In vitro biomechanical testing of a micro external skeletal fixator

R. Deiss; M. S. Bali; M. Doherr; D. Spreng; U. Rytz; S. J. Ferguson

doi:10.3415/VCOT-12-10-0126

Veterinary and Comparative Orthopaedics and Traumatology, Table of Contents

Vet Comp Orthop Traumatol 2013; 26(05): 385-391
DOI: 10.3415/VCOT-12-10-0126

Original Research

Schattauer GmbH

In vitro biomechanical testing of a micro external skeletal fixator

R. Deiss

¹Veterinary Practice Kiesen, Kiesen, Switzerland

,

M. S. Bali

²Small Animal Hospital Stommeln, Stommeln, Germany

,

M. Doherr

³University of Bern, Veterinary Medicine, Clinical Research, Bern, Switzerland

,

D. Spreng

⁴University of Bern, Small Animal Clinic, Bern, Switzerland

,

U. Rytz

⁴University of Bern, Small Animal Clinic, Bern, Switzerland

,

S. J. Ferguson

⁵Swiss Federal Institute of Technology Zurich (ETH), Institute for Biomechanics, Zurich, Switzerland

› Author Affiliations

Abstract

Summary

Objective: To biomechanically test the properties of three different Universal Micro External Fixator (UMEX™) configurations with regard to their use in very small animals (<5kg) and compare the UMEX system to the widely used IMEX External Skeletal Fixation (SK™) system in terms of stiffness, space needed for pin placement and weight.

Methods: Three different UMEX configurations (type Ia, type Ib, and type II modified) and one SK configuration type Ia were used to stabilize Delrin plastic rods in a 1 cm fracture gap model. These constructs were tested in axial compression, craniocaudal bending, mediolateral bending, and torsion. Testing was conducted within the elastic range and mean stiffness in each mode was determined from the slope of the linear portion of the load-deformation curve. A Kruskal Wallis one-way analysis of variance on ranks test was utilized to assess differences between constructs (p <0.05).

Results: The UMEX type II modified configuration was significantly stiffer than the other UMEX configurations and the SK type Ia, except in craniocaudal bending, where the SK type Ia configuration was stiffer than all UMEX constructs. The UMEX type Ia configuration was significantly the weakest of those frames. The UMEX constructs were lighter and smaller than the SK, thus facilitating closer pin placement.

Conclusions: Results supported previous reports concerning the superiority of more complex constructs regarding stiffness. The UMEX system appears to be a valid alternative for the treatment of long-bone fractures in very small animals.

Keywords

External skeletal fixation - frame configuration - close pin placement - miniature dogs - cats

Full Text

References

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