home Auditorium 7 Dorsal stabilization for atlantoaxial instability in toy dog breeds. Atlantoaxial instability in dogs Cervical vertebrae displacement in dogs

Dorsal stabilization for atlantoaxial instability in toy dog breeds. Atlantoaxial instability in dogs Cervical vertebrae displacement in dogs

(Atlanto-axial instability/C1-C2 instability in toy breeds of dogs)

Doctor of Veterinary Sciences Kozlov N.A.

Gorshkov S.S.

Pyatnitsa S.A.

Abbreviations: AAN - atlanto-axial instability, AAS - atlanto-axial joint, AO ASIF - international association of medical traumatologists and orthopedists, C1 - first cervical vertebra (atlas), C2 - second cervical vertebra (epistrophy), Malformation - developmental defect, ZOE – odontoid process of the epistrophy (blue tooth of the second cervical vertebra), CT – computed tomography MRI – magnetic resonance imaging, PS – spinal column, KPS – dwarf dog breeds OA – general anesthesia, PMM – polymethyl methacrylate

Introduction

Atlanto-axial instability- (syn. atlanto-axial subluxation (subluxation), dislocation (luxation)) - is excessive mobility in the atlanto-axial joint, between C1 - the first and C2 - the second cervical vertebrae, which leads to compression of the spinal cord in this area and how the consequence is manifested by varying degrees of neurological deficit. AAN is one of the anomalies (malformations) of the spinal column. (R. Bagley, 2006) This pathology is typical for dwarf dog breeds (DeLachunta.2009), but also occurs in large breeds (R. Bagley, 2006).

Anatomical features

The atlantoaxial joint provides rotation of the skull. In this case, vertebra CI rotates around the odontoid process of CII. There is no intervertebral disc between CI and CII, so the interaction between these vertebrae is carried out mainly due to the ligamentous apparatus. In dwarf dog breeds, congenital instability of the connection of the first and second cervical vertebrae is explained by the following reasons (DeLachunta.2009):

— Underdevelopment of the ligaments that hold the epistrophy tooth.

— Absence of a tooth in the second cervical vertebra, associated with its postnatal degeneration, malformation or aplasia.

According to Dr. DeLachunta and a number of colleagues, the epistrophy tooth undergoes degeneration in the first months of the animal’s life. This degeneration process is similar to the mechanism of development of such pathology as avascular necrosis of the femoral head (Legg-Calvé-Perthes disease), which is also typical for dwarf dog breeds (De Lachunta, 2009).

The completion of the process of ossification of the tooth epistrophy occurs at the age of 7-9 months. (DeLachunta.2009).

The absence of the odontoid process and/or its underdevelopment occurs in 46% of cases. Rupture of the ligamentous apparatus - in 24% of cases (Jeffery N.D, 1996.) These anomalies in the development of the spinal column are congenital, but injuries to this area can force the appearance of clinical symptoms of the disease (Ellison, 1998; Gibson K.L, 1995).

Predisposition

Yorkshire Terrier, Chihuahua, Miniature Poodle, Toy Terrier, Pomeranian, Pekingese.

Etiology. Pathogenesis

It was proposed to distinguish 2 main forms of AAN (H. Denny, 1998):

— Congenital atlantoaxial dislocation (primary).

The pathology is typical for dwarf dog breeds. The basis is a minor injury, a jump from hands, a sofa, etc.

— Acquired atlantoaxial dislocation(directly traumatic).

Occurs suddenly as a result of severe trauma, for example in a traffic accident or fall. It can occur in any animal, regardless of breed and age. More often, acquired atlantoaxial dislocations are very severe, which is associated with sudden simultaneous and massive compression of the spinal cord by the epistrophic tooth and displaced vertebral arches.

Often, animals that have received minor trauma have a more severe degree of neurological deficit than those that have been exposed to moderate or significant trauma.

This depends on how long the transverse ligament of the epistrophic tooth can withstand and resist the dorsal displacement of the tooth of the second cervical vertebra towards the spinal canal directly during trauma (DeLachunta.2009).

Also, atlantoaxial dislocation can be acute or chronic.

Acute– often provoked by injury (falling from one’s hands, jumping from a sofa). Chronic- develop unnoticed, gradually, without obvious motivating reasons, with a minimal degree of neurological deficit. If a relapse occurs, after treatment of AAN with a similar course, the clinical symptoms are more significant and the treatment is more difficult.

