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

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.

Inclusion criteria

Adults aged 55 to 65 years, male or female. Diagnosis of knee osteoarthritis with radiographic evidence (Kellgren-Lawrence grade 2 or higher).

Knee osteoarthritis grade II or III according to the American Rheumatism Association (ARA) classification criteria.

History of moderate to severe knee pain on most days during the past month. Able and willing to provide written informed consent and comply with study procedures.

Exclusion criteria

Other diseases affecting the knee, such as rheumatoid arthritis, ankylosing spondylitis, fibromyalgia syndrome, or chronic fatigue syndrome.

Use of steroid medication or acupuncture or moxibustion treatment within the previous 3 months.

Intra-articular hyaluronate injection within the previous 6 months. Arthrocentesis or arthroscopy within the previous 1 year. Knee or hip replacement surgery, or planned joint replacement surgery during the trial period.

Use of other external treatments during the trial (e.g., topical medication for knee pain).

Body mass index (BMI) greater than 30 kg/m². Lower-limb fracture or injury affecting function. Neurological disorders or nerve root compression affecting the lower limb.