Chapter 53 - Vertebral column part 1 Flashcards
what the new studies of imaging revealed concerning the angulation and subluxation of C3 and C4 on radiographs?
such as angulation or subluxation at C3 to C4 that suggest cervical spinal cord compression on plain radiographs, are not always confirmed as the site of compression on myelography
Are changes in the articular processes of C5, C6, C7 a common findin and always responsible for neurologic problems?
No, changes seen in the articular processes of C5,
C6, and C7 may be associated with spinal cord compression
but they are also a common finding in horses without neurologic
problems and may be present in horses with ataxia attributable
to another cause or to compression at another site
is there association btw OA of the caudolateral aspects of the caudal cervical facet joints and clinical symptoms?
In fact, there is no clear association between osteoarthritis of the caudal cervical facet joints and clinical symptoms. Recent postmortem study showed 18% with craniolat OA and caudal articular process in 52%
what is the ideal surgical patient for spinal cord lesions?
young horse showing mild neurologic signs as a result of CVSM for a short period of time or a trauma patient exhibiting no or only minimal neurologic deficits
what are the 2 materials most used for vertebral interbody fusion?
Kerf-Cut cylinder (KCC) or a LCP
What are the surgical approachs to the cervical vertebrae?
ventral, lateral, dorsal, lateral and dorsal
Pateint position is crucial for vertebral sx, Describe how to position the horse for ventral approach
DR
extended neck and head held in position by foam cushion or custom made wedge pads that stabilize the neck in a vertical position
FL tied in flexed position and pulled caudally
Fluoroscopy or radio previous, during sx
why is important that the markers, staples, are placed the closest to the x-ray cassete?
to prevent excessive distortion as a result of parallax, and they should be placed over the affected articulation as well as ventrally at the level of the incision
What are the 2 recumbencies for the dorsal approach?
sternal recumbency with all four limbs flexed on a padded table and the head extended
positioning the horse in lateral recumbency with the neck in full flexion
After aseptic preparation and imaging the incision in either dorsal and ventral will have to abaxially deviate the muscles. What instrument will you use?
Weitlaner retractors can be used to maintain access to the vertebrae
In the ventral approach after skin incision centered over affected vertebrae what muscles were incised?
cutaneous muscle is incised, and the sternohyoid and** sternothyroid muscles** are separated on the midline to the level of the trachea, which is** retracted to the left** side
In the ventral appraoch after cutaneous muscle, sternohyoid, stenothyroid muscles are separated how is the dissection continued?
blunt dissection is continued dorsad down to the** right side of the trachea, separating it from the carotid artery and vagosympathetic trunk**. The trachea and other structures are protected with moistened gauze pads. Weitlaner retractor is inserted and longus colli muscle accessed.
longi colli can be mistaken with
esophagus
which vessel you have to be careful in the caudal cervical region?
Before the fascia of the** longus colli muscle is incised, all important vessels must be cauterized or ligated. An important branch of the carotid artery** is located in the** caudal cervical region**. The fascia and longus colli muscle are subsequently incised to gain access to the cervical vertebrae
describe the ventral access to the vertebra
DR
Incision of skin
Incision of cutaneous muscle, sternothyroid and **sternohyoid **muscles, ID trachea + separate vagosympathetic trunk and carotid artery
Moistened gauze to the trachea
**Weitlaner retractor **positioned at the cranial and caudal aspect of the incision
Cauterize important vessls - branch of carotid artery
incise longus colli muscle and gain acess to cervical vertebrae
*C3 be careful that esophagus can b mistaken with longi colli
At what level is the esophagus in the midline?
At C3 level
Describe the dorsal approach to the cervical vertebrae
20 to 30 cm incision through skin on dorsal midline
Incise subcutaneous tissue and fat overlying the funicular part of the nuchal ligament and expose the fibrous tissue of the ligament
Once you incised dorsal nuchal ligament place a self-retaining Finochietto or Balfour retractor
Describe the lateral approach to the cranial recess cervical vertebrae Tucker 2021 Vs
slightly curved, 6 cm skin incision was made in a cranioventral to caudodorsal direction centered over the craniodorsal margin of the APJ, as identified using ultrasound.
