Trauma and pulmonary thromboembolism: an experimental study on their correlation.

OBJECTIVE: To investigate the correlation between trauma and pulmonary thromboembolism. METHODS: Comminuted fractures and extensive soft-tissue contusion at both hind limbs were made by a falling weight from a height in 16 rabbits. Lung perfusion scanning was performed to obtain the radioactivity counts before trauma, at 1 h, 48 h and 96 h after trauma. All the data were divided into 4 groups based on the above 4 time points. The rabbits were sacrificed when positive findings on the pulmonary perfusion scanning appeared. Their lungs were harvested to be paraffin-embedded and stained with hematoxylin-erosin method for histological examination of thromboembolism. The randomized block design ANOVA and the method of least significant difference (LSD) were used for statistical analysis of the radioactivity counts. RESULTS: The histological findings showed that pulmonary embolism developed in 6 of the 16 rabbits (37.5%). Five of the 6 pulmonary embolism rabbits presented neither clinical symptoms nor positive pulmonary embolism manifestations in the lung perfusion scanning. A significant difference was found in lung perfusion radioactivity between the pre-traumatic, post-traumatic 1h groups and post-traumatic 48 h and 96 h groups(P less than 0.05). CONCLUSIONS: Fractures of the hind limbs accompanied with extensive soft-tissue contusion may cause pulmonary micro-embolism that is not sensitive to lung perfusion scanning and tends to have no clinical symptoms. Pulmonary embolism development may take more than two days after trauma.

[Bone defect repair with a new tissue-engineered bone carrying bone morphogenetic protein in rabbits].

OBJECTIVE: To construct a new tissue-engineered bone with poly (D, L-lactide-co-glycolide) (PLGA), bone morphogenetic protein (BMP) and bone marrow-derived stem cells (BMSCs) and observe its effect in repairing segmental bone defects. METHODS: A 15-mm bone defect in the right radius was induced in New Zealand white rabbits, and the models were randomized into three groups to receive implantation of the tissue-engineered bone grafts constructed with PLGA carrying 5 mg BMP and about 1 x 10(6) BMSCs (experimental group), grafts of PLGA with about 1 x 10(6) BMSCs (control group), or grafts of exclusive PLGA (blank control group), respectively. The osteogenesis in the bone defect after the implantation on was evaluated X-ray films, and the histological changes of the tissues sampled from the bone defect 4, 8, and 12 weeks after operation were observed and new bone formation was measured by image analysis. RESULTS: The bone defect was completely repaired in the experimental group 12 weeks after the implantation, showing the best results among the 3 groups. The bone defects in the blank control group was filled with only fibrous and connective tissues at 12 weeks. CONCLUSION: This tissue-engineered bone constructed with PLGA, BMP and BMSCs possesses good ability in repairing segmental bone defect.