Arthrodesis of the equine proximal interphalangeal joint: a biomechanical comparison of two parallel headless, tapered, variable-pitched, titanium compression screws and two parallel 5.5 mm stainless-steel cortical screws.
OBJECTIVE
To compare the biomechanical characteristics, failure mode, and effects of side (left or right limb) and end (forelimb or hindlimb) of different screws in 2-screw, parallel-screw proximal interphalangeal joint arthrodesis constructs in horses.


METHODS
In vitro experimental study.


METHODS
Twenty limbs from 6 cadavers (4 complete limb sets, 2 partial sets-total of 4 forelimb and 6 hindlimb pairs).


METHODS
Two parallel 5.5 mm cortical (AO) screws were inserted in lag fashion in 1 randomly allocated limb of a pair, and 2 parallel headless, tapered, variable-pitched, titanium compression screws (Acutrak-Plus) were inserted in the contralateral limb. Constructs were tested in 3-point bending in a dorsopalmar (plantar) direction using a materials-testing machine at a loading rate of 5.83 mm/s. Maximal bending moment at failure and composite stiffness were calculated from data generated on load-displacement curves. Data were analyzed using a Friedman 2-way analysis of variance and Wilcoxon's signed-rank tests.


RESULTS
No significant difference was detected for bending moment or stiffness values in proximal interphalangeal joint arthrodesis constructs using 2 parallel Acutrak-Plus or AO screws for fixation. Mean stiffness values were significantly different between forelimb and hindlimb constructs.


CONCLUSIONS
Performance of 2 parallel Acutrak-Plus screws was biomechanically comparable with 2 parallel AO 5.5 mm cortical screws in in vitro pastern arthrodesis constructs.


CONCLUSIONS
Acutrak-Plus screws may provide an alternative means of fixation for proximal interphalangeal joint arthrodesis.
Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada. rrw928@mail.usask.ca
Ryan R E
RR
Wolker
James L
JL
Carmalt
David G
DG
Wilson
D000818:Animals; D001174:Arthrodesis / Q000295:instrumentation / Q000379:methods / Q000662:veterinary*; D001696:Biomechanical Phenomena; D001863:Bone Screws / Q000662:veterinary*; D002102:Cadaver; D005552:Forelimb; D006614:Hindlimb; D006736:Horses; D013193:Stainless Steel; D014025:Titanium
D013193:Stainless Steel; D014025:Titanium