In vitro biomechanical testing of a micro external skeletal fixator

Deiss, Ramona; Bali, M. S.; Doherr, Marcus; Spreng, D.; Rytz, U.; Ferguson, S. J. (2013). In vitro biomechanical testing of a micro external skeletal fixator. Veterinary and comparative orthopaedics and traumatology, 26(5), pp. 385-391. Schattauer 10.3415/VCOT-12-10-0126

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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.


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).


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.


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.

Item Type:

Journal Article (Original Article)


05 Veterinary Medicine > Department of Clinical Veterinary Medicine (DKV)
04 Faculty of Medicine > Pre-clinic Human Medicine > Institute for Surgical Technology & Biomechanics ISTB [discontinued]
05 Veterinary Medicine > Department of Clinical Veterinary Medicine (DKV) > Small Animal Clinic > Small Animal Clinic, Surgery
05 Veterinary Medicine > Department of Clinical Veterinary Medicine (DKV) > Small Animal Clinic
05 Veterinary Medicine > Department of Clinical Research and Veterinary Public Health (DCR-VPH) > Veterinary Public Health Institute

UniBE Contributor:

Deiss, Ramona; Bali, Monty; Doherr, Marcus; Spreng, David; Rytz, Ulrich and Ferguson, Stephen John


600 Technology > 630 Agriculture
600 Technology > 610 Medicine & health








Simone Forterre

Date Deposited:

05 Mar 2014 14:18

Last Modified:

27 Oct 2019 01:33

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Uncontrolled Keywords:

External skeletal fixation cats close pin placement frame configuration miniature dogs




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