Biomechanical Analysis Of The Effect Of Pulsed Electromagnetic Field On The Repair Of Femoral Injury After Exercise

Objective:Skeleton in human body, being a kind of the important supporting organ which afford the key muscle attachment points and join points, provide effective support and the protection of important function for the internal space, and play an irreplaceable role in the human body normal exercise, and in the human body the completion of high quality life activities. As a result, the research about the bone morphology, structure, physiological function, metabolic characteristics and all kinds of disease's prevention has been launched widely and deeply. Fracture is one of serious complications associated with osteoporosis disease. At present, the most commonly used treatment fracture of the human body is surgery. However, the status of bone nonunion which attached with various reasons is still the important factors which influencing the fracture healing and functional recovery in the process of surgical treatment. Pulsed electromagnetic fields, being an important means of exogenous treatment of bone injury, has positive significance and play absorb the apoptosis of cartilage matrix at the same time promote the bony remodeling in the process of fracture healing.Method:In this study, SD male rats were regarded as the research object in this experiment, aerobic trained and untrained rats were respectively used as bone damage model to observe the intervention effect of recovery of pulse electromagnetic field. Osteogenic differentiation induced by mesenchymal stem cells under the pulse electromagnetic field parameters to determine the appropriate parameters of the pulse electromagnetic field, and applying to the trained and untrained bone injured rats. The animals were randomly divided into 5 groups, with 10 rats in each group, respectively:normal control group ?NC?, training control group, training control ?TC?, drilling injury group ?DC?, moving drilling ?TC?, motion drill hole electromagnetic intervention group ?TDE?. The effect of electromagnetic interference test, pentobarbital sodium anesthesia to be put to death, and according to the anatomical location were about to intercept the rat femur, Micro-CT scan analysis is used to the changes of the ultrastructure of the femur, three point bending test is used to analysis the change of the characteristics of biomechanics of bone, ultimately reflected pulse electromagnetic field on bone injury recovery effect, and the rat body weight, holding power and general index of the influence of the change detection of bone damage model.Results:1. Osteoblast induced condition of pulse electromagnetic field on proliferation of mesenchymal stem cells by CCK 8 experiments, it can be obtained between groups of absorbance value ?OD value? and cell proliferation, induced by using a pulse electromagnetic field interference in osteogenesis after Id,4d,7d. after 1 d, intensity is lmt,5mt, lOmt and 20mt does not appear significant difference; After the intervention treatment 4 d, compared with the control group, there was a significant difference when the intensity of 1mt ?p<0.05?, the intensity is 5mt, lOmt and 20mt does not appear significant difference; After the intervention treatment 7d, intensity of 1mt appeared significant difference ?p<0.05?,20mt appeared significant difference ?p<0.05?, the intensity is 5mt and 10mt no significant difference occurred.2. ALP detection between pulse electromagnetic field on osteoblast inducing differentiation of mesenchymal stem cells:through detection of ALP activity, it can calculate out in each group of mesenchymal stem cells under the effect of pulsed electromagnetic fields, which determine the pulse electromagnetic field on mesenchymal stem cells to the osteoblast differentiation. Compared with the control group, after the intervention in 4d/lmt appeared significant difference ?p<0.05?, other groups were not significant differences; After 7 d, strength for 1mt and 20mt are significant difference ?p<0.05?; After 14 d, lmt and 20mt are significant difference ?p<0.05?.3. The rat body weight, body length, holding power and bone results:compared with NC group, CT group weight increased, but there was no significant difference; DC group compared with TC group, weight was significantly lower than the DC group ?p<0.05?; Length of the rats in each group were not significant difference; Grip strength test results show that compared with NC group, the strength of TC group were significantly increased ?p<0.05?; DC group compared with TC group, the grip strength of DC group was significantly decreased ?p<0.01?, the DC group compared with NC group, there was no significant difference; TD group compared with TC group, grip strength showed significantly decreased ?p<0.05?; TDE group compared with DC group, the size of the grip strength significantly increased ?p<0.01?; The weight of the femur after 4 w exercise, or after modeling and 4 w electromagnetic field