Sometimes, as a result of chronic dislocation, atrophy of the dorsal (upper) arch of the atlas gradually develops from constant pressure, which is clearly visible on an x-ray in the form of the absence of the dorsal part of the atlas.

Clinical symptoms

Clinical signs of this pathology can vary from a slight pain reaction in the neck to tetraparesis of the limbs. Symptoms may also be as follows:

The most common clinical signs of pathology:

1) acute pain syndrome- which manifests itself when turning or raising the head in the form of a loud “squeal”;

2) ventroflexion– forced position of the head and neck no higher than the level of the withers;

3) proprioceptive deficit thoracic limbs;

4) tetraparesis/tetraplegia.

Symptoms of brain damage may also be seen, which may be a consequence of impaired cerebrospinal fluid circulation and the development or progression of hydrocephalus, which is often present in 95% of toy dog breeds (Braun, 1996) but without clinical signs. In animals, hydrocephalus may also be accompanied by syringo(hydro)myelia.

Compression of the basilar artery by the odontoid process of the epistrophy can cause symptoms such as disorientation, behavioral changes, and vestibular deficit.

Diagnostics

Differential diagnosis of this pathology includes (H. Denny):

Tumors of the PS and spinal cord

Herniated discs

Discospondylitis

A similar clinical picture may include:

Spinal fractures

Herniated discs Hansen type 1

Hypoglycemia is a common pathological condition in Yorkshire terrier puppies and other miniature dogs.

Visual diagnostics includes data from the following studies:

X-ray examination of the cervical spine in the lateral projection
X-ray contrast study (myelography). To exclude other pathologies - Computed tomography
Magnetic resonance imaging
Ultrasound of the atlanto-axial joint

An X-ray allows one to clearly visualize the area of the AA joint, mainly in dwarf dog breeds, due to the very small thickness of the vertebrae (the average thickness of the dorsal arch of the atlas in the period from 1-3 months is 1-1.2 mm (McCarthy R.J., Lewis D.D., 1995)) . Also, using an X-ray image, you can evaluate the increase in the distance between the C1 and C2 vertebrae.

It is recommended to take the picture without general anesthesia, since relaxation and relief of pain (if any) will aggravate damage to the spinal cord, which can, due to ascending edema, lead to paralysis of the respiratory center and death.

However, spinal cord compression cannot be judged in any way based on an x-ray. (Sotnikov V.V., 2010.) To do this, you need to perform a CT or MRI.

These methods are not for everyone and are often not always available, due to the insolvency of the financial situation of the animal’s owners, as well as the lack of CT and MRI machines in ordinary veterinary clinics in the Russian Federation.

In this case, as an additional method for diagnosing AAN in dwarf breeds of dogs, you can resort to ultrasound of the AA joint. This method is possible and used (Sotnikov V.V., Conference materials: Neurology of small domestic animals // St. Petersburg, 2010.)

MRI data provides more complete information about spinal cord edema, myelomalacia or syringohydromyelia (Yagnikov, 2008).

Currently, we use the following to surgically solve the problem: surgical stabilization techniques(if there are indications for surgery):

Ventral stabilization;
Stabilization using – 2 spokes (2 mini-screws);

Rice. 1 and 2. Intraoperative photo

Dorsal stabilization. As a possible solution to the problem, it is possible to use a dorsal tie (Kishigami) as a fixator.

Clinic of Experimental Therapy of the Russian Oncological Research Center named after. N.N. Blokhin RAMS

Yagnikov S.A., Lukoyanova M.L., Kornyushenkov E.A., Kuleshova Y.A., Pronina E.V., Krivova Yu.V., Sedov S.V.

Introduction

Atlantoaxial instability is a congenital pathology of the spinal column in dwarf dog breeds, which is characterized by displacement of the first cervical vertebra (atlas) relative to the second (epistrophy) (Fig. 1).

Fig.1. Radiographs of the cervical spine in the lateral projection (a). Atlantoaxial instability (increased distance between the dorsal arch of the atlas and the spinous process of the epistrophy, displacement of the odontoid process of the epistrophy into the spinal canal, displacement between the articular fossae of the atlas and the cranial articular processes of the epistrophy.

The atlantoaxial joint provides rotation of the skull. In this case, vertebra C I rotates around the odontoid process C II. There is no intervertebral disc between C I and C II, so the interaction between these vertebrae is carried out mainly due to the ligamentous apparatus 1,2.

