Thermal analysis of the muscle-bone interface in test samples after the use of therapeutic ultrasound

Abstract

Introduction: Ultrasound used in diathermic therapies aims to achieve temperatures between 40 and 45°C, since temperatures above 45°C are known to cause tissue necrosis and burns. Many studies have been conducted to investigate the effect of therapeutic ultrasound in the presence of metallic implants, using phantoms (test samples) and in vivo and ex vivo animal models. In most of these studies, the ultrasound probe is fixed in one area, while in clinical practice, it is recommended that it be moved to avoid possible local overheating. Objective: To analyze the thermal field at the muscle-bone interface in phantoms in the presence or absence of metallic implants after the application of therapeutic ultrasound. Methods: Phantoms composed of layers simulating fat and muscle, and a layer of beef rib bone, with and without a titanium metallic implant, were prepared. The experiment in-volved different intensities (1.0, 1.5, and 2.0 W/cm2) and exposure times (5 and 10 minutes), common in clinics, with linear scanning of the probe. Results: The experiments indicated that the muscle/implant interface heated less than the muscle/bone interface, especially at intensities of 1.5 and 2.0 W/cm2, after 5 and 10 minutes of treatment. Conclusion: The results suggest the possibility of using therapeutic ultrasound in patients with metallic implants, encouraging future research to develop evidence-based protocols and safe recommendations in physiotherapy.