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Mechanical characterization of external fixator stiffness for a rat femoral fracture model
Author(s) -
Willie Bettina,
Adkins Kyle,
Zheng Xing,
Simon Ulrich,
Claes Lutz
Publication year - 2009
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1002/jor.20792
Subject(s) - stiffness , materials science , fixation (population genetics) , external fixator , bone healing , biomechanics , limiting , biomedical engineering , orthodontics , composite material , anatomy , medicine , engineering , mechanical engineering , population , environmental health
Clinical and experimental studies have shown that several mechanical factors influence the fracture healing process. One such factor, interfragmentary movement, is affected by loading and the stiffness of the fixation device. This study evaluated the stiffness of different external fixation devices for a rat femoral fracture model, using in vitro and analytical methods. The contribution to the stiffness of the fixation construct was dominated by the flexibility of the pins in relation to their offset, diameter, and material properties. The axial stiffness increased with decreasing offset and increasing pin diameter. Titanium pins resulted in significantly lower axial stiffness compared to stainless steel pins of the same design. The fixator body material and fixator length had a less pronounced influence on fixation stiffness. Mechanically characterized external fixation devices will allow in vivo study of the fracture healing process utilizing pre‐calculated fracture fixation stiffness. These characterized fixation devices will allow controlled manipulation of the axial and shear interfragmentary movement to achieve a flexible fixation resulting in callus formation compared to a more rigid fixation limiting callus formation in a rat femoral fracture model. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 687–693, 2009