This pathology is most common in young dogs of toy breeds (Yorkshire terriers, Chihuahuas and toy poodles). However, the age range for manifestation of the disease may vary. Cases of the disease have been reported in cats and large breeds of dogs, such as Rottweiler, Doberman Pinscher, Basset Hound and German Shepherd.

Atlantoaxial instability develops in dogs with the absence or underdevelopment of the odontoid process or with its fracture, as well as in dogs with rupture of the ligamentous apparatus at the level C I - C II. The absence of the odontoid process and/or its underdevelopment occurs in 46% of cases, and rupture of the ligamentous apparatus occurs in 24% of cases. These anomalies of the spinal column are congenital, but injury to this area can precipitate the onset of clinical symptoms of the disease 1,2.

The main clinical symptoms of the disease are: 1) acute pain, which manifests itself when turning or raising the head in the form of a loud “squeal”; 2) ventroflexion - forced position of the head and neck no higher than the level of the withers, 3) proprioreceptive deficit of the thoracic limbs, 4) tetraparesis/tetraplegia. Symptoms of brain damage may also be noticed, which may be a consequence of impaired circulation of cerebrospinal fluid and the development or progression of hydrocephalus (Fig. 2). Hydrocephalus may also be accompanied by syringohydromyelia.

Fig.2. CT scan of the brain of a dog with atlantoaxial instability. Segmental cut. Enlargement of the right lateral cerebral ventricle ().

Another potential explanation for forebrain symptoms in dogs with atlantoaxial instability is hepatic encephalopathy secondary to portosystemic shunts. This is another favorite condition in small breed dogs, occurring in two out of six dogs operated on for atlantoaxial instability.

Compression of the basilar artery by the odontoid process can cause symptoms such as disorientation, behavioral changes, and vestibular deficits.

To make a diagnosis of atlantoaxial instability, it is necessary to conduct an X-ray examination of the cervical spine in a lateral projection (Fig. 1). In some cases, slight flexion of the neck may be required to see the deviation from the axis, but in no case should it be severe 1,2,3,4.

Myelography is not necessary for diagnosis. In addition, injection of a contrast agent into the cerebellomedullary cistern can be fatal. If, after a survey X-ray, there are still doubts about the correctness of the diagnosis, you can perform a contrast spondylography of the cervical spine through a lumbar puncture.

Computed tomography or magnetic resonance imaging of the cervical spine will differentiate the disease from disc herniation, discospondylitis, tumors of the spinal column and spinal cord, and will also provide more complete information regarding spinal cord edema, myelomalacia, or syringohydromyelia (Fig. 5).

Priority in the treatment of this pathology is given to the surgical method of treatment. Although there is data in the literature about successful conservative treatment of atlantoaxial instability. Conservative treatment includes immobilization of the head and neck with a brace and analgesics. A number of authors note that after 3.5 months, animals with atlantoaxial instability could walk without motor deficits of the limbs 3 . However, in 30-60% of animals, after removing the corset, a relapse of the disease was noted. The technique of applying a corset requires a certain skill from the doctor, and the main requirement is stable immobilization, without squeezing soft tissues by the corset design. If the neck is stretched too much, the animal may aspiration of food into the respiratory tract, since the act of swallowing is unnatural for a dog in this position.

However, this treatment may be an excellent alternative for dogs that have contraindications to general anesthesia 3 . For traumatic fractures C I - C II, conservative management of the patient gives much better results than surgical treatment.
But most authors consider congenital atlantoaxial subluxation to be a direct indication for surgery 1,4,5,6. There are two main ways to stabilize C I - C II through dorsal and ventral approaches.

Dorsal stabilization consists of drawing a wire suture around the dorsal arch of the atlas (C I), repositioning the vertebrae C I - C II, followed by their fixation with a wire loop to the spinous process of the epistrophy (C II) (Fig. 6.0 and 6.1) 4. However, with this technique, the frequency of complications is quite high in the form of rupture or fracture of the fixing implant, cutting through the arch of the atlas with a wire suture, which leads to relapse of instability and requires repeated surgical intervention in 25-63% of cases, and mortality with this surgical intervention technique was noted in 8-63% of cases. 38% of cases (Fig. 7) 1.4,5. With a successful outcome of the operation, residual pain symptoms persist in 6-11% of cases, and residual ataxia in 44-83% 1.4,5.

