tibia due to the mismatch of its geometric parameters (shape, size) to the geometric parameters of the tibia diaphysis. The analogue material [3] is not capable of fulfilling the function of a bone tissue growth catalyst; it is inert, does not exhibit biological activity, and does not promote osteoinduction. It does not fully create conditions for the formation of bone tissue in the area of the defect.

A known implant for the replacement of bone defects ([4], RU 162540). The implant consists of a carbon-carbon material containing a pyrocarbon matrix and a carbon fiber reinforcing frame made in the form of a cylindrical segment of a truncated straight circular cylinder, cut off by a plane parallel to the cylindrical axis, while the length of the cut-off segment in the plane of the base of the cylinder is 0.3-0, 8 from the diameter of the base of the cylinder, and the dihedral angle between the planes of the bases of the truncated cylinder is 10-50 °. Implants [4], according to their authors, combine biological compatibility, strength, fixation properties associated with the features of the carbon material, and a shape that provides better fit to the shapes of a large group of replaceable bone defects.

This analogue [4] performs the function of an inert, passive matrix (conductor, scaffold), but does not have the properties of a bone tissue growth catalyst. The analogue is inert, does not exhibit biological activity, and therefore is not able to initiate osteoinduction. The material of the analogue [4] does not create centers of crystallization of hydroxyapatite necessary for the formation of osteoid. With significant sizes of the defect of the tibial diaphysis, the analogue [4] is also relatively large and does not fully integrate into the bone, even several months after the operation, its full germination by bone tissue does not end. The implant [4] does not take into account the geometry of the tibia. The tibia in the diaphysis in the cross section has a shape close to triangular. The analogue [4] does not have an external abutment surface in the form of a rim, therefore, the stability of implant fixation in the area of the defect decreases.

The technical solution - a bioactive cellular triangular implant to replace the defect of the tibia (hereinafter referred to as the "implant") - is aimed at reducing the time of surgical restoration of the anatomical integrity of the tibia in the area of the diaphysis in case of a defect. The technical task of the utility model is to provide a complete, as quickly as possible osseointegration of the implant. The implant should have osteoconductive and osteoinductive properties, should be a catalyst for reparative osteogenesis, and contribute to the formation of bone tissue both on the surface of the implant and inside it. The implant should allow to simultaneously replace the defect of the diaphysis of the tibia, should be close in shape to the surface of the bone, while providing the opportunity for the successful implementation of biological processes aimed at the growth of bone tissue. The implant should be able to lock its position relative to bone fragments and an additional supporting surface.

The technical result consists in ensuring the simultaneous replacement of the defect of the tibia diaphysis with the implant, ensuring the full osseointegration of the implant and reducing its duration.

The technical result is achieved by the fact that the bioactive cellular triangular implant for replacing the tibia defect is made according to the additive technology by layer-by-layer building up of the material in the form, size, structure specified by the three-dimensional mathematical model, in the form of a triangular prism equipped with triangular support rims from the ends, the prism dimensions correspond to the size of the diastasis of the bone in the area of the defect, contains a network of similar longitudinal and transverse through channels in the form of cells, a network of pores, is covered biologically active layer, holes are made on the support rims.

This entity allows you to achieve the claimed technical result.

It is assumed that the implant is made using additive technology on a 3D printer. In order to form a non-degradable implant, it is provided that the implant material is an alloy of a metal powder based on titanium alloyed by selective layer-by-layer laser melting. Also, the use of a biodegradable (degradable) thermoplastic polymer based on polylactic acid, form L-PLA, is provided as a material. The final products of the conversion of lactic acid in the body are carbon dioxide and water, which are removed using the body's respiratory system. Due to the lack of peptide chains in PLA and biodegradable nature, its effect on the tissues of living organisms does not cause immunological reactions. Preferably, the biologically active layer of the implant is made on the basis of calcium phosphate - in particular hydroxyapatite. All surfaces of the implant are coated with a bioactive layer. The macrostructure of the implant has a structure in the form of a network of similar longitudinal and transverse through channels (cells), the transverse size of which is in the range from 1 to 1.5 millimeters, which do not form an enclosed space, and are communicated. The microstructure of the material - a network of pores - transverse through pores, the size of which is in the range from 300 to 500 micrometers and communicating pores in size from 18 to 150 micrometers.

The utility model is illustrated by graphic materials:

FIG. 1 - implant, general view;

части;FIG. 2 - implant, general view with a cutout

parts;

FIG. 3 - implant, side view in section;

FIG. 4 - implant, top view;

FIG. 5 - implant, surface layer, pores and bioactive layer are shown.

Implementation of a utility model.

