Background: The objectives of this study were to determine whether
intramedullary reaming increases bone temperature in vivo to a level that is
high enough to produce bone necrosis and to determine the influence of the
size and the condition of the reamers on the temperature increase.
Methods: Bone temperature variations were recorded in vivo during
intramedullary tibial reaming in fourteen minipigs. The left tibiae were
progressively reamed from 6 to 9 mm. The right tibiae were reamed with only 8
and 9-mm reamers. The variables studied were the initial and final temperature
and the increase in the temperature. Two weeks after reaming, the tibiae were
removed and studied histologically.
Results: Intramedullary reaming produced an average increase (and
standard deviation) in bone temperature of 6.9°C ± 4.1°C. The
peak temperatures ranged from 34.9°C to 49.4°C. The average maximum
bone temperature was 38.1°C ± 2.8°C when the reaming was done
progressively from 6 to 9 mm and 41.1°C ± 4.4°C when the
reaming was done only with the 8 and 9-mm reamers. The mean increase in the
temperature in the second group of animals (8.2°C ± 4.3°C) was
greater than that in the first group (5.4°C ± 3.5°C). Reaming
with sharper reamers in the first seven animals resulted in a smaller mean
increase in temperature than did reaming with less sharp reamers in the last
seven animals (4.6°C compared with 9.2°C; p = 0.001). Histological
examination of the tibiae showed periosteal proliferation and an altered
disposition of the osteons at the inner cortex with occasional necrotic bone
fragments in the medullary canal.
Conclusions: Intramedullary reaming in the minipig increased bone
temperature. When the reamer initially used was larger than the diameter of
the medullary canal and when the reamers were blunted by repeated use, the
maximum temperature reached by the bone was higher. This increase in
temperature with use of typical medullary reaming techniques did not exceed
the limits that would produce bone necrosis.
Clinical Relevance: Use of appropriately sized reamers in good
condition reduces the increase in bone temperature that occurs during