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Fracture healing in mice under controlled rigid and flexible conditions using an adjustable external fixator
Author(s) -
Röntgen Viktoria,
Blakytny Robert,
Matthys Romano,
Landauer Mario,
Wehner Tim,
Göckelmann Melanie,
Jermendy Philipp,
Amling Michael,
Schinke Thorsten,
Claes Lutz,
Ignatius Anita
Publication year - 2010
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.21148
Subject(s) - bone healing , external fixation , osteotomy , femur , materials science , mechanobiology , external fixator , stiffness , intramembranous ossification , biomedical engineering , callus , ossification , biomechanics , bending stiffness , fixation (population genetics) , cartilage , endochondral ossification , anatomy , orthodontics , medicine , composite material , surgery , biology , population , genetics , environmental health
Mice are increasingly used to investigate mechanobiology in fracture healing. The need exists for standardized models allowing for adjustment of the mechanical conditions in the fracture gap. We introduced such a model using rigid and flexible external fixators with considerably different stiffness (axial stiffnesses of 18.1 and 0.82 N/mm, respectively). Both fixators were used to stabilize a 0.5 mm osteotomy gap in the femur of C57BL/6 mice (each n = 8). Three‐point bending tests, µCT, and histomorphometry demonstrated a different healing pattern after 21 days. Both fixations induced callus formation with a mixture of intramembranous and enchondral ossification. Under flexible conditions, the bending stiffness of the callus was significantly reduced, and a larger but qualitatively inferior callus with a significantly lower fraction of bone but a higher fraction of cartilage and soft tissue was formed. Monitoring of the animal movement and the ground reaction forces demonstrated physiological loading with no significant differences between the groups, suggesting that the differences in healing were not based on a different loading behavior. In summary, flexible external fracture fixation of the mouse femur led to delayed fracture healing in comparison to a more rigid situation. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1456–1462, 2010