In vitro biomechanical comparison of a 4.5 mm narrow locking compression plate construct versus a 4.5 mm limited contact dynamic compression plate construct for arthrodesis of the equine proximal interphalangeal joint.
Authors: Ahern Benjamin J, Showalter Brent L, Elliott Dawn M, Richardson Dean W, Getman Liberty M
Journal: Veterinary surgery : VS
Summary
# Editorial Summary: Locking vs Dynamic Compression Plating for Equine PIP Arthrodesis Proximal interphalangeal joint arthrodesis in horses demands robust fixation, yet limited evidence directly compares the biomechanical performance of different plate designs in this high-motion region. Researchers tested eight paired equine forelimbs using two competing constructs—a 4.5 mm narrow locking compression plate (PIP-LCP) and a 4.5 mm limited contact dynamic compression plate (LC-DCP), each with two transarticular screws—subjecting them to both cyclic loading (1 kN over 3600 cycles) and single-cycle failure testing via four-point bending. The PIP-LCP demonstrated significantly superior resistance to cyclic displacement (0.17 mm versus 0.46 mm; P = .016) and substantially greater stiffness (279.8 versus 183.9 N/mm; P = .011), whilst both constructs showed equivalent failure loads around 150–165 N·m with identical failure patterns (bone fracture at the transarticular screw sites followed by plate bending). For practitioners, these findings suggest that locking plate technology provides clinically meaningful advantages in resistance to micromotion during the early healing phase, potentially supporting more stable arthrodesis and earlier weight-bearing in cases where construct rigidity is prioritised, though both systems proved comparable in ultimate strength.
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Practical Takeaways
- •The locking compression plate (PIP-LCP) provides superior stability with less micromotion during cyclic loading, which may reduce complications and promote faster arthrodesis healing compared to the LC-DCP
- •Both plate types demonstrate equivalent ultimate strength, so plate selection can be guided by the superior stiffness of the PIP-LCP and its resistance to micromotion
- •Failure occurs at the transarticular screws regardless of plate type, suggesting screw integrity and positioning warrant careful attention in clinical application
Key Findings
- •PIP-LCP constructs showed significantly less displacement in cyclic testing (0.17 mm) compared to LC-DCP (0.46 mm) at 1 kN load over 3600 cycles
- •PIP-LCP constructs were significantly stiffer (279.8 N/mm) than LC-DCP constructs (183.9 N/mm)
- •No significant difference in maximum bending moment to failure between PIP-LCP (164.6 Nm) and LC-DCP (148.7 Nm) constructs
- •All constructs failed by transarticular screw bone fracture followed by plate bending at the middle hole