Summary
The purpose of this project was to compare the ability of skin and muscle to revascularize
cortical bone segments in the canine distal limb. A model mimicking severe combined
soft tissue and orthopaedic injury with bone devascularization involving the canine
metatarsus was developed. Soft tissue defects were reconstructed with a reverse saphenous
conduit flap or a free trapezius muscle flap. Cortical bone blood flow was determined
by the radiolabeled microsphere method at 21 days post-reconstruction. In addition
cortical porosity, the amount of fluorescent labelled intracortical new bone, and
the maximum depth of periosteal new bone were determined. Significant differences
were not detected between skin and muscle reconstructions for any of the measured
parameters of cortical revascularization. The mean values for cortical bone blood
flow were higher than expected from previous studies, and did not correlate with subjective
assessments of adhesion quality between bone and reconstructive tissue onlay. The
reverse saphenous conduit flap, and the free trapezius muscle flap, may respectively
provide superior blood supply to underlying bone than local random pattern skin and
local pedicled muscle. The reverse saphenous conduit flap has a robust and reliable
vascular supply, unlike that to random pattern skin. The free transfer of muscle maintains
a vigorous blood supply, and has shown improvements in blood flow over pedicled muscle.
Blood flow to both tissue types may be favourably affected by the denervation associated
with transfer, causing arteriolar vasodilation and reductions in vascular resistance.
In this model, comparable revascularization of cortical bone at 21 days was seen beneath
reverse saphenous conduit flaps and free trapezius muscle flaps. However, a role for
endosteal revascularization cannot be excluded.
Cortical revascularization by skin and muscle reconstruction was compared at 21 days
in a canine metatarsal model. Significant differences in cortical bone blood flow
were not detected
Keywords
Revascularization - muscle - skin - bone blood flow - bone - microvascular