This is a multicenter , double-blinded, double-dummy, randomized controlled clinical trial to evaluate the efficacy of moxibustion for osteoarthritis of the knee.

Aim: To evaluate the effectiveness of moxibustion treatment for patients with osteoarthritis of the knee, with respect to relieving pain, improving the dysfunction and improving their quality of life as well.

Design: A multicentre, double-blinded, double-dummy, randomized controlled clinical study will be performed in China. Eligible participants will be randomly assigned to moxibustion group (real moxibustion plus placebo gel) and the control group (diclofenac sodium gel plus sham moxibustion) with a 1:1 allocation ratio. Participants in both groups will receive 12 sessions of real/sham moxibustion in 4 weeks at 3 acupoints (ST35, EX-LE4, ST36 ). Either diclofenac sodium gel or placebo gel will be applied 4 g per knee 4 times daily for 4 weeks. 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 primary outcome measure will be the change of the global scale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at the end of the course. The secondary outcomes include the change of other subscales (pain, stiffness, and function) of WOMAC, Visual Analogue scale (VAS) and Patient Global Assessment (PGA). Safety will be assessed at every visit.

Inclusion Criteria:

• Male or female, aged between 40 and 75 years, with knee osteoarthritis diagnosed according to American College of Rheumatology criteria
• Radiologic confirmation of osteoarthritis in 1 or both knees (Kellgren-Lawrence score 2 or 3)
• Had knee pain in one or both knee(s) of longer than 3 months'duration
• The average severity of knee pain at least 3 points on a10-point of visual analogue scale(VAS)
• Never experienced moxibustion before this trial
• Participants who are willing to comply with our study protocol
• Participants who agree to sign the consent form

Exclusion Criteria:

• Subjects with serious diseases including cancer, uncontrolled hypertension, diabetes mellitus requiring insulin injection, life-threatening cardiovascular or neurological events, chronic respiratory disease, a haemorrhagic disorder and serious mental diseases
• Subjects had pain in the knee may caused by inflammatory, malignant, autoimmune disease or traumatic injury;
• Subjects received knee replacement surgery for the affected knee
• Subjects received knee arthroscopy within the past year, steroid or hyaluronic acid injection in the knee joints within the previous 3 months
• Subject who currently participate in another clinical trial
• Subjects received physiotherapy or other treatments for osteoarthritis knee pain (with the exception of non-steroidal anti-inflammatory drugs) during the previous 4 weeks;