载银硼酸玻璃涂层钛板预防骨折术后感染研究

Implant-related infection in orthopaedic surgery has gradually become a significant rising complication as more patients received biomedical implants. The infection accounts for an enormous medical costs, increased morbidity and decreased patient satisfaction. Clinical practice has shown that systemic antibiotic administration is unable to provide effective treatment for the implant-related infections. However, systemic administration of antibiotics has many disadvantages such as relatively low drug concentration at the target site and potential toxicity, and which should cause the development of antibiotic-resistant bacterial strains. There is a high demand for novel prevention techniques for implant-related infections. It is believed that implant-related infection are the result of bacterial adhesion and subsequent bio-film formation at the implantation site. Bacterial adhesion is the first and most important step in implant-related infection. And inhibiting bacterial adhesion is often regarded as the most critical step to prevent implant-related infection. Implant surface modification to alter the physio-chemical surface properties to repel bacteria colonization is an important and economic way. Bioactive borate glass shows excellent biocompatibility, biodegradable property, osteoconductivity and osteoinductivity. Which is regarded as the potential candidate materials for biocompatible coating on titanium. Silver has long been known to have strong inhibitory and bactericidal effects as well as a broad spectrum of antibacterial activities. And almost no drug resistant bacterial arises. Based on its good antibacterial ability, excellent biocompatibility, and satisfactory stability, silver is very attractive alternative from the perspective of doping of biomaterials. In this study, silver-containing bioactive borate glass (AgBG) coating titanium was made by melting. In vitro, bioactive activity, osteoconductive and osteoinductive activity, and spectrum of antibacterial activities of AgBG coating titanium implant were investigated. In vivo antibacterial efficacy of the AgBG coating Titanium implants in preventing the infection were investigated in rabbits model of tibia bone fracture. The antibacterial mechanism, osteoconductive and osteoinductive activity of AgBG coating titanium were analyzed. A new way to prevent implant-related infection in orthopaedic surgery should be developed.

骨折术后感染是临床上面临的一个难题，病人需要为此忍受巨大的病痛，并为此额外支付高昂的医疗费用。现在临床上主要通过围手术期抗生素应用来预防，但不能有效杜绝此类感染，且容易带来副作用及导致耐药菌株的产生。目前认为通过改变内固定表面性能，使其具有良好组织相容性的同时具备抗菌性能，是预防骨折术后感染发生的关键。研究表明硼酸玻璃（borate glass, BG）具有良好的促成骨性能，而银离子具有广谱抗菌性，且极少会产生耐药菌株。本研究中，我们根据大量前期载银BG研究，以BG作为载体、Ag作为抗菌剂，将两者作为涂层材料，通过高温烧融法将该载银BG涂覆于钛板表面。通过对该载银硼酸玻璃涂层钛板体外生物活性、促成骨性能、抗菌性能及抗菌谱的检测，以及在动物骨折术后感染模型的应用等多个层面，对该载银硼酸玻璃涂层钛板的抗菌性能及机制进行全面深入分析探讨，从而为骨折术后感染的预防探索一条可行途径和模式。

骨折术后感染是临床上面临的一大难题，临床上主要通过围手术期抗生素应用来预防，但不能有效杜绝此类感染，且容易带来副作用及导致耐药菌株的产生。目前认为通过改变内固定表面性能，使其具有良好组织相容性的同时具备抗菌性能，是预防骨折术后感染发生的关键。研究表明硼酸玻璃（ borate glass, BG）具有良好的促成骨性能，而银离子具有广谱抗菌性，且极少会产生耐药菌株。本研究中，首先采用高温熔融法制载银0.75wt%、1.0wt%及2.0wt%的硼酸玻璃，通过SEM扫描、XRD、PH值测定、重量损失测定等检测其降解性能和转化羟基磷灰石性能；原子发射光谱法（ICP-AES）检测不同载银含量的硼酸玻璃的在SBF中的缓释性能；MTT试验及LDH含量测定以评定其对L929细胞毒性及对MC3T3-E1成骨细胞增殖的影响，ALP含量测定、光镜及电镜细胞形态观察，以评定其对成骨细胞分化的影响；抑菌圈测定及微孔板细菌增殖法检测载银硼酸玻璃对金黄色葡萄球菌、大肠杆菌、铜绿假单胞菌等的抑制作用。然后，综合上述研究结果，采用高温熔融法制备载银0.75wt%和1.0wt%的硼酸玻璃抗菌涂层钛板，体外检测涂层的理化性能，以及ICP-AES检测抗菌涂层钛板的体外银离子释放性能；菌落计数法检测抗菌涂层钛板对金黄色葡萄球菌、大肠杆菌、铜绿假单胞菌的体外抑制作用。最后，通过建立大白兔胫骨骨折模型，同时金黄色葡萄球菌局部断端注射，建立骨折术后感染模型。用载银硼酸玻璃抗菌涂层钛板进行固定，定期观察切口情况及X线摄片；术后8周处死动物，获取胫骨，通过组织学、微生物学、生物力学、Micro-CT等方法对载银硼酸玻璃抗菌涂层钛板的抗菌性能及生物安全性进行综合评价。结果表明：1.载银0.75wt%及1.0wt%的硼酸玻璃具有良好的生物安全性和抗菌性能。2. 载银0.75wt%及1.0wt%的硼酸玻璃抗菌涂层具有良好的生物降解性，其Ag+释放呈缓慢持续过程，所释放的Ag+达到其MIC，对金黄色葡萄球菌、大肠杆菌、铜绿假单胞菌菌有明显抑制作用。3. 载银0.75wt%及1.0wt%硼酸玻璃抗菌涂层钛板能有效降低动物骨折术后感染的发生率，与空白对照组相比具有明显差异（P<0.05），且其抗感染能力与银含量的大小一致。而且涂层钛板与骨组织结合性能良好。上述研究成为将为骨折术后感染的预防提供一条新的途径。