A tapered-sleeve transcortical pin external skeletal fixation device for use in horses: development, application, and experience.
Authors: Nunamaker David M, Nash Ronald A
Journal: Veterinary surgery : VS
Summary
# Editorial Summary Nunamaker and Nash (2008) developed a tapered-sleeve transcortical pin external skeletal fixation device (TSP ESFD) specifically designed to address complications arising from pin-bone interfaces in severely comminuted fractures of the equine distal limb, particularly proximal phalanx injuries. Their methodology combined mechanical testing on cadaveric third metacarpal bones with optimisation of pin diameter (7.94 mm) and sleeve attachment methods, followed by clinical application in seven horses presenting with severe P1 or P2 fractures. The clinical cohort achieved a 71% survival rate; notably, the single fatality in a mare with contralateral laminitis and one other adverse outcome (fracture through a distal pin hole) occurred in horses with concurrent systemic limb pathology rather than fixation failure alone. The tapered-sleeve design represents a meaningful refinement in transcortical pin mechanics, potentially reducing stress-riser effects and bone necrosis at the pin-bone interface that have historically compromised external fixation outcomes in distal limb fractures. For practitioners managing severe distal limb trauma in horses, this device offers an evidence-based alternative with improved stress distribution characteristics, though careful patient selection remains critical—particularly avoiding application in horses with contralateral limb disease.
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Practical Takeaways
- •TSP ESFD is a viable option for managing severely comminuted fractures of the proximal or second phalanx when other treatments have failed, with approximately 7 in 10 horses expected to survive to useful function
- •Monitor closely for complications including bone fracture at pin interfaces, pin-site infections, and secondary laminitis in the contralateral limb
- •This device design represents an improvement over earlier ESFD models due to optimized pin diameter and attachment methods, reducing pin-interface fracture risk
Key Findings
- •Tapered-sleeve transcortical pin external skeletal fixation device (TSP ESFD) using 7.94 mm diameter pins achieved 71% survival rate in 7 horses with severe distal limb fractures
- •Device design successfully addressed mechanical concerns identified through cadaveric testing and optimization analysis
- •Complications included pin-site bone fractures, infection, and contralateral laminitis contributing to poor outcomes in 2 of 7 cases