RU2722945C1 - Method for vertebral column stabilization in cervical spine in dogs with wobbler syndrome - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine and veterinary science and can be used for spinal column stabilization in cervical spine in dogs with Wobbler syndrome. Using MRI, or myelo CT, or dynamic myelography, a pathological portion of the cervical spine is detected, instability, as well as protrusion of the intervertebral disc, and ventral approach are detected between the vertebrae. First, a slot is formed to install the TTA-cage in vertebral bodies and to remove the disc substance and bone exostosis. A TTA-cage is tightly inserted between the vertebral bodies and fixed to the vertebral bodies with two monocortical screws. At the second stage, four holes are drilled, two per each vertebra, in the vertebral bodies in the ventral cortical layer; the drill is performed so that the drill passes through only one cortical layer. Screws are tightened up to the stop in a dorsal cortical layer. That is followed by forming a single conglomerate between screws and TTA-cage using bone cement, wherein bone cement is applied on protruding parts of screws; at the final stage, layer wound closure is performed. To apply cement, it is dried with sterile napkins.

EFFECT: method provides reduced risk of iatrogenic spinal cord injury, spinal nerves, as well as feeding arteries, required distraction due to stable fixation of spinal column.

1 cl, 15 dwg

Description

DESCRIPTION

The invention relates to veterinary medicine and can be used to stabilize the spinal column in the cervical region in dogs with Wobbler's syndrome (cervical spondylomyelopathy).

The well-known work is "Surgical Treatment of Disk-Associated Wobbler Syndrome by a Distractable Vertebral Titanium Cage in Seven Dogs", Article in Veterinary Surgery 40 (5): 544-54, May 2011 [https://www.researchgate.net/publication/ 51095469_Surgical_Treatment_of_Disk-Associated_Wobbler_Syndrome_by_a_Distractable_Vertebral_Titanium_Cage_in_Seven_Dogs].

The technical problem of the described method is the lack of stability of the structure (cage and screws). The author indicates cases of insolvency struts. Stabilization only with bicortical vitamin and cement is not stable, as indicated by cases of structural fracture. The use of a necklace plate also involves bicortical screws, which, as mentioned above, pose too high risks of iatrogenic damage. The use of a spacer only is not a stable fixation, since there are known cases of “spacing” of a spacer due to constantly acting forces on the structure in the cervical spine. A technique with a washer that is placed between the vertebrae and a screw that is inserted from the body of one vertebra into the washer and into the body of another is technically very difficult to implement.

Known patent US8496707, publ. 07/30/2013. The technique described in the prototype allows only distraction of the vertebrae to be achieved and does not have an additional fixing component. There are known cases of failure of such implants in large dogs in the remote postoperative period. Since the cervical vertebrae are quite mobile, the dynamic load on the implant is quite large, over time this can lead to migration of the spacer from the space between the vertebral bodies.

The closest analogue is the article by Ulanova N.V., Gorshkov S.S., Veterinary Clinic "Best", Novosibirsk / N. Ulanova, S. Gorshkov, Veterinary Clinic "Best", Novosibirsk Journal: No. 2 - 2016. [ http://vetpharma.org/articles/59/6048/]. This paper discusses the use of two different methods for stabilization of the spinal column (PS) in case of disassociated cervical spondylomyelopathy (DA SCM) and degenerative lumbosacral stenosis (DP CS) in dogs. This work describes the first experience in the Russian Federation using a transpedicular fixation system for the treatment of degenerative lumbosacral stenosis and cervical spondylomyelopathy in dogs based on a series of clinical cases.

In this publication, the authors describe the use of both a traction device and a locking device (provides stable fixation). However, this technique involves bicortical polyaxial screws. This means that the screws pass through the vertebral body through the spinal canal. Screws are held along “safe corridors” to exclude iatrogenic spinal cord injury, however, without the use of intraoperative navigation, which is currently not common in veterinary medicine, there is a risk of a screw being inserted directly into the spinal canal, which is associated with spinal cord injury, and this may lead to serious complications up to tetraparesis and death.

The prototype methodology involves the use of a distractor using a fixing design based on monocortical insertion of screws, that is, the screw passes through 1 cortical layer of the vertebral body and does not pass through the second-internal, this excludes the penetration of the screw into the spinal canal and spinal cord injury with the screw (subject to surgical technique ) The screws are fixed to each other by means of bone cement based on polymethyl methacrylate.

