Effects of Low-Dose Microwave on Healing of Fractures with Titanium Alloy Internal Fixation: An Experimental Study in a Rabbit Model

Abstract

BackgroundMicrowave is a method for improving fracture repair. However, one of the contraindications for microwave treatment listed in the literature is surgically implanted metal plates in the treatment field. The reason is that the reflection of electromagnetic waves and the eddy current stimulated by microwave would increase the temperature of magnetic implants and cause heat damage in tissues. Comparing with traditional medical stainless steel, titanium alloy is a kind of medical implants with low magnetic permeability and electric conductivity. But the effects of microwave treatment on fracture with titanium alloy internal fixation in vivo were not reported. The aim of this article was to evaluate the security and effects of microwave on healing of a fracture with titanium alloy internal fixation.MethodsTitanium alloy internal fixation systems were implanted in New Zealand rabbits with a 3.0 mm bone defect in the middle of femur. We applied a 30-day microwave treatment (2,450MHz, 25W, 10 min per day) to the fracture 3 days after operation. Temperature changes of muscle tissues around implants were measured during the irradiation. Normalized radiographic density of the fracture gap was measured on the 10th day and 30th day of the microwave treatment. All of the animals were killed after 10 and 30 days microwave treatment with histologic and histomorphometric examinations performed on the harvested tissues.FindingsThe temperatures did not increase significantly in animals with titanium alloy implants. The security of microwave treatment was also supported by histology of muscles, nerve and bone around the implants. Radiographic assessment, histologic and histomorphometric examinations revealed significant improvement in the healing bone.ConclusionOur results suggest that, in the healing of fracture with titanium alloy internal fixation, a low dose of microwave treatment may be a promising method.

Enhancement of Apoptosis by Titanium Alloy Internal Fixations During Microwave Treatments for Fractures: An Animal Study

“…When applied to the subjects with titanium alloy implants in this study, this dose of microwave treatments caused apoptosis in the muscles Enhancement of Apoptosis by Titanium Alloy during Microwave Treatments around the implants. In previous experiments, we found that 25 W microwave treatment did not cause damage to the bone tissues and cells around titanium alloy internal fixations between the implanted and the non-implanted control group [13]. TUNEL assays of bone tissues also showed that 40 W microwave treatment also did not cause obvious damage to the bone cells in both the implanted group and the non-implanted control group (S1 Fig). The TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling) technique has been described as a sensitive method for the detection of apoptotic nuclei in tissues and the preferential staining of apoptotic strand breaks.…”

Low dose of continuous – wave microwave irradiation did not cause temperature increase in muscles tissue adjacent to titanium alloy implants – an animal study

“…Previous studies in vivo and in vitro suggested that a low dose of microwaves reduced edema [2,41]. It also reduced pain by facilitating the 'pain gate' mechanism [8,12].…”

Effect of 2100 MHz mobile phone radiation on healing of mandibular fractures: an experimental study in rabbits

“…In some studies, various RF exposures have been reported to result in burns in the tissues secondary to the increased temperature on the implanted metals. [41] It was reported that 900 and 1800 MHz plane waves can result in temperature rises around the implant with less than 0.25 C and 0.10 C, respectively. [42] On the other hand, compared to stainless steel, titanium alloy, which is frequently preferred in medical implants, have low magnetic permeability and electric conductivity.…”