The incision was continued through
-m. brachiocephalicus*
-*/m. omotransversarius,
- m. longissimus cervicis, dissection was directed toward the
palpable craniodorsal rim of the APJ
19 gauge needle was placed through the incision into the palpable joint space and the joint was distended with approximately 5 ml sterile polyionic fluid
stab incision was made with a number 11 scalpel
blade through m. intertransversarii** and the joint
capsule, to enter the cranial outpouching of the joint
Introduction of conical obturator and arthroscope sleeve craniodorsal to caudoventral angled 60º with 4 mm 30º endoscope
Fluid distension 60mmHg
created approximately 20 mm cranial and 20 mm ventral
to the arthroscope portal
For which condition do you go for lateral approach?
treatment of cervical articular process joint osteochondrosis,
describe the surgical approach to the caudodorsal recess according to Tucker et al 2021
5 cm skin incision was created in a slight craniodorsalto-
caudoventral plane at the level of the caudodorsal border
of the **APJ, as identified by intraoperative ultrasound
imaging
The joint was distended with fluid and a stab
incision created through m multifidus cervicis and the
joint capsule, similar to the approach to the cranial
recess.
arthroscope was inserted into the joint, angled in a caudodorsal to cranioventral direction,
An instrument portal** was
created **caudoventral to the arthroscope portal **but its
close proximity to the arthroscope invariably resulted in
the creation of a single mini-arthrotomy
Tucker et al 2021 how were retrieved the osteochondral fragments?
Smaller fragments were retrieved with 4-6 mm Ferris-
Smith rongeurs. Larger fragments were removed with a
curved hemostat
description and diagnosis
FIGURE 3 Orthogonal
transverse (A) and sagittal
(B) multiplanar reconstructed CT
images centered on the right C5/C6
articular process joint of the same
horse (Table 1, case 4). Circular,
mineral-attenuating loose bodies are
situated in a cranioventral location
within the joint
For the dorsal approach to the cervical vertebrae, what is often profuse initially?
Hemorrhage
What aids retraction in the dorsal approach to the cervical vertebrae?
Finochietto or Balfour retractors
What is the lateral an dorsal approach to the thoracolumbar vertebrae?
skin incision located** 6 cm lateral to the midline** with the dorsal spines exposed by dissecting the supraspinous ligament off its dorsal edge
modification of this technique uses a midline approach for the skin incision and the dorsal spines are exposed by splitting the supraspinous ligament
The** supraspinous ligament **is split longitudinally and the ligament and longissimus dorsi muscle attachments are sharply dissected off the affected processes and partly off the adjacent processes beyond the impingement lesions
what is the dorsal approach to the sacrum and the coccygeal vertebrae plate fixation? how do you close it?
longitudinal and along the midline
For the** dorsal sacral and coccygeal approach,** only the subcutaneous tissue is sutured in a simple continuous pattern and the skin is apposed using a continuous intradermal pattern.
what instrument is used in the dorsal approach to the coccygeal vert and sacrum?
pointed reduction forceps
how do you close the ventral cervical approach
the longus colli muscle is apposed followed by the ventral cervical muscles, the** cutaneous muscle** together with the subcutaneous tissues, and finally the skin.
When closing the dorsal cervical approach, the laminar portions of the nuchal ligament come together and need to be apposed only along the most superficial aspect of the ligament using absorbable monofilament suture material in a simple continuous suture pattern.
how do you close the dorsal cervical approach
The funicular portion of the nuchal ligament, the subcutaneous tissues, and the skin are all apposed using absorbable suture material in a simple continuous suture pattern in each layer. When
how do you close the lateral cervical approach?
When finishing the lateral cervical approach, the joint capsule is closed in a simple interrupted pattern and the muscle layers are closed in two layers. A sterile stent bandage is sutured over the incision for protection of the incision during recovery and replaced with a sterile dressing when the horse has returned to its stall. **Placement of a suction drain **is an option to prevent seroma formation, and a neck bandage can be applied but is not mandatory
How do you close the lateral and dorsal thoracolumbar approach?
the** supraspinous ligament** is sutured in a simple continuous pattern and the skin is apposed using a continuous intradermal pattern
how should be performed the recovery of horses after cervical intervention?
Hand recovery of horses with tail and head ropes is preferred by many surgeons
Steroids can be administered when the grade of ataxia is greater than
(out of 5 according to Mayhew’s grading system15)
Sling recoveries are sometimes necessary, especially in horses with
severe ataxia (grade >3).
what are the postoperative care following cervical sx?
Hay and feed should be offered at shoulder level
4-6 w stall rest After this time, hand-walking can be initiated
After 60 to 90 days the horse should be turned out for at least 6 months or until clinical signs resolve
How much time can take the cervicals to fuse following surgery?
