A clinically relevant porcine model of flail chest: Development and multimodal validation

BACKGROUND: Flail chest has high mortality, but large-animal models with thoracic anatomy comparable to humans are lacking. The objective of this study was to develop a clinically relevant porcine flail chest model that preserves pleural, pulmonary, and neurovascular integrity, and to validate it using multimodal assessment including computed tomography (CT) imaging and physiologic parameters. METHODS: Twelve male Landrace pigs were randomly assigned to a flail chest (FC) group and a multiple single rib fracture (MRF) group (n=6 per group). Under general anesthesia, controlled osteotomies were performed on the fifth to eighth ribs. The intercostal neurovascular bundle was protected, and the parietal pleura was bluntly separated before each osteotomy to preserve pleural integrity. In the FC group, each rib was transected at two sites to create a four-rib flail segment; in the MRF group, a single transection was made per rib. Paradoxical chest wall motion was visually confirmed in the FC group before layered closure. Invasive arterial pressure, heart rate, pulse oxygen saturation (SpO₂), and end‑tidal carbon dioxide tension (ETCO₂) were monitored throughout. Chest CT was performed on Day 7. RESULTS: All surgeries were successful, with no mortality. Paradoxical chest wall motion was confirmed in all FC animals after emergence. The SpO₂/FiO₂ ratio declined postoperatively in both groups, with a significantly greater decrease in the FC group than in the MRF group (221.0±1.4 vs. 260.2±1.9, P<0.001). Heart rate and mean arterial pressure increased in both groups and were significantly higher in the FC group (P<0.001). CT confirmed the intended fracture patterns and flail-segment displacement, with no evidence of pleural breach, pulmonary injury, pneumothorax, or hemothorax. CONCLUSIONS: A standardized porcine flail chest model was established that preserves pleural, pulmonary, and neurovascular integrity, allowing the isolated study of rib fracture pathophysiology. This model will facilitate future research on fixation materials and surgical techniques. STUDY TYPE: Basic Science/ Animal Study.