Effects of Carbon Dioxide Infrared Laser Moxibustion on Pain and Function in Knee Osteoarthritis

Overview

Knee osteoarthritis is a prevalent degenerative joint disorder characterized by chronic knee pain, stiffness, reduced range of motion, and limitations in daily functional activities. Exercise therapy is widely recommended as a first-line conservative approach to reduce symptoms and improve physical performance; however, a substantial proportion of patients continue to experience persistent pain and functional impairment despite adherence to exercise-based rehabilitation. Carbon dioxide (CO2) infrared laser moxibustion is a non-invasive far-infrared thermal stimulation modality intended to reproduce the localized heating effects of traditional moxibustion without smoke or odor. It is hypothesized to enhance local microcirculation, support tissue oxygenation, and modulate inflammatory activity, thereby contributing to symptom relief and improved joint function. This double-blind, parallel-group randomized controlled trial will evaluate whether adding carbon dioxide (CO2) infrared laser moxibustion to a standardized knee osteoarthritis exercise program provides greater improvement than exercise alone. Eligible participants with radiographic knee osteoarthritis will be randomly allocated to either (1) an exercise-only program or (2) the same exercise program plus carbon dioxide (CO2) infrared laser moxibustion delivered over an 8-week treatment phase (24 sessions). Outcomes will be measured at baseline and at follow-up visits at Month 3 and Month 6 to determine changes in pain intensity measured by the Numerical Pain Rating Scale (NPRS), knee range of motion measured by goniometry, articular cartilage thickness measured by magnetic resonance imaging (MRI), and biochemical markers including bone alkaline phosphatase (BAP) and serum calcium.

This study is a double-blind, parallel-group randomized controlled trial examining the effectiveness of carbon dioxide (CO2) infrared laser moxibustion as an adjunct to exercise therapy in individuals with knee osteoarthritis. Knee osteoarthritis is a multifactorial degenerative condition involving mechanical stress, low-grade inflammation, and progressive joint tissue changes that contribute to pain, restricted movement, and functional limitations. Exercise therapy represents a core component of conservative management; however, residual symptoms are frequently reported, supporting the evaluation of additional non-pharmacological approaches. Carbon dioxide (CO2) infrared laser moxibustion is a non-invasive modality that delivers far-infrared thermal stimulation to predefined knee-related treatment points, intended to reproduce the therapeutic effects of traditional moxibustion without smoke exposure. Proposed mechanisms include enhancement of local microcirculation, modulation of inflammatory activity, neuromodulatory analgesic effects, and potential support of local tissue metabolism. Participants with radiographic knee osteoarthritis will be allocated to either a standardized exercise program alone or the same exercise program combined with carbon dioxide (CO2) infrared laser moxibustion delivered during an 8-week treatment period. Participants will be assessed at baseline, at the end of the 8-week intervention period, and during follow-up visits at Month 3 and Month 6 to evaluate short-term and medium-term changes in pain and knee-related outcomes. The findings of this study will contribute to the evidence base for rehabilitation strategies in knee osteoarthritis and inform the potential role of carbon dioxide (CO2) infrared laser moxibustion as an adjunct conservative intervention.