1 year
The owner and trainer should be warned that it may take at least 1 year before the clinical signs resolve and that a carefully executed rehabilitation program is of utmost importance for a good result.
cervical fractures are common in young or adult horses?
foals and young
possible explanation: exuberant nature of most foals and young horses and their smaller muscle mass compared with mature horses; the musculature has a considerable protective and stabilizing effect on the vertebral column.
Which type of vertebral fractures is more common in adult horses? Where?thoracolumbar fractures common in young or adult?
Thoracolumbar fractures
The most common sites of vertebral body fracture are the first three thoracic vertebrae, followed by the thoracic vertebrae in the T12 area = greatest lateral bending and axial rotation
A vertebral fracture may involve the
vertebral body
vertebral arch
facet joints
spinous process
describe image and diagnosis
Figure 53-6. Transverse computed tomography image of a fracture of the axis, which was missed with radiographic examination. The black arrow shows the fracture line of the vertebral body.
Projection and diagnosis
Figure 53-5. Oblique radiographic view showing a fracture of the atlas with ventral displacement of the fragments (arrow).
projection and diagnosis
Figure 53-7. (A) Laterolateral radiographic view showing fracture (arrow) of the dens. (B) Laterolateral radiographic view showing fracture of the dens (arrows) with severe displacement of the articulation between the atlas and the axis. ([
what are the different traumatic injuries to the cervical spine
1) fracture to the atlas and axis
2) Atlantoaxial subluxation and luxation
3) Cervical vertebral fractures (C3 to C7)
4) Fractures involving one or 3 vertebra
5) Fractures of the articular process
Which surgical approach involves the separation of the sternohyoid and sternothyroid muscles on the midline?
Ventral approach to the cervical vertebrae
Which vertebrae differ greatly from the remaining cervical vertebrae?
Atlas and axis
What is the recommended course of action for horses with severe disruption of the thoracolumbar spinal cord?
Euthanasia
What is a common cause of vertebral fractures in horses?
Trauma
How can vertebral fractures without trauma occur?
such as lymphosarcoma, spinal abscess, or septicemia, or occur after failure of surgical intervertebral stabilization
What is a common surgical technique for repairing fractures of the dens?
A) Dorsal laminectomy
B) Ventral atlantoaxial fusion (plate LCP or screws)
C) External fixation with Steinmann pins
At what age does the physis of the dens or odontoid process close in horses?
8 to 12 months
How do you diagnose fractures of axis and atlas?
These injuries cause neck pain and stiffness.
Some patients exhibit no neurologic deficits
Radiographs a (lateral, oblique, and ventrodorsal projections) Myelography, and if available, CT scanning (Figure 53-6) or MRI
what is the goal of surgery to the atlas or axis fracture?
The goal of surgery is to provide decompression at the fracture site by realigning the vertebrae and providing stability through some form of fixation
what are the ligaments that attach axis to the atlas?
Apical
Transverse
Alar ligaments
Neurologic deficits from axis and atlas trauma
range from a stiff gait and splinted neck to total tetraparesis or even sudden death
The prognosis for recovery from atlas and axis injury is correlated to
severity to spinal cord damage
with only paresis having favorable survival prognosis
Nonsurgical management of atlas/axis fracture can be attempted?
yes with stall rest and AINS and with time fibrous union btw the dens and axis may develop and enuro deficits decrease. late-developing neurologic deterioration indicates that proliferative bony callus or soft tissue hypertrophy can cause cord compression
Which approach is NOT described for the surgical repair of a fractured axis?
Lateral approach, only dorsal and ventral are described
Dorsal laminectomy of the caudal half two-thirds of the dorsal arch of atlas is done why?
to relieve the spinal cord compression created by a fracture callus and may result in a long-term improvement in the neurologic status of the horse
Describe the placement of LCP plate by ventral approach to correct atlas or axis fracture
30-cm midline ventral skin incision centered on the vertebra with radio guidance
Flattened the ventral spinous process with rongeur or curved osteotome
Align the ventral vertebra is corrected and maintained with bone-holding forceps
Depending on size of patient: broad or narrow 3.5/4.0-mm ir 4.5/5.0-mm LCP is contoured to the shape of vertebra to the ventral aspect of C2
One cortex screw inserted into each fragment in load fashion
Length of screws estimated with fluoro and remaining holes filled with LHS screws
extremly important to avoid spinal cord damage when inserting the screws
what other tx beside ventral LCP has been described?
