Kivonat:
We used a model of tibial lengthening in rabbits to study the
postoperative pain pattern during limb-lengthening and
morphological changes in the dorsal root ganglia (DRG),
including alteration of substance P (SP) expression. Four
groups of animals (naive; OG: osteotomised only group;
SDG/FDG: slow/fast distraction groups, with 1 mm/3 mm
lengthening a day, respectively) were used. Signs of
increasing postoperative pain were detected until the 10(th)
postoperative day in OG/SDG/FDG, then they decreased in OG
but remained higher in SDG/FDG until the distraction
finished, suggesting that the pain response is based mainly
on surgical trauma until the 10(th) day, while the
lengthening extended its duration and increased its
intensity. The only morphological change observed in the DRGs
was the presence of large vacuoles in some large neurons of
OG/SDG/FDG. Cell size analysis of the S1 DRGs showed no cell
loss in any of the three groups; a significant increase in
the number of SP-positive large DRG cells in the OG; and a
significant decrease in the number of SP-immunoreactive small
DRG neurons in the SDG/FDG. Faster and larger distraction
resulted in more severe signs of pain sensation, and further
reduced the number of SP-positive small cells, compared to
slow distraction.