This is a two-armed randomised controlled pilot study that investigates the component efficacy of moxibustion for osteoarthritis of the knee. Participants will be randomised to receive either warm needle acupuncture or needle acupuncture. Participants and acupuncturists will be blinded to group allocation. The primary and secondary outcome measures are WOMAC and SF36 respectively. Qualitative interviews will be used to gather information on the patients' experiences and perceptions of the trial and the treatment provided.