Ventral stabilization of the atlantoaxial junction by inserting two 6.5-mm cancellous screws across the articulation after removal of cartilage from the articular surfaces - risk vertebral
arteries and first cervical nerves abaxially
dorsal plate inserted in the dorsal spinous process in case of fractures of the body of C2
cerv
projection and diagnosis
(A) Laterolateral radiographic view showing a complete transverse fracture (arrow) of the second cervical vertebra. (B) Dorsoventral radiographic view.
treatment
(C) Laterolateral radiographic view of the axis after fixation of the fracture with a narrow 7-hole 4.5-mm dynamic compression plate.
projection and diagnosis
Figure 53-10. (A) Laterolateral radiographic view showing subluxation of the atlantoaxial joint (arrow). (B) Laterolateral radiographic view showing complete luxation of the atlantoaxial joint
what are the pathologies common in atlas and axis region?
1) vertebral fracture (body, arch), spinous process, articular process,
2) subluxation and luxation
What complication can occur from drilling screw holes in the vertebral arches of the atlas?
Penetration of the spinal canal
What age range is most commonly affected by subluxation of the atlantoaxial articulation in horses?
Up to 3 years of age
What indicates a complete luxation of the atlantoaxial articulation?
Displacement of the dens ventral to the atlas
what are the clinical signs of atlas or axial subluxation?
The neurologic signs can be acute or chronic and can vary in severity from mild ataxia to recumbency.
The horse may have abnormal head and neck carriage and r**esent manipulation **of the neck, and there may be local swelling at the site of acute injuries
when is the nonsurgical treatment is an option?
Nonsurgical treatment is indicated for acute complete luxations of C1 to C2, when closed reduction is **possible under GA **in acute injuries
what is the surgical option for horses that show neuro deterioration or persistance of neuro deficits in C1 or C2 subluxation?
Horses with atlantoaxial subluxation can be successfully treated with** subtotal dorsal laminectomy. Removal of the caudal two-thirds of the dorsal arch of the atlas relieves spinal cord compression and allows preservation of the normal range of motion of the atlantoaxial articulation. A portion of the dorsal atlantoaxial ligament is left intact
NO SX TX for complete atlantoaxial luxation(AUER but Schulze 2019 describes VS)
Arthrodesis with human disal femural plate - chronic cases**
diagnosis and projection
Figure 53-12. Laterolateral radiographic view showing subluxation between C2 and C3 (arrow).
Figure 53-13. Laterolateral radiographic view showing chronic fracture of the cranial articular process of the fourth cervical vertebra. The sclerotic and cystic changes are signs of nonunion, which are depicted by the black arrows.
Figure 53-8. Laterolateral radiographic view showing fixation of the subluxation of the atlantoaxial joint with a human distal femur locking compression plate. This is the same patient as shown in 53-7, B. (B) Slightly oblique radiographic view showing fixation of the subluxation 15 months postoperatively of the patient shown in 53-7, B. Bone bridging between the atlas and the axis can be observed (black arrow). Bone lysis around many screws and the plate are clearly evident (white arrows).
Figure 53-15. Postmortem specimen of a comminuted fracture of C4 with severe spinal cord damage. The white arrow shows the fracture of the fourth vertebra and the black arrow shows the severe damage to the spine at the location of the vertebral fracture.
what happened?
Figure 40.3 Chronic fracture of the atlas with secondary spinal cord compression in a two‐year‐old Quarter Horse. The horse was injured
during a training incident as a yearling. (A) Lateral myelographic image shows multiple bony densities in the ventral arch of the atlas
(white arrows), massive thickening of the dorsal arch of the atlas, and compression of the spinal cord (arrowheads). (B) Intraoperative view
shows laminectomy of the caudal two‐thirds of the dorsal lamina of the atlas. (C) Completed laminectomy prior to insertion of nuchal fat.
Cranial cervical congenital subluxations name them and recommended tx
- occipitoatlantoaxial malformation (OAAM) - arabian horses
- atlantoaxial subluxation (AAS) - absence or separation of dens from axis
- and atlantoaxial instability (AI)
congenital absence of the dens
Tx: standard LCP or** dstal femur LCP** for OAAM
subtotal dorsal laminectomy of the impinging dorsal arch for AAS
No tx for AI
Figure 40.2 Fracture of the atlas in an adult horse with upper neck stiffness but no neurologic deficit. (A) Lateral radiograph identifies
non‐destabilizing fractures (arrows) in the lateral arches of the atlas. (B) Oblique radiograph indicates that the fracture extends to the
cranial foramen of the atlas (arrows).
