  Various mathematical models represent the effects of local mechanical
environment on the regulation of skeletal regeneration. Their relevance relies
on an accurate description of the evolving mechanical properties of the
regenerating tissue. The object of this study was to develop an experimental
model which made it possible to characterize the temporal evolution of the
structural and mechanical properties during unloaded enchondral osteogenesis in
the New Zealand rabbit, a standard animal model for studies of osteogenesis and
chondrogenesis. A 25mm segment of tibial diaphysis was removed sub-periosteally
from rabbits. The defect was repaired by the preserved periosteum. An external
fixator was applied to prevent mechanical loading during osteogenesis. The
regenerated skeletal tissues were studied by CT scan, histology and mechanical
tests. The traction tests between 7 to 21 days post-surgery were done on
formaldehyde-fixated tissue allowing to obtain force/displacement curves. The
viscoelastic properties of the regenerating skeletal tissues were visualized
throughout the repair process.
