Analysis of fracture healing in osteopenic bone caused by disuse: experimental study

Abstract

Osteoporosis has become a serious global public health issue. Hence, osteoporotic fracture healing has been investigated in several previous studies because there is still controversy over the effect osteoporosis has on the healing process. The current study aimed to analyze two different periods of bone healing in normal and osteopenic rats. Sixty, 7-week-old female Wistar rats were randomly divided into four groups: unrestricted and immobilized for 2 weeks after osteotomy (OU2), suspended and immobilized for 2 weeks after osteotomy (OS2), unrestricted and immobilized for 6 weeks after osteotomy (OU6), and suspended and immobilized for 6 weeks after osteotomy (OS6). Osteotomy was performed in the middle third of the right tibia 21 days after tail suspension, when the osteopenic condition was already set. The fractured limb was then immobilized by orthosis. Tibias were collected 2 and 6 weeks after osteotomy, and were analyzed by bone densitometry, mechanical testing, and histomorphometry. Bone mineral density values from bony calluses were significantly lower in the 2-week post-osteotomy groups compared with the 6-week post-osteotomy groups (multivariate general linear model analysis, P<0.000). Similarly, the mechanical properties showed that animals had stronger bones 6 weeks after osteotomy compared with 2 weeks after osteotomy (multivariate general linear model analysis, P<0.000). Histomorphometry indicated gradual bone healing. Results showed that osteopenia did not influence the bone healing process, and that time was an independent determinant factor regardless of whether the fracture was osteopenic. This suggests that the body is able to compensate for the negative effects of suspension.

Effects of microgravity on bone

“…Bone remodeling balance relates a variety of mechanisms, internal and external factors can affect this regulation causing bone disease. 9 For example osteoporosis is a disease characterized by low bone mineral density, high bone porosity and low bone strength. Bone in this condition is weakened and fracture risk increases.…”

“…Bone in this condition is weakened and fracture risk increases. 9 Old age people could develop osteoporosis for changes of hormonal levels in post menopause. Furthermore, osteoporosis can be originated by other conditions in which bone is deprived of mechanical stimulus.…”

Efeitos das membranas de látex natural e/ou colágeno na regeneração óssea guiada em tíbias de ratos

“…Schwarz et al (2006) Quando se observa o processo de cicatrização da fratura entende-se que o osso passa por uma segunda fase de reabsorção, que permite que o osso seja remodelado, se transformando em uma estrutura de osso lamelar com uma cavidade central medular (GERSTENFELD et al, 2003). Conforme ocorre a maturação óssea, tanto as qualidades funcionais como a integridade mecânica retornam às condições ósseas normais (PAIVA et al, 2016).…”

“…Os resultados do presente trabalho contribuem com os encontrados por Paiva et al (2016), quanto à DMO e rigidez relativa, pois, animais avaliados após 6 semanas de osteotomia apresentavam maiores valores se comparados aos grupos de 2 semanas.…”

“…O osso está em constante formação e reabsorção, este equilibrado fenômeno acontece de forma natural e é conhecido como processo de remodelação, onde um processo de manutenção da homeostase se dá pela constante substituição de osso antigo por osso novo (PAIVA et al, 2016). Este processo permite a renovação de 5 a 15% da massa óssea total por ano (MORAES et al, 2012), harmonicamente, e por toda a vida, mas pode ser alterado se houver desequilíbrio entre eles (MORAES et al, 2012).…”