Figure 40.2 Fracture of the atlas in an adult horse with upper neck stiffness but no neurologic deficit. (A) Lateral radiograph identifies
non‐destabilizing fractures (arrows) in the lateral arches of the atlas. (B) Oblique radiograph indicates that the fracture extends to the
cranial foramen of the atlas (arrows).
What is a necessary condition for atlantoaxial luxation to develop?
Complete disruption of the ligamentous attachments of the dens
Total luxation of the C1 and C2 was corrected with placement of TLACP plate describe the surgical procedure by Schulze
20-cm skin incision was made on ventral midline, centered over the atlas and axis.
The** musculus cutaneous colli was bluntly dissected, and the sternohyoid and sternothyroid muscles** were separated in midline.
After the trachea was identified, it was retracted to the left with **Langenbeck retractors
blunt dissection was continued in a dorsal direction,** to the** right side of the trachea.** The carotid artery and vagosympathetic trunk were identified and carefully retracted by using a **Penrose
drain. The aponeurosis of the longus colli muscles** was incised, and the muscles were retracted with Hohmann retractors to
gain access to the ventral aspect of the atlas and to expose the
luxated dens of the axis (Figure 2).
With the aid of the **pulley system, traction was applied to
the occipital area of the head of the horse in an attempt to perform open reduction of the luxation. Reduction was supported by placing a Hohmann retractor **between the caudal aspect of
the atlas and the dens by using it as a lever to gently walk the
dens back to its physiological position. **The reduction of the
luxation was unsuccessful despite the application of strong
traction, and the dens axis was subsequently excised with an
oscillating saw . The alignment of
the atlas and the axis was achieved after removal of the
dens axis. The ventral spinous process of the body of the axis** was flattened by using a curved osteotome and bone rongeurs. The** cartilage
of the caudal articular joint surface of the atlas, and the cranial articular surface of the axis was removed with a curette.
The alignment of the atlas and axis was finally optimized under
fluoroscopic guidance and maintained with bone reduction forceps (Figure 3). A 4.5-mm six-hole T-locking compression
plate (T-LCP) was contoured and fixed to the caudal aspect of the atlas with a 5-mm locking head screw (36 mm) that was
inserted in the central screw hole at the T end of the plate. The correct length of the screws was determined
with fluoroscopic guidance. The second screw was a 4.5-mm cortical screw (28 mm) placed in load position in the cranial
aspect of the axis (fourth screw hole). Four 5.5-mm cortical screws (68 mm) were placed in lagfashion
across the atlantoaxial articulation to
provide additional stability. The medial and lateral cortical
screws were tightened simultaneously to maintain axial alignment.**
The remaining screw holes of the T-LCP were filled with
locking head screws with the exception of the second screw
hole of the plate, which was positioned over the atlantoaxial
articulation (Figure 4a,b).
Prior to closure, the wound was flushed with sterile polyionic
fluids. The longus colli muscles (USP 2 polyglactin
910), ventral cervical muscles (USP 2 polyglactin 910),
cutaneous muscle together with subcutaneous tissue (USP
2-0 polyglyconate), and** skin** (USP 2-0 polypropylene)
were apposed in simple continuous fashion. The surgical
site was protected with a stent
diagosis and projection
FIGURE 1 Left-lateral radiograph of a complete luxation of the
dens axis in an American quarter horse yearling. The dens axis can be
identified ventral to the ventral arch of the atlas. A, C1 (atlas); B, C2
(axis); a, dens axis; b, cranial aspect of the vertebral body of C2; c,
caudal aspect of the vertebral body of C2; d, vertebral canal of C2; e,
articular process joint C2/C3; f, concavity of atlas where the dens
should be located; g, dorsal spinous process of C2
what is happening?
FIGURE 2 Ventral intraoperative photograph of the luxated
dens of the axis. The aponeurosis of the longus colli muscles was incised, and the muscles were retracted laterally with Hohmann retractors to gain access to ventral aspect of the atlas and the axis. a, cranial; b, caudal; c, Hohmann retractor; *, luxated dens of the axis
FIGURE 3 Ventral intraoperative photograph of the bone
reduction forceps keeping the alignment of atlas and axis after removal of the dens axis. The ventral spinous process of the body of the axis has been flattened, and the 4.5-mm six-hole T-locking compression plate is in position. a, cranial; b, caudal; c, bone reduction forceps; *, removed dens of the axis with T-plate positioned over the atlantoaxial
articulation. Schulze
What was the surgical technique used to stabilize the atlantoaxial articulation in the case report?