Using these treatment techniques, we encountered the above complications, or more precisely, a fracture of the fixing wire loop and cutting through the arch of the atlas with a wire suture, which led to relapse of instability and neurological symptoms (Fig. 7).

Literature data and our own negative experience forced us to reconsider the technique of dorsal stabilization for atlantoaxial instability.

Materials and methods: The work was performed on 4 dogs of toy breeds aged from 9 months to 3 years. Two dogs were Yorkshire terriers, one was a toy terrier and one was a miniature poodle. The animals came to the clinic with complaints of acute pain, ventroflexion, tetraparesis and ataxia. In three animals, the disease history was 7-20 days. One dog has an unknown medical history. Based on the radiographic examination of the cervical spine in the lateral projection, spondylolisthesis C I relative to C II was revealed on radiographs in all animals (Fig. 1). Owners are recommended to undergo surgical treatment.

Operation stages. Obtaining a bone autograft from the iliac wing. Skeletonization by removing soft tissue fragments from the surface of the autograft. A dorsal approach was made to the arch of the atlas and the spinous process of the epistrophy, and the dura mater was opened cranial and caudal to the dorsal arch of the atlas. A bone autograft from the iliac wing was placed from the dorsal surface onto the dorsal arch of the atlas and fixed with three wire cerclages made of wire with a diameter of 0.6 mm at three levels (Fig. 8). Three holes were formed in the spinous process of the epistrophy at different levels in height and length using a Kirschner wire with a diameter of 1 mm. The cranial surface of the spinous process of the epistrophy was skeletonized from soft tissues. C I was reduced relative to C II, achieving a good comparison, and the vertebrae were fixed with three wire sutures (Fig. 9). The space between the arch of the atlas and the spinous process of the epistrophy was filled with collapan granules. The soft tissues were sutured in layers with interrupted sutures using 5-0 prolene. Immobilization of the head and cervical spine in relation to each other and the chest was ensured using a plastic turbocast corset for 30 days (Fig. 10)

If there were positive dynamics, the animals were sent home. Control radiography was performed on the 30th day after surgery. If there was no vertebral displacement or fracture of the wire sutures visible on the radiograph, the corset was removed. After removing the corset, owners were advised to limit their dogs' movement for one month.

Treatment results

On days 3-9 after surgery, the animals’ ability to walk improved or was restored, and the animals moved more and more actively. In two dogs with an acute pain symptom at the time of initial admission (whining when moving the head and neck), no pain was noted in the postoperative period.
Animals could eat on their own.

At the time of removal of the corset, the bone callus was not detected on radiographs. The contours of the callus along the dorsal surface of the vertebrae were visualized on days 45-60 (Fig. 11).

Evaluation three months after surgery showed that persistent relief of the pain symptom was noted in all four dogs, partial ataxia persisted in one animal.

X-ray examination showed that in all observations the position of the vertebrae did not change after reposition. And a bone callus has formed along the dorsal surface of the dorsal arch of the atlas and the spinous process of the epistropheus.

The owners of three animals did not observe any symptoms characteristic of atlantoaxial instability 5 or more months after surgery (Fig. 12). Ataxia persists in one animal. However, restoration of the ability to move and relief of acute pain symptoms, according to the owners, significantly improved the patient’s quality of life.

Discussion

The method we tested for stabilizing the spinal column at levels C I - C II allowed us to obtain a lasting improvement in animals with atlantoaxial instability.

The chosen surgical technique is not accidental. It is based on a theoretical rationale, the main goal of which was bony fusion between the dorsal arch of C I and the spinous process of C II.

The choice of surgical approach (ventral or dorsal) and, accordingly, the surgical technique (ventral stabilization or dorsal stabilization) had the following rationale.
We gave priority to the dorsal method of stabilization after analyzing the distribution of forces acting on the ventral and dorsal surfaces of the cervical vertebrae C I - C II. Between the dorsal arch of the atlas and the spinous process of the epistrophy, tensile forces act along the dorsal surface of the spinal column. And along the ventral surface at the junction of these two vertebrae (the articular fossae of the atlas and the cranial articular processes of the epistrophy) there are compression forces (Fig. 13).

This distribution of distraction and compression forces is determined by the laws of physics. The head, as a part of the body, has gravitational forces. When holding the head along the ventral surface of the spinal column, compression forces predominate, and along the dorsal surface, distraction forces predominate. And these forces exist almost always at any moment of movement or rest of the animal (Fig. 13.1).

