ASME Journal of Biomechanical Engineering, 121:348-354, 1999
Reduced gap strains induce changes in bone regeneration during distraction.
Richards M, Waanders NA, Weiss JA, Bhatia V, Senunas LE, Schaffler MB, Goldstein SA, Goulet JA
A bilateral New Zealand white rabbit model of
distraction osteogenesis (DO) was used to investigate the
relationship between strain environment and bone regeneration
during limb lengthening. In sever (n=7) rabbits, a stiffener
was applied to the fixator on one side to reduce strains within
the gap tissue after lengthening was completed. Animals were
euthanized six days later and their distraction zones were
harvested and analyzed for changes in new bone volume and
architechture. Nonlinear finite element analyses (FEA) were
performed to predict changes in the gap strain environment.
FEA results predicted a nearly uniform sevenfold decrease in
average strain measures within the distraction zone. No change
in total average new bone volume and significant decreases in
both bone volume fraction (BV/TV) and trabecular thickness
(Tb.Th) were observed in tibia in which gap strains were
reduced experimentally, compared to contralateral controls.
These results suggest that fixator stiffening influenced the
architecture but not the amount of newly formed bone. This
animal model of distraction might be used to study the
mechanisms by which strain fields affect events in bone repair
and regeneration, such as cell proliferation, precursor tissue
differentiation, and altered growth factor and nutrient
delivery to tissues.