An in vitro biomechanical comparison of a locking compression plate fixation and kerf cut cylinder fixation for ventral arthrodesis of the fourth and the fifth equine cervical vertebrae.
OBJECTIVE
To (1) define mechanical properties in flexion, extension, and left lateral bending of cadaveric equine 4th and 5th cervical (C4-C5) articulations, (2) compare biomechanical properties of C4-C5 when stabilized with a kerf cut cylinder (KCC) compared with a ventrally placed 4.5 mm locking compression plate (LCP).


METHODS
In vitro biomechanical investigation.


METHODS
Cadaveric adult equine cervical vertebral columns (n=54).


METHODS
Cervical vertebrae aged by horse dentition and size measured from radiographs were divided into 3 age groups then randomly allocated to 3 groups. The C4-C5 articulation was treated differently in each of the groups: KCC group; KCC-implanted LCP group; 8-hole 4.5 mm LCP implanted and intact group; no implant. Specimens were randomly subdivided into 1 of 3 loading conditions, before testing to failure under 4-point bending. Stiffness, yield bending moment, failure bending moment, and failure mode were recorded. General linear models were performed to analyze associations between biomechanical properties and test variables.


RESULTS
All specimens failed at the C4-C5 intervertebral articulation. The cervical vertebrae with the LCP construct had significantly higher stiffness, yield bending moment, and failure bending moment than the KCC-implanted cervical vertebrae. Failure modes differed between groups and varied with loading direction: KCC group, fractures of C5 associated with the KCC were common; LCP group, screw pull out or fractures (of C4 and C5 bodies, during extension and the caudal aspect of C4 during left lateral bending) were common; and intact group, subluxations were most common.


CONCLUSIONS
In this model, LCP constructs had superior biomechanical properties compared with KCC constructs. Further research investigating the effect of repetitive loading is indicated.
Reardon
Richard J M
RJ
Division of Companion Animal Sciences, Faculty of Veterinary Medicine, University of Glasgow, Glasgow, UK. r.reardon@vet.gla.ac.uk
Bailey
Robert
R
Walmsley
John P
JP
Heller
Jane
J
Lischer
Christoph
C
D000818:Animals; D001174:Arthrodesis / Q000379:methods / Q000662:veterinary*; D001696:Biomechanical Phenomena; D001860:Bone Plates / Q000662:veterinary*; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006734:Horse Diseases / Q000503:physiopathology / Q000601:surgery; D006736:Horses / Q000601:surgery; D016268:Internal Fixators / Q000662:veterinary*; D016014:Linear Models; D020393:Manipulation, Spinal / Q000662:veterinary; D008422:Materials Testing / Q000295:instrumentation / Q000379:methods / Q000662:veterinary; D008954:Models, Biological; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology; D013117:Spinal Cord Compression / Q000503:physiopathology / Q000601:surgery / Q000662:veterinary