In vitro biomechanical comparison of locking compression plate fixation and limited-contact dynamic compression plate fixation of osteotomized equine third metacarpal bones.
Authors: Sod Gary A, Mitchell Colin F, Hubert Jeremy D, Martin George S, Gill Marjorie S
Journal: Veterinary surgery : VS
Summary
# Editorial Summary Selecting the optimal plate fixation method for equine third metacarpal fractures remains clinically important given the high-performance demands placed on this bone. Sod and colleagues conducted an in vitro biomechanical comparison of locking compression plates (LCP) versus limited-contact dynamic compression plates (LC-DCP) using 12 paired cadaveric equine third metacarpal bones, each subjected to mid-diaphyseal osteotomies and stabilised by one of the two fixation methods before undergoing single-cycle bending and torsional failure testing, as well as cyclic fatigue loading. The LCP fixation demonstrated significantly superior performance across multiple measures: higher yield loads, greater failure moments, superior composite rigidity, and markedly improved fatigue resistance under repetitive palmarodosal bending—the loading pattern most clinically relevant to equine limb mechanics. These findings suggest that locking plate technology offers biomechanical advantages over traditional dynamic compression plating for metacarpal fracture repair, potentially translating to improved load-bearing capacity during the rehabilitation and return-to-work phases. Whilst in vitro data cannot fully replicate biological healing or soft tissue interactions, these results provide evidence-based guidance for practitioners selecting fixation systems for long bone fractures in performance horses, where fatigue resistance and load tolerance directly influence athletic function and prognosis.
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Practical Takeaways
- •When selecting fixation methods for equine MC3 fractures, locking compression plates provide superior biomechanical strength and fatigue resistance compared to LC-DCP plates, potentially offering better outcomes for high-demand fracture cases
- •LCP fixation may be particularly advantageous in cases where cyclic loading and repetitive stress are anticipated, as fatigue life was significantly extended compared to traditional compression plating
- •These laboratory findings support considering LCP as the preferred broad plate fixation method for equine long bone fractures where biomechanical demands are substantial
Key Findings
- •Locking compression plate (LCP) fixation demonstrated significantly greater yield load, failure load, and failure bending moment compared to LC-DCP fixation in 4-point bending tests
- •LCP fixation showed significantly greater cycles to fatigue failure than LC-DCP fixation under palmarodorsal 4-point bending cyclic loading
- •LCP fixation exhibited superior biomechanical properties under torsional testing with greater yield load, composite rigidity, and failure load than LC-DCP fixation
- •Both static overload resistance and cyclic fatigue resistance favored the 4.5 mm LCP over the LC-DCP for equine long bone fracture repair