Effects of a simulated plateau environment on fracture healing in rats / 中华创伤骨科杂志

ABSTRACT

Objective:To study the effects of a simulated plateau environment on fracture healing in rats.Methods:A rat model of mid-femoral fracture was established by hacksaw truncation and intramedullary fixation with Kirschner wires in 60 male Wistar rats which were divide into 2 groups ( n=30) by the random number table method. The rats in the control group were raised in the animal experiment center of The 940 Hospital of Joint Logistic Support Force of Chinese PLA at an altitude of 1,400 m, while the rats in the plateau group were placed in an animal experimental cabin in a simulated plateau environment at a simulated altitude of 5,000 m. The body weight was weighed once a week and X-ray films were taken every 2 weeks. Blood samples were collected after 4 weeks for detection of biochemical indicators of bone metabolism. After 8 weeks, the femurs of the surgical side were taken for bone biomechanical detection and the bone mineral density of the healthy side was detected. After 4 and 8 weeks, the femurs of the surgical side were taken for in vitro Micro-CT scanning and angiography detection. After 1, 2, 4 and 8 weeks, the femurs of the surgical side were taken for bone histopathologic detection. Results:During the entire experiment, no rats in the control group died while the mortality rate of the rats in the plateau group was as high as 26.7% (8/30). In the plateau group, some organs were pathologically damaged in the rats, fracture union was delayed, and the callus differentiated and matured slowly with the chondrocytes still dominant at the 8th week. The bone mineral density and the maximum load of the femur in the plateau group were significantly lower than those in the control group ( P< 0.05). Angiography showed that the rats in the plateau group had microvascular proliferation which did not penetrate the fracture end at the 8th week. The bone formation indexes like osteocalcin, procollagen type Ⅰ N-terminal propeptide (PⅠNP), and osteoprotegerin of the rats in the plateau group were significantly lower than those in the control group at the 4th week ( P<0.05). The bone resorption indexes like tartrate resistant acid phosphatase 5b (TRACP-5b) and receptor activator for nuclear factor-κB ligand (RANKL) in the plateau group were significantly higher than those in the control group ( P<0.05). Conclusion:A simulated plateau environment at an altitude of 5,000 m may lead to delayed fracture healing in rats.