高纯镁在体内定量载荷下的降解行为

目的 定量研究力学载荷对高纯镁在体内降解的影响。方法 将直径2 mm、长14 mm的圆柱状高纯镁（99.99 wt.%）试件装配到聚醚醚酮（PEEK）制成的圆环上。PEEK环可使镁试件分别处于3种应力状态：无应力、压应力［(6.2±0.6) MPa］和拉应力［(4.6±0.1) MPa］。将不同应力状态的试件植入SD大鼠背部皮下4周后取出。通过试件失重、剩余体积、表面形貌和周围软组织染色分析高纯镁的降解行为。结果 植入大鼠皮下的高纯镁试件均出现降解，并且被胶原纤维囊包裹。受到压、拉应力的试件与无应力试件在失重和剩余体积上无显著差别。在各应力状态下的试件都趋于均匀腐蚀。结论 在体内皮下环境中，PEEK环对高纯镁施加4～6 MPa压、拉应力对高纯镁降解行为无明显影响。研究结果为镁基可降解植入物的设计与临床应用提供理论依据。
Objective To study the effects of mechanical load on in vivo degradation performance of high-purity magnesium (HP Mg, 99.99 wt.%) quantitatively. Methods Cylindrical Mg specimens, with a 2 mm diameter and a 14 mm length, were mounted in polyetheretherketone (PEEK) rings to bear compressive stresses ［（6.2±0.6） MPa］, tensile stresses ［（4.6±0.1） MPa］ or no stress (as control). The specimens under different stress states were implanted subcutaneously in dorsal abdominal regions of SD rats for 4 weeks. The mass loss, residual volume and surface morphology of the specimens and staining of surrounding soft tissues were used to analyze the degradation rate of HP Mg. Results Specimens and rings were completely encapsulated by membranous tissues after implantation for 4 weeks. No significant differences in the degradation rates were noted between specimens bearing stress and the control. The corrosion layers of specimens under each stress state were uniform. Conclusions The compressive and tensile stresses (4-6 MPa) could not affect significantly HP Mg degradation performance in vivo. The research findings provide theoretical references for the design and clinical application of Mg-based degradable implants.