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

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

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

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 ableto mimic the behavior of intactspine compared with ventral slotand Pin+PMMA groups.

History

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

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

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

To evaluate:a) the immediate post-operative recoveryb) the short-, intermediate- and long term follow-up

of dogs with one level and multi-level disc-associated-wobbler-syndrome (DAWS) treatedwith cervical disc arthroplasty (CDA).

Objectives

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

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

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

Implant Design Modification

7 different disc sizes

Set of dedicated tools

Threaded pins

• to hold the assembled prosthesis

Dedicated tools

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

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

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

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

Caspar Cervical Distractor

• To maintain vertebral distraction during implantation

• To allow visualization through the disc space to the dorsal longitudinal ligament

Dedicated tools

Disc space prepared for the implant

Vertebral end plate

Dorsal Long. Lig.

CDA video clip – Implant Placement

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

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

C3C4

C5C6

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

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

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

C7C6

C5

Pre-op

Post-op

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

2 years post-op when possible

As needed, in the event of recurrence of clinical signs

MRI re-evaluation

Results

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

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

C6C7

C3 C4

C5C6

C3C4

C5

C6

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

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

Distraction:

Minor Subsidence: Distraction lost

compared to immediate post-op, but maintainedwhen 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

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

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

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

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

Patch: 6 y old MN Dalmatian 6 mo ambulatory tetraparesis

worsening 2 mo prior to presentation

Complications and Poor Outcome

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

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 withextensor 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

Poor Outcome2 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

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”

C7C6

C5

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*

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

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

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 decreasesubsidence

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™

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

Questions

Contact:

Filippo Adamo, DVM, DECVN

East Bay Veterinary Specialists

Walnut Creek – California

Phone: 925.937.5000

flppadamo@yahoo.com

Wobblersyndrome.com