RU2626134C2 - Intervertebral disk revisional endoprosthesis - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: revisional endoprosthesis of the intervertebral disc contains oppositely and coaxially located support plates with spear-like flat fixation elements on the outer sides against transverse displacement relative to the vertebrae, and a disk of alloplastic material that is a part of the movable plates connection. T-shaped through grooves for plate adapters are made on the inner surfaces of support plates and fixed on the end surfaces of the insert located between the support plates and having the form of a flat, sealed membrane box consisting of two elastic corrugated disk diaphragms fixed to each other, with the cavity filled by a bioinert liquid with antifriction nanoparticles of unmodified carbon, and containing axially symmetrically mounted hirulen disk and titanium alloy stop attached to the membrane bottom parts and facing each other, respectively; their convex and concave spherical end surfaces form a spherical movable joint. The through grooves are provided with stops for plate adapters at one end and flat elastic latches at the other end, and the spear-shaped locking elements are bifurcated and resilient in the radial direction and are provided with facets with opposite angles of inclination on the outer side surfaces.

EFFECT: increased stability of the mutual arrangement of endoprosthesis elements, simplifed installation, reduced wear of element surfaces, forming a flexible joint, increased implant service life, reduced duration of surgery and significantly reduced duration of the postoperative recovery period.

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Description

The invention relates to medical equipment and can be used in vertebrology and neurosurgery in the treatment of diseases and injuries of the spine.

In medical technology, implant designs in the form of cages are used that are used in the surgical treatment of osteochondrosis of the spine, which are box-shaped metal inserts with holes and cavities of various configurations, fixation elements in the form of teeth on supporting surfaces intended for insertion into the vertebral bodies between which it is placed , instead of the remote intervertebral disk (Patent of Ukraine No. 41079 A dated 10.15.2001, Bull. No. 9; export@gmreis.com.br - Posterior Lumbar Spacer).

The main distinguishing feature of such implants is that they rigidly connect two neighboring vertebrae, depriving them of relative mobility in all directions, thereby limiting the flexibility and functionality of the human spinal column.

The restoration of the mobility of the elements of the spine is ensured by endoprostheses of the intervertebral discs, consisting of two opposite and coaxially located support plates of a permeable-porous superelastic material, between which there is an intermediate element made of fluoroplastic, connected to the plates using a buffer layer (Patent RU No. 2140229 from 10.27.1999).

Also known is the design of an endoprosthesis (implant) of the intervertebral disc, containing two support plates with fixation elements and a disk of alloplastic material located between the plates. The fixation elements are made of a material with a memory effect, which allows them to rotate the fixators about the axis and fix the plates in the vertebral bodies (Patent RU No. 2080841, IPC A61F 2/44, 1997).

The design flaws include: installation complexity; the need to heat fixators during implantation, which adversely affects the bone tissue of the vertebrae; the occurrence of electrocorrosion due to various materials of the parts of the endoprosthesis, which reduces the reliability of fixation and causes its increased wear; low bioinertness due to the presence of nickel in the material of fixatives, causing a toxic effect on bone tissue and the human body as a whole; a short period of time before conducting revision operations associated with the replacement of a worn endoprosthesis.

The design of the endoprosthesis (implant) of the intervertebral disc (Patent RU No. 2200510 C1, IPC 7 A61F 2/44, 2003), containing two axisymmetric plates and a disc made of alloplastic material (silicone rubber) between them, was taken as a prototype. The inner opposing surfaces of the support plates have a concavity in the center and a fixing annular protrusion, providing lateral fixation of the disk and the possibility of rotation around the axis. The mechanical properties of the material of the disk provide the possibility of angular displacements and shock absorption of the plates. The fixation elements relative to the vertebrae have a lance-like flat shape and are placed on the outside of the support plates.

The main disadvantages of this design of the endoprosthesis (implant) are:

- instability of the relative spatial arrangement and mobility of the elements of the endoprosthesis due to the significant elasticity of the silicone disk and low wear resistance;

- short service life due to the possibility of ingress of wear products between the movable elements, which leads to their closure between themselves, i.e. to deprivation of their relative mobility;

- the complexity of the installation associated with ensuring the alignment of all parts of the endoprosthesis in the inaccessible space between the vertebral bodies;

- the duration of the surgical intervention during the revision surgery associated with the replacement of a worn endoprosthesis;

- additional traumatic effect on the vertebral bodies when removing fixation elements from them;

- a large period of postoperative recovery of the patient associated with the ingrowth of fixing elements in the vertebral bodies.

