| Summary: | 博士 === 國立陽明大學 === 生物醫學工程學系 === 105 === The materials used in recent years to make orthopedic implants have typically been metal and polymer. Metal has good mechanical properties, but its Young’s modulus is much higher than human bone, which may cause stress shielding effects and lead to osteoporosis. In addition, the patient may feel uncomfortable due to the friction between the implant and the soft tissue or muscle, thus may need secondary surgery to remove the metal implant. The Young’s modulus of biodegradable polymer is quite low; yet polymer implants sometimes break on insertion or result in a foreign body reactions in surrounding tissue. Over the past decade, magnesium has gained much attention due to its distinctive properties: its Young’s modulus is similar to bone, it is biodegradable, and can induce bone ingrowth. Unfortunately, the degradation rate of magnesium is too rapid - magnesium implants may completely degrade before tissue regeneration. Moreover, the fast degradation rate raises the pH-value and subsequently results in tissue inflammation.
In this study, four different Mg-based types of bulk metallic glass (BMG) and its composite (BMGC) were chosen and fabricated. The degradation rate of these four different Mg-based BMG and BMGC were measured by an immersion test, a compressive test, and microstructure analysis, and surface observation was carried out before and after immersion. Next, the Mg-based alloy (Mg60Zn35Ca5 BMGC) which had the lowest degradation rate was further evaluated with and without a collagen coating and compared with commercial Ti6Al4V alloy and PLA by cytotoxicity and staining for extracellular calcium deposition. Biocompatibility and osteointegration were also measured by in vivo tests on New Zealand white rabbit.
Compared with the Ti6Al4V alloy and PLA, Mg60Zn35Ca5 BMGC and Mg60Zn35Ca5 BMGC coated with collagen had good biocompatibility and superior osteointegration, thus have great potential for use as orthopedic fixation implants.
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