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.
Authors: Wolker Ryan R E, Carmalt James L, Wilson David G
Journal: Veterinary surgery : VS
Summary
# Editorial Summary Proximal interphalangeal joint (pastern) arthrodesis in horses traditionally relies on parallel cortical screws, but headless compression screws offer potential advantages including improved load sharing and reduced stress concentration. This in vitro biomechanical study compared two-screw fixation constructs using either titanium Acutrak-Plus headless compression screws or conventional 5.5 mm stainless-steel cortical screws, testing ten limb pairs from equine cadavers under three-point bending in the dorsopalmar/plantar direction to failure. The researchers found no significant difference in maximal bending moment or composite stiffness between the two fixation methods, indicating that Acutrak-Plus screws provided biomechanical performance equivalent to the established AO cortical screw technique; notably, stiffness values did differ significantly between forelimbs and hindlimbs, reflecting the different loading demands and anatomical structure of these regions. For practitioners considering surgical options, these findings suggest that headless compression screws represent a viable alternative to cortical screws for pastern arthrodesis, potentially offering benefits such as reduced soft tissue trauma and improved blood supply at the fusion site, though clinical outcomes and long-term follow-up data would be needed to confirm advantages in living animals.
Read the full abstract on PubMed
Practical Takeaways
- •Acutrak-Plus screws perform equally to standard AO cortical screws for pastern fusion, offering surgeons an alternative fixation option with potentially different handling characteristics
- •Consider limb type when selecting fixation for PIP arthrodesis, as forelimbs demonstrate different biomechanical properties than hindlimbs
- •Both screw systems achieved adequate stiffness for arthrodesis; clinical choice can be based on surgeon preference, cost, and availability rather than biomechanical superiority
Key Findings
- •No significant difference in bending moment or stiffness between Acutrak-Plus titanium compression screws and AO 5.5 mm cortical screws for PIP arthrodesis
- •Mean stiffness values were significantly higher in forelimb constructs compared to hindlimb constructs
- •Both screw types demonstrated biomechanically comparable performance in 3-point bending testing