Evaluation of Three Human Cervical Fusion Implants for Use in the Canine Cervical Vertebral Column.
OBJECTIVE
To assess technical feasibility and mechanical properties of 3 locking plate designs (Zero-P, Zero-P VA, and Uniplate 2) for use in the canine cervical spine.


METHODS
Prospective ex vivo study.


METHODS
Cadaver cervical spines from skeletally mature large breed dogs (n = 18).


METHODS
Specimens were screened using radiography and allocated into balanced groups based on bone density. Stiffness of intact C4-C5 vertebral motion units was measured in extension, flexion, and lateral bending using nondestructive 4-point bend testing. Uniplate 2 was then implanted at C4-C5 and mechanical testing was repeated. Mechanical test data were compared against those from 6 spines implanted with monocortical screws, an allograft ring spacer, and PMMA.


RESULTS
The Zero-P and Zero-P VA systems could not be surgically implanted due to anatomical constraints in the vertebral column sizes of the canine cervical spines used in this study. Fixation with Uniplate 2 or with screws/PMMA significantly increased stiffness of the C4-C5 vertebral motion units compared to unaltered specimens (P < .001) in extension. Stiffness of the titanium screw/PMMA fixation was significantly greater than the Uniplate 2 construct in extension. Flexion and lateral bending could not be evaluated in 3 of 6 specimens in the Uniplate 2 group due to failure at the bone/implant interface during extension testing.


CONCLUSIONS
Fixation with Uniplate 2 was biomechanically inferior to screws/PMMA. Particularly concerning was the incidence of vertebral fracture after several testing cycles. Based on our results, Zero-P, Zero-P VA, and Uniplate 2 cannot be recommended for use in dogs requiring cervical fusion.
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Ohio State University, Columbus Ohio.
Emily J
EJ
Morrison
Department of Orthopaedics, College of Medicine, Ohio State University, Columbus Ohio.|Department of Biomedical Engineering, College of Engineering, Ohio State University, Columbus Ohio.
Alan S
AS
Litsky
Department of Veterinary Medicine, University of Cambridge, United Kingdom.
Matthew J
MJ
Allen
Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, South Africa.
Geoffrey T
GT
Fosgate
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Ohio State University, Columbus Ohio. bianca.hettlich@vetsuisse.unibe.ch.
Bianca F
BF
Hettlich
D000818:Animals; D001860:Bone Plates / Q000662:veterinary*; D001863:Bone Screws / Q000662:veterinary; D002102:Cadaver; D002574:Cervical Vertebrae / Q000601:surgery*; D004285:Dogs / Q000293:injuries / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D016059:Range of Motion, Articular; D016103:Spinal Fractures / Q000453:epidemiology / Q000209:etiology / Q000662:veterinary; D013123:Spinal Fusion / Q000379:methods / Q000662:veterinary*