Association Between Infrared Thermal Characteristics and Clinical Response to Fire Needle Therapy in Knee Osteoarthritis: A Retrospective Study

Abstract

Objective This study aimed to investigate whether baseline infrared thermography (IRT) features are associated with clinical response to fire needle therapy and evaluate their predictive value for identifying potential responders. Methods A retrospective study included 109 patients with early-to-moderate knee osteoarthritis receiving thermal imaging-guided fire needle therapy (January 2023–December 2025) and 50 healthy volunteers. Knee IRT was performed before treatment to record temperatures in four regions. Patients received six fire needle sessions over 2 weeks. Visual analog scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were assessed before and after treatment and at 6-month follow-up. Patients were classified into response and non-responder groups, and logistic regression was used to identify independent predictors of treatment efficacy. Results Baseline temperatures of the anterior, medial, and lateral knee regions were significantly higher in KOA patients than in healthy volunteers ( P <0.05). After treatment, VAS scores decreased from a median of 6–2, and WOMAC scores decreased from 54.2 ± 8.8 to 24.6 ± 12.1. At the end of the 2-week treatment course, the overall effective rate was 80.7% (88/109). The non-responder group showed a higher pretreatment anterior knee temperature difference than the responder group ( P <0.05). Multivariate analysis identified Kellgren–Lawrence grade III (odds ratio [OR] = 0.232, 95% confidence interval [CI]: 0.076–0.714, P = 0.011) and anterior knee temperature difference (OR = 0.150, 95% CI: 0.035–0.638, P = 0.010) as factors associated with lower odds of treatment response. Conclusion IRT features were associated with therapeutic outcomes of fire needle therapy in KOA. Pretreatment anterior knee ΔT may serve as a potential objective auxiliary indicator for identifying patients more likely to respond to fire needle therapy; its clinical utility warrants prospective validation.