The Related Safety Experimental Study Of Noval Biphasia Calcium Composite Bone Cement With A Negative Surface Charge

Background:The recent report shows that about 200 million osteoporosis patients among the world of which about 0.75% occur osteoporotic fracture in which osteoporotic vertebral compression fractures (Osteoporotic Vertebral Compression fracture, OVCF) has highest incidence. Traditional treatment including keep lie in bed lumbar external fixation and oral calcium medication, not only take a long time for treatment but also aggravate osteoporosis due to a bone loss caused by less movement thus lead to a heavy burden to patients and their families and the entire society. With the development of Vertebroplasty that infusion the bone cement into the fresh fracture vertebral body not only stable the pathological vertebral bodies but also played a significant analgesic effect thus the patient can early ambulate and reduce the incidence of complications. Clinical report shows that 70 to 80% patients after vertebroplasty has significant pain relief. But the current clinical vertebroplasty material is polymethylmethacrylate (polymethylmethacrylate, PMMA) playing a significant role in heat production in the coagulation process. Because it can burn the surrounding tissue such as nerve root and spinal cord after leakage. The pressure in the process of the injection and bone cement monomer can cause adipose embolus formation which can lead to pulmonary embolism and complications such as heart and lung function changes. From long-term point of view, bone cement will not be degraded in the body because it can’t be absorption, and parts of the bone tissue at the junction with the bone cement will gradually be absorbed, resulting in the decline of vertebral body strength and adjacent vertebral collapse fracture. For these reasons, looking for other types of bone cement has become an important part of the field of orthopedic research.British Biocomposities Company has produced a new type of negatively charged calcium sulfate/β-tricalcium phosphate bone cement (biphasic calcium composite bone cement with a negative surface charge, BCC) is the application of the Zata electric potential control technology, calcium sulfate and β-tricalcium phosphate composite into a new generation of bone cement.The experimental studies confirmed that calcium phosphate and calcium sulfate as a bone substitute material, and it is quite an ideal bone substitute materials, because after solidification it’s strength as normal cancellous bone. With good bone conduction and tissue compatibility and not generate heat during the curing process, biodegradable coordination with osteogenic activity in the bone remodeling process, and it is gradually replaced by normal bone. Calcium sulfate have a strong bone formation, but the degradation is relatively fast, usually in two to three months on degradation and absorption. The osteoblast of calcium phosphate is poor, but the degradation is relatively slow, about six to eight months of degradation and absorption. The BCC bone cement have the respective advantages of calcium sulfate and calcium sulfate and avoid the possible complications of the injection of bone cement. It has a theoretical advantage, a possible alternative to PMMA bone cement. The BCC bone cement usually can be injected, used for osteoporosis vertebral body enhancement surgery, violent fracture of the thoracic and lumbar vertebral augmentation, and the enhancement of the pedicle screw surgery. However, there is no report and clinical data about BCC bone cement at present.Objection:1. To provide a new implant material for the treatment of osteoporosis and compression fractures in clinic. Test its safety and biocompatibility in vitro and in vivo.2. Establish model of vertebral compression fractures in vitro. Using BCC bone cement to do a vertebroplasty surgery then test its biomechanics and the leakage of the BCC bone cement.3. To establish the model of pulmonary embolism induced by BCC bone cement. Test the change of Hemodynamics and blood gas also the change of coagulation indicators caused by BCC bone cement.Methods and materials:1. BCC bone cement compatible studyIsolation and culture of human fibroblasts with BCC bone cement extract liquid then using MTT assay draw the cell proliferation growth curve. Infusion BCC bone cement extract liquid into the rabbit ear vein then measuring the temperature of the rabbit anal. BCC bone cement specimen implanted into rabbit muscle to observe the inflammatory response and fibrous capsule formation. Evaluate biocompatibility of the BCC bone cement by Hemolysis detection and other methods.2. The BCC bone cement vertebroplasty studyThoracolumbar spine specimens (T11-L2) obtained from four elderly corpses. Do x-ray films to exclude congenital malformations fractures and tumors. Test bone mineral density of each specimen to confirm that these are osteoporosis specimens. To free these specimens into 16 single vertebral bodies randomly divided them into 2 groups-the BCC bone cement group and the PMMA bone cement group. Flex load the specimens using biomechanical material testing machine to establish the model of vertebral compression fracture. Shooting x-ray after inject bone cement by 2ml/min into vertebral bodies