This document summarizes a study on cervical disc arthroplasty using an artificial disc to treat disc-associated wobbler syndrome in 33 dogs. The key findings were: 1) 91% of dogs showed improvement in neurological grade after surgery, with 30 dogs having satisfactory to excellent outcomes. 2) Complications included vertebral fractures during surgery in 2 dogs, immediate subsidence in 1 dog, and subsidence in 7 disc spaces. 3) Poor outcomes occurred in 2 dogs with severe, long-standing neurological signs that did not improve after surgery.

1. ECVS 24th Symposium July 4th 2015 - Berlin, Germany, Europe
Cervical Arthroplasty:
A Non-Fusion Technique for Disc Associated
Wobbler Syndrome in dogs
Copy of this presentation: Wobblersyndrome.com
under the menu’ tab: “For Veterinarians”
Filippo Adamo, DVM, Dipl. ECVN
East Bay Veterinary Specialists – Walnut Creek, CA

2. ECVS Surgery Symposium
July 2-4, 2015
Disclosure
 I designed and developed the medical device included
in this presentation.
 Currently involved in the distribution trough Applied
Veterinary Technology, LLC

3. Goals:
Preserve motion after neural
decompression while providing
distraction and stability
Potentials:
May prevent “domino lesions”
Advantages:
Treatment of multiples adjacent &
not adjacent spaces
Cervical Disc Arthroplasty (CDA)
Indications:
 Disc Associated Wobbler Syndrome

4. Phase 1.
DESIGN
 Madison, WI 2003
Phase 2.
IN VITRO BIOMECHANICAL STUDY
 Adamo, Kobayashi et al. Vet Surgery 2007
4 Groups of 6 cervical spines (C5-C6)
a) Arthroplasty,
b) Ventral Slot,
c) Pins+PMMA fixation,
d) and normal spine
 The artificial disc was better able
to mimic the behavior of intact
spine compared with ventral slot
and Pin+PMMA groups.
History

5.  Phase 3.
Pilot clinical study in 2 client-owned dogs with
DAWS
Titanium alloy
 Results
 Follow up to 3½ years post-op
 Both dogs died for unrelated neurological
diseases
 MRI re-check 2 years post-op
 No evidence of compression at the treated
and adjacent sites

 Conclusions
 Cervical arthroplasty was well tolerated
and provided excellent outcome in both
dogs
 Warranted further study:
 Large number of patients
 Longer follow-up
Adamo JAVMA, 239(6), 2011

6. Cervical Disc Arthroplasty using
the Adamo Spinal Disc™ in 33 dogs
affected by Disc Associated
Wobbler Syndrome
at Single and Multiple Levels.
In preparation to be Submitted to JAVMA

7. Study Authors
 F Adamo, DECVN
 East Bay Vet Specialists – CA
 R Da Costa, DACVIM (Neurology)
 The Ohio State University – OH
 R Kroll, DACVIM (Neurology)
 VCA Northwest Vet Specialists – OR
 C Giovannella, DACVIM (Neurology)
 Gulf Cost Vet Neurology/Neurosurgery – TX
 M Podell, DACVIM (Neurology)
 Chicago Vet Specialty Group – IL
 P Brofman, DACVIM (Neurology)
 Veterinary Specialty Care, SC
A Multi-Center Prospective Study

8. To evaluate:
a) the immediate post-operative recovery
b) the short-, intermediate- and long term follow-up
of dogs with one level and multi-level disc-
associated-wobbler-syndrome (DAWS) treated
with cervical disc arthroplasty (CDA).
Objectives

9. Material & Methods
 Implant: Similar to that in the pilot study but with several modifications
1st generation
- Ball Titanium
- Dual Ac Etch
2nd generation
- Ball in PEEK
- Thinner size
- Dual Ac. Etch
3rd generation
- Hydroxyapatite Coating
Calcium Phosphate complex
 Porosity
 Osteoconduction
8.5 mm

10. Spinal Disc 2nd & 3rd Gen.
 Internal surfaces
 Convexity is PEEK
(PolyEther Ether Ketone)
 Thermoplastic polymer
 Decreases friction
 Prevent metallic debris
from a metal to metal joint
 Concavity is titanium
 Ball and socket
Patent: US 8,496,707 B2

