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Ex vivo biomechanical comparison of a 3.5 mm locking compression plate applied cranially and a 2.7 mm locking compression plate applied medially in a gap model of the distal aspect of the canine radius

Authors

  • Justin M. Uhl DVM, MS,

    Corresponding author
    • JD Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California, Davis, California
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  • Amy S. Kapatkin DVM, MS, Diplomate ACVS,

    1. JD Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California, Davis, California
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  • Tanya C. Garcia MS,

    1. JD Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California, Davis, California
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  • Susan M. Stover DVM, PhD, Diplomate ACVS

    1. JD Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California, Davis, California
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  • Presented in part at UC Davis, STARS in Science Day September, 2008, and the American College of Veterinary Surgeons Annual Conference, Chicago Illinois November 2011
  • Funded in part by the Center for Companion Animal Health and UC Davis STARS in Science.

Corresponding Author

Justin M. Uhl, DVM, MS, Department of Veterinary Clinical Sciences, College of Veterinary Medicine, University of Minnesota, 1365 Gortner Ave, Saint Paul, MN 55108. E-mail: jmuhl@umn.edu

Abstract

Objective

To compare a medially applied 2.7 mm locking compression plate (LCP) to a cranially applied 3.5 mm LCP in a cadaveric distal radial fracture gap model.

Study Design

In vitro mechanical testing of paired cadaveric limbs

Sample Population

Paired radii (n = 8) stabilized with either a 2.7 mm LCP medially or a 3.5 mm LCP cranially.

Methods

Simulated distal radial comminuted fractures were created and stabilized with an LCP plate on the cranial surface in 1 limb, and on the medial surface in the contralateral limb. Gap stiffness, gap strain, and failure properties were compared between cranial and medial plate positions. Limb constructs were axially loaded, cyclically through 4 conditions that allowed mediolateral or craniocaudal bending at walk and trot loads, before monotonic failure loading. The effects of plate position on mechanical variables were assessed using paired t-tests.

Results

Gap stiffness was greater for cranial plate constructs than medial plate constructs for axial loading with mediolateral bending, but lower with craniocaudal bending. However, in loading that facilitated craniocaudal bending the medial plate construct also had bending apparent in the mediolateral direction. Gap strains for the different conditions followed similar trends as stiffness. Cranial plate constructs had significantly higher monotonic stiffness, yield, and failure loads.

Conclusion

The larger, cranially applied LCP was biomechanically superior to the smaller, medially applied LCP in our distal radial fracture gap model, however the medial plate was superior to the cranial plate in cyclic loading allowing craniocaudal bending.

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