therapy, there was no significant change.4. The muscle tissue of rats weight between groups of the quadriceps muscle and heart weight and weight had no significant difference; TC group compared with NC group, the weight of the TC group of gastrocnemius show significantly increased ?p<0.05?, the TDE group compared with DC group, the group TDE gastrocnemius weight significantly increased ?p<0.05?;TC group compared with NC group, the weight of the soleus show significantly increased ?p<0.05?;DC group compared with TC group, the weight of the soleus significantly decreased ?p<0.01?;TD group compared with TC group, the weight of the soleus have significantly decreased ?p<0.05?; TDE group compared with DC group, the weight of the soleus have significantly increased ?p<0.05?.5. The rat serum index:total ALP in serum, blood phosphorus and calcium values have no significant change, but resistance to tartaric acid phosphatase appeared a significant difference, DC group significantly increased compared with NC group a ?p<0.01?, TD group compared with the TC group significantly increased ?p<0.01?, the TDE group no matter compared with DC or TD group are significantly increased ?p<0.01?.6. Three point bending test results:rats compared with TC group, TC, TD group and the maximum load of TDE group were present to varying degrees of significantly decreased ?p<0.01; p<0.01; p<0.05?; DC, NC group, compared to the DC group, the maximum load was significantly decreased ?p<0.01?. On stiffness of bone measurements showed that compared with the TC group, DC, TD group and TDE groups all have different degrees of significantly decreased ?p<0.01; p<0.01; p<0.01?; TC group compared with NC group, showing a significant increased ?p<0.05?. In terms of energy absorption, compared with NC group, DC and TD groups show different degree of decreased ?p<0.01;p<0.05?; Compared with the TC group, DC and TD group all have different degrees of significantly decreased ?p<0.01;p<0.01?; TDE group compared with DC group, the energy absorption value of bone have significantly increased ?p<0.05?. By testing the elastic modulus of bone showed that compared with NC group, DC and TD group all have different degrees of significantly decreased ?p<0.01,p<0.05?; Compared with the TC group, DC, TD group with the elastic modulus value of TDE group were different degrees of significantly decreased ?p<0.01;p<0.01; p<0.05?.7. The rat cancellous bone Micro-CT quantitative analysis:Micro-CT quantitative analysis, according to the results of TC group compared with NC group, Tb. N, BMD^trab and BV/TV are significantly increased ?p<0.05; p<0.05,p<0.05?;DC group compared with NC group, Tb. Th and BMD^trab were significantly decreased ?p<0.05;p<0.01?;TD and TC group contrast, Tb. Th, BV/TV and BMD^trab are significantly decreased ?p<0.05; p<0.05;p<0.01?;TD group compared with DC group, Tb. N and BMD^trab are significantly increased ?p<0.05;p<0.05?;TDE group compared with DC group, Tb. N, Tb. Th, BV/TV and BMD^trab were significantly increased ?p<0.01; p<0.05; p<0.05, p<0.01?;TDE compared with TD group, Tb. N, Tb. Th and BV/TV has increased, but there is no significant difference, only BMD^trab show significantly increased ?p<0.05?.8. The bone density values of rat cortical bone:compared with NC group, in BMD^cort value of DC group was significantly decreased ?p<0.05?; Compared with the TC group, DC and TD group BMD^cort also present a significantly decreased ?p<0.01; p<0.05?; TDE group compared with DC group, cortical bone BMD^cort appear significantly increased ?p<0.01?; TDE group compared with TD group, rat femur BMD^cort show significant increase ?p<0.05?.9. The rat femur PEARSON correlation detection:PEARSON correlation test showed that the maximum load and BV/TV ?p<0.05?, BMD^trab ?p<0.05?, and SMI ?p<0.01? significant correlation; Stiffness and Tb. Sp ?p<0.05?, BV/TV ?p<0.05?, BMD^trab ?p<0.05?, and SMI ?p<0.01? significant correlation; Energy absorption with Tb. Th ?p<0.01?, BV/TV ?p<0.05?, BMD^cort ?p<0.05?, BMD^trab ?p<0.05?, and SMI ?p<0.05? significantly related; Modulus of elasticity with Tb. Th ?p<0.05?, BV/TV ?p<0.05?, BMD^trab?p<0.05?, and SMI ?p<0.05? showed significant correlation.Conclusion:1. Rats after 4w exercise training is not effective to eliminate the negative influence on the mechanics of bone injuries, whether the rats trained or not, the negative influence of biomechanics of bone properties are remarkable.3. In rats bone injury recovery, exercise training is better than that of rats without the effect of exercise training, this recovery advantage is not only reflected on the performance of the mechanical properties, but also reflected in the aspects including density and bone microstructure.4. The pulse electromagnetic field can increase the recovery rate of the femoral injury in rats after training. Mechanical properties of the femur and femoral microstructure has significant correlation, it can be used as a noninvasive detection of the choices of bone health.