The effect of external coaptation on plate deformation in an ex vivo model of canine pancarpal arthrodesis

S. Woods; R. J. Wallace; J. R. Mosley

doi:10.3415/VCOT-12-01-0002

Veterinary and Comparative Orthopaedics and Traumatology, Table of Contents

Vet Comp Orthop Traumatol 2012; 25(06): 439-444
DOI: 10.3415/VCOT-12-01-0002

Original Research

Schattauer GmbH

The effect of external coaptation on plate deformation in an ex vivo model of canine pancarpal arthrodesis

S. Woods

¹Royal (Dick) School of Veterinary Studies, Division of Veterinary Clinical Sciences, The University of Edinburgh, Hospital for Small Animals, Easter Bush Veterinary Centre, Roslin, Midlothian, Scotland

,

R. J. Wallace

²Edinburgh Orthopaedic Engineering Centre, The University of Edinburgh, The Chancellor's Building, Edinburgh, Scotland

,

J. R. Mosley

¹Royal (Dick) School of Veterinary Studies, Division of Veterinary Clinical Sciences, The University of Edinburgh, Hospital for Small Animals, Easter Bush Veterinary Centre, Roslin, Midlothian, Scotland

› Author Affiliations

Abstract

Summary

Objectives: Since external coaptation is applied clinically to prevent plate failure during healing in canine pancarpal arthrodesis (PCA), we tested the hypothesis that external coaptation does not significantly reduce plate strain in an experimental ex vivo model of canine PCA.

Methods: Ten thoracic limbs from healthy Greyhounds euthanatized for reasons un- related to the study were harvested and the carpus was stabilised with a dorsally applied 2.7/3.5 mm hybrid PCA plate. The strain in the plate adjacent to the most distal radial screw hole (R4) and the radial carpal bone (RCB) screw hole was measured as the limbs were loaded axially to a load that approximated that of controlled walking. Each limb was tested with and without external coaptation in place.

Results: Mean strain amplitude at the RCB was –177.2 με (± 20.78) without external coaptation. Following cast application, strain reduced significantly to –34.7 με (± 9.84) (p <0.002). Mean strain at R4 was –89.4 με (± 22.10) without external support and –66.9 με (± 10.74) following application of a cast. This reduction in recorded strain was not statistically significant.

Clinical significance: The application of a cast to the distal portion of the limb significantly reduced strain in the 2.7/3.5 mm hybrid PCA plate, but the magnitude of the measured strain was low, suggesting that fatigue damage is unlikely to accumulate as a result of this type of loading and that external coaptation may not be necessary to prevent fatigue failure of the plate.

Keywords

Pancarpal arthrodesis - hybrid plate - strain - external coaptation - implant failure

Full Text

References

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