Objective To review the progress of in vivo study on degradable magnesium alloys application as bone-implant materials. Methods Recent literature was extensively reviewed and summarized, concerning the in vivo study on degradable magnesium alloys as orthopaedic implants. Results Magnesium alloys possess a natural ability to degrade via corrosion in vivo, which is promising candidate material for orthopaedic medical device applications. A great progress has been made to improve in vivo performance and integration with bone tissue. However, the degradation mechanism of magnesium-based materials in the physiological environment and long-term effect on body are not available. The modulation of the corrosion rate of magnesium alloys must also be accomplished. Conclusion Magnesium alloys have the potential to serve as degradable implants for orthopaedic applications, but a great deal of further investigation is still necessary.
The retina of SD rats was incubated in four types of the Eagle solution respectively. The results showed the cAMP level of retinas was the lowest in the hGnMg(high glucose with normal magnesium) solution but the cAMP level was significantly increased in the hGhMg(high glucose with high magnesium) and higher than that of normal control group. The cAMP level was the highest in the nGhMg(normal glucose with high magnesium). The results suggested that magnesium might play an important role in maintaining the normal metabolism of glucose of the retinal tissue. （Chin J Ocul Fundus Dis,1992,8:138-140）
Objective To investigate the effect of magnesium phosphate cement (MPC) to fix fractures.Methods In vitro: fifty four pairs of fresh pig femoral heads were made 1 cm2 fracture and divided into 6 groups(n=9 pairs ). MPC was used to agglutinate fracture of femoral headsat 100% humidity and at 25℃, 37℃ respectively. At 30 minutes, 2 and 24hours after agglutination, the biomechanical strength was measured. In vivo:the tibia plateau fracture models on both sides of 24 rabbits were made, one side was fixed with “L” shaped plate, and the other side was fixed with MPC. Then the effect of treatment was investigated by macrography, micrography, radiography and the changes of serum electrolyte levels at 3 days, 3，6 and 9 weeks after operation. Results In vitro: the adhesive ability of MPCwas b. At 24 hours after MPC agglutination, the average tensile strength was 117.16±23.29 N/cm2. In vivo:after 6 weeks of fixation, the X-ray results showed that all rabbits’ tibia plateau fractures were healed without displacement, and MPC was absorbed gradually. The changes ofserum electrolyte levels were very minimal. The macrography observation showed that reduction of fracture were good at 3 days after operation, partial MPC remained in fracture end at 3 weeks, fracture line disappeared at 6 weeks and good remodeling was achieved at 9 weeks after operation in the experimental group. Themicrography observation showed that the interface between bone and MPC was distinct at 3 days, MPC was degraded gradually and trabeculae began to grow into MPCat 3 weeks, and almost all MPC was degraded at 6 and 9 weeks of operation. Conclusion MPC is a promising biomaterial, and might potentially be used for fracture treatment.
ObjectiveTo explore the degradation of AZ31 magnesium alloy and poly (lactic-co-glycolic acid) (PLGA) in the femoral condyle, and then evaluate the laws of degradation of AZ31 magnesium alloy by Micro-CT images and data. MethodsForty 3-month-old male New Zealand white rabbits (weighing, 2.5 kg) were randomly divided into 4 groups, 10 rabbits each group. Forty micro-arc-oxidized AZ31 magnesium alloy pins and 40 PLGA pins were implanted into the right and left femoral condyle, respectively. Micro-CT images and data analysis were used to evaluate the degradation at 4, 8, 12, and 16 weeks after operation (n=10). Degradation was evaluated by weight difference between pre-and post-implantation. The inflammatory response was observed around the implants by HE staining. The weight loss of magnesium alloy and Micro-CT results were compared. ResultsThe Micro-CT images showed that PLGA pins had gray low signal, which was similar to the soft tissue around. At 4 weeks after operation, no signs of degradation were observed, and there were little corrosion pitting on the magnesium alloy. At 8 weeks, corrosion pitting gradually expanded, the boundary between the longitudinal axis and the cross section became blurred; at 16 weeks, corrosion pitting became bigger, and the boundary was discontinuous. Micro-CT quantitative analysis showed that the volume fraction of magnesium pins decreased slowly at 4 and 8 weeks; it was significantly lower at 12 and 16 weeks than 4 and 8 weeks (P < 0.05). The magnesium cylinder mineral density continuously decreased during the study period, it had a rapidly speed from 12 to 16 weeks (P < 0.05). However, the magnesium CT image density showed a slight change (P>0.05). The surface-to-volume ratio of the pins constantly increased, and the ratio was significantly larger at 12 and 16 weeks than 4 and 8 weeks, and at 16 weeks than 12 weeks (P < 0.05). There was more and more corrosion pitting on the surface with time, which resulted in a decrease in the radius that mean trabecular thickness gradually decreased, showing significant