Use of infrared thermography for the diagnosis and grading of sprained ankle injuries

Abstract

Ankle joint sprains are a common medical condition estimated to be responsible for 15–25% of all musculoskeletal injuries worldwide. The pathophysiology of the lesion can represent considerable time lost to injury, as well as long-term disability in up to 60% of patients. A percentage between 10% and 20% may complicate with chronic instability of the ankle joint and disability in walking, contributing to morbidity and poor life quality. Ankle sprains can be classified as grade I, II, or III, based on the extent of damage and number of ligaments affected. The diagnostic grading is important for setting further treatment and rehabilitation, since more severe injuries carries risk of recurrence, added morbidity and decrease in life quality.The aim of this work was to evaluate the adequacy of infrared thermography as a potential complimentary diagnostic tool of the distinct lesions grades. Evaluation of different thermographic values of the ankle region (in both affected and non-affected foot) was conducted for this purpose.The principal results to be highlighted are that some of the regions, namely anterior view for non defined time after injury analysis, and anterior, frontal, posterior and anterior talofibular ligament regions and proximal calcaneofibular ligament regions in acute lesions (herein defined as less than 6h post-traumatic event) presented consistent profiles of variation. The analyses were performed considering affected and non-affected ankles results on plotted graphics representing termographic evaluation and grading of these lesions performed using ultrasound by experimented medical radiologists. An increase in temperature values was observed when progressing from mild to severe ankle sprain injuries, with these regions presenting lower values for the affected ankle when compared to the non-affected ankle in all the analysis performed. The remaining analysed regions did not present the same variations. Statistical analysis using Kruskal–Wallis tests for non-parametric samples, however, did not confer statistical significance to the differences encountered in the graphics analysis (p>0.05).The major conclusions were that thermographic analysis of ankle sprain injuries might have some potential to be used clinically, especially in acute settings such as those that occur in hospital emergency areas and in sports practice. There is currently no practical technology to be used for grading ankle sprain lesions, with the gold standard being magnetic resonance imaging. Thermography provides results rapidly and without the need for extensive equipment operating expertise. Based on scientific data present in the literature, this is the first description of the use of this technology with such an objective regarding ankle sprain lesions. Further work is needed, nonetheless, to amplify the sample number with the herein chosen parameters and possibly use dynamic thermography.