Background Macrophages and inflammatory cytokines play important roles in bone fracture healing. However, the expression patterns of macrophages and inflammatory cytokines during fracture healing under the condition of postmenopausal osteoporosis have not been fully revealed. Methods Tibia transverse fracture was established 12 weeks after ovariectomy or sham operation in 16-week old female mice. Tibias were harvested before fracture or 1, 3, 5, 7, 14, 21, 28 days after fracture for radiological and histological examinations. M1/M2 inflammatory macrophages, osteal macrophages and gene expressions of tumor necrosis factor-α, interleukin-6, interleukin-1β and macrophage conversion related molecules in the fracture haematoma or callus were also detected. Results The processes of fracture healing, especially the phases of endochondral ossification and callus remodeling, were delayed in ovariectomized mice. The expressions of tumor necrosis factor-α and interleukin-6, but not interleukin-1β, in the fracture haematoma or callus were disturbed. Expressions of tumor necrosis factor-α were decreased at 1, 14 and 21 days post-fracture (DPF), and were increased at 3, 5 and 7 DPF. Interleukin-6 expressions at 1, 3 and 21 DPF were significantly increased. We found the decreases in M1 and M2 macrophages at 1 DPF of the initial inflammatory stage. M2 macrophages at 14 DPF of the middle stage and osteal macrophages at 14, 21 and 28 DPF of the middle and late stages of fracture healing were also reduced in ovariectomized mice. Conclusions The expressions of macrophages and inflammatory cytokines were impaired in ovariectomized mice, which might contribute partially to poor fracture healing.

Background: Macrophages and inflammatory cytokines plays important roles in bone fracture healing. However, the expression patterns of macrophages and inflammatory cytokines during fracture healing under the condition of postmenopausal osteoporosis has not been fully revealed.Methods:Tibia transversefracture was established 12 weeks after ovariectomyor shamoperation in 3-month old female mice. Tibias were harvested before fracture or 1, 3, 5, 7, 14, 21, 28 days after fracture for radiological and histological examinations. M1/M2 inflammatorymacrophages, ostealmacrophages and gene expressions of tumor necrosis factor-α,interleukin-6, interleukin-1βand macrophage conversion related molecules in the fracturehaematoma or callus were also detected.Results:The process of fracture healing,especially the phases of endochondral ossification and callus remodeling, was delayed in ovariectomized mice.The expressions of tumor necrosis factor-α andinterleukin-6, but not interleukin-1β, in the fracturehaematoma or callus were disturbed. We also foundthe decreases in M1 and M2 macrophages inthe initialinflammatory stage, M2 macrophagesin the middle stage and ostealmacrophagesin the middle and late stages of fracture healing in ovariectomized mice.Conclusions: The expressions of macrophages and inflammatory cytokines were impaired in ovariectomized mice, which might contribute partially to poor fracture healing.