Experimental Study Of Accelerating Fracture Healing With High-voltage Electrostatic Therapy

ObjectiveTo observe the effects of high-voltage electrostatic therapy on fracture healing, explore its mechanism and provide theoretical evidences for the use in fracture patients.MethodsForty-eight (3months old) male SD rats weighted250to300gram were enrolled. Animal model of cortical bone defect in right proximal tibia of rats were performed under sterile operating conditions, and then forty-one succeed rats were randomly divided into experimental group (21rats) and control group (20rats). The experimental group were given high voltage electrostatic therapy (Healthtron AC high voltage electrostatic therapeutic equipment with a voltage of30kV, current less than0.5mA, and frequency of50Hz)30minutes daily while the control group had sham exposure also30minutes daily. Each group were randomly divided into day7, day14, day21, and day28four subgroups with5rats each (while in day14experimental group there were6rats) before treatment, then rats of relevant subgroup in each group were sacrificed at day7,14,21, and28. After blood collection, the right tibiae and fibula of each animal were procured with muscle and soft tissue removed, the bone mineral density of the callus at the fracture point was measured using dual X-ray energy absorptiometry (DEXA). Then the callus were cut down and fixed, decalcificated and sliced for histological and immunohistochemistry observation. At the same time the serum osteocalcin and bone alkaline phosphatase were also detected by the way of ABC-ELISA.Results1. The BMD examination showed that callus BMD in experimental group were higher than those in control group at day14and day28.2. Serum osteocalcin and bone alkaline phosphatase in experimental group were higher at day14and day21, with osteocalcin still higher at day28.3. Histological examination showed that at day7, the hematoma absorption and organization appeared earlier in experimental group than those in control group, with remarkable osteoblast and chondroblast proliferation. At day14and day21, both intramembranous ossification and entochondrostosis in experimental group were much faster than those in control group. At day28, trabeculas were mostly fused and no cartilage island can be seen in the experimental group, while in control group, trabecular bones were still detached with several residual cartilage islands among them.4. Immunohistochemical test showed that the expression of collagen Ⅱ in experimental group were significantly higher than those in control group at day7and day14, and the expression of collagen I in experimental group were a little higher than those in control group at day7.Conclusion1. In the earlier period, High voltage electrostatic therapy may accelerate hematoma absorption and organization, and lead to an earlier appearance of osteoblasts and chondroblasts.2. High voltage electrostatic therapy can accelerate osteoprogenitor cell differentiation, and promote osteoblasts and chondroblasts proliferation as well as bone matrix proteins synthesizing and mineralization, and finally, lead to fracture healing earlier.3. High voltage electrostatic therapy can also promote bone remodeling in the late phase of fracture healing by the way of accelerating maturation of trabecular bones4. Our experiment thus provides a theoretical evidence for the clinical use of high voltage electrostatic therapy in fracture patients.