With dorsal fixation of the vertebrae, we can neutralize the tensile forces that exist physiologically between C I - C II. These forces can be neutralized by creating compression using a wire clamp between the dorsal arch of the atlas and the spinous process of the epistrophy. Compression along the ventral surface of the vertebrae, between the articular fossae of the atlas and the cranial articular processes of the epistrophy exists physiologically. By neutralizing tensile forces along the dorsal surface of the vertebrae, creating compression using the dorsal fixator, we create compression between C I - C II along the ventral and dorsal surface, which increases the stability of fixation (Fig. 13.2).

With ventral fixation of the spinal column, the tensile forces existing between the dorsal arch of the atlas and the spinous process of the epistrophy are preserved, which leads to a cranial-caudal displacement of the dorsal arch of the atlas relative to the spinous process of the epistrophy. Kirschner wires or screws passed through the articular processes of these two vertebrae will experience flexion and shear forces, which can lead to their premature migration or fracture, and, accordingly, to recurrence of instability between C I - C II (Fig. 13.3).

Therefore, from a biomechanical point of view, dorsal fixation C I - C II has priority.

The choice of implant for fixation of C I - C II during dorsal stabilization determines the anatomical structure of the vertebrae. And today, wire is the only material that can be used to fix the vertebrae at this level. However, the use of a wire suture as an implant fixing the vertebrae was marred by relapses of instability due to destruction of the atlas arch by the wire and fracture of the wire suture.

To stop these complications, we needed to solve several problems. The first is to prevent destruction of the dorsal arch of the atlas. It is for this purpose that we implanted a cancellous autograft of the iliac wing onto the arch of the atlas. It is spongy bone that is capable of revascularization and restructuring in a short period of time, and it is spongy autograft that has the maximum potential for osteoinduction, osteoconduction and osteogenesis. We also needed cancellous bone to stimulate the fusion of C I - C II.

To fix the autograft to the arch of the atlas, we used three wire sutures with wire with a diameter of 0.4-0.6 mm. This made it possible to reduce the pressure of the wire sutures on the bone at the site of their contact, and the fixation of the wire sutures to the arch of the atlas and the autograft made it possible to neutralize the effect of “sawing” and the effect of “displacement” of the wire sutures to the center of the arch. This is a very important point. Since the central part of the arch of the atlas in young animals is represented by cartilaginous tissue, and it is this place of the arch that has the greatest tendency to destruction.

Why three wire seams and not four or five? There are certain rules for fixing bone fragments and fragments, formulated by ASIF JSC. It is fixation with three implants that provides the most stable fixation in comparison with one or two implants. And the use of four and five implants does not significantly increase the strength of fixation of fragments and splinters. Therefore, three wire seams are the “gold standard”.

I would like to once again dwell on the theory that we based our method: reposition of the vertebrae, stable fixation, fusion of the vertebrae.

After reposition, the vertebrae are held in place with wire sutures for 20 days after surgery. But with active movements of the animal, this structure breaks down. Yes, we placed three wire sutures, but this does not guarantee us that the fusion of our patient’s vertebrae will occur before metal fatigue during active head movements causes a fracture of the wire sutures. After all, any implant can withstand a certain number of cyclic movements.

To reduce the load on the wire sutures, it is necessary to eliminate head movements, and this requires additional immobilization of the spinal column. To ensure immobility in the cervical spine, it is necessary that the corset extends as a single block to the head, cervical spine and chest of the patient.

We have created conditions for the fusion of C I - C II. The formation of callus between C I and C II can be stimulated using spongy autologous bone. We implanted cancellous bone on the arch of the atlas, reduced the vertebrae, and achieved good alignment between the vertebrae. However, there are gaps that it is advisable to fill with spongy autologous bone in order to increase the area of fusion of the vertebrae. But in dwarf dog breeds, it is impossible to collect spongy autologous bone from tubular bones, as is done in other breeds of dogs and even cats. The only way out is to use the spinous processes of the first thoracic vertebrae or ceramic implants. Unfortunately, the latter have only osteoconductive properties.

The condition of the animal on the 5th day and one and a half months after the operation.

The condition of the animal before surgery, on the first day after surgery, on the 15th day after surgery and on the 30th day after surgery.

