Abstract
Pulsed Electromagnetic Fields (PEMF) is reported to encourage the healing of nonunion fractures. However, the mechanism by which this occurs is still not known. Wnt signaling pathways are believed to be important signaling pathways in bone formation. This study will evaluate the healing of delayed union femur fracture, given PEMF exposure. 48 Spraque Dawley rats were fracturized at the left femoral shaft. These rats were randomized into two groups: A control group (24 rats) and the PEMF group (24 rats). The PEMF group was given PEMF exposure of 1.6 mT, with a frequency of 50 Hz for 4 h every day for 5, 10, 18 and 28 days, while the control group was not given PEMF exposure. Consequently, on days 5, 10, 18 and 28 days after fracture, 6 rats from each group were sacrificed. Callus bone was used for histological and RT-PCR examination on the expression of Wnt10b, Wnt5a and β-catenin. Blood samples were taken to examine Alkaline Phosphatase (ALP) activity using the ELISA method. Hematoxylin Eosin (HE) staining results showed that in the initial phase of healing, fibrous tissue in the fracture gap of the PEMF group was less compared to the control group. In the PEMF group, ALP activity increased significantly on day 10. This is thought to be related to an increase in osteoblast activity in a bone matrix formation. Furthermore, RT-PCR examination results showed that Wnt10b, Wnt5a and β-catenin gene expression was higher in the PEMF group compared to the control group. It can be concluded that PEMF exposure is thought to accelerate delayed union fracture healing through the Wnt signal pathway.
Highlights
Various strategies have been used to encourage fracture healing, including the use of biological and biochemical methods
Histological examination at day 5 in both the control and Pulsed Electromagnetic Fields (PEMF) groups shows that the fracture gap is still clearly visible and dominated by hematoma, inflammatory cells, fibrin clot, granulation tissue and fibrous tissues with amorphous properties (Fig. 1)
At day 10 of observation, the callus in the PEMF exposure group was dominated by hyaline cartilage in the hypertrophy phase and bone, whereas only fibrous tissue and cartilage was observed in the control group (Fig. 2)
Summary
Various strategies have been used to encourage fracture healing, including the use of biological and biochemical methods Another method is the use of physics-based methods, such as Low-Intensity Pulsed Ultrasound (LIPUS) and Pulsed Electromagnetic Fields (PEMF) that have been widely studied and reported to encourage fracture healing (Kooistra et al, 2009). In a preliminary study using delayed union fracture rat model, PEMF exposure was reported to improve fracture healing based on radiographic examination and RUST score analysis (Dilogo et al, 2018). In vitro studies by Fu et al reported that single PEMF exposure was able to accelerate osteogenic differentiation from hBMSCs and increase the bone mineral formation and neo-vascularization (Fu et al, 2014).
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