unilateral. Obtain strength and stiffness data after recompress the vertebral bodies. Initial compressed and recompress data were all measured. Observation of the leakage areas:including the spinal canal front of the vertebral body side of the vertebral body and end plate. Biomechanical test of strength and stiffness of enhanced vertebral body.3.Study of pulmonary embolism in cardiopulmonary caused by BCC bone cement leading to the Hemodynamic change.Injection of the BCC bone cement and PMMA bone cement into pulmonary trunk then continuous monitoring of hemodynamic parameters including mean pulmonary arterial pressure mean arterial pressure heart rate PaO2 PaCO2 PH HCO3- and BE. Lung specimens examined by CT and three-dimensional reconstruct the shape of cement in blood vessels.STATISTICAL ANALYSISThe data obtained was represent by mean ± standard deviation (x±s), using SPSS 13.0 software package for statistical analysis. P＜0.05 represent significant differences.Results:1 Fibroblast grows well in culture medium with bone cement extraction liquid. Cell relative growth rate was between 90.1-100.4% that under level 1 of toxicity criteria which means BCC bone cement is basically non-toxic to cell growth. Hemolysis rate was between 0.074-1% that means there is no obvious hemolytic reaction in red blood cells after mixed with bone cement extraction liquid can meet the medical material hemolytic requirements. Body temperature of 6 rabbits increased (0.13 ± 0.07 ° C) no more than 1.4 ° C that means it can not cause heat production can meet the medical material requirements of non heat induction.2. Animal was in good condition and has no wound infection also without implants discharge after surgery. There were a small number of lymphocytes and fibroblasts around implant but no macrophages two weeks after surgery. Initial formation of the fibrous capsule was at 8 weeks after surgery meanwhile still visible a few lymphocytes inflammatory cells around them. Not only the lymphocytes reduce or even disappear and the formation of fibrous capsule was stable that the thickness of the capsule is less than 30mm plus there was no thickening trend also inflammatory cells and fibrous capsule evaluation all in Class Ⅰ but also the surrounding muscle tissue has always been to maintain the normal structure and there is no infection or death also the degradation and absorption of the bone cement is of great signification between 16-24 weeks after surgery. BCC bone cement was completely absorbed and there is no inflammation fibrous scar formation and calcified nodules around implant also inflammatory cells and fibrous capsule evaluation all in Class I meanwhile the surrounding muscle tissue has always been to maintain the normal structure in contrast there is no absorption of PMMA bone cement 24 weeks after surgery.3. Six vertebral body which stands 75% of in total in BCC bone cement group were leakage higher than that 50% in PMMA bone cement group.4. Maximum vertebral load and stiffness before fracture of BCC group is 1726± 287.3N and 1120.1±157.8N/mm respectively. Maximum vertebral load and stiffness before fracture of PMMA group is 1756.4±311.1N and 1103.9±154.2N/mm respectively. There is no statistical difference between these two groups as to maximum vertebral load and stiffness before fracture. Maximum vertebral load and stiffness after surgery of BCC group is 3161.8±882.9N and 933.8±231.0N/mm respectively. Maximum vertebral load and stiffness after surgery of PMMA group is 3267.1±981.4N and 975.3±255.1N/mm respectively. There is statistical difference between these two groups as to maximum vertebral load after surgery and there is no statistical difference as to stiffness after surgery.5. The change of mean pulmonary arterial pressure in BCC group at lOmin 20min 30min 40min 50min 60min is lower than that in the PMMA group (p<0.05). The change of mean arterial pressure in BCC group at 10min 20min 30min 40min 50min 60min is lower than that in the PMMA group (p<0.05). The change of heart rate in BCC group at 10min 20min 30min 40min 50min 60min is lower than that in the PMMA group (p<0.05).6. The change of PaCO2 in BCC group at 30min 60min is lower than that in the PMMA group (p<0.05). The change of PaO2 in BCC group at 30min 60min is lower than that in the PMMA group (p<0.05). The change of HCO3- in BCC group at 30min 60min is lower than that in the PMMA group (p<0.05). The change of PH in BCC group at 10min 30min 60min is lower than that in the PMMA group (p<0.05). The change of BE in BCC group at 10min 30min 60min is lower than that in the PMMA group (p<0.05).7. The A-Ⅲ in BCC group at 10min 30min 60min is lower than that in the PMMA group (p<0.05). The D-Ⅱ polymer in BCC group at 10min 30min is lower than that in the PMMA group (p<0.05).Conclusion1. BCC bone cement has good biocompatibility and its end product is small particle with tiny size thus can be well absorb in body.2. The BCC bone cement has very good biological enhancement ability but it is easy to leakage when filling in the osteoporotic vertebral body.3. BCC bone cement can cause mean pulmonary artery pressure increase so as to mean arterial pressure and heart rate also can lead to hypoxemia hypercapnia and acidosis but the consequences is less serious than that caused by PMMA.