| ObjectiveTo investigate the agglutination strength of fixing the pig tibial fractures by using a new type of inorganic bone cement (Magnesium Phosphate Cement, MPC) in vitro. To explore agglutination strength, the speed of absorption and degradation, the effect on the fracture healing process of Magnesium Phosphate Cement (MPC) and the changes of electrolyte ion concentration (phosphorus, magnesium, calcium) in pigs.Methods1.60 pig tibias were made 1 cm2 fracture, and the defects covered with MPC had been compressed firmly together for about 15 minutes. Under the room temperature and the 37℃ã€simulated body fluid terms, the agglutination specimen of pig tibias were setted, after 30 minutes,2 hours and 24 hours, the biomechanical strength of tension was measured.2. Tibial fracture model of 15 healthy adult pigs was caused by a chisel. The test side was fixed with MPC, and the control side was fixed with bolts, postoperative without making external fixation. The effectiveness of treatment was investigated by macrography, imageological diagnosis and microscope, and the changes of serum electrolyte levels in 1 month,3 months and 6 months after surgery.Results1. The average tensile strength between the two pig tibias at 30 minutes,2 hours, 24 hours at room temperature and 37℃ simulated body fluid was 98.310±14.961N/cm2 and 91.330±9.104N/cm2,117.330±22.929N/cm2 and 114.280±12.193N/cm2, 118.780±20.007N/cm2 and 119.590±20.958N/cm2 after MPC setting. The differentiation between the groups under two condition after same setting has no statistical meaning (P>0.05).30 minutes and 2 hours later at roome temperature and 37℃〠Simulated Body Fluid, the average tensile strength between the pig tibials was account for 82.8% and 76.4%,98.8% and 95.6% of the ultimate strength respectively.2. The blood electrolyte ion concentration was tested preoperative and postoperative. And the analysis of variance was conducted to group data. There was no significant difference of phosphorus, magnesium and calcium ion concentration in pigs’ blood before surgery and at 1 month,3 months and 6 months after surgery.3. After 1 month of fixation, all pigs’tibia fractures were unioned without delayed union. The same effect was seen in the control groups fixed with bolts. However, the malunion happened in one pig’s tibial fracture at 3 months. MPC was degraded gradually and the speed of MPC absorption and degradation was similar to the fracture healing process, and the process of bone union was same to normal.Conclusion1. New type of inorganic bone cement should have some certain adhesive ability to fix fractures, it can achieve the best bonding strength at room temperature when the clinical surgery conducting, and the setting process is suitable to the clinical operation, so MPC might potentially be used for fractures treatment.2. New type of inorganic bone cement has some agglutination strength in the body, and the changes of serum electrolyte levels were minimal. The speed of degradation is similar to the process of bone healing, so that it has no effect on the fracture healing process.3. New type of inorganic bone cement can realize the direct bonding between bone and bone. Its strong adhesive force is easy to be absorbed. Therefore, MPC has a further prospect of development as a biological material. |
