Arthrodesis of the equine proximal interphalangeal joint: a biomechanical comparison of two 7-hole 3.5-mm broad and two 5-hole 4.5-mm narrow dynamic compression plates.
Authors: Watt Bruce C, Edwards Ryland B, Markel Mark D, McCabe Ron, Wilson David G
Journal: Veterinary surgery : VS
Summary
# Editorial Summary Surgical arthrodesis of the proximal interphalangeal joint (PIPJ) remains a salvage procedure for horses with severe degenerative joint disease or catastrophic injury, but optimal fixation methods continue to evolve. Watt and colleagues conducted a biomechanical comparison of two commonly used dynamic compression plate (DCP) configurations by testing paired cadaver limbs from five horses, applying dorsal-to-palmar bending loads until construct failure and measuring composite stiffness, yield point, and maximal bending moment. Both the broad 7-hole 3.5-mm plate construct and the narrow 5-hole 4.5-mm plate construct demonstrated equivalent biomechanical properties with no significant differences in stiffness, yield point, or failure load, though the broader plates showed slightly higher screw damage (11% versus 8% of fasteners). For practitioners, this equivalence suggests that plate selection can be based on surgical convenience and anatomical fit rather than biomechanical superiority—the narrower construct may be simpler to position in confined distal limb anatomy, whilst the broader option offers greater versatility should additional fracture fixation be required in the same region.
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Practical Takeaways
- •Either plating technique is biomechanically suitable for PIP arthrodesis; choice can be based on surgeon preference and anatomical considerations rather than structural superiority
- •The 5-hole 4.5-mm narrow DCP may offer practical advantages in ease of application, while the 7-hole 3.5-mm broad DCP provides greater versatility if fracture repair rather than arthrodesis is needed
- •Plate bending with subsequent screw head pullthrough is a potential failure mode; consider this in case selection and post-operative monitoring
Key Findings
- •No significant differences in composite stiffness, yield point, or maximal bending moment between 7-hole 3.5-mm broad DCP and 5-hole 4.5-mm narrow DCP constructs
- •Screw damage occurred in 11% of 3.5-mm screws (mostly heads pulling through bent plates) versus 8% of 4.5-mm screws
- •Both fixation techniques demonstrated equivalent biomechanical performance in single-cycle 3-point bending to failure