Abstract:
Objectives: We investigated thermal changes associated
with the application of the Ilizarov transosseous wires, the
extent of necrosis and the factors affecting necrosis.
Me t h o d s : We used a pair of tibiae from a 1-year-old cow. After
removal of metaphyseal areas, each of four equal diaphyseal
zones marked on both tibiae was drilled at 600, 900, 1,200 and
1,800 rpm, each time with a new wire. Heat changes were
recorded with heat electrodes during the application and the
speed of the wire was calculated. For histopathological examination,
specimens were obtained at the access and exit sites to
assess the extent of necrosis. Thermal changes between the
zones and immediate and remote cortices were compared. The
most significant factor affecting the heat changes was analyzed
by linear regression.
R e s u l t s : Heat changes varied between 48.4 ¡C (at 1,200 rpm)
and 151.9 ¡C (at 600 rpm). The thickness of the immediate cortex,
the time and speed for the wire to pass the cortex were
found as significant parameters in heat changes (p=0.003,
p=0.01, and p=0.01, respectively). A negative correlation was
found between the speed of the wire and the thickness of the
necrotic area (r=-0.901, p=0.001). Regression analysis showed
that the time for the wire to pass through the cortex was the
most significant factor in inducing heat changes in both cortices
(p=0.001, p=0.003, respectively). Histopathologically, the
extent of necrosis and bone erosion was associated with lower
drill speeds. Necrosis was significantly notable in the immediate
cortex than that of the remote one (p=0.006).
Conclusion: Transosseous wires should be passed at high
drill speeds and with earliest time elapses to reduce thermal
necrosis.
