RU2753142C1 - Hybrid multi-vector endofixator for stabilising cervical dislocations and platform for installation thereof - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: endofixator for ventral cervical spinal fusion after discectomy and reduction of cervical dislocation includes a pentagonal plate, a fenestrated block for pressing into the interbody space, and a fixing screw. The plate is equipped with a rectangular window, at the corners with lugs with round holes with slots with a corrugated surface to accommodate the corrugated surface of the heads of the screws screwed into the holes of the plate. Guides for said fenestrated block, pins of the locks and four hooks with sharp edges at the ends for placement in the cavity formed after removal of the disc, oriented in the direction perpendicular to the plate, configured to be brought together and pushed apart, are arranged on the inner side of the plate around the rectangular window. The fenestrated block for pressing into the interbody space consists of a body with slits, wherein guides for the fenestrated block, holes for the fixing screw and spring plates engaging with the pins of the locks enter said slits. The apparatus for installation of the described endofixator for ventral cervical spinal fusion after discectomy and reduction of cervical dislocation constitutes a platform consisting of two parts positioned by pins and retained in the brought together state by a pressing plate and provided with grips for holding the plate of the endofixator, holes serving as guides for screwing the plate of the endofixator to the vertebral bodies, and a recess. In the centre of the platform, in the brought together state, a channel is made expanding towards the base and including a thread, wherein a sleeve is located matching the shape of the channel, with an external thread and an internal threaded hole and slit. Said recess and slit are intended for positioning the fenestrated block for pressing into the interbody space, and the recess transitions into the inner threaded hole of the sleeve, intended for screwing a press screw to press said fenestrated block. The press screw is made with a head intended for rotation by a socket wrench.

EFFECT: inventions provide an increase in reliability of fixation while ensuring simplicity of installation of the endofixator.

2 cl, 12 dwg

Description

The group of inventions relates to medicine, namely to neurosurgery and traumatology, and is intended for performing operations on the cervical spine, and can be used for fixing dislocations of the cervical spine.

The need for a combined anterior and posterior approach for fixing the cervical spine in trauma was paid attention even despite the development of biomechanically more rigid cervical structures [1]. The use of a hybrid multi-vector endofixator will make it possible to perform cervicospondylodesis for dislocations of the lower cervical spine only from the anterior approach and narrow the indications for combined stabilizing operations.

Known device [2], including one or more open bodies for placement of bones in them for introduction between two vertebrae during discectomy. In this case, the body has an outer lamellar element (on its rear surface, extending on both sides of the body) in a plane perpendicular to the plane of insertion of the body, and equipped at each of its ends with means for fixing the plate on at least two adjacent vertebrae, which must be attached to each other with a cage. The device can be divided into two parts: a cage and a plate.

The disadvantage of such a device is the low reliability of fixation, by means of two screws passed through the holes of the plate exclusively in the anteroposterior direction, as well as a short arm of the lever formed by a segment of the outer plate element from the body to its end, which is insufficient to counteract repeated dislocation of the vertebra. Also, the disadvantages of this technical solution include the lack of structural elements placed in the interbody space to counteract the recurrent displacement of the vertebra.

Known device [3], containing an implant with jagged edges and a window for bone insertion, as well as a plate movable at the attachment point with the possibility of its removal.

The disadvantage of such a device is the low reliability of fixation provided by two screws inserted through the holes of the plate exclusively in the antero-posterior direction.

Known vertebral prosthesis [4], containing a lamellar part, which can be connected to two adjacent vertebrae using screws, characterized in that in its middle zone, the specified lamellar part transversely carries an artificial graft made of material for bone growth, and having on its surface means for stimulating such bone growth.

The disadvantage of such a device is the low reliability of fixation provided by means of screws, which are passed through the holes of the plate exclusively in the anteroposterior direction.

Known device [5], having the size and shape for insertion into the intervertebral fissure separating the opposite surfaces of two adjacent vertebrae, and additionally contains at least one intervertebral separator, made in the form of a ring, having a bar with a height along the axis of the spine, which is less than the rest of the delimiter. The bar of the intervertebral separator contains at least one hole in the bar for inserting a protruding part of the fastening structure for attaching the intervertebral separator to at least one of the vertebrae.

The disadvantage can be called the relatively low reliability of fixation carried out by means of two screws inserted through the holes of the plate exclusively in the anteroposterior direction.

Known device [6], which is a regular hollow prism with a base in the form of an isosceles trapezoid with two supporting surfaces, each of which has teeth and a cervical plate (curved shape) with two holes for screws.

The disadvantage can be called the relatively low reliability of fixation, carried out only by means of only two screws inserted through the holes of the plate exclusively in the anterior-posterior direction.