The implant is made of VT-6 titanium powder fused by selective layer-by-layer laser melting, in the form of a triangular prism 1 (Fig. 1; 2; 4), the height of the prism mainly corresponds to the standard sizes - 10 mm, 20 mm, 30 mm, 40 mm, 50 mm , 60 mm, 70 mm. From the ends, the triangular prism 1 is equipped with supporting rims 2,3 (Fig. 1, 2) with a height of 4 to 10 millimeters, performing the supporting function. The rims 2, 3 are equipped with holes 4 (Fig. 1, 2) for bone screws 5 (Fig. 1. 3). The implant is covered with a bioactive layer 6 (Fig. 5) of hydroxyapatite. The geometric shape, dimensions, structure are built on the basis of a digital three-dimensional mathematical model. The longitudinal dimensions of the triangular prism 1 are close in size to the size of the diastasis of the tibia diaphysis. The cross section of prism 1 is an isosceles triangle, the dimensions of the sides of the triangle correspond to the most common transverse dimensions of the diaphysis of the tibia. The rims 2, 3 are designed to be mounted on bone fragments 7, 8 (Fig. 3). In the central part of the prism 1 contains a network of similar longitudinal and transverse through channels 9 (Fig. 2, 3) in the form of cells 10 (Fig. 4), a network of transverse through pores 11 (Fig. 5), communicating with channels 9, and a network of communicating then 12 (Fig. 5). The implant is manufactured using additive technology on a 3D printer. Based on statistics on the most common sizes of tibial defects, a group of standard sizes is formed (length of a prism, length of a side of a triangle, angles of a triangle). Using software, they form mathematical three-dimensional models of implants with various size options, up to 7 sizes. Using computer and software, they simulate the macro- and microstructure of the material, the spatial structure of the implants. The macrostructure of each implant has a structure in the form of a network of similar longitudinal and transverse through channels 9 in the form of cells 10. The cross section of the channel 9 is in the form of a rhombus, with an acute angle of 60 degrees, side length 1 mm (mm), pitch between cells 1.2 mm , the channel wall thickness of 0.15 mm The through channels 9 are parallel to the longitudinal axis of the prism 1 in its central part. The channels 9 are also located transversely, directed from the outer surface, the faces of the prism, to the longitudinal channels 9. The implant surfaces are porous. The channels 9 are connected by transverse through pores 11, the size of which is 400 micrometers, and are covered by interconnected pores 12 (micropores) of 50 micrometers in size. The rims 2, 3 with a thickness of 1 mm contain three through holes with a diameter of 2 millimeters, for fixing the implant with screws 5 to the bone fragments 7, 8. Perform several implant sizes in accordance with the most common sizes of defects. Digital data on three-dimensional mathematical models of implants is imported into the format used by a 3D printer for three-dimensional metal printing using Direct Metal Selective Laser Melting (SLM) technology. Implants are being printed. Hydroxyapatite is applied to the implants by ion-plasma spraying, forming a bioactive layer 6. The hydroxyapatite powder is passed through a plasma torch, the powder particles are melted in a plasma jet and deposited on the surface of the implant. The implants are sterilized.

Implant use

Replacement of the defect of the tibia with an implant is as follows. Before surgery, computed tomography of the tibia with a defect is performed. The size of the defect area is determined and the 3 closest implant sizes are selected. In the operating room, under anesthesia, a soft tissue incision is made at the level of the defect. The muscles are pushed apart, the bone is exposed. The defective bone tissue is removed, the adjacent ends of the proximal 7 and distal 8 bone fragments are stripped, and implants in diastasis are tried on. Choose the most appropriate implant. Fragments of bone 7, 8 are installed in the position corresponding to the anatomically normal tibia, the implant is placed with shells 2, 3 on the adjacent ends of bone fragments 7, 8. The implant is fixed to the bone through holes 4 with screws 5. Holes 4 on the rims 2, 3 allow the surgeon to rigidly fix the implant by holding 3 screws 5 at each end. The implant rigidly binds fragments 7, 8, thereby ensuring the integrity of the tibia. The wound is sutured in layers, an orthosis is applied to the limb for the next postoperative period, the load is limited. In the postoperative period, a network of longitudinal and transverse through channels 9 in the form of cells 10 and a network of through 11 and communicating 12 pores allows biological fluids to circulate and penetrate biological materials into the implant, and blood vessels, capillaries from surrounding tissues, can freely grow into the implant. Hydroxyapatite-based bioactive layer 6 provides the formation of crystallization nuclei and initiates the osteoinductive process. Bioactive layer 6 has osteoinductive properties, provides osseointegration of the implant and reduces the recovery time of the anatomical integrity of the bone in the area of the defect. The implant replaces the defect, grows with bone tissue and integrates fully with bone fragments 7 and 8, the bone becomes whole and functionally identical to the anatomically healthy tibia.

Industrial applicability - the implant can be manufactured using modern equipment, using additive technology, a computer and related software. It can be used in trauma clinics.

Claims (5)

1. The bioactive cellular triangular implant to replace the defect of the tibia, characterized in that it is made according to the additive technology, by layer-by-layer building up of the material in the form, size, structure specified by the three-dimensional mathematical model, in the form of a triangular prism, equipped with triangular support rims at the ends, dimensions prisms correspond to the size of the diastasis of the bone in the area of the defect, contains a network of similar longitudinal and transverse through channels in the form of cells, a network of pores, covered with a biologically active layer , holes are made on the support rims. 2. The bioactive cellular triangular implant for replacing the tibia defect according to claim 1, characterized in that it is made of a titanium-based metal powder fused by selective layering laser smelting. 3. The bioactive cellular triangular implant for replacing the tibia defect according to claim 1, characterized in that it is made of a biodegradable polymer. 4. The bioactive cellular triangular implant to replace the defect of the tibia according to claim 1, characterized in that the biologically active layer is made on the basis of hydroxyapatite. 5. The bioactive cellular triangular implant for replacing the tibia defect according to claim 1, characterized in that the transverse size of the cells is in the range of 1 to 1.5 millimeters, the transverse size of the through pores is in the range of 300 to 500 micrometers.

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