Establishment and evaluation of a rabbit model of femoral delayed union using external fixation / 中国组织工程研究

ABSTRACT

BACKGROUND: Mechanisms related to bone fracture and nonunion have been clarified, but the healing time and treatment strategy of delayed union remain controversial. OBJECTIVE: To establish a reliable model of femoral delayed union using external fixation in the New Zealand white rabbit. METHODS: Seventy-two New Zealand white rabbits were randomized to three groups. After removal of 10-mm femoral middle bone cortex with internal and external periosteum and bone marrow, a uniplanar external fixator was used. There was a 1 mm gap between broken ends (group A), and the broken ends were sealed by bone wax (group B). For controls, only bone cortex was cut and then fixed to contact the broken ends. The gross, radiological and histological observations were performed to observe the bone healing at 4, 8 and 12 weeks after modeling. RESULTS AND CONCLUSION: The control group achieved bone healing at the 4th week, which was considered as the normal time of bone healing. The groups A and B achieved healing at the 12th week, which was remarkably longer than that in the control group. The rabbit femoral delayed union model showed the typical X-ray imaging and pathological features of delayed union. Our results suggest that the model is reasonable and reliable, which can provide reference for clinical research.