Known device [7], containing a hollow body and wing-shaped ebbs with holes. The body is made along the front surface with a technological hole for installing bone-plastic material, and on the ends - with teeth to prevent displacement. The technological hole for the installation of osteoplastic material has a height corresponding to the height of the interbody defect. The holes in the wing-shaped ebbs are made in three, one of which is threaded for the locking screw, and two holes are made with internal convergence for inserting screws into them. There are oval transitions between the body and the pterygoid tides for entering the formed grooves in the vertebral bodies.

The disadvantage of this technical solution is the relatively low reliability of fixation due to fixation only by means of screws passed through the holes of the plate exclusively in the anteroposterior direction.

The closest is the device [8] containing the first and second elements for fixing the bones, an insert, a plate engaged with the insert and the first and second spring-loaded latches preventing the backward extension of the first and second elements for fixing bones.

The disadvantage of the prototype is the relatively low reliability of fixation, which is carried out by means of two screws that pass through the holes of the plate exclusively in an obliquely diverging direction. Also, the disadvantage of the prototype is the small size of the plastana, which does not allow to provide a sufficient lever arm to resist repeated dislocation of the vertebra.

A technical problem is the need to develop an effective hybrid multi-vector endofixator to stabilize dislocations of the cervical spine, devoid of the above disadvantages, as well as the need to develop appropriate instruments for installing an endofixator.

The technical result consists in increasing the reliability of fixation while ensuring the ease of installation of the endofixer.

The technical result is achieved by the fact that the endofixer for ventral cervicospondylodesis after discectomy and reduction of the dislocation of the cervical spine includes a pentagonal plate, a fenestrated block for pressing into the interbody space and a fixing screw, the plate is equipped with a rectangular window, at the corners with lugs with round holes with holes with grooves a surface for placing the grooved surface of the heads of screws screwed into the holes of the plate, on the inner side of the plate around the rectangular window there are guides for the aforementioned window block of the pins of the locks and four hooks with sharp edges at the ends facing in the direction perpendicular to the plate for positioning in the cavity formed after removing the disk, having the ability to converge and push apart, the fenestrated block for pressing into the interbody space consists of a housing with slots, which include guides for the fenestrated block, holes for the fixing screw and spring p fins engaging with the pins of the locks.

The technical result is also achieved by means of a device for installing an endofixer for ventral cervicospondylodesis after discectomy and reduction of dislocation of the cervical spine is a platform of two parts, which are positioned by pins and held in a reduced state by a crimping plate, and also have grips for holding the endofixator plate, holes, serving as guides when screwing the endofixator plate to the vertebral bodies, and a niche, in the center of the platform in the reduced state there is a channel that expands to the base and includes a thread, in which a channel-shaped sleeve is located, having an external thread and an internal threaded hole and a slot, while the mentioned the niche and the slot are intended for the location of the fenestration block for pressing into the interbody space, and the niche goes into the inner threaded hole of the sleeve, which is intended for screwing in the screw press in order to press the said window block, and the screw press made with a head designed for rotation with a socket wrench.

In the claimed invention, the screws are passed through the channels for the conduction of screws in a platform with a rigid grip of the screw head with a screwdriver tip and a sleeve, which ensures accurate centering of the screw in the hole of the plate and the fit of its head in the hole, in which the grooved surfaces of the hole and the screw head clearly coincide.

The above design provides an increase in the reliability of fixation, which reduces the risks of arbitrary screw loosening and recurrent dislocations of the cervical spine. The developed toolkit provides the convenience of installing the endofixator.

The claimed invention is illustrated by the following drawings:

Figs 1 and 2 - the inventive endofixator in various projections;

fig. 3 - platform for installation in an exploded view;

Fig. 4 - the platform for installation in the state, the lock sleeve and the press screw are unscrewed;

fig. 5 - complete screwdriver with fixing sleeve and nut;

fig. 6 - screwdriver assembly with a fixing sleeve and nut in a different perspective compared to FIG. 5, providing an opportunity to view the hexagonal end of the screwdriver;

fig. 7 - screwdriver fixing sleeve separately;

fig. 8 - screwdriver without fixing sleeve and nut;

fig. 9 - fixing screw;

fig. 10 - screw for fixing the window block;

fig. 11 - endofixer installed in the platform, the block is not pressed in;

fig. 12 - endofixer installed in the platform, the block is pressed in.

The hybrid endofixator is a plate 1 with hooks with sharp edges at the ends 2, guides for the fenestration block 3 and pins 4 of the locks. There are holes 5 for screws on the plate, and each hole has a tooth 6 for locking a screw screwed into it. The end block 3 consists of a body 7 with slots 8 (or, slots) and windows 10, which include the guides of the window block 3 (and holes 11 for the fixing screw 12 and the spring plate 9, which engage with the pins 4 of the locks.

