Abstract
Objectives To develop the canine vertebral screw and rod fixation system (CVSRF) and to compare
the biomechanical properties between CVSRF and the screw and polymethylmethacrylate
(Screw-PMMA) technique for internal fixation of the vertebral column in dogs.
Methods The CVSRF consisted of vertebral screws with monoaxial side-loaded head, rods and
specific inner screws connecting rod to the screw head. The CVSRF prototype was made
from titanium alloy and manufactured by the rapid prototype machine. Vertebrectomy
models were simulated by ultra-high-molecular-weight polyethylene blocks and tested
with the CVSRF system (n = 8) and the Screw-PMMA technique (n = 8). The models were developed according to the American Society for Testing and
Materials (ASTM F-1717–04). The biomechanical parameters were the compressive bending
yield load, the compressive bending stiffness, the compressive ultimate load and the
load displacement curve.
Results The mean values of the compressive bending yield load, compressive bending stiffness
and compressive ultimate load of the CVSRF were significantly higher than those of
the Screw-PMMA technique (p < 0.01). The load displacement curve of the CVSRF showed higher rigidity and durability
than that of the Screw-PMMA technique.
Clinical Significance This mechanical study indicated that the CVSRF system can be used for canine vertebral
stabilization and the biomechanical properties were better than those for the Screw-PMMA
device.
Keywords
dog - canine - spine - pedicle screw and rod fixation - vertebral screw