Thus, the technical problem of the described method is the need to use intraoperative navigation to find safe corridors for bicortical screw insertion. Bicortical screw insertion correlates with greater iatrogenic risks of injury to the intravertebral structures, spinal nerves and spinal arteries.

The objective of the invention is to eliminate the imperfection of existing methods of stabilization of the spinal column in dogs with Wobbler's syndrome.

The technical result of the invention is to reduce the risks of iatrogenic damage to the spinal cord, spinal nerves, as well as the supply arteries. Also, it provides both the necessary distraction and absolutely stable fixation of the spinal column at the same time, which is the key to recovery.

The specified technical result is achieved due to the fact that the claimed method of stabilization of the spinal column in the cervical region in dogs with Wobbler syndrome, characterized in that using MRI, or myeloid CT, or dynamic myelography, a pathological section of the cervical vertebral column is revealed, instability is revealed between the vertebrae as well as a possible protrusion of the intervertebral disc, perform ventral access, characterized in that they first form a slot for installing the TTA cage in the vertebral bodies and for removing the disc substance and bone exostoses, tightly insert the TTA cage, fix on the vertebral bodies two monocortical screw; at the second stage, four holes are drilled, two into each vertebra, in the vertebral bodies in the ventral cortical layer, and drilling is carried out in such a way that the drill passes only one cortical layer, the screws are twisted completely into the dorsal cortical layer, then a single conglomerate between the screws and the TTA cage using bone cement, whereby the bone cement is applied to the protruding parts of the screws, forming together with the TTA cage a single conglomerate; at the final stage, layered wound closure is performed.

Previously, the field for applying cement is dried with sterile wipes.

Brief Description of the Drawings:

Figure 1 shows the axial projection of bone cement (a - before applying cement, b - after applying cement).

Figure 2 shows a diagram of the application of bone cement in the ventro-dorsal projection

(a - a ventral slot, b - a place for installing a TTA cage, c - after applying cement).

Figure 3 shows a schematic illustration of the formation of a ventral slot.

Figure 4 shows an MRI T2 of the cervical spine of the dog, where the arrows indicate the compression sites.

Figure 5 shows the surgical access to the ventral surface of the vertebral bodies. Slot formation with a high-speed surgical cutter. Simultaneous removal of disk material.

Figure 6 shows the stage when the ventral slot is formed, the site for the installation of the TTA cage is prepared.

Figure 7 shows the evaluation of the slot volume and the selection of the corresponding cage.

On Fig shows the installation phase of the cage.

Figure 9 shows the location of the cage in the slot.

Figure 10 shows the drilling of holes in the bodies of the vertebrae and monocortical holding screws.

Figure 11 shows the appearance of the structure before applying bone cement.

On Fig shows the field for applying cement is dried with sterile wipes.

13 shows the application of bone cement to a metal structure.

14, bone cement is applied, a single conglomerate is formed between the screws, cage and bone cement.

On Fig shows the appearance of the structure before suturing the wound.

In the drawings: 1 - Screw held monocortical. 2 - Part of the screw with a hat that protrudes from the vertebral body to the outside. 3 - Slot for installing the TTA cage. 4 - Bone cement is applied to the protruding parts of the screws, forming together with the TTA cage a single conglomerate. 5 - TTA cage.

The implementation of the invention

To implement the claimed method, bone cement based on polymethylmethacrylate, four cortical screws of the corresponding diameter and length (selected based on data on the patient size, radiographic measurements) and a cage for Kyon TTA with screws for it are required.

Detected with the help of MRI, or CT myelo, or dynamic myelography, the pathological site of the cervical spine. Between the vertebrae, instability and sometimes protrusion of the intervertebral disc are revealed. Pathology is characteristic of large dog breeds, especially Dobermans and Great Dane. Pathology is more common in the caudal cervical region). Perform ventral access and form a slot 3 (see Figure 1, Figure 2) to install the TTA-cage 5 in the vertebral bodies and to remove the substance of the disc and bone exostoses, a TTA-cage 5 is tightly inserted between the bodies, fixed to the vertebral bodies two screws monocortical. TTA cage 5 is put into the slot as shown in FIG. 2 (b). A schematic representation of the formation of a ventral slot is shown in FIG. 3.

The formation of the ventral slot includes the following steps.

Surgical access to the ventral surface of the vertebral bodies. Slot formation with a high-speed surgical cutter. Simultaneous removal of the substance of the disk (see Figure 5).

The stage when the ventral slot 3 is formed, a place is prepared for the installation of the TTA cage 5 (see Fig. 6).

