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.
Wolker
Ryan R E
RR
Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada. rrw928@mail.usask.ca
Carmalt
James L
JL
Wilson
David G
DG
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