Conclusion

Dorsal stabilization of the cervical spine in dogs with atlantoaxial instability should include the following steps: repositioning of the vertebrae, autologous bone grafting of the dorsal arch of the atlas, fixation of the vertebrae with wire cerclages and immobilization in a brace, which will allow for bone fusion along the dorsal surface of the vertebrae. This method will avoid the most common complications during dorsal stabilization of C I - C II in dogs with atlantoaxial instability.

Literature review:

Beaver D.P., Ellison G.W., Lewis D.D., Goring R.L., Kubilis P.S., Barchard C. Risk factors affecting the outcome of surgery for atlantoaxial subluxation in dogs: 46 cases (1978-1998). Journal of the American Veterinary Medical Association, 2000, 216, 1104-1109.
Gibson K.L., Ihle S.L., Hogan P.M. Severe spinal cord compression caused by a dorsally angulated dens. Progress in Veterinary Neurology, 1995, 6, 55-57.
Hawthorne J.C., Cornell K.K., Blevins W.E., Waters D.J. Non-surgical treatment of atlantoaxial instability: a retrospective study. Veterinary Surgery, 1998, 27, 526.
Jeffery N.D., Dorsal cross pinning of the atlantoaxial joint: new surgical technique for atlantoaxial subluxation. Journal of Small Animal Practice, 1996, 37, 26-29.
Knipe M.F., Stuges B.K., Vernau K.M., Berry W.L., Dickinson P.J., Anor S., LeCouteur R.A. Atlantoaxial instability in 17 dogs. Journal of Veterinary Internal Medicine, 2002, 16, 368.
Sanders S.G., Bagley R.S., Silver G.M. Complications associated with ventral screws, pins and polymethylmethacrylate for the treatment of the atlantoaxial instability in 8 dogs. Journal of Veterinary Internal Medicine, 2000, 14, 339.

Atlanto-axial instability is a congenital disease of dwarf dog breeds, characterized by instability of the first cervical vertebra (atlas) in relation to the second (axis). With this position of the vertebrae, the protruding part of the second vertebra - the tooth - is inserted into the cavity of the spinal canal and causes compression of the spinal cord. As a rule, atlantoaxial instability develops during the first year of life, but sometimes 5-7 year old animals with this pathology are also encountered. As a result of this, the animal experiences sharp pain, which manifests itself when the head position changes, loss of coordination of movements, in severe cases this leads to paralysis of the limbs.

For diagnosis, MRI and plain radiography are used, which make it possible to identify the degree of vertebral displacement and select the correct treatment method.

In some cases, in addition to a plain X-ray, stress films are used to make an accurate diagnosis: for this, the dog is given general anesthesia and X-rays are performed in a special projection. This allows you to accurately assess the displacement of the vertebrae when moving the head. Treatment of this disease is mainly carried out surgically, since conservative treatment is ineffective and provides only temporary relief of symptoms, without relieving the animal of the cause of suffering. Surgical treatment consists of correcting the pathological displacement of the vertebrae and fixing them in this position with special materials. There are several methods for treating atlantoaxial instability: dorsal and ventral stabilization. The technique is selected individually by the operating surgeon.

Ventral stabilization of atlantoaxial instability in the Yorkshire terrier.

Dorsal stabilization of atlantoaxial instability in a toy poodle.

Toy poodle after surgery to stabilize atlantoaxial instability.

Very often, atlantoaxial instability occurs with a whole complex of genetic developmental pathologies that lead to disruption of the outflow of cerebrospinal fluid through the spinal canal, manifested by hydrocephalus, Chiari syndrome (incarceration of the cerebellum in the foramen magnum) and syringomyelia (enlargement of the central spinal canal). Clinically, this is manifested by pain, neurological disorders, ataxia, convulsions, and paresis. And only MRI can reveal the true cause of this condition, on which the surgical approach to treatment will depend.

Hydrocephalus, Chiari-like syndrome, syringomyelia in a toy terrier

Question answer

Is it possible to fix an old fracture (radius bone of the dog's front right leg)? If yes, what is this operation called? A week later we made an appointment for an examination and an x-ray of the old fracture, we are waiting to see what they say. But I would also like to get an answer to the question above... The fracture healed crookedly, a dog from the street. Julia

Question: Is it possible to fix an old fracture in a dog?

Hello! Maybe. This is metal osteosynthesis. But you can tell more accurately only from the picture.

Hello. Please tell me the approximate amount of total costs, including additional ones, for prosthetic paws for a cat. Amputated as a result of falling into a trap, up to the wrist area.