The device for installing a multi-vector endofixator is a platform consisting of two expandable parts 13 and 14, which are positioned by pins 15. The expandable parts of the platform are compressed by a clamping plate 16. They also have holes 17 that serve as guides when screwing the endofixator plate to the vertebral bodies. One of the parts of the platform has an internal thread 18, into which a lock sleeve 19 with an external thread and an internal threaded hole 20. The lock sleeve has a slot 21, into which the window block is placed. A screw-press 22 is screwed into the inner threaded hole of the lock sleeve, which serves to press the window block into the inter-disk space when installing the endo-fixator. In this case, the locking sleeve prevents the premature removal of the device for installation from the endofixator plate until the moment of complete pressing (installation) of the fenestrated block into the interdisk space. The start of rotation of the lock sleeve serves as a signal that the window block is fully installed.

The key for screwing in the cortical screws consists of a screwdriver 23 with a hexagonal end 24, a fixing sleeve 25 for fixing the cortical screw and a clamping nut 26. The fixing sleeve has an internal thread 27 on one side, into which the threaded head of the cortical screw is screwed, and on the other side collet chuck 28, which is clamped by a clamping nut.

The cortical screw consists of a threaded head 29 with a hexagonal slot 30 for a screwdriver, a threaded part 31 of an oval cross-section to prevent the screw from loosening and a tip 32 in the form of a drill. Also, the head of the cortical screw has corrugations 33 from below, into which, when the screw is tightened, the counter tooth of the plate hole gets into and prevents the screw from loosening.

The claimed invention works as follows.

The hybrid multi-vector endofixator is placed on the installation platform so that the grippers hold the endofixator plate on the platform, and the end block is located in the platform niche and in the slot of the sleeve 21 under the press screw 22, and the hooks with pointed ends at the ends were in a reduced state and their rods crossed ... Both parts 13 and 14 of the platform are brought together by pins and are held by a crimping plate 16.

After discectomy and repositioning of the dislocation, an endofixator is placed in the wound so that its plate 1 is placed on the anterior surface of the vertebrae above and below the plane of dislocation, and the angle of plate 1 with one hole would be on the underlying vertebra, and the brackets of the fenestrated block 3 and the hook with sharp points on the ends 2 in the collapsed state were placed in the cavity formed after the removal of the disc. With a socket wrench, the press screw 22 rotates in a clockwise direction inside the sleeve of the platform 19 and, when screwed in, acts on the block from top to bottom. The terminal block 3 of the endofixator is pressed into the interbody space, acting on the stems of the hooks with tapering at the ends 2 and thereby pushing the hooks with tapering at the ends in mutually opposite directions, the spears of the hooks with tapering at the ends 2 are introduced into the vertebral bodies from the side of the endplates. After lowering the block 3, which locked the bushing on the platform, the latter gains freedom of rotation. With the beginning of the movement of the sleeve 19, the screwing in of the press screw stops 22, the key is removed from the head of the press screw. The fixing screw is put on the tip of the screwdriver (the head has an external thread) and is fixed with a sleeve having a thread at the end of the tip. From the side of the handle, the screwdriver sleeve 25 is fixed by means of a nut 26, which crimps the collet of the sleeve 28. The screws fixed in the screwdrivers are passed through the channels 17 of the platform and screwed into the bone until it stops, the collet 28 is loosened by unscrewing the nut 26, the sleeve is twisted from the screw head and lifted up to the handle of the screwdriver 23, where it is fixed with a collet chuck 28, the screw reaches out, while the corrugated surface 33 of the screw heads sits on the corrugated surface 6 of the hole of the pentagonal plate 1, the screwdriver is removed from the channel of the platform 17. The plate is fixed in the same way through the remaining holes of the pentagonal plate 1. The wrench is placed on the head of the press screw and continues to rotate clockwise. The bushing is screwed in along the platform thread, and its expansion spreads the halves of the pads along the pins, the grippers release the plate, and the platform is removed. A screw is screwed in along the threaded channel of the block in an obliquely ascending direction, at the final stage after exiting the block channel, it is screwed into the bone. If necessary, the screws are pulled, X-ray control is performed, the wound is sutured.

The claimed invention is illustrated by examples.

Example 1

Patient E., 42 years old, was admitted to the neurosurgical department 4 hours after the injury as a result of a fall.

According to the X-ray CT, dislocation of the C5 vertebra. Diagnosis: "Closed uncomplicated dislocation of the C6 vertebra". On an urgent basis, an open reduction of the dislocation, ventral cervicospondylodesis with the claimed hybrid multi-vector endofixator was performed. External immobilization with an orthosis. Activated the next day after surgery.