11.  External surface
 Convex
 To resemble natural
concavity of vertebral end
plates
Spinal Disc 2nd & 3rd Gen.
 Concentric grooves + Central notch
 To provide “grip” & to prevent implant migration

12. Implant Design Modification
 7 different disc sizes
 Set of dedicated tools

13. Threaded pins
• to hold the assembled prosthesis
Dedicated tools

14.  Thick end
 Parallel channels to hold
the assembled prosthesis
during implantation
 Thin end
 Slotted to remove the pins
after implantation
Barrel Holder – Double function
Dedicated tools

15. Sizing Probes
• Resemble at each end the shape of either
mthe S, M, or W disc size
•To probe/test the disc space during
nburring, before final disc implantation
Dedicated tools

16. Small burr
• To clean end-plates and begin
creating concavity
Large burr
• matches the external disc
convexity
• To facilitate implant
accommodation by the disc
space
Large burrSmall burr
Two dedicated burrs
Dedicated tools

17. 20 degree angle attachment for the Surgairtome
 To facilitate working at an angle parallel to the disc
space during burring
 Particularly useful at C6-C7 (and C7-T1 !!)
Dedicated tools

18. Caspar Cervical Distractor
• To maintain vertebral distraction during implantation
• To allow visualization through the disc space to the dorsal
longitudinal ligament
Dedicated tools

19. Disc space prepared for the implant
Vertebral end plate
Dorsal Long. Lig.

20. CDA video clip – Implant Placement

21.  Sample population:
 First 33 clients-owned dogs w/ over 2
mo. history of DAWS
 Diagnosed by MRI or CT myelo
 Weight over 23 kg, but one (12.2 Kg)
 Neurologically and
radiologically evaluated
 Prior to surgery
 Shortly after surgery
 within 24 hrs
 At 2 wks & 3, 6, 12 & 24 mo. after
surgery
Including Criteria

22.  Total = 50 disc sites treated
 Single, two and three level lesions
 Neurological Assessment
 Grade 0 to 6
 De Decker, et al. JAVMA 2012; 240:848–857
C3
C4
C5
C6
Material and Methods
0: No apparent neurological deficits
1: Cervical hyperesthesia w/o deficits
2:: Hind limb ataxia w/o visible paresis
3: Hind limb ataxia with paresis &
no appreciable forelimb ataxia
4:: Ambulatory tetraparesis: broad-
based ataxia hind limbs & choppy
gait forelimbs (“two engine gait”)
5:: Non-ambulatory tetraparesis: able
to stand/walk few steps before collapse
6: Tetraplegia

23.  Optimal
 Implant well centered in
the disc space on lateral
& VD views
 Sub-optimal
 Off midline on VD
 Inadequate
 Not seated in center of
the disc space on lateral
view
Inadequate position
Implant Position

24.  Relative Distraction ratio (RDR):
 Ratio between post-op and pre-op
width at the treated space
 Adequate / Ideal*
 RDR > 1.7 and < 2
* Equivalent to a
distraction of 2-3 mm
 Under distraction
 RDR < 1.7
 Over-distraction
 RDR > 2
Distraction
C7C6
C5
C7
C6
C5
Pre-op
Post-op

25. Ventro-flexion
Dorsi-flexion
Neutral
Mobility
 Distance between dorsal and ventral
edge of the 2 faces of the implant in
neutral and stressed views
 Present
 Not detectable

26.  2 years post-op when possible
 As needed, in the event of
recurrence of clinical signs
MRI re-evaluation

27. Results

28.  Breeds:
 17 Doberman Pinchers (50%)
 3 Dalmatians
 2 Labrador
 2 Bernese Mountain dog
 1 Standard Poodle
 1 Weimeraner
 1 Boxer
 1 Greyhound
 5 Mix
 Sex:
 21 M; 12 F
 Age:
 4 - 13 y; Mean 8.3 y
 27% over 10 y old