A) Manual reduction
B) 4.5-mm T-locking compression plate (T-LCP)
C) Spinal fusion
D) External fixation
B) 4.5-mm T-locking compression plate (T-LCP)
What complication is commonly associated with complete atlantoaxial luxation in horses?
A) Fracture of C4 and C5
B) Poor prognosis for survival
C) Respiratory distress
D) Increased instability of the neck
B) Poor prognosis for survival
What percentage of vertebral fractures in horses involve the cervical vertebrae?
Approximately 50%
What are the most common types of cervical vertebral fractures?
Compression fractures of the vertebral body and articular process fractures
What typically causes cervical vertebral fractures in horses?
Head-on collisions or falls over jumps or obstacles
At what age do the caudal cervical vertebral body physes close in horses?
4 to 5 years old
name the instrument
Langenbeck
Figure 53-16. Laterolateral myelographic view showing static compression of the spinal cord at C7 in a horse that sustained a fracture of C7 2 years previously. The black arrows indicate the ventral compression of the spine at the location of the callus formation.
Diagnosis and projection
Figure 53-17. (A) Preoperative laterolateral radiographic view showing an oblique displaced fracture of the caudal part of the C4 involving the disc (black arrow). (B) Laterolateral radiographic view taken 3 years after surgical fixation with a narrow 5-hole 4.5/5.0-mm locking compression plate.
treatment?
Figure 53-17. (A) Preoperative laterolateral radiographic view showing an oblique displaced fracture of the caudal part of the C4 involving the disc (black arrow). (B) Laterolateral radiographic view taken 3 years after surgical fixation with a narrow 5-hole 4.5/5.0-mm locking compression plate.
Describe the placement of LCP fixation in the cervical fractures
Disc removal is important
bone graft in the ventral intervertebral space can be good
s**tandard 4.5/5.0-mm narrow **or broad 8-hole LCP is used with 5.0-mm self-tapping locking head screws under radiographic control.
Self-drilling and self-tapping screws should not be used, because a considerable amount of threaded screw length is lost because of the drilling device at the tip of the screw.
Most plate holes are filled with 5.0-mm locking head screws, but if a nonperpendicular angulation is necessary, 4.5- or 5.5-mm cortex screws are inserted as position screws (Figure 53-20). It is important to use the longest screws possible and to place the central cortex screw across the intervertebral articulation as a position or lag screw (Figure 53-21).
what happened?
Figure 53-22. Inadvertent penetration of the spinal canal and spinal cord during drilling (arrow).
what happen?
Figure 53-23. Five months postoperative laterolateral radiographic view of the cervical spine with a narrow 14-hole 4.5/5.0 locking compression plate applied to the ventral aspect of C3 to C5. The plate broke at two sites (black arrows) and one 4.5-mm cortex screw is broken as well (white arrow). In addition, the locking head screw broke through the combi plate hole (grey arrow). Some remodeling callus is present.
Hohmann retractor
describe the image
(A) Bone phase gamma scintigraphic lateral
images of the cervical vertebrae showing increased
radiopharmaceutical uptake of the right C4/C5 and C5/6 APJs. Tucker at al
projection and diagnosis
describe image and diagnosis
FIGURE 3 Orthogonal
transverse (A) and sagittal
(B) multiplanar reconstructed CT
images centered on the right C5/C6
articular process joint of the same
horse (Table 1, case 4). Circular,
mineral-attenuating loose bodies are
situated in a cranioventral location
within the joint Tucker et al 2020
diagnosis
describe according to Tucker et al 2021 where is performed the skin incision and instrument portals to the cranial articular process joint
LR - affected APJ uppermost and neck in neutral position
5L fluid bag placed beneath the neck to open the joint space
slightly curved,** 6 cm skin**
incision was made in a cranioventral to caudodorsal direction
centered over the craniodorsal margin of the APJ, as
identified using ultrasound
what happened?
Figure 34.4 Anatomic specimen demonstrating
dorsal laminectomy of the atlas. Cranial is to the
left. A high-speed
burr is used to remove an oval
shape from the caudal two-thirds
of the dorsal
arch of the atlas (white arrows). The dorsal
atlantoaxial ligament (AtAxL) and interspinous
ligament are separated from their attachments
to the dorsal arch of the atlas. SC: spinal cord;
DS: dural sac just dorsal to the defect. The dural
sac and the atlantoaxial membrane have been
removed at the level of the atlantoaxial joint.
