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Vet Comp Orthop Traumatol 2019; 32(03): 222-233
DOI: 10.1055/s-0039-1678734
Original Research
Georg Thieme Verlag KG Stuttgart · New York

Problem of Pin Breakage in Equine Transfixation Pin Casting: Biomechanical Ex Vivo Testing of Four Different Pins

Sara A. Keller
1   Equine Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
,
Sebastian Valet
2   EMPA Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
,
Ann Martens
3   Department of Surgery and Anaesthesiology of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
,
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 Funding None.
Further Information

Publication History

26 June 2018

08 January 2019

Publication Date:
07 March 2019 (online)

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Abstract

Objective The aim of this study was to evaluate cyclic fatigue behaviour of a new pin with a thread run-out design in comparison with three other types of pins commonly used for equine transfixation pin casting.

Materials and Methods Twenty-four pairs of equine cadaveric third metacarpal bones (MC3) equipped with one transfixation pin placed horizontally in the distal metaphysis were tested using a simplified model, mimicking the biomechanical situation of equine transfixation pin casting. A 6.3/8.0-mm Imex Duraface pin with thread run-out design (ITROP) was compared with a 6.1-mm smooth Steinmann pin (SSP), a Securos 6.2-mm, positive-profile pin (SPPP) and an Imex 6.3-mm, positive-profile pin (IPPP) under cyclic loading until failure in axial compression of MC3.

Results All pins broke at clinically relevant load levels and cycle numbers. The SSP endured significantly (p = 0.0025) more cycles before failure (mean: 48685) than the ITROP (mean 25889). No significant differences in cycles to failure were observed comparing the SPPP versus ITROP, and the IPPP versus ITROP, respectively.

Clinical Significance A thread run-out design does not necessarily lead to higher resistance against pin breakage under cyclic loading conditions. The SSP was most resistant against cyclic failure in these testing conditions, even though it was associated with more lateromedial displacement and cortical wear-out. This could outweigh reported disadvantages of the SSP such as reduced resistance to axial extraction and pin loosening.

Keywords

horse - transfixation - pin - breakage - cyclic loading

Author Contribution

Sebastian Valet and Jan M. Kümmerle contributed to conception of study, study design, acquisition of data and data analysis and interpretation. Sara A. Keller contributed to study design, acquisition of data and data analysis and interpretation. Ann Martens, Bernhard Weisse, and Anton E. Fürst contributed to conception of study, study design, and data analysis and interpretation. All authors drafted, revised and approved the submitted manuscript.


 

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