The expected technical results from the invention are:

- increase the stability of the relative positioning of the elements of the endoprosthesis;

- simplification of manipulations on its installation;

- reducing wear on the surfaces of the elements forming the movable joint;

- increase the life of the endoprosthesis;

- reduction in the duration of surgery;

- a significant reduction in the length of the postoperative recovery period of the patient.

The achievement of these results is due to the fact that in the revision endoprosthesis of the intervertebral disc, containing opposite and coaxially located supporting plates with spear-shaped flat fixation elements on the outer sides from the lateral displacement relative to the vertebrae and the disk of alloplastic material, which is part of the movable connection of the plates, on the inner surfaces base plates are made of T-shaped through grooves for plate adapters mounted on the end surfaces of the of the insert between support plates in the form of a flat membrane sealed box consisting of two connected by the outer generatrix corrugated elastic Belleville membranes.

The through grooves are provided with stops for plate adapters at one end and flat elastic latches at the other end.

In the cavity of the box filled with a bioinert liquid with anti-friction nanoparticles of unmodified carbon, a disk and an abutment attached to the bottom parts of the membranes are mounted axisymmetrically, facing each other, respectively, the convex and concave spherical end surfaces of which form a spherical movable joint (sliding bearing).

Spear-shaped fixation elements are bifurcated and elastic in the radial direction and are equipped with chamfers with opposite angles of inclination on the outer side surfaces.

Between the totality of the claimed features of the invention and the expected technical results provided by the proposed invention, there is a causal relationship, which consists in the following.

Firstly, the movable joint is made of wear-resistant and high-strength materials (chirulen - titanium alloy) and is placed in a sealed cavity filled with a highly effective synthetic lubricant based on unmodified carbon nanoparticles, which helps to reduce friction and, consequently, wear of the movable joint elements and changes in their original shape .

Secondly, wear products do not enter the human body, which eliminates the need for their removal from the body’s tissues during the revision of the replacement prosthesis.

Thirdly, the elastically deformed state of the box membranes ensures constant contact between the spherical surfaces of the disk and the stop, their alignment, which reduces wear and helps to stabilize the relative position of the vertebrae.

Fourthly, the presence of three integral autonomous parts in the endoprosthesis design — two supporting plates and a membrane box in the form of an insert, the overall height of each of which is significantly smaller than the assembled total overall height of the endoprosthesis, allows their separate installation without increasing intervertebral space and vertebral closure plates of special guide grooves for the fixing elements of the support plates.

Fifthly, the design of the liner equipped with plate adapters provides the desired accuracy of its installation between the support plates previously fixed in the vertebral bodies, i.e. between the vertebrae, and does not require complicated expensive surgical instruments.

In FIG. 1 shows a cross-section of a revised endoprosthesis in a half-assembled form; in FIG. 2 is a view along arrow A in FIG. one; in FIG. 3 is a view along arrow B in FIG. one; in FIG. 4 is a view along arrow B in FIG. one; in FIG. 5 is a view along arrow D in FIG. 3; in FIG. 6 is a view along arrow D in FIG. four; in FIG. 7 - bifurcated spear-shaped element of fixation of support plates in the vertebral bodies; in FIG. 8 is a view along arrow E in FIG. 7; in FIG. 9 is a view along arrow G in FIG. 7.

The revision endoprosthesis includes two support plates 1 and 2 with bifurcated fixation elements 3 of a spear-shaped shape, symmetrically located on their outer surfaces (Fig. 1, 2). Between the supporting plates there is an insert in the form of a round flat sealed membrane box formed by two elastic corrugated disk membranes 4 and 5 connected along the outer generatrix.

