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.