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An In Vitro Biomechanical Comparison of Equine Proximal Interphalangeal Joint Arthrodesis Techniques: An Axial Positioned Dynamic Compression Plate and Two Abaxial Transarticular Cortical Screws Inserted in Lag Fashion Versus Three Parallel Transarticular Cortical Screws Inserted in Lag Fashion

Authors

  • GARY A. SOD DVM, PhD,

    1. Equine Health Studies Program, Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA
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  • Laura M. RIGGS DVM, PhD, Diplomate ACVS,

    1. Equine Health Studies Program, Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA
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  • COLIN F. MITCHELL BVMS, MS, Diplomate ACVS,

    1. Equine Health Studies Program, Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA
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  • JEREMY D. HUBERT BVSc, MS, Diplomate ACVS,

    1. Equine Health Studies Program, Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA
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  • GEORGE S. MARTIN DVM, MS, MBA, Diplomate ACVS

    1. Equine Health Studies Program, Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA
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  • Dr. Martin's current address is Sawtooth Equine Service, 708 N. Main St., Bellevue, ID 83313.

Corresponding author: Gary A. Sod, DVM, PhD, Equine Health Studies Program, Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803. E-mail: gsod@vetmed.lsu.edu.

Abstract

Objectives— To compare in vitro monotonic biomechanical properties of an axial 3-hole, 4.5 mm narrow dynamic compression plate (DCP) using 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion (DCP-TLS) with 3 parallel transarticular 5.5 mm cortical screws inserted in lag fashion (3-TLS) for the equine proximal interphalangeal (PIP) joint arthrodesis.

Study Design— Paired in vitro biomechanical testing of 2 methods of stabilizing cadaveric adult equine forelimb PIP joints.

Sample Population— Cadaveric adult equine forelimbs (n=15 pairs).

Methods— For each forelimb pair, 1 PIP joint was stabilized with an axial 3-hole narrow DCP (4.5 mm) using 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion and 1 with 3 parallel transarticular 5.5 mm cortical screws inserted in lag fashion. Five matching pairs of constructs were tested in single cycle to failure under axial compression, 5 construct pairs were tested for cyclic fatigue under axial compression, and 5 construct pairs were tested in single cycle to failure under torsional loading. Mean values for each fixation method were compared using a paired t-test within each group with statistical significance set at P<.05.

Results— Mean yield load, yield stiffness, and failure load under axial compression and torsion, single cycle to failure, of the DCP-TLS fixation were significantly greater than those of the 3-TLS fixation. Mean cycles to failure in axial compression of the DCP-TLS fixation was significantly greater than that of the 3-TLS fixation.

Conclusion— The DCP-TLS was superior to the 3-TLS in resisting the static overload forces and in resisting cyclic fatigue.

Clinical Relevance— The results of this in vitro study may provide information to aid in the selection of a treatment modality for arthrodesis of the equine PIP joint.

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