RU2626139C2 - Closed design spinal implant - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: closed-design spinal implant comprises upper and lower oppositely and symmetrically arranged supporting plates with fixing elements provided on their outer sides, providing protection against their lateral displacement relative to the vertebrae and an alloplastic disc installed between them. A flat membrane box is place between plates, which is formed by two oppositely arranged resilient poppet corrugated membranes connected together along the outer generatrix, with flat end surface attached to the lower support plate. In the box cavity filled with a biocompatible fluid with anti-friction nanoparticles of unmodified carbon, a hirulen disc and umbrella-shaped titanium thrust are installed, convex and concave spherical surfaces of which provide a movable spherical connection. The disc is fixed in the center of the membrane, located near the bottom plate via a curved vertical wall of a ring with L-shaped cross-section fixed to the same membrane by a horizontal wall. The umbrella-shaped thrust is installed and fixed secured by means of its rod portion in the opening opening of the cantilevered tubular hub belonging to the upper support plate and located in the central opening of the adjacent membrane, reinforced by an alloplastic ring of U-shaped cross-section of alloplastic material forming a radial-thrust journal bearing with the outer cylindrical surface of the hub and the facing end surface of the thrust cap.

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

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Description

The invention relates to medical equipment and can be used in vertebrology and neurosurgery in the treatment of injuries, 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 a 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 adjacent 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 latches around 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 for heating the clamps during installation, 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 disk 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 are spear-shaped and 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 surgery.

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;

- reducing the duration of surgery.

The achievement of these results is due to the fact that in the closed-back spinal implant containing the upper and lower axisymmetrically and opposedly located support plates with fixation elements made from lateral displacement relative to the vertebrae on their outer sides and an alloplastic material disc, which is part of the movable connection of the plates, between the plates there is a flat membrane box formed by two opposed elastic corrugated disk membranes wounds interconnected along the outer generatrix, which is attached with a blank end surface to the lower support plate.

In the cavity of the box coaxially to the plates and membranes, a disk and a mushroom-shaped emphasis are installed, having respectively convex and concave end spherical surfaces forming a spherical movable joint. The disk is fixed in the center of the membrane located at the bottom plate using a curved vertical wall of an L-shaped ring attached to the same membrane with its horizontal wall, and the mushroom-shaped stop is mounted and fixedly fixed with its rod part in the hole of the cantilever tubular hub belonging top support plate.

The hub is placed in the hole made in the center of the membrane adjacent to this plate, which is reinforced with a U-shaped ring of alloplastic material, which forms an angular contact sliding bearing with the outer cylindrical surface of the hub and the end face of the stop cap facing it.

The cavity of the membrane box is filled with a biologically compatible liquid containing anti-friction nanoparticles of unmodified carbon (fullerene).

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 (hirulen - titanium) and is placed in a sealed cavity filled with a highly effective artificial 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 to remove them from the body tissues when performing revision operations to replace the endoprosthesis.

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.

Fourth, the presence of an elastic membrane box connecting the support plates to each other ensures structural integrity, which simplifies the installation of the implant in the intervertebral space, reduces the time of surgery and does not require complicated expensive surgical instruments for its installation.

In FIG. 1 shows a sectional view of a spinal implant; in FIG. 2 is a view along arrow A in FIG. one; in FIG. 3 is a view along arrow B in FIG. one.

The closed-back spinal implant (Figs. 1, 2) consists of two opposite and coaxially arranged support plates 1 and 2 with fixation elements 3 made on the outer surfaces in the form of flat serrated consoles with transverse holes 4 (Fig. 3). The upper support plate 2 is provided with a cantilever tubular hub 5 installed in the hole of the U-shaped ring 6, reinforcing the edges of the central hole adjacent to the upper plate of an elastic corrugated disk membrane 7, connected along the outer generatrix with a lower, similar in shape, membrane 8.

Membranes 7 and 8 form a flat membrane box attached by the flat end surface of the membrane 8 to the lower support plate 1, the cavity of which is filled with a biocompatible fluid with non-modified carbon antifriction nanoparticles - fullerene C ₆₀ (Churilov G.N. Fullerenes: Synthesis and formation theory / G .N. Churilov, N.V. Bulina, A.S. Fedorov, Russian Academy of Sciences, Siberian Branch, Novosibirsk: SORAN Publishing House, 2007.- 230 p.).

In the cavity of the membrane box, the disk 9 and the mushroom-shaped stop 10 are placed axisymmetrically, the convex and concave end surfaces facing each other, respectively, are made spherical and form a movable spherical connection. Disc 9 is made of Chirulen high molecular weight 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 is secured against lateral displacements and rotation with the help of a curved vertical wall of the ring of the L-shaped section 11, attached with its horizontal wall to the membrane 8. The mushroom-shaped stop 10 is installed and secured with its rod part 12 in the hole of the hub 5, the outer cylindrical surface of which 13 and the end -hand flat surface 14 of the cap form stops radially thrust bearing with adjacent surfaces of the U-shaped ring 6.

The possibility of relative angular displacements of the disk and the stop is provided by the elastic properties of the membrane box, and rotational by the angular contact sliding bearing. The constancy of the pressing of the inner end surface of the ring 6 to the end surface of the cap of the stop 10, provided by the elastic properties of the membrane box in the axial direction, eliminates the gap between them, and therefore prevents leakage of the fluid - fullerene located in the cavity of the box.

All metal parts of the implant are made of bioinert titanium alloys. 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).

Installation of the implant is as follows.

First, the failed disc is removed (osteochondrosis, trauma). Then, using a retractor, the necessary interbody space is created and deaf paired grooves are used in the vertebral end plates, which are guides for the fixing elements, open towards the direction of implant insertion, the implant is inserted to the length of the deaf grooves (to the stop), which ensures its location in the center of the vertebrae , and insert the fixing elements into the bone tissue until the supporting plates contact the vertebral body using the previously used device.

Subsequent osteogenesis, i.e. germination of bone structures in the holes of the fixing elements securely fix the implant in the vertebral bodies.

The proposed design provides installation reliability, relative rotational, angular and axial movements of the support plates, while blocking their radial (transverse) displacements.

Claims (1)

Closed spinal implant containing the upper and lower axisymmetrically and oppositely located support plates with fixation elements made on their outer sides from lateral displacement relative to the vertebrae and an alloplastic material disc installed between them, characterized in that a flat membrane box formed by two is placed between the plates opposed elastic corrugated disk membranes interconnected along the outer generatrix, attached A disk made of chirulen and a mushroom-shaped stop made of titanium, convex and concave respectively end-face spherical surfaces of which form a movable spherical joint, are mounted with a flat end surface to the lower support plate, in the cavity of the box filled with a biocompatible liquid with anti-friction nanoparticles of unmodified carbon, this disk is fixed in the center of the membrane located at the bottom plate, using a curved vertical wall of the ring of the L-shaped section, attached to the same membrane by a horizontal wall, and the mushroom-shaped emphasis is mounted and fixedly fixed with its rod part in the hole of the cantilever tubular hub belonging to the upper supporting plate and located in the central hole of the adjacent membrane reinforced with a U-shaped ring of alloplastic material forming with the outer cylindrical surface of the hub and the end surface of the stop cap facing it, an angular contact sliding bearing.

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