Vet Comp Orthop Traumatol 2021; 34(06): 394-400
DOI: 10.1055/s-0041-1733859
Original Research

The Effect of Reducing the Bone to Cast Distance in an Equine Transfixation Pin Cast: An Ex Vivo Biomechanical Study

Caroline M. Bernath
1   Equine Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
,
Sebastian Valet
2   EMPA Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
,
Fabrice Rossignol
3   Clinique Equine Grosbois, Boissy-St-Léger, France
,
Bernhard Weisse
2   EMPA Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
,
Anton E. Fürst
1   Equine Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
,
Jan M. Kümmerle
1   Equine Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
› Author Affiliations

Abstract

Objective The aim of this study was to evaluate the effect of reducing the bone to cast distance on the resistance of the pin to cyclic loading in equine transfixation pin casts.

Study Design Eleven pairs of cadaveric equine third metacarpal bones were prepared and one 6.3/8.0 mm transfixation pin was placed in standard fashion 10 mm proximal to the distal physeal scar into each bone. One metacarpus of each pair was tested with a distance of 10 mm (10 mm group) and the contralateral metacarpus with a distance of 20 mm (20 mm group) between the outer cortex of the bone and the fixation of the pin. Eight pairs were tested using a simplified test set-up in which the pins were fastened at both ends to polyoxymethylene-copolymer sleeves. The pins of the remaining three pairs of bones were incorporated into a fibreglass cast. All specimens were tested under cyclic loading until failure of the pin in axial compression.

Results All pins failed uni- or bilaterally at clinically relevant load levels. Pins of the 10 mm group endured significantly (p < 0.05) higher load levels and total number of cycles until failure compared with the pins of the 20 mm group.

Conclusion The distance between the bone surface and the cast at the location of pin insertion has a significant effect on resistance of the pins to cyclic loading. Therefore, the amount of padding applied underneath an equine transfixation pin cast can have an influence on the overall stability and durability of the construct.

Authors' Contributions

C.M.B., S.V. and J.M.K. contributed to acquisition of data, data analysis and interpretation. F.R., S.V., B.W., A.E.F. and J.M.K. contributed to conception of the study, study design and data interpretation. All authors drafted, revised and approved the submitted manuscript.




Publication History

Received: 15 December 2020

Accepted: 17 June 2021

Article published online:
20 August 2021

© 2021. Thieme. All rights reserved.

Georg Thieme Verlag KG
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