difference between different time points after 8 weeks (P < 0.05). The weight loss detection showed that the degradation of magnesium pin and PLGA gradually increased with time (P < 0.05), and the degradation rate of magnesium pin was significantly lower than that of PLGA at 8-12 weeks (P < 0.05), but the degradation rate of magnesium pin was higher than that of PLGA at 16 weeks. At each time point, the weight loss of magnesium alloy was similar to that by Micro-CT, but mass fraction was lower than volume fraction and had significant differences at 8, 12, and 16 weeks (P < 0.05). HE staining revealed that slight inflammatory response was observed around the magnesium pins at 4 weeks, and inflammatory reaction gradually reduced with time and disappeared at 16 weeks, but no inflammatory reaction was seen around PLGA. ConclusionMicro-CT has the advantages of non-trauma, in vivo detection, quantitative analysis, and precise data in evaluating the degradation of AZ31 magnesium alloy. Regarding the degradation of the magnesium alloy and PLGA in vivo, the degradation rate is slow in the early stage, and then increases with time. The degradation of PLGA is faster and earlier but it is then overtaken by AZ31 magnesium alloy at 16 weeks. During the degradation, the density of the magnesium has almost no change. The biomaterials can not firmly attach to the surrounding tissues due to inadequate holding forces.
ObjectiveTo summarize the research and application progress of magnesium and magnesium alloys implants in the orthopedics. MethodsThe domestic and foreign related literature about the research progress and application of magnesium and magnesium alloys implants in the orthopedics was reviewed. ResultsCurrently approved and commonly used metallic implants in orthopedics include stainless steels, titanium alloys, and chromium alloys having many disadvantages of poor biocompatibility, mismatch with the biomechanical properties of the bone tissue, and need of second surgical procedure to remove. Compared with traditional implants, magnesium and magnesium alloys have biomechanical properties closer to natural bone tissue, and in vivo degradation, which have the potential to serve as new biocompatible and degradable implants. Although magnesium and magnesium alloy materials have their own advantages, but the degradation rate is still too fast and so on. At present, the research and development of medical magnesium and magnesium alloy materials are to improve their corrosion resistance and control the rate of degradation. ConclusionMagnesium and magnesium alloys have great potential as a implant material in the orthopedics, through further systematic and in-depth study, it is expected to become a new generation of degradation biological implant materials.
Eighteen SD rats with streptozotocin-induced diabetes were observed for the influence of magnesium in glycolytic pathway in their retinal tissue.The diabetic rats were divided into 3 groups:6 of them drank 0.5% Mgso4 solution every day,6 received intramuscular Mgso4 (0.05/kg)in half month interval,and the another 6 drank tape water every day.Six normal rats were employed as employed as nondiabetic control.The activity of the three crucial rate-limiting enzymes ralating to glycolytic pathway-hexokinase,phosphofructokinase and pyruvate kinase in retinal tissue of the rats was investigated after a period of 30days.The results revealed that the levels of the enzymes were significantly depressed in diabetic rats not taking magnesium,while the enzyme levels maintained nearly the same in diabetic rats taking magnesium,while the enzyme levels maintained nearly the same in diabetic rats taking magnesium as in the control group.This suggested that the glycolytic pathway in retinal tissue was disturbed in early stage of diabtes,and magnesium might play an important role in maintaining the normal metabolism of glucose. （Chin J Ocul Fundus Dis,1993,9:81-83）
Objective To review the research progress of magnesium and magnesium alloy implants in the repair and reconstruction of sports injury. Methods Relevant literature of magnesium and magnesium alloys for sports injury repair and reconstruction was extensively reviewed. The characteristics of magnesium and its alloys and their applications in the repair and reconstruction of sports injuries across various anatomical sites were thoroughly discussed and summarized. Results Magnesium and magnesium alloys have advantages in mechanical properties, biosafety, and promoting tendon-bone interface healing. Many preclinical studies on magnesium and magnesium alloy implants for repairing and reconstructing sports injuries have yielded promising results. However, successful clinical translation still requires addressing issues related to mechanical strength and degradation behavior, where alloying and surface treatments offer feasible solutions. Conclusion The clinical translation of magnesium and magnesium alloy implants for repairing and reconstructing sports injuries holds promise. Subsequent efforts should focus on optimizing the mechanical strength and degradation behavior of magnesium and magnesium alloy implants. Conducting larger-scale biocompatibility testing and developing novel magnesium-containing implants represent new directions for future research.