Question: can you tell me the approximate amount for a prosthetic paw for a cat?

Hello! Regarding prosthetics, write to us by email [email protected] with a note to Sergei Sergeevich Gorshkov. An examination and analysis of the case is necessary. No one can tell you the approximate cost offhand.

Atlantoaxial instability typically occurs in small breed dogs and begins clinically in young animals, although it can occur at any age. This condition can be inherited or result from injury. With atlantoaxial instability, subluxation, or displacement, of the second cervical vertebra (epistrophy) relative to the first (atlas) occurs, followed by compression of the spinal cord, which leads to severe neurological symptoms: tetraparesis, paralysis, and proprioceptive deficit. The disease may be accompanied by hydroencephaly and syringohydromyelia. Among the main causes of atlantoaxial instability are the following:

Abnormal shape of the odontoid process or its absence
Underdevelopment of the odontoid ligaments
Post-traumatic rupture of the atlantoaxial ligaments
Fracture of the odontoid process due to trauma (strong flexion of the neck)

Anatomically, there are no intervertebral discs between the occipital bone, atlas and epistropheus, and these vertebrae form a flexible segment of the cervical spine, providing good mobility of the neck. The interaction between the first and second cervical vertebrae is carried out due to the articular surfaces, ligaments and the odontoid process of the epistrophe, which enters the fossa of the atlas tooth. The odontoid process, in turn, is fixed by the longitudinal and alar ligaments, as well as the transverse ligament of the atlas. The epistrophic crest is attached to the dorsal arch of the atlas by the dorsal atlantoaxial ligament.

Rice. 1 - ligamentous apparatus of the atlanto-axial joint.

Rice. 2 - congenital absence of the odontoid process, predisposing to rupture of the dorsal atlantoaxial ligament and leading to the displacement of the epistrophy dorsally, and the atlas - ventrally.
Rice. 3 - fracture of the odontoid process and rupture of the transverse atlas ligament, rupture of the dorsal atlanto-axial ligament (can occur independently of each other).

Normally, the odontoid process is fixed by strong ligaments that reliably articulate the first two vertebrae. These ligaments can be weak or underdeveloped and can be damaged by the slightest impact on the cervical spine. If the odontoid process has an abnormal shape, then the ligaments, as a rule, are torn, and the epistrophy is displaced relative to the atlas. The odontoid process may be completely absent - in this case, the vertebrae are not fixed in any way, which also leads to subluxation of the atlanto-axial joint and compression of the spinal cord. Although atlantoaxial instability is a congenital disorder found in small breeds, ligament rupture and subsequent vertebral displacement can occur as a result of trauma in any animal.

Clinically, the disease manifests itself as pain in the cervical spine, as well as partial or complete loss of sensitivity, paresis and paralysis. Proprioceptive deficits, resulting from an excessive increase in the amount of cerebrospinal fluid in the cranial cavity (hydroencephaly), are characterized by impaired motor skills and coordination of movement. Congenital atlantoaxial instability is often combined with syringohydromyelia (formation of cysts and cavities in the central canal of the spinal cord).

Some dogs with congenital AO instability also have portosystemic shunts: this may be due to the inheritance of genes that influence the development of these two diseases. Thus, if one of them is detected, it is advisable to conduct diagnostic studies aimed at identifying (or excluding) the other.

The disease is diagnosed based on X-ray examination. A radiograph of an animal with AO instability shows a sharp increase in the space between the epistrophic crest and the dorsal arch of the atlas, which indicates a rupture of the dorsal atlantoaxial ligament. With a fracture of the odontoid process and its abnormal shape, the lower contour of the epistrophy is displaced dorsally and does not coincide with the lower contour of the atlas (the dorsal AO ligament may be intact, and the separation of the atlas from the epistrophy may not be observed).

Rice. 4 - radiographs: normal spine (A), AO instability (B). White arrows indicate an increase in the distance between the epistrophic crest and the dorsal arch of the atlas

The images are taken in a lateral projection, with the head bent at the cervical spine, which should be done extremely carefully, since excessive force directed at the damaged segment of the spine can cause damage to the spinal cord. Direct and axial views can also be useful in assessing the shape of the odontoid process. Myelography is contraindicated because it can cause unnecessary compression of the spinal cord and cause seizures.

