This is a multicentre, randomised, single blinded, parallel-group design clinical trial to assess the effect of moxa smoke in the treatment using moxibustion for Knee Osteoarthritis.

Aim: To assess the effect of moxa smoke in the treatment using moxibustion for knee osteoarthritis.

Design: This is a multicentre, randomised, single blinded, parallel-group design clinical trial. 138 eligible participants will be randomly allocated into 2 groups (moxibustion group or smoke-free moxibustion group) with a 1:1 allocation ratio, and receive 12 sessions of moxibustion treatment over a period of 4 weeks, three sessions per week. Each session will last 30 minutes. The whole study period is 13 weeks, with a 1 week run in period, 4 week treatment phase, and 8 week follow-up phase.The participants will receive moxibustion treatment at three acupoints (EX-LE04,ST35,ST36). In moxa-free smoke moxibustion group, investigators place a purification device(Shenzhen Conyson Electronic Technology Co, Ltd,C200 moxa smoke purification device,Shenzhen,China) at the top of the moxibustion to remove the moxa smoke. The primary measurement outcomes are the mean change in the global scale value of the Western Ontario and McMaster Universities Osteoarthritis Index(WOMAC) pain and function scores from baseline to 4 weeks. The secondary outcomes are the Visual Analogue Scale (VAS) and the patient global assessment. Investigators will assess participants at the second visit (before starting moxibustion treatment) and at the 2, 4, 8, and 12 week respectively after the baseline.

Inclusion Criteria:

Participants meeting the following criteria will be included:

1. aged between 40 and 75 years
2. diagnosed with knee osteoarthritis formulated by the American College of Rheumatology (ACR).
3. the average severity of knee pain not more than 7 points on a visual analogue scale for most days during the past month
4. agree not have the paregoric during the whole treatment phase
5. willingness to participate in a randomized study and to sign the informed consent form.

Exclusion Criteria:

Participants will be excluded if they have these experiences:

1. inflammatory diseases, including rheumatoid arthritis, cancer, traumatic injury that might be related to the current knee pai
2. autoimmune disease, uncontrolled hypertension
3. diabetes mellitus requiring insulin injection
4. life-threatening cardiovascular or neurological events within the past year
5. chronic respiratory disease,a haemorrhagic disorder
6. alcohol or drug addiction
7. an active infectious disease including tuberculosis
8. a significant knee joint deformity
9. knee replacement surgery for the affected knee
10. knee arthroscopy within the past year
11. steroid injection in the knee joints within the past 3 months
12. injections in the knee joints or joint fluid injection within the past 6 months
13. accept acupuncture, moxibustion, cupping, or herbal medicine within the past 4 weeks