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Vet Comp Orthop Traumatol 2022; 35(01): 026-032
DOI: 10.1055/s-0041-1735550
Original Research

Effect of Bidirectional Insertion of External Skeletal Fixation Pins on Axial Pullout Strength in Canine Cadaveric Bone

Authors

  • Jane Park

    1   Oklahoma State University, Veterinary Clinical Sciences, Stillwater, Oklahoma, United States

  • Danielle Dugat 

    1   Oklahoma State University, Veterinary Clinical Sciences, Stillwater, Oklahoma, United States

  • Mark Rochat

    2   Purdue University, Veterinary Clinical Sciences, West Lafayette, Indiana, United States

  • Hall Griffin

    3   IMEX Veterinary, Inc., Longview, Texas, United States

  • Mark E. Payton

    4   Rocky Vista University, Parker, Colorado, United States

Funding This project was funded by the Cohn Family Chair for Small Animals at Oklahoma State University.
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Abstract

Objective The aim of this study was to evaluate the effect of bidirectional insertion on axial pullout strength of tapered run out (TRO), traditional negative profile (TNP) and positive profile (PP) pins.

Study Design Cadaveric adult canine tibiae were harvested. Tapered run out pins (Group 1) were inserted unidirectionally to the desired position; bidirectionally past the desired position, then withdrawn to the desired position (Group 2); and bidirectionally as described for Group 2, repeated twice (Group 3). Traditional negative profile pins (Group 4–6) and PP pins (Group 9–11) were placed in the same manner. Tapered run out (Group 7), TNP (Group 8) and PP pins (Group 12) were driven unidirectionally such that the shaft of the pin violated the cis-cortex. A servohydraulic testing machine extracted the pins and measured axial peak pullout strength.

Results Positive profile pins had significantly greater pullout strength than TRO and TNP pins placed unidirectionally to the desired position. Method of insertion had no effect on peak pullout strength of TNP pins. TRO and PP pins inserted unidirectionally to the desired position had significantly greater peak pullout strengths than insertion bidirectionally or if the shaft of the pin violated the cis-cortex.

Conclusion The authors recommend that pins used for external skeletal fixation should be placed unidirectionally to the desired position with fluoroscopic guidance, intra-operative depth gauge measurements or measurements from preoperative radiographs. Repositioning pins results in loss of peak pullout strength with TRO and PP pins.

Keywords

tapered run out - pin loosening - bidirectional insertion - external skeletal fixation - dogs

Authors' Contributions

J.P. provided input and organization with study concept and design, executed data collection, performed statistical evaluation, manuscript preparation and critical review of manuscript, agrees to be publicly accountable for the content of the manuscript. D.D., project mentor to J.P., provided input and organization with study concept and design, executed data collection, evaluation of statistical data, manuscript preparation and critical review of manuscript, agrees to be publicly accountable for the content of the manuscript. M.R. provided input and organization with study concept and design, evaluation of statistical data, manuscript preparation and critical review of manuscript, agrees to be publicly accountable for the content of the manuscript. H.G. provided input and organization with study concept and design, evaluation of statistical data, manuscript preparation and critical review of manuscript, agrees to be publicly accountable for the content of the manuscript. M.P. provided input with study concept and design and power analysis, performed statistical evaluation and provided interpretation of statistical evaluation, manuscript preparation and critical review of manuscript, agrees to be publicly accountable for the content of the manuscript.


Supplementary Material



Publication History

Received: 27 January 2021

Accepted: 24 July 2021

Article published online:
21 September 2021

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