29.  Single level: 19 dogs
 C6-C7 (13 dogs)
 C5-C6 (5 dogs)
 C3–C4 (1 dog)
 Two levels: 10 dogs
 C5-C6 & C6-C7 (8 dogs)
 C4-C5 & C5-C6 (1 dog)
 C3-C4 & C5-C6 (1 dog)
Lesion Localization
 Three levels: 3 dogs
 C3-C4, C5-C6 & C6-C7 (2 dogs)
 C2-C3, C5-C6 & C6-C7 (1 dog)
TOTAL: 50 Spaces treated
C6
C7
C3 C4
C5 C6
C3
C4
C5
C6

30. Inadequate position
Immediate Post-op Radiographs
 Implant position:
• Optimal (42 sites)
• Sub-optimal (7 sites)
• Off midline on VD
• Inadequate (1 sites)
• Improper technique
 Excessive burring of caudal
endplate
 immediate subsidence

31. Caudal subsidence
 Distraction:
• Over-distraction (15 sites)
• Mostly with 1st generation (thicker)
implant
• Adequate distraction (34 sites)
• Mostly with 2nd & 3rd generation
(thinner) implant
• Under-distraction: (1 site)
• Improper technique
 Excessive burring of caudal
endplate – immediate
subsidence
Immediate Post-op Radiographs

32. Distraction:
 Minor Subsidence: Distraction lost
compared to immediate post-op, but maintained
when compared to pre-op
 All sites
 More pronounced with 1st generation (thicker)
implant
 Less pronounced with 2nd and 3rd generation
(thinner) implant
 Severe Subsidence
Distraction lost compared to pre-op
 7/50 sites (14%)
Serial Radiographic Assessment

33.  Mobility
 Decreased or not detectable over time in the
majority of patients.
 Maintained at 2 wks post-op in 88% of 24 dogs examined
 Maintained at 6 mo post-op in 23% of 14 dogs examined
 Maintained at 9 mo post op in one dog
 Maintained at 3 years post-op in one dog
♬ In 7 dogs where dynamic study was performed
immediately after surgery: mobility although
expected was not detectable in 5 out of 10 treated
spaces
in 3 dogs was later detectable on the serial
follow-ups.
 No Implant migration
 No Implant infection
Serial Radiographic Assessment
Ventro-flexion
Dorsi-flexion

34.  3 dogs: 7-24 mo post-op
 Osteophites or Heterotopic Ossification.
 Didn’t affect the clinical status
 1st and 2nd generation implant
 3 dogs: 24-36 mo post-op
 No signs of disc degeneration or
compression at treated and adjacent sites
 1 dog: 6 wks post-op
 Spinal compression secondary to
immediate subsidence
 Improper technique
 Improved with single dorsal
decompression
MRI Re-assessment: 7 dogs
C3-C4 C5-C6
C5 C6 C7
C5-C6 6 wks post – op
C6 C7*
 In all dogs the implant didn’t affect the spinal cord visibility

35.  Post-op recovery time
 Immediate in all dogs
 Neurological status unchanged compared
to pre-op status in all dogs
 Post-op hospitalization time *
 5 dogs: Discharged same day
 26 dogs: 1- 3 days
 2 dogs: 4 - 5 days
 Based on the severity of the neurological
status pre-surgery
Clinical Assessment

36. Follow-up: Mean 24 mo, (range 2 wks - 42 mo)
 21 dogs still alive
 12 dogs deceased
 9 for non-neurological diseases
 3 euthanasia: insufficient improvement or complications
Patient Outcome
 91% have shown improvement of at least 1+
neurological grade
 Satisfactory to Excellent: 30 dogs
 Unsatisfactory: 1 dog
 Poor: 2 dogs
 Better Outcome: mild and short duration of signs on
presentation
 Worse Outcome: chronic non-ambulatory tetraparesis +
extensor rigidity of front legs not resolving under general
anesthesia
 No Domino lesions during the observation period

37. Patch: 6 y old MN Dalmatian
6 mo ambulatory tetraparesis
worsening 2 mo prior to presentation

38. Complications and
Poor Outcome

39. Complications
 Vertebral fissure fracture during distraction: 2 dogs
 Improper Caspar pins placement
 +/- excessive distraction with Caspar Distractor
  Did not affect the outcome
 Immediate subsidence: 1 dog
 Improper technique: over-burring.
 Surgical revision with dorsal laminectomy
  Regained improvement
 Subsidence: 7/50 disc spaces
 Too thick and too narrow discs
  Except for 1 dog, did not affect the outcome
Improper technique