Computed tomography provides more detailed diagnostic information than x-ray examination. However, the presence or absence of syringohydromyelia can be concluded only from the results of MRI. These diagnostic methods are associated with anesthetic risk, since the animal must be under general anesthesia at the time of the study.

Rice. 5 - computed tomograms: A - normal, B - AO instability. An asterisk indicates an abnormal odontoid process; the displacement of the lower contour of the epistrophe is indicated by a white arrow.

Treatment is mainly surgical, aimed at fixing the vertebrae with wire cerclages or bone cement. If the odontoid process has an abnormal shape, its resection is performed. If there are cysts in the central canal of the spinal cord, they are drained.

Conservative treatment is also possible, when the animal is placed in a cage and the cervical region is immobilized with a bandage. But it is ineffective and is mainly used as a temporary measure for animals that have contraindications for surgery, for example, with deep paresis and an individual who is too young. This treatment aims to stabilize the animal before surgery and allows young animals to reach a relatively safe age for surgery.

According to D.P. Beaver and others, the prognosis for dogs with congenital AO instability is in most cases favorable if the animal survives the operation and tolerates the postoperative period well. Operative mortality reaches about 10% of cases, and about 5% of animals require reoperation.

The joint between the first (atlas) and second (axis) cervical vertebrae is the most important moving part of the spine, but it has little inherent stability compared to other parts of the spine.

Atlantoaxial instability in dogs is caused by traumatic or rheumatic destruction of the ligaments that hold the odontoid process in place.

In dogs of dwarf breeds, AAN is a congenital pathology, the distinctive feature of which is the instability of the atlas in relation to the axis. It causes an abnormal bend between two bones and, as a result, compression of the spinal cord.

In most cases, congenital atlantoaxial instability in dogs makes itself felt before the age of one year, but there are also animals with this pathology older than 5 years.

Traumatic subluxation of the joint is possible in representatives of any breed and does not depend on age. The degree of damage to the spinal cord varies depending on both the severity of the compression and the duration of the condition.

Symptoms

Symptoms of atlantoaxial instability vary in dogs, and their progression may gradually increase or worsen rapidly.

Neck pain is the most common symptom. Often it is the only sign of pathology. The severity of pain can be quite severe.
Loss of coordination.
Weakness.
Neck drooping.
Impaired supportability of all limbs up to complete paralysis, which can also lead to paralysis of the diaphragm, as a result of which the animal cannot breathe.
Brief fainting (rare)

Diagnostics

The diagnosis is made on the basis of breed predisposition, medical history, clinical symptoms and the results of a neurological examination, as well as the results of an X-ray examination or MRI/CT diagnostics (depending on the clinic’s facilities).

What is the difference between these diagnostic methods? With mild instability, X-ray examination may be ineffective and often only indirectly indicates this pathology. MRI diagnostics allows you to most clearly visualize the spinal cord, the degree of its compression and swelling. CT diagnostics allows the most accurate visualization of bone structures and is more effective in cases of suspected atlantoaxial instability due to a traumatic fracture.

Treatment

Conservative treatment of atlantoaxial instability in dogs is rarely used, but may be prescribed if symptoms and compression are minor or if there are medical contraindications to surgery. Conservative treatment consists of:

Severe restriction of mobility
Use of steroids and pain medications

With conservative treatment, there is always a risk of persistence of symptoms or their progression up to sudden paralysis and death of the animal. For this reason, surgery is most often recommended to relieve spinal cord compression and stabilize the joint. The choice of technique depends on the size of the animal and the presence of associated fractures.

Forecast

The prognosis depends on the severity of the spinal cord injury and the results of neurological deficits. Animals with mild symptoms have a favorable prognosis. When paralysis is present, the prognosis is generally guarded, but significant recovery is possible if prompt surgical intervention is performed. Significantly greater success with surgery is seen in younger dogs (less than 2 years of age), dogs with more acute problems (less than 10 months of symptoms), and dogs with less severe neurological problems.

Dorsal stabilization for atlantoaxial instability in toy dog ​​breeds. Atlantoaxial instability in dogs Cervical vertebrae displacement in dogs

Introduction

Anatomical features

Predisposition

Etiology. Pathogenesis

Clinical symptoms

Diagnostics

Symptoms

Diagnostics

Treatment

Forecast

Dorsal stabilization for atlantoaxial instability in toy dog breeds. Atlantoaxial instability in dogs Cervical vertebrae displacement in dogs