根据Ⅰ型胶原氨基端末肽、Ⅰ型胶原羧基端末肽、骨钙素及骨特异性碱性磷酸酶早期诊断骨不连

C- and N-terminal telopeptides of type Ⅰ collagens, osteocalcin and bone-specific alkaline phosphatase used for the early diagnosis of bone nonunion

背景:对血液中骨代谢标志物的浓度进行检测以对骨折愈合情况进行评估具有使用简单、创伤小、变异小的特点,如何找到一种合适的标志物以预测骨不连的发生是当前该领域研究的热点。目的:建立骨折不愈合动物模型,探讨实验性骨折不愈合的生化指标变化规律。方法:选取五六月龄纯种新西兰大白兔20只,随机均分为2组,骨缺损组在左前臂桡骨中段截除1.5 cm(包括骨膜),骨断端用骨蜡封闭髓腔;骨折组只是在前臂桡骨中段造成骨折。2组分别于术前、术后2-8,10,12周进行前臂的X射线片检查观察桡骨缺损区愈合情况,并抽取血清采用生物素双抗体夹心ELISA法检测骨吸收特异标志物(包括Ⅰ型胶原羧基端末肽、Ⅰ型胶原氨基端末肽、人抗酒石酸酸性磷酸酶5b)及骨形成特异标志物(包括骨钙素、骨特异性碱性磷酸酶)的表达变化。结果与结论:1分析2组手术前后骨代谢指标的变化发现,骨缺损组骨代谢一直持续在较高水平,骨不连早期诊断的临床预测可以依赖于多个血清生化指标的同时跟踪监测;2除人抗酒石酸酸性磷酸酶5b意义不大之外,骨缺损组中I型胶原羧基端末肽在术后第5周均值最高,骨钙素、骨特异性碱性磷酸酶、Ⅰ型胶原氨基端末肽在术后4或5周均值明显下降,可以说明Ⅰ型胶原羧基端末肽、Ⅰ型胶原氨基端末肽、骨钙素、骨特异性碱性磷酸酶能快速随骨形成和骨吸收而迅速改变,敏感地反映体内骨代谢的具体状态;3系统性监测生化指标如Ⅰ型胶原羧基端末肽、骨钙素、骨特异性碱性磷酸酶、Ⅰ型胶原氨基端末肽的变化能反映兔骨折不愈合的早期进程,它们是否均可以作为反映骨吸收与骨形成的敏感性、特异性较强的指标,是否可以早期诊断兔骨不连,需要进一步深入探讨。

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.