Are Clinical Symptoms Of Running Overuse Injuries Associated With Thermographic Response? A Proof-of-concept Study

Abstract

Medical infrared thermography (MIT), a non-radiating imaging technology, detects changes in skin temperature. Musculoskeletal injuries result in blood flow changes which may produce patterns of associated changes in skin temperature that can be visually detected by MIT. PURPOSE: To determine if clinical symptoms of distal lower extremity overuse injuries in runners are associated with visually detectible changes in MIT. METHODS: 29 competitive distance runners (age 18-25y, running >25 miles per week) enrolled and participated. Once weekly, runners reported to lab for MIT photos of bilateral lower limbs taken with an infrared camera. Prior to MIT, runners acclimatized to lab conditions for 15 minutes and the camera was calibrated to the room temperature and humidity. A modified Oslo Sports Trauma Research Centre (OSTRC) overuse injury questionnaire was used for athlete-reported musculoskeletal symptoms and problems. MIT photos and OSTRC scores were obtained on a weekly basis for 8 weeks. Runners’ photos were grouped into those with no reports of any lower extremity problems (Controls: OSTRC = 0, n=5); and those with reports of significant lower extremity problems (Injured: OSTRC >50, n=7). Photos from each group were placed into an online viewer and evaluated by 7 blinded clinicians. For the injured group, a photo from the week of the highest reported OSTRC score was paired with a baseline (OSTRC <25) photo. For the control group, two uninjured photos were paired. The reference photo for each pair was labeled. The order of photos (control vs. injured) was randomized and reviewers were not provided the number of included injured runners. Clinicians visually inspected 12 image pairs and decided whether or not the photo suggested a lower extremity problem existed. Diagnostic accuracy statistics were computed for each evaluator. RESULTS: The median (interquartile range) for the seven evaluators were: sensitivity=0.43 (0.29), specificity=0.60 (0.2), positive likelihood ratio=1.43 (0.0), negative likelihood ratio=0.71 (0.18). CONCLUSIONS: Low diagnostic accuracy and considerable inter-rater variability suggests evaluator training of MIT interpretation is necessary to accurately confirm or disconfirm presence of injury based on MIT findings.