Infrared thermal imaging reveals distinct patterns in adolescent anterior knee pain: A pilot study.

Purpose: The two most common types of anterior knee pain (AKP) in adolescents are patellofemoral pain (PFP) and Osgood-Schlatter disease (OSD). Accurate diagnosis is essential to guide treatment, but can be challenging due to overlapping clinical features of these two conditions. Infrared thermography (IRT) offers a noninvasive method to detect physiological differences such as local inflammation or altered perfusion. The aim of this exploratory study was to evaluate whether IRT can detect distinct thermal profiles in adolescents with unilateral PFP or OSD and explore its potential as a supplementary diagnostic tool. Methods: This within-subject study included 28 adolescents with unilateral AKP (17 with PFP, 11 with OSD) who underwent infrared thermography. Mean skin temperatures were recorded for both symptomatic and contralateral knees, and side-to-side differences were calculated for each participant. These individual asymmetries were then summarised descriptively within each diagnostic group and compared between groups. Results: In the OSD group, symptomatic knees exhibited higher skin temperatures than contralateral knees (mean ΔT = +0.48 ± 0.47°C 95% confidence interval [CI]: 0.16-0.80), whereas in the PFP group, symptomatic knees showed lower temperatures (mean ΔT = -0.78 ± 90°C, 95% CI: -1.25 to -0.32). The between-group contrast corresponded to a large standardised mean difference (Hedges' g = 1.58, 95% CI 0.71-2.45), indicating distinct condition-specific thermal patterns. Conclusion: Infrared thermography revealed contrasting thermal asymmetries in adolescents with PFP or OSD. These preliminary findings suggest that IRT may help characterise distinct thermal patterns associated with AKP. Level of Evidence: Level III.