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BACKGROUND:Currently, X-ray examination is mainly used for diagnosis of nonunion. However, this method that relies only on the clinician’s experience and degree of calus mineralization has less accuracy because it is vulnerable to projection, processing conditions and subjective factors. OBJECTIVE:To establish an animal model of nonunion and to detect the variation of biochemical markers and bone mineral density. METHODS: Twenty New Zealand white rabbits were randomly divided into two groups, and bone defect and fracture models were made in the midshaft of the forearm radius, respectively. X-ray examination of the forearm, quantitative CT measurement of bone mineral density and serological test were carried out before and at 2, 3, 4, 5, 6, 7, 8, 10, 12 weeks after surgery.RESULTS AND CONCLUSION:Postoperative X-ray films showed that the in the bone defect group, a little calus formed in three rabbits at 2 weeks, the calus formed stably at 5 weeks, but there was stil no healing at 8 weeks; in the fracture group, the fracture line was blurred at 2 weeks and a large number of caluses formed at 6-8 weeks. Compared with the fracture group, the value of bone mineral density in the bone defect group began to decrease significantly at 5 weeks after surgery. Results from the serological test showed that in the bone defect group, the activity of bone-specific alkaline phosphatase increased after surgery, reached peak at 4 weeks, began to decrease at 5 weeks and became stable at 6 weeks; the activity of tartrate-resistant acid phosphatase 5b increased after surgery, peaked at 4 weeks, then decreased and stabilized basicaly; the expression of N-terminal telopeptide of type I colagen decreased significantly at 5 weeks after surgery and became stable at 6 weeks. These findings indicate that the systematic monitoring of changes in bone mineral density and biochemical indicators such as bone-specific alkaline phosphatase, tartrate-resistant acid phosphatase 5b and type I colagen N-terminal telopeptides may help to reflect the early progress of rabbit nonunion.
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BACKGROUND:Detecting the serum levels of biochemical markers to assess bone fractures is simple, mini-invasive and specific. Thereafter, to predict bone nonunion by choosing an appropriate marker has become a hotspot. OBJECTIVE:To establish an animal model of bone nonunion and explore the changing rules of the biochemical markers during the process of nonunion. METHODS:Twenty New Zealand white rabbits aged 5-6 months were enrol ed and divided into two groups. In bone defect group, a 15-mm length of bone (including the periosteum) was removed from the left mid-radius, and the medul ary cavities were closed with bone wax. In bone fracture group, the mid-radius was fractured. X-ray examination was taken and blood samples were extracted preoperatively and at 2, 3, 4, 5, 6, 7, 8, 10, and 12 weeks after surgery. The serum levels of osteocalcin and bone-specific alkaline phosphatase (BSAP) as markers of bone formation, and C-terminal telopeptide of type I col agen (CTX), N-terminal telopeptide of type I col agen (NTX), and tartrate-resistant acid phosphatase 5b (TRACP 5b) as markers of bone resorption, were measured using biotin double-antibody sandwich ELISA. RESULTS AND CONCLUSION:In the bone defect group, the bone metabolism was at a high level, suggesting that the early diagnosis of bone nonunion depends on several biochemical indicators. In the bone defect group, the serum level of CTX peaked at 5 weeks, and the serum levels of osteocalcin, BSAP and NTX decreased obviously at 4 or 5 weeks, while the serum TRACP 5b concentration did not change significantly, indicating that al above markers except TRACP 5b sensitively reflect the bone turnover in vivo. Further studies are needed to determine whether systematic monitoring of the biochemical markers can reflect the bone turnover effectively and can be used for the early diagnosis of nonunion in the rabbit model.
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Objective To study the effect of methylprednisolone therapy assisted by direct current field to treat spinal rord injury.Methods In order to make up for the defect that the direct current field could tiol reduce or remove spinal-cord edema,methylprednisolone was used 2 hours after spinal-cord injury.24 Chinese dogs wore randomly divided into two groups.Their spinal cords were made completely injured with Allen method.In Group A the electric stimulator was put into the body directly 6 hours after the spinal cord injury,while in Group B a large dose of rneuiylprednisolone was first injected 2 hours after thf spinal cord injury and then the electric stimulator was put into the body 6 hours after the spinal cord injury.In both groups the nerve function,cortical somatosensory evoked potential and three kinds uf morphometric changes were observed at 1,2,and 3 months after the injury.Results All the indexes mentioned above in Group B were much better than those in Group A.The differences between the two groups were statistically significant.Conclusion The direct current field can promote spinul curd regeneration effectively.A large dose of methylprednisolone assisted by direct current field has synergislic effects in treatment of spinal cord injury,especially in accelerating neurological functional recovery.