Evaluation of the volume of slot 3 and the selection of the corresponding cage 5 (see Fig.7).

The installation phase of the cage 5 (see Fig.8). Figure 9 shows the location of the cage in the slot.

The second stage is the drilling of four holes (two in each vertebra) in the vertebral bodies in the ventral cortical layer (the drill passes only one cortical layer, which is the main fact of minimizing the risks of iatrogenic trauma to the spinal cord, spinal nerves and feeding vessels), tightening the screws to focus on the dorsal cortical layer, the formation of a single conglomerate between the screws 1 and the cage using bone cement 4. Figure 10 shows the drilling of holes in the vertebral bodies and monocortical screws.

The appearance of the structure before applying bone cement can be seen in Fig.11.

The cement application field is dried with sterile wipes (see FIG. 12).

Bone cement 4 is applied to the protruding parts of the screws, forming together with the TTA-cage 5 a single conglomerate (see Fig.13).

When bone cement is applied, a single conglomerate is formed between the screws, cage and bone cement (see Fig. 14).

On Fig shows the appearance of the structure before suturing the wound.

The final stage of the operation is layered wound closure. The result of the operation according to the described method described) is distraction and stabilization of the vertebrae, decompression of the spinal cord.

Distinctive features of the method is the monocortical insertion of screws 1 into the vertebral bodies without the need for intraoperative navigation systems. In addition, the required distraction is achieved by a spacer, in which, if necessary, you can also place either autobone if necessary, fusion of the vertebrae or an antibiotic in the presence of a bacterial infection.

These distinctive features allow you to achieve the claimed technical result.

The principle of the method is that the titanium cage (spacer) 5 provides distraction of the vertebrae, thereby relieving compression from the spinal cord caused by excessive pressure of the intervertebral disc and vertebral bodies on the spinal cord, the insertion of four monocortical screws 1 into the ventral cortical layer of adjacent vertebral bodies subsequently bonded to each other using bone cement 4 based on polymethylmethacrylate ensure stable fixation of the vertebrae in the distraction position.

The end of the screw 1 (see Figure 1) abuts against the distal cortical layer of the vertebral body without penetrating the canal. In this case, part of the screw with the cap 2 (see Figure 1, Figure 2) remains above the ventral surface of the vertebral body.

Bone cement 4 is closely packed on all surfaces of screws 1 and the protruding surface of cage 5, in contact with soft tissues along the edges, i.e. envelops screws 1.

The contact area of the screws 1 with cement 4 is all parts of the screws with a cap 2, which protrude from the vertebral body to the outside.

TTA-cage 5 is placed at the place of formation of the ventral slot - literally in the hole itself, formed between the vertebrae.

Cage 5 is always inserted the same way with the same effort and technique. The described method is not able to implement a stabilization system without the use of a cage.

Figure 1 in axial projection where the end of the screw is the boundary of the second cortical layer into which the screw does not penetrate.

The area of a single conglomerate between the screws 1 and the cage 5 using bone cement 4 is shown in Figure 1 (b) and Figure 2 (c). In this area, the screws 1 are immersed in cement 4.

In Fig.4, you can see the result of the operation (MRI T2 of the cervical spine of the dog, where the compression points are indicated by arrows), from which it follows that over time, the vertebrae are distracted and stabilized, and the spinal cord is decompressed. Distraction was assessed radiologically by comparing the distance between the vertebral bodies before and after the operation, the dynamics of the state was assessed by a veterinarian neurologist, interpreting the degree of neurological deficit.

Claims (2)

1. A method of stabilization of the spinal column in the cervical region in dogs with Wobbler's syndrome, characterized in that, using MRI, or myeloid CT, or dynamic myelography, a pathological section of the cervical spine is revealed, instability and protrusion of the intervertebral disk are revealed between the vertebrae, ventral access, characterized in that at first they form a slot for installing the TTA cage in the vertebral bodies and for removing disc material and bone exostoses, a TTA cage is tightly inserted between the vertebral bodies, and it is fixed monocortically to the vertebral bodies with two screws; at the second stage, four holes are drilled, two in each vertebra, in the vertebral bodies in the ventral cortical layer, and drilling is carried out in such a way that the drill passes only one cortical layer, the screws are twisted completely into the dorsal cortical layer, then a single conglomerate between the screws and the TTA cage using bone cement, wherein bone cement is applied to the protruding parts of the screws; at the final stage, layered wound closure is performed. 2. The method according to p. 1, characterized in that the field for applying cement is dried with sterile wipes.

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