Summary
An in vitro experimental cadaveric mechanical testing study was performed using 20 radiographically
mature dogs, weighing between 18–33 kg. The aim of the study was to compare the axial
pull-out strength of 3.5 mm cortical and 4.0 mm cancellous bone screws inserted in
the canine proximal tibia using manual and power tapping techniques. 3.5 cortical
and 4.0 cancellous bone screws were inserted in canine cadaver proximal tibiae using
a manual or power tapping technique. The screws were extracted using a servohydraulic
materials testing machine in order to measure axial pullout strength. Axial pull-out
strength was recorded relative to the total bone width and total cortical width of
each tibia. The mean axial pull-out strength for all constructs was 717.8±56.5 N without
any statistically significant difference among groups (p=0.4183). The groups were
equal in animal body weight, cortical width and total bone width (p=0.2808). The axial
pull-out strength in proportion to cortical and total bone width was not significantly
different among groups (p=0.5318). Axial pull-out strengths of 3.5 mm cortical and
4.0 mm cancellous bone screws inserted in the proximal tibial metaphysis were not
significantly different. Axial pull-out strength was not affected by the use of power
tapping in either screw type.
Keywords
Canine proximal metaphysis - screw insertion techniques - Mechanical testing - tibia