Effect of static magnetic field and platelet-rich plasma on fracture healing in rabbits: A comparative experimental study

Introduction

Fracture is defined as a break in the continuity of bone with or without displacement of fragments (Tyagi and Singh, 2017) [10] . Fracture healing is a complex biological process involving cellular proliferation, biochemical reactions, and tissue remodeling. Healing of fractures generally occurs through sequential stages including inflammation, soft callus formation, hard callus formation, and remodeling. Although bone possesses an inherent capacity for regeneration, several therapeutic interventions have been developed to accelerate and improve the quality of healing. Various methods such as bone grafting, hydroxyapatite implants, ultrasound therapy, electrical stimulation, and magnetic field therapy have been employed to enhance fracture repair (Oryan et al., 2013) [7] . Among these modalities, static magnetic field therapy and platelet-rich plasma have gained considerable attention because of their regenerative and osteogenic properties (Wang et al., 2023) [11] . Magnetic fields are known to stimulate endothelial proliferation, osteoblastic differentiation, collagen synthesis, and matrix calcification (Cho et al., 1999) [1] . Static magnetic field therapy improves blood circulation, oxygen availability, and calcium ion deposition at the fracture site, thereby enhancing callus formation and tissue repair (Gujjalapudi et al., 2016) [2] . Platelet-rich plasma (PRP) is an autologous concentration of platelets enriched with growth factors and cytokines. When applied at the fracture site, PRP releases bioactive molecules that stimulate angiogenesis, cellular proliferation, and bone regeneration (Wroblewski et al., 2010) [12] . Keeping these beneficial effects in view, the present investigation was designed to evaluate and compare the effects of static magnetic field, platelet-rich plasma, and their combined application on fracture healing in rabbit.

Materials and Methods

The present study was conducted on healthy adult male New Zealand White rabbits of similar age at College of Veterinary Science and Animal Husbandry, Rewa. The animals were procured from certified animal house and was maintained on standard diet and ad libitum water. Seven days acclimatization period was provided to the animals prior to the initiation of the experimental procedures. Group D received a combination treatment consisting of splint immobilization, static magnetic field therapy, and plateletrich plasma administration.

Anaesthesia and surgical procedure

The rabbits were anesthetised by inducing using xylazine hydrochloride @ 5 mg/kg body weight intramuscularly followed by ketamine hydrochloride @ 50 mg/kg body weight intramuscularly. The anterolateral aspect of the radius was aspetically prepared before the surgery. Animals were positioned in lateral recumbency. The forelimb was painted with povidone iodine and an incision was given on lateral aspect between elbow and carpal joint. The muscles were separated using artery foreceps to visualize radius bone. A complete transverse fracture was created in the midshaft region of radius using an orthopedic wire saw through gentle to-and-fro movements. The muscles were sutured using absorbable suture material in simple continuous fashion and skin was sutured using non absorbable suture material in simple interrupted pattern. Post-operatively the rabbits were treated with enrofloxacin @ 5mg/kg and meloxicam @ 0.5mg/kg for three days. Immediately after surgery wooden splints were applied medio-laterally to the test limb for immobilization. Radiographic evaluation was done for the assessment of healing.

Application of static magnets

Two neodymium permanent magnets measuring 20 mm × 5 mm × 2 mm. were fixed medially and laterally for the duration of six hours daily at the fracture site using bandages.

Preparation and application of platelet rich plasma

Platelet-rich plasma was prepared following the modified double centrifugation method described by Jeong et al. (2020) [5] . Blood was initially centrifuged at 160 × g for 10 minutes to separate plasma and buffy coat. The separated fraction underwent second centrifugation at 400 × g for 10 minutes. Platelet-poor plasma was discarded and the remaining platelet-rich fraction was collected as platelet rich plasma (PRP). Prepared PRP was transplanted directly at the fracture site on 0, 7 th and 14 th postoperative days (Jee et al., 2016) [4] .

Application of platelet rich plasma static magnetic field

Statistical analysis

The data was analysed by employing statistical method as described by Snedecor and Cochran (1968) [9] using version 20 of SPSS software.

Results and Discussion

Radiographic Findings

In the present study, radiographic examinations were performed using 8 x 10″ radiographic films with exposure factors of 56 kVp, 10 mAs, and a focal film distance (FFD) of 90 cm (Singh et al., 2009) [8] . Radiographs were taken on the 0, 14 th , 28 th , 42 nd and 56 th postoperative days to evaluate callus formation and fracture union, following the protocol described by Hammer et al. (1985) [3] . In present study radiographic examination revealed accelerated callus formation and earlier fracture union. Periosteal reaction and bridging callus formation appeared. On postoperative day 42, radiograph demonstrated advanced callus formation with evidence of radiographic union in most animals. Complete radiographic union was observed by 56 th postoperative day. The enhanced radiographic healing observed in magnetic field-In the present study, radiographic examinations were performed using 8 x 10″ radiographic films with exposure factors of 56 kVp, 10 mAs, and a focal film distance (FFD) of 90 cm (Singh et al., 2009) [8] . Radiographs were taken on the 0, 14 th , 28 th , 42 nd and 56 th postoperative days to evaluate callus formation and fracture union, following the protocol described by Hammer et al. (1985) [3] . In present study radiographic examination revealed accelerated callus formation and earlier fracture union. Periosteal reaction and bridging callus formation appeared. On postoperative day 42, radiograph demonstrated advanced callus formation with evidence of radiographic union in most animals. Complete radiographic union was observed by 56 th postoperative day. The enhanced radiographic healing observed in magnetic field-treated animals may be attributed to increased vascularization, collagen synthesis, osteoblastic differentiation, and calcium ion deposition. PRP likely accelerated healing through release of growth factors that promoted angiogenesis and osteogenesis (Meglei et al., 2025) [6] .

Conclusion

The present study demonstrated that static magnetic field therapy and platelet-rich plasma individually enhanced fracture healing in rabbits. However, combined application of static magnetic field and platelet-rich plasma produced superior healing outcomes compared to either therapy alone. The combination therapy resulted in improved radiographic union. Therefore, combined application of static magnetic field and platelet-rich plasma may be considered an effective therapeutic strategy for enhancing fracture healing in clinical veterinary practice.

References

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