Experimental Studies On MAO-ZK6O Magnesium Alloy Bio-safety, Degradation And Bone-inducing In Vivo

OBJECTIVE To study MAO-ZK60magnesium alloy bio-safety, degradation andbone-inducing in condyles of femora of beagle dogsMETHORDS Twelve adult beagle dogs were randomly divided into four groups(2W,4W,8W,12W), MAO-ZK60alloy Cancellous Bone Screws were planted into thecondyles of femora of the dogs. After monitoring of general postoperative conditions,the dogs were put to death respectively in2W,4W,8W,12W to acquire materials.Each dog underwent venous blood routine tests and biochemistry tests before andafter operations. All heart, liver, lung, spleen, kidney tissue was dealt with HEpathological staining. All bone tissue was examined by micro-CT scanning andthree-dimensional reconstruction to observe degradative effect. Volumetric changesin screw caps and bodies were calculated and compared. The measurement parametersof bone tissue adjacent to screws were analyzed. Changes in the interface ofscrew-cancellous bone were observed by SEM, elemental analysis was acquired byEDS.RESULTS: Blood test results were normal before operation and execution in eachgroup. No abnormalities were found in heart, liver, lung, spleen, kidney tissuepathological examinations. No obvious gas accumulation and inflammation wasobserved in local tissue. Micro-CT scanning and three-dimensional reconstructionrevealed that MAO-ZK60magnesium alloy screws degraded gradually as time lapses.New bone tissue was found around screws in8W and12W, with the12W moreevident. The volume of screw caps and bodies declines, and the declining ratedecreases. There’s no statistical difference in degree of changes between caps andbodies. The measurement parameters of surrounding bone tissue found that BMC,BVF, TB.Th in group12W and8W were more than those of group2W and4W, TB.Nin group12W more than those of group4W and8W, BMD in group8W and12W more than that of group4W，which reveals that new bone tissue was generated in8weeks and12weeks after MAO-ZK60magnesium alloy screws being planted intocancellous bones of beagle dogs. SEM and EDS revealed deposition of Ca and P inthe interfaces of MAO-ZK60and cancellous bones in group8W and12W, in group12W the deposition was more evident and Ca/P was closer to that of normal beagledogs.CONCLUSIONS:MAO-ZK60magnesium alloy screws have satisfactory bio-safety, degradation inbeagle dogs, and fine bone–inducing in8W and12W after being planted.