Objective To investigate the differences in characteristics and susceptibility factors between infectious stones and calcium oxalate stones, and provide reference value for screening infectious stones in clinical work. Methods According to the results of analysis of stone components in the extracorporeal shock wave lithotripsy center of West China Hospital of Sichuan University between June 2014 and April 2017, 392 patients with infectious stones (including 56 patients with magnesium ammonium phosphate stones in group A and 336 patients with calcium carbonate apatite in group B) and 392 patients with calcium oxalate stone (group C) were selected to discuss the difference of clinical features by retrospectively analyzing the clinical data. Results The proportion of females, the long diameter of stones and the proportion of staghorn stones in group A [75.0%, (3.9±2.5) cm, 41.1%] were higher than those in group B [39.3%, (2.4±1.3) cm, 6.0%], and the proportion of females and the long diameter of stones in group A and B were larger than those in group C [30.1%, (1.9±0.7) cm]; the differences above were statistically significant (P<0.05). There was no significant difference among the three groups in surgically history or complicated factors of urinary tract such as ureteral stricture (P>0.05). The prevalences of diabetes, renal tubular acidosis and hyperlipidemia in patients with infectious stones were higher than those in group C. The prevalences of renal tubular acidosis and hyperlipidemia in group A (16.1%, 39.3%) were higher than those in group B (0.6%, 21.1%), the positive rate of urine culture in group A (58.9%) was higher than that in group B (20.5%), which were both higher than that in group C (8.9%); these differences were statistically significant (P<0.017). The bacteria cultured from urine were mainlyProteus mirabilis and Escherichia coli in group A, and Escherichia coli in group B and group C. Conclusion Patients with large volume of stones, complicated with diabetes, renal tubular acidosis, hyperlipidemia and positive urine culture are more likely to have infectious stones.
Objective To systematically evaluate the effects of magnesium sulfate on postoperative pain and complications after general anesthesia. Methods A literature search was conducted in following databases as The Cochrane Library, EMbase, PubMed, EBSCO, Springer, Ovid, CNKI and CBM from the date of establishment to September 2011 to identify randomized controlled trials (RCTs) about intravenous infusion of magnesium sulfate during general anesthesia. All included RCTs were assessed and the data were extracted according to the standard of Cochrane systematic review. The homogenous studies were pooled using RevMan 5.1 software. Results A total of 11 RCTs involving 905 patients were included. The results of meta-analyses showed that compared with the control group, intravenous infusion of magnesium sulfate during general anesthesia significantly reduced the visual analog scale (VAS) scores at the time-points of 2, 4, 6, 8, 16, and 24 hours, respectively, after surgery, the postoperative 24 hours morphine requirements, and the incidents of postoperative nausea and vomiting (RR=0.61, 95%CI 0.40 to 0.91, P=0.02) and chilling (RR=0.29, 95%CI 0.14 to 0.59, P=0.000 7). Although the incidents of bradycardia (RR=1.93, 95%CI 1.05 to 3.53, P=0.03) increased, there were no adverse events or significant differences in the incidents of hypotension and serum concentration changes of magnesium. Conclusion Intravenous infusion of magnesium sulfate during general anesthesia may obviously decrease the pain intensity, and the incidents of nausea and vomiting and chilling after surgery, without increasing cardiovascular adverse events and risk of hypermagnesemia. The results still need to be confirmed by more high-quality and large-sample RCTs.
Tweenty-one SD rats with streptozotocin-induced diabetes were investigated for the influence of magnesium in cAMP level in the retina of the diabetic rats. The diabetic rats were divided into 3 groups: group 1, drinking tap hehwater; group 2, drinking 0.5% MgSO4 solution and group 3, receiving intramuscular MgSO4(0.1g/kg) once a month. In addition, group 4, a controlgroup of normal nondiabetic rats fed with tap water. In aperiod of 5 months examination, the growth and health conditions of diabetic rats were found to be nearly normal in group 2, 3 and 4, manifested by gaining weight and soft, smooth hairs on the skin, in contrast with loss in weight, rough hairs and even dying of infection in 2 of the diabetic rats in group 1. furthermore, the level of cAMP content in retina was found significantly higher in the diabetic rats taking Mg++ in spite of the route of administration(group 2, 3), as well as in the control group(group 4) than that of the diabetic rats which were fed with tap water. These results demonstrated that Mg++ might play an important role in improving the metabolism of diabetic rats including the retinal tissue by influencing the level of cAMP content, which is necessary in nuclear acid metabolism, protein synthesis, proliferation and differentiation, and other intracellular metabolic processes. （Chin J Ocul Fundus Dis,1992,8:141-143）