Histomorphometric assessment of bone necrosis produced by two cryosurgery protocols using liquid nitrogen: an experimental study on rat femurs.
OBJECTIVE
The aim of this study was to evaluate the effects of liquid nitrogen cryosurgery on the femoral diaphysis of rats.


METHODS
The femoral diaphyses of 42 Wistar rats were exposed to three local and sequential applications of liquid nitrogen for 1 or 2 min, intercalated with periods of 5 min of passive thawing. The animals were sacrificed after 1, 2, 4 and 12 weeks and the specimens obtained were processed and analyzed histomorphometrically.


RESULTS
The depth and extent of peak bone necrosis were 124.509 µm and 2087.094 µm for the 1-min protocol, respectively, and 436.424 µm and 12046.426 µm for the 2-min protocol. Peak necrosis was observed in the second experimental week with both cryotherapy protocols.


CONCLUSIONS
The present results indicate that the 2-min protocol produced more marked bone necrosis than the 1-min protocol. Although our results cannot be entirely extrapolated to clinical practice, they contribute to the understanding of the behavior of bone tissue submitted to different cycles of liquid nitrogen freezing and may serve as a basis for new studies.
Division of Stomatology, Department of Clinical Dentistry, Federal University of Ceará, Sobral, CE, Brazil. fwildson@yahoo.com.br
Fábio Wildson Gurgel
FW
Costa
Gerly Anne de Castro
GA
Brito
Rosana Maria Andrade
RM
Pessoa
Eduardo Costa
EC
Studart-Soares
D000818:Animals; D003452:Cryosurgery / Q000009:adverse effects* / Q000379:methods; D018483:Diaphyses / Q000473:pathology / Q000601:surgery; D004195:Disease Models, Animal; D005269:Femur / Q000473:pathology / Q000601:surgery*; D005271:Femur Head Necrosis / Q000139:chemically induced / Q000473:pathology*; D008297:Male; D009584:Nitrogen / Q000627:therapeutic use*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D016896:Treatment Outcome
D009584:Nitrogen