Figure 34.12 (a) Custom-made
V-shaped block used to stabilize the neck in a strictly vertical position and hold a radiographic cassette. (b) Horse positioned for surgery: neck in the block (white arrows), head square and secured. Skin staples (black arrows) mark the affected vertebra. A mobile X-ray machine (large white arrow) is mounted on an arm at an appropriate fixed angle to ensure
accurate intra-operative
imaging.
Figure 34.13 Instruments for efficient exposure of the ventral
aspect of the vertebrae. Left to right: curved osteotomes,
self-retaining
Inge retractors (x2) and Beckman–Adson retractor.
Upper left: bone gouge forceps (rougeurs
Figure 34.19 Anatomic specimen demonstrating dorsal laminectomy. Cranial is to the left. (a) A peripherical rectangular channel is burred,
outlining the lamina to be removed from each vertebra. Care is taken not to damage the spinal cord when reaching the thin inner cortex.
(b) The free lamina of the cranial and the caudal vertebra are removed avoiding excessive lateral excavation. Following decompression, a fat
graft is placed in the defect, covering the dural sac (the latter has been removed in the photograph). SC: spinal cord.
diagnosis
Lateromedial radiographic view of a 3.5-year-old Swiss Warmblood mare with occipitoatlantoaxial malformation
what happened?
Figure 53-44. Laterolateral radiographic view of the cervical spine with a distal femoral locking compression plate applied to the ventral aspect of C1 and C2 of a horse, which was presented for an atlantoaxial subluxation. The implant pulled out of C2 because the screws inserted were too short (arrows).
cer
what is the goal of foraminotomy?
To decompress cervical spinal nerves. Bone specimen(A) showing the middle third of the ventralaspect of the cranial articular process (reddashed circle), representing the optimal region of the needle position.
FIGURE 5 Bone specimen(A) showing the middle third of the ventralaspect of the cranial articular process (reddashed circle), representing the optimalregion of the needle position. Cadavercervical spine (B) showing the needlepositioning. The yellow needle representsthe optimal needle position. Note the flowof the cerebral spine fluid from the greenneedle hub (indicating an iatrogenic injuryof the spinal canal), which is positionedonly a couple of millimetres ventral to theyellow. (C) Transverse CT image ofanother cadaver showing the optimal(A) and suboptimal (B) needle position.
FIGURE 1 Endoscope structure
including working channel, optical and
light system, and irrigation canal.
FIGURE 1 Endoscope structure
including working channel, optical and
light system, and irrigation canal.
Cervical vertebra stenosis has to go accordingly to a Mayhew grading neurologic grading. Describe the grading
Figure 53-35. (A) Illustration showing the intra- and intervertebral sagittal ratio measurement. a, Longest distance of the cranial aspect of the vertebral body, measured perpendicular to the vertebral canal; b, shortest distance measured from the dorsal aspect of the vertebral body to the ventral border of the dorsal laminae; c, shortest distance from the dorsal aspect of the physeal scar of the more cranial vertebra to the cranial dorsal lamina of the more caudal vertebra; c1, shortest distance from the caudal dorsal lamina of the more cranial vertebra to the dorsal aspect of the cranial physeal scar of the more caudal vertebra. (B) Laterolateral radiographic view showing lines of measurement for determination of the intra- and intervertebral sagittal ratio.
Figure 53-36. (A) Laterolateral myelographic view for the measurement of the dorsal myelographic column (DMC). A diagnosis of spinal cord compression is made when there is a 50% or greater decrease in the sagittal diameter of the dorsal column; the intervertebral DMC is compared with the intravertebral DMC of the next cranial site. (B) Laterolateral myelographic view for the measurement of the entire dural diameter (DD). Spinal cord compression is suspected when there is a 20% height reduction of the DD at the intervertebral site compared to the intravertebral site.
Figure 53-37. Laterolateral myelographic view showing a compression (arrow) at the articulation of C5 to C6. (Courtesy F. Rossignol, Paris, France.)
Spinal cord compression can be evaluated myelographically using three criteria based on reduced height of the myelographic column (Figures 53-36 and 53-37): (1) the entire dural diameter (DD)—the DD reduction rule implies that compression can be suspected when the minimal intervertebral DD is at least 20% reduced compared to the maximal intravertebral DD; (2) the dorsal myelographic column (DMC)—the DMC rule diagnosis spinal cord compression when there is as 50% or greater height reduction of the intervertebral DMC compared to the maximal intravertebral DMC at the level of the vertebral body just cranial to it; and (3) the 2-mm rule—this rule indicates compression when the DMC is less than 2 mm in height
Which approach is used for surgery on the caudal cervical vertebrae?