40. Complications
 Vertebral Axial Compression fracture: 1 dog
 Nikkie
 Sheltie Mix, F, 12.4 y old,
 29 lb = 12.2 kg
History: 4 years ambulatory ataxia,
6 month prior to referral non ambulatory tetraparesis with
extensor rigidity all 4 legs, not resolving under anesthesia
 Overdistraction
 RDR 3.2 (normal > 1.7 and < 2)
 2 weeks post-op: Declined to non-ambulatory
tetraparesis; Intense cervical pain; Suspected
Axial compression fracture C6 + Ventral implant
migration Euthanasia - no histopathology
2 weeks post-op
Pre-op
Immediate Post-op
C5 C6 C7
• What went wrong?
• Dog’s size too small: 12.2 Kg
• Over-distraction
 Poor patient selection

41. Poor Outcome
2 dogs
 Chow Mix, F, 13.5 y old
 Doby, M, 12 y old
History
 8-14 months progressive non ambulatory tetraparesis
 Severe extensor rigidity all 4 legs, not resolving under anesthesia
Outcome:
 Dog 1 (Chow): Euthanized 8 mo. after surgery d/t insufficient
improvement
 Dog 2 (Doby): Neuro score improved only from 6 to 5
• What went wrong?
• Neurological signs too severe
• Irreversible spinal cord damage
 Poor patient selection
Pierce Simon

42. Advantages of CDA
 Less invasive than traditional surgeries
 Rapid post-surgical recovery
 Can be performed on a out-patient basis
 Treatment of multiple lesions at adjacent or non-adjacent sites
 Prophylactically for “Incipient lesions”
 May prevent “Domino lesions”
 Spinal cord decompression & “dynamic stabilization”
C7
C6
C5

43.  Immediate relief of radicular pain
and vascular compression at the
intervertebral foramina
 Enable MRI re-assessment
 for complications
 for long term re-assessment of
domino lesions
Other Benefits
C6 C7*

44. Disadvantages – Limitations
 Concurrent Dorsal spinal compression
 The possible decrease of distraction may
exacerbate the dorsal compression
 It might be necessary to combine CDA with
dorsal decompression at the affected site
 Not good candidate for CDA
 < 23 Kg
 Too advanced neurological status
 Severe front legs extensor rigidity not
resolving under general anesthesia

45. Conclusions
 CDA using this prosthesis appears to be safe
and effective
 Suitable for medium and large breed dogs
 Rapid post-surgical recovery
 Ideal for treating multiple levels
 Not technically difficult and easy to master
 May prevent “Domino Lesions”
Case selection, Early Intervention and Correct
execution of the surgical technique may be critical factors
for the outcome
“Case selection is King,
…. technique is the Prince”
 number 6 of the most commonly cited attributes of a “great”
surgeon!
Dr. Zelman column

46. Currently in use
4th Generation Spinal Disc™
 Thinner implants: 8.3mm
  To avoid over-distraction
  To allow implant positioning along the
natural angle of disc space
 Additional wider & taller sizes
 S1, M1, M2, WT1, WT2, + WL1 & WL2
  To increase contact surface
implant/vertebral endplate  To decrease
subsidence

47.  Two External Layers of Coating:
 Commercial Pure Titanium (CPTi):
 To create sponge porosity
 HA
 To promote bone/implant
incorporation
CPTi + HA
Future Directions
5th Generation Spinal Disc™

48. 3 mo. post-op
4th practical CDA Course
 November 5, 2015
 Las Vegas, Oquendo Center
Program: Wobblersyndrome.com
Event Coordinator:
Nancy Kroll: nkroll@appliedvt.com

49. Questions
Contact:
Filippo Adamo, DVM, DECVN
East Bay Veterinary Specialists
Walnut Creek – California
Phone: 925.937.5000
flppadamo@yahoo.com
Wobblersyndrome.com