RT control on the next day and on radiographs after 10 days - the dislocation was adjusted, the endofixator was in satisfactory position. She was discharged for 11 days without neurological deficit.

Example 2

Patient Z., 27 years old, was admitted to the neurosurgical department with complaints of weakness in the arms and legs 2 hours after a diving injury.

According to the X-ray CT data - dislocation of the C6 vertebra with a fracture of the lower articular processes. Diagnosis: "Closed complicated dislocation of the C6 vertebra". On an urgent basis, an open reduction of the dislocation was performed, and ventral cervicospondylodesis with a plate and own bone was performed. External immobilization with an orthosis. On the next day, the dislocation was adjusted with a control CT examination, and the plate was in satisfactory position. On the 3rd day he complained of pain in the cervical spine, weakness in the arms. On RCT - a relapse of dislocation. Reoperation was performed - revision of the postoperative wound, removal of the plate, reduction of recurrent dislocation of C6, ventral cervicospondylodesis with the claimed hybrid multi-vector endofixer. External immobilization with an orthosis. RT-control on the next day and on radiographs after 2 weeks - the dislocation was adjusted, the endofixator was in satisfactory position. In the postoperative period, an increase in strength in the limbs. Discharged on day 21 with moderate neurological deficit.

The claimed invention has been successfully tested in 5 patients, 2 of which - due to primary dislocations in the cervical spine, 3 - during revision operations due to recurrent dislocations of the cervical vertebrae.

Thus, the inventive endofixer for performing operations on the cervical spine, in contrast to the prototype, provides:

- multi-vector counteraction to recurrent displacement of the vertebra;

- efficient use of the interbody space for fixation from the endplate side by means of hooks with pointed ends at the ends, forming the second fixation horizon.

Sources of information

1. Mcafee, PC; Bohlman, HH; Ducker, TV; Zeidman, SM, at Goldstein, JA: One stage anterior cervical descompression and posterior stabilization. A study of one hundred patients with a minimum of two years of follow-up. JBoneJointSurg, 77A (12): 1791-1800, 1995.

2. Intersomatic setup and fusion system: US patent 6235059, United States of America, application number US 19980147083; app. 12/02/1998; publ. May 22, 2001.

3. TRYPTIK MC cervical modular cage [Electronic resource]: Interbody cages // Spineart website. URL: http://spineart.ru/product-platforms/5/13 - date of access: 03/28/2020.

4. Vertebral prosthesis, in particular for cervical vertebrae: patent FR 2570594 B1, France, application FR 8414791, France, app. 09/26/84; publ. 04/30/1986.

5. Vertebral separation device with modular attachment: patent RU 2344792, Russian Federation, application RU 2004104341; app. 07/12/2002; publ. 27.01.2009.

6. Cervical vertebrae support device: US patent 6231610, United States of America, US application 19990382808; app. 25.08.1999, publ. 05/15/2001.

7. Endofixator plate for the cervical spine: patent RU 2299045, Russian Federation, application RU 2005121108; app. 05.07.2005; publ. 20.05.2007.

8. The intervertebral insert and the assembled plate attached to it: patent RU 2506930, Russian Federation, application RU 2011122797; app. 06.11.2009; publ. 02/20/2014.

Claims (2)

1. Endofixer for ventral cervicospondylodesis after discectomy and reduction of dislocation of the cervical spine, including a pentagonal plate, a fenestrated block for pressing into the interbody space and a fixing screw, the plate is equipped with a rectangular window, at the corners with lugs with round holes with holes with grooved surface for placement the surfaces of the heads of the screws screwed into the holes of the plate, on the inner side of the plate around the rectangular window there are guides for the said window block of the pins of the locks and four hooks with sharp edges at the ends facing in the direction perpendicular to the plate for location in the cavity formed after the removal of the disk, having the possibility of converging and pushing away, the fenestration block for pressing into the interbody space consists of a housing with slots, which include guides for the fenestration block, holes for the fixing screw and spring plates that engage with the pin amy locks. 2. A device for installing an endofixator for ventral cervicospondylodesis after discectomy and reduction of dislocation of the cervical spine according to claim 1, which is a platform of two parts, which are positioned by pins and held in a reduced state by a crimping plate, and also have grips for holding the endofixator plate, holes , serving as guides when screwing the endofixator plate to the vertebral bodies, and a niche, in the center of the platform in the reduced state there is a channel that expands to the base and includes a thread, in which a bushing is located in the shape of a channel, having an external thread and an internal threaded hole and a slot, while the said niche and the slot are intended for the location of the window block for pressing into the interbody space, and the niche goes into the inner threaded hole of the sleeve, which is intended for screwing the screw press in order to press the said window block, and the screw press is made with a head designed to oh for rotation with a socket wrench.

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