A disk 6 made of high molecular weight Chirulen polyethylene (UHMWPE cross-linked polyethylene) (NEW POLYS FOR OLD: CONTRIBUTION OR CAVEAT / S. Greenwald, TW Bauer, MD Ries / American Academy of orthopedic surgeons. - 68 ^th Annual meeting, February 28 - March 4, 2001, San Francisco, California) and a disk-shaped stop 7 made of a titanium alloy with spherical, respectively, convex and concave end surfaces forming a spherical movable joint (spherical plain bearing), the lubrication of which is carried out by filling the cavity with a bioinert liquid with highly antifriction properties of unmodified carbon nanoparticles C ₆₀ (fullerene) (Churylov GN Fullerenes: Synthesis and theory of formation / GN Churylov, NV Bulina, A. Fedorov, Ross Acad Sciences, Sib... Department, Novosibirsk: SORAN Publishing House, 2007 .-- 230 p.). Using fullerene C ₆₀ reduces the friction coefficient by 8 ... 10 times, which leads to a significant increase in the life of the endoprosthesis (Lashneva VV, Dubok VA, Tkachenko Ju.G. Physiko - chemical properties of fullerene C ₆₀ based coatings // Book of abstract. VIII International Conference - ICHMS 2003, Sudak, Crimea, Ukraine, 14-20 Sept., 2003. - P. 718-721).

The connection of the insert with the support plates is realized using T-shaped through grooves 8 made on their inner surfaces (Figs. 1, 3) for similar in cross-sectional shape of plate adapters 9 with chamfers 10 made at an angle β at one of their ends (Fig. . 4, 6) attached by means of disks 11 to the ends of the membrane box (Fig. 1, 4)

The fixed location of the liner in the center of the support plates is provided by stops 12 and flat elastic latches 13 located at a distance L from each other at the ends of the grooves (Fig. 3), equal to the length of the plate adapters. Flat elastic latches 13 (Fig. 3, 5) are formed in the bodies of the support plates with the help of the slots 14 and 15 and bent towards the bottom parts of the through grooves (Fig. 5), preventing the unauthorized extension of the plate adapters of the insert from the grooves.

Spear-shaped elements of fixation of 3 support plates 1 and 2 of the endoprosthesis relative to the vertebrae are bifurcated (Fig. 7). Each half of the locking element is provided with chamfers 16 on the lateral curved surfaces with opposite angles of inclination α (Fig. 8).

All metal parts of the endoprosthesis are made of bioinert titanium alloys, including alloys with a high coefficient of elasticity (membranes, fixation elements).

Installation of the implant is as follows.

First, the failed disc is removed (osteochondrosis, hernia, trauma). Then, using a retractor, the necessary interbody space is created, the support plates are inserted alternately (or simultaneously) into it and, applying a force F ₀ (Fig. 7), their fixing elements are inserted into the bone tissue until the outer surfaces of the support plates come into contact with the vertebral bodies using previously used device.

When the fixation elements are introduced into the vertebral bodies, due to the chamfers 16 on their lateral sides (Fig. 7.8), reaction forces R are generated that are normally directed towards their surfaces, causing the creation of forces F (Figs. 8, 9) that deform in opposite directions in within the elastic range, both parts of the spear-shaped fixation elements, thereby changing the trajectory of their introduction into the vertebral bodies. As a result, both parts of the fixation elements are placed in the bone tissue with a certain angular gap with respect to each other (Fig. 9). Subsequent osteogenesis, i.e. the germination of bone structures in the space between them, provides reliable fixation of the supporting plates in the vertebral bodies.

The proposed design ensures the reliability of the installation of the endoprosthesis, the ease of replacing a worn insert, as well as the relative angular and axial movements of the support plates, while blocking their radial (transverse) displacements.

Claims (1)

An auditory endoprosthesis of the intervertebral disc, containing opposite and coaxially located support plates with spear-shaped flat fixation elements on the outer sides from lateral displacement relative to the vertebrae and an alloplastic material disk, which is part of the movable connection of the plates, characterized in that T-shaped are made on the inner surfaces of the support plates through grooves for plate adapters mounted on the end surfaces of the liner located between the supporting plates in the form of a plate a tight sealed membrane box, consisting of two elastic corrugated disk membranes fastened to each other along the outer generatrix, in the cavity of which, filled with a bioinert liquid with antifriction nanoparticles of unmodified carbon, a disk made of chirulen and a stop made of titanium alloy are mounted axially symmetrically, facing each other to each other, respectively, convex and concave spherical end surfaces of which form a spherical movable connection, and through elements are provided with stops for the adapter plate at one end and a flat resilient latch at the other end, and kopeobraznye fixing elements are bifurcated and elastic in the radial direction and are provided with bevels in the direction opposite angles on the outer lateral surfaces.

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