DR with extended neck
Muscles that insert on vertebrae must be retracted abaxially and acess to the ventral aspect
Carefull to avoid arteries and veins
Forelimbs tied flexed and pulled somewhat caudally to allow acessto the caudal portion of the neck by imaging (C-arm) and surgeon
How deep should the drilling be according to the surgical guidelines?
25 to 30 mm
What is the minimum amount of bone that should be left between the drill and the bottom of the spinal canal?
10 mm
Figure 53-42. (A) Illustration showing positioning of the K-wire and the large centering pin. (B) Illustration showing the K-wire, the large centering pin, and the four-pronged drill guide hammered into the vertebrae. (C) Illustration of the the drill bit. (D) Illustration of the Kerf cutter. (E) Illustration of the partially threaded Kerf-cut cylinder. (F) Illustration of the fully threaded Kerf-cut cylinder.
Figure 53-42. (A) Illustration showing positioning of the K-wire and the large centering pin. (B) Illustration showing the K-wire, the large centering pin, and the four-pronged drill guide hammered into the vertebrae. (C) Illustration of the the drill bit. (D) Illustration of the Kerf cutter. (E) Illustration of the partially threaded Kerf-cut cylinder. (F) Illustration of the fully threaded Kerf-cut cylinder.
what is this procedure?
Tap procedure during kerf cut cylinder insertion
What is the surgical approach once you reach the vertebra?
Ventral midline approach (same as KCC)
Top L– Prep bone: ventral spinous process of affected vertebrae flattened withcurved osteotome + bone rongeur
Lmiddle – Disc material removed, multiple parallel drill lines (5.5mm drill bit) under rx guidance Bottom
L – expose ventral surface affected vertebrae, alignment is corrected andmaintained with bone holding forceps
What is the surgical approach once you placed the holding forceps?
Top R– appropriately sized plate applied – SMALL or BROAD 3.5/4.0 or 4.5/5.0mm LCP used MINIMALPLATE BENDING NEEDED
Rmiddle – 1 cortex screw inserted In EACH vertebra in LOAD position – correct length determined with fluoroscopic guidance (DO NOT DAMAGE CORD)
BottomR – Remaining holes – locking head screws Similar closure to KCC
Postop management SAME as KCC implant
LCP placement with good results. What is the surgical technique?
The ventral spine of the CV was flattened using an oscillating saw or osteotome.
The** intervertebral disc **was partially removed using a Ruskin Rongeur, spoon curette or 3.2 to 4.5 mm drills depending on surgeon’s preference.
A stainless-steel LCP was applied to the ventral surface of the affected vertebrae under fluoroscopic control. Length and type of the plate depended on the location and extent of the cervical instability.
The plate was carefully contoured to the surface of the vertebrae.
Whenever possible, 5.0-mm locking head screws were inserted into the plate holes; **4.5- or 5.5-mm cortical screws ** were only used if angulation of a screw wasrequired or the threaded part of the combi-hole was damaged. All plate holes were filled with screws
what is this tex?
Titanium polyaxial pedicle screw kit, consisting of pedicle screws, connecting rod and set screws. (A) Porous metal interbodyfusion device measuring 15 x 15 x 35 mm. (B) Drawing of polyaxial pedicle screw and rod construct with screws placed on right and leftside of ventral keel and placement of a porous metal interbody fusion device in situ. The connecting rod is placed within the tulip heads ofthe pedicle screws. Set screws are then placed on top of the connecting rods and locked in place using a torque-limited driver, resulting inangulation capacity of 50 degrees of the shaft of each pedicle screw.
describe which tx this instruments are used?
Pedicle screw and Rod constructs was state of art in lumbar spine fusion of humans.
WHERE DO YOU PLACE 2 POLYAXIALPEDICLE SCREWS?
Cranial vertebra 1 cm cranial to the defect 1 to the L and1 to the R of midline
Caudal vertebra 1 cm caudal to the ventral edge of thedisk space - 1 to the L and 1 to the R of midline
Two 5.5-mm diameter precut titanium rods (orange) were placed through the heads ofthe pedicle screws pediclescrew compression tool (blue)wasmoderately applied to the screws R and L of midline to minimize any dead spaceon the CR or CD edges of the IFD (blue) Set screws were inserted into the tulip heads (green arrow) of the pedicle screws to lock the rods in place with compression applied acrossthe IFD and disk space
