Evaluating physiological progression of chronic tibial osteomyelitis using infrared thermography

Abstract

Purpose: Medical infrared thermography (IRT) was used as a complementary means for the clinical evaluation of musculoskeletal trauma and progression of chronic tibial osteomyelitis. Methods: Twenty-two adult patients with a medical diagnosis of chronic tibial osteomyelitis were followed up by IRT performed along with standard radiography. Thermal data of the affected limb were compared with those of the healthy contralateral limb based on the thermal profile of the lower limbs as per the medical thermography guideline (32 °C). Data were acquired in the following regions of the lower limb: proximal tibia, diaphysis, and distal tibia, using a FLIR infrared camera, and data were processed using MATLAB®. Results: For patients with active infections, an increase in the average temperature of the affected limb above + 1.0 °C was observed when compared with the temperature of the contralateral. The wound region of the patients showed an increased temperature (32.3 °C) compared with the temperature of the contralateral (31.4 °C). In contrast, in latent infections, the thermal differences were small, generally below 0.3 °C, and thus were within the threshold of normality. In contrast, in areas diagnosed with reduced blood supply, the affected limb showed an average temperature up to − 5.7 °C below normal. Additionally, the initial temperature range (26.5 to 34.5 °C) decreased during the treatment to 29.8 to 34.1 °C, indicating a convergence toward normality. Conclusion: IRT has significant potential as a complementary imaging modality in the follow-up of patients with bone lesions with a diagnosis of osteomyelitis as it does not use ionizing radiation, thus allowing repetitive use as desired. Thermal images show important physiological information related to vascularization necessary for bone repair, as well as provide a good indication of the boundary of the infected area, adjacent to the trauma, which is useful for positioning the radiography equipment. However, it should be noted that IRT cannot replace other medical imaging techniques, as it provides information about the skin and cannot directly evaluate the interior of the body.