The knee joint is a weight-bearing joint with a large range of motion, carrying almost the entire body weight. After middle and old age, the knee joint is the most prone to aging due to years of wear and tear. The aging knee joint is often prone to osteoarthritis in the fall and winter, causing mobility problems. Osteoarthritis of the knee is also commonly known as “old cold leg”. In the fall and winter, because of the low temperature and air pressure, the latent cold in the body and the cold air outside are superimposed on each other, and this kind of disease is especially prone to recurrence. Winter treatment to treat the symptoms of the main, not to eliminate the root cause of the disease. In contrast, in summer, when the natural temperature is the highest, the body’s yang energy is at its peak, the qi of the meridians is fluid, the acupuncture points are sensitive, and there are fewer climatic factors affecting the onset of the disease. The hottest days of the year, the three volt days, are when the cold is relatively weak, and it is the easiest time to clear the cold, when the symptoms of the disease are usually mild, and there is enough time to support the root, improve the immune system and achieve the purpose of healing. Chinese medicine uses specially formulated drugs to moxibustion at specific points on the knee to stimulate the acupuncture points and the penetration and absorption of the drugs to unblock the meridians and blood, warm the meridians and open the channels. The moxibustion methods commonly used include warm needle moxibustion, spacer moxibustion, scar moxibustion, wheat grain moxibustion, and solid press moxibustion. This method is based on the principle of “treating the symptoms when it is urgent, and treating the root cause when it is slow”, and it is called “winter disease and summer treatment” to treat chronic diseases that are prone to develop or aggravate in winter and remit in summer. The treatment with acupuncture is called “voltaic acupuncture” or “voltaic moxibustion” therapy. It is a method of treating osteoarthritis of the knee joint by applying moxibustion to the acupuncture points of the knee and extra meridian points, such as Blood Sea, Liang Qiu, Calvary, and Foot San Li, on the day of three volts.