Abstract:
OBJECTIVE : To compare biomechanical stiffness of cadaveric canine cervical spine
constructs stabilized with bicortical stainless steel pins and polymethylmethacrylate
(PMMA), monocortical stainless steel screws with PMMA, or monocortical titanium
screws with PMMA.
STUDY DESIGN : Biomechanical cadaver study.
ANIMALS : Eighteen canine cervical vertebral columns (C2–C7) were collected from
skeletally mature dogs (weighing 22–32 kg).
METHODS : Specimens were radiographed and examined by dual energy X‐ray
absorptiometry. Stiffness of the unaltered C4–C5 intervertebral motion unit was
measured in extension, flexion and lateral bending using non‐destructive 4‐point bend
testing. Specimens were then stabilized by (1) bicortical stainless steel pins/PMMA, (2)
monocortical stainless steel screws/PMMA, or (3) monocortical titanium screws/
PMMA. Mechanical testing was repeated and stiffness data from unaltered specimens
and the 3 treatment groups were compared.
RESULTS : All 3 surgical methods significantly increased stiffness of the C4–C5 motion
unit compared with the unaltered specimen (P < .001 for all treatments), but stiffness
was not significantly different among the 3 fixation groups (P ¼ .578).
CONCLUSIONS : In this model, monocortical screw fixation (with stainless steel or
titanium screws) was biomechanically equivalent to bicortical fixation.
