A novel rat model of tibial fracture for trauma researches: a combination of different types of fractures and soft tissue injuries

BACKGROUND: The outcomes for open tibial fractures with severe soft tissue injury are still a great challenge for all the trauma surgeons in the treatment. However, most of the existing open tibial fracture models can only provide minimal soft tissue injury which cannot meet the requirement of severe trauma research. Our goal is to investigate a novel tibial fracture model providing different fractures combined with soft tissue injury for better application in trauma research. METHODS: A total of 144 Sprague-Dawley rats were randomly divided into 4 groups. With group 1 as control, the other groups sustained different right tibial fractures by the apparatus with buffer disc settings either 3 mm, 10 mm, or 15 mm. X-ray and computed tomography angiography (CTA) were performed at 6 h to evaluate the fracture patterns and vascular injuries. Peripheral blood and tibialis anterior muscle were harvested at 6 h, 1 day, 3 days, 7 days, 14 days, and 28 days for ELISA and histological analysis. RESULTS: X-ray and μCT results indicated that different fractures combined with soft tissue injuries could be successfully provided in this model. According to OTA and Gustilo classification, the fractures and soft tissue injuries were evaluated and defined: 36 type I in group 2, 34 type II in group 3, and 36 type III in group 4. The CTA confirmed no arterial injuries in groups 1 and 2, 2 arterial injuries in group 3, and 35 in group 4. ELISA indicated that the levels of pro-inflammatory cytokines TNF-α and IL-1β were significantly higher in group 4 than in other groups, and the levels of anti-inflammatory cytokines TGF-β and IL-10 were significantly higher in surgery groups than in group 1 in later stage or throughout the entire process. HE, Masson, and caspase-3 stains confirmed the most severe inflammatory cell infiltration and apoptosis in group 4 which lasted longer than that in groups 2 and 3. CONCLUSIONS: The novel apparatus was valuable in performing different fractures combined with soft tissue injuries in a rat tibial fracture model with high reproducibility and providing a new selection for trauma research in the future.