發(fā)布時間：2019-06-20 05:26

【摘要】：隨著社會經濟的發(fā)展、交通工具的普及和建筑業(yè)快速發(fā)展,導致車禍、高空墜落等引起的骨折頻發(fā);骨質疏松患者和過于肥胖患者的增多以及人口老齡化進程的加快,需要骨缺損治療的患者逐年遞增,對骨修復材料及功能重建的需求越來越多。內固定物固定治療骨折是目前臨床主要的常規(guī)方案和技術手段。本文設計了一種生物可降解Zn-ZnMg-Mg梯度合金材料骨科內固定物,使其能滿足骨折早期愈合堅強固定要求,隨后在體內逐漸降解過渡到動態(tài)固定,避免固定骨折部位應力遮擋效應達到骨折愈合目的。最終內固定物在體內失去材料力學性能被完全吸收,避免二次手術取出。本文進行了生物可降解Zn-ZnMg-Mg梯度合金髓內釘研制及其固定股骨干骨折愈合機理的生物力學相關研究。根據骨折愈合生物力學機理對于材料的需求及鎂、鋅金屬材料降解腐蝕特性,設計研制出一種生物可降解Zn-ZnMg-Mg梯度合金。該合金以鎂金屬為基體,通過粉末擴散退火滲鋅的方法在鎂基體表面形成鋅鎂復合層,再用電鍍法鍍一鋅層。提出了一種制備鎂基表面鍍鋅的工藝,并通過表面形貌觀察、物相分析、體外浸泡實驗和電化學測試,對其進行了層厚測量、成分檢測、腐蝕速率評價,結果表明該生物可降解梯度合金材料符合預期設計要求。用力學測試及數值模擬評價鐵、鎂、鋅、梯度合金材料及人皮質骨的生物力學性能,實驗結果顯示各金屬的生物力學性質一致性較高,有限元數字模擬得出的彈性模量基本符合髓內釘材料屬性,梯度合金材料彈性模量低于純鐵的彈性模量,但高于純鎂、純鋅的彈性模量。得出Zn-ZnMg-Mg梯度合金材料力學性能更優(yōu),為生物可降解材料的設計提供了可靠的力學參考依據。建立梯度合金髓內釘與鐵制髓內釘置入固定大鼠股骨干骨折的模型,通過大體觀察、影像學檢查、Micro-CT重建、組織形態(tài)學及力學性能測試等指標。檢測了骨折愈合過程中不同時期大鼠骨折部位骨痂及可降解梯度合金髓內釘在體內的生物學特性,觀察了生理載荷下大鼠骨折愈合過程和治療骨折的效果,實驗結果顯示在骨折愈合早期梯度合金組不穩(wěn)定的生物力學環(huán)境不利于骨折愈合,但通過骨痂體積的增大代償骨折端的不穩(wěn),在骨折愈合后期,隨著梯度合金髓內釘吸收,骨痂的生物力學性能和礦化水平明顯提高。對梯度合金髓內釘和鐵制髓內釘固定大鼠股骨干骨折進行數值仿真計算,模擬了不同時期骨折愈合和髓內釘降解對骨折愈合的生物力學影響。得到了大鼠骨折愈合不同時期的髓內釘應力及股骨應力,在大鼠股骨干骨折愈合早期,梯度合金髓內釘應力峰值、股骨應力峰值及應力分布與鐵制髓內釘相似,之后梯度合金髓內釘應力逐漸減小,明顯低于鐵制髓內釘。結果顯示符合骨折愈合要求,早期實現堅強固定,之后通過逐漸降解達到動態(tài)固定,避免應力遮擋,實現骨折愈合。
[Abstract]:With the development of social economy, the popularization of transportation and the rapid development of construction industry, resulting in frequent fracture caused by car accidents and falling from high altitude, the increase of osteoporosis patients and obese patients and the acceleration of population aging process, the number of patients in need of bone defect treatment is increasing year by year, and there is more and more demand for bone repair materials and functional reconstruction. Internal fixation is the main routine and technical method in the treatment of fracture. In this paper, a biodegradable Zn-ZnMg-Mg gradient alloy material orthopaedic internal fixation was designed to meet the requirements of early fracture healing and rigid fixation, and then gradually degraded and transitioned to dynamic fixation in vivo to avoid the stress occlusion effect of fixed fracture site to reach the goal of fracture healing. Finally, the internal fixation lost the mechanical properties of the material in the body and was completely absorbed to avoid the removal of secondary surgery. In this paper, the development of biodegradable Zn-ZnMg-Mg gradient alloy intramedullary nail and the biomechanical study on the mechanism of fracture healing of fixed thigh shaft were carried out. According to the demand of fracture healing biomechanical mechanism and the degradation and corrosion characteristics of magnesium and zinc metal materials, a biodegradable Zn-ZnMg-Mg gradient alloy was designed and developed. The alloy is based on magnesium metal and forms a zinc-magnesium composite layer on the surface of magnesium matrix by powder diffusion and annealed galvanizing, and then plating a zinc layer by electroplating. A process for preparing zinc plating on magnesium base surface was proposed. The coating thickness, composition detection and corrosion rate of the biodegradable gradient alloy were measured by surface morphology observation, phase analysis, immersion test in vitro and electrochemical test. The results show that the biodegradable gradient alloy material meets the expected design requirements. The biomechanical properties of iron, magnesium, zinc, gradient alloy materials and human cortical bone were evaluated by mechanical test and numerical simulation. The experimental results show that the biomechanical properties of each metal are consistent. The elastic modulus obtained by finite element digital simulation basically accords with the properties of intramedullary nailing material. The elastic modulus of gradient alloy material is lower than that of pure iron, but higher than that of pure magnesium and pure zinc. It is concluded that the mechanical properties of Zn-ZnMg-Mg gradient alloy materials are better, which provides a reliable mechanical reference for the design of biodegradable materials. The model of femoral shaft fracture fixed with gradient alloy intramedullary nail and iron intramedullary nail was established. The indexes such as gross observation, imaging examination, Micro-CT reconstruction, histomorphology and mechanical properties were tested. The biological characteristics of fracture site and biodegradable gradient alloy intramedullary nail in rats at different stages of fracture healing were measured. The process of fracture healing and the effect of fracture treatment under physiological load were observed. The experimental results showed that the unstable biomechanical environment of gradient alloy group was not conducive to fracture healing in the early stage of fracture healing, but the instability of fracture end was compensated by the increase of callus volume, and the instability of fracture end was compensated by the increase of callus volume. With the absorption of gradient alloy intramedullary nails, the biomechanical properties and mineralization level of eschar were significantly improved. The biomechanical effects of fracture healing and degradation of intramedullary nail on fracture healing in rats were simulated by numerical simulation of femoral shaft fracture fixed with gradient alloy intramedullary nail and iron intramedullary nail. The intramedullary nail stress and femoral stress in different stages of fracture healing in rats were obtained. in the early stage of fracture healing in rats, the peak stress, peak stress and stress distribution of gradient alloy intramedullary nail were similar to those of iron intramedullary nail, and then the stress of gradient alloy intramedullary nail decreased gradually, which was significantly lower than that of iron intramedullary nail. The results showed that it met the requirements of fracture healing and achieved strong fixation in the early stage, and then achieved dynamic fixation through gradual degradation to avoid stress occlusion and achieve fracture healing.
【學位授予單位】：天津大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：R683;R318.08

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1 馬劍雄;生物可降解Zn-ZnMg-Mg梯度合金髓內釘研制及其固定股骨干骨折愈合機理的生物力學研究[D];天津大學;2015年

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本文編號：2502973