”The hot sun is like fire, the king’s grandson shakes the fan”, this is Shi Nai’an’s writing of the summer heat situation. Today’s people seem to have long used the fan, air conditioning fans have become the main tool to avoid the heat. However, while we enjoy modern tools with abandon, please do not forget that they may have a hideous side to human health. The past decade has been the decade of “Bones and Joints”, an initiative of the World Health Organization to raise awareness of bone and joint diseases, especially osteoarthritis. Osteoarthritis (OA) is a common disease in the middle-aged and elderly, with many patients starting to suffer from the disease before the age of 40, with a prevalence of up to 50% in people over 60 and up to 80% in people over 75 in China. The main symptom of osteoarthritis is disability due to pain in the joints, with a disability rate of up to 53%, which seriously affects the survival and quality of life of patients. Osteoarthritis can affect all joints in the body, but the two major joints of the lower extremities, the hip and the knee, are the ones that have the most significant impact on the quality of life of patients. Osteoarthritis is essentially a joint disease caused by a variety of factors that lead to fibrosis, cracking, ulceration, and loss of joint cartilage, and this “aging” of the joint cartilage is usually irreversible. Other symptoms include enlargement of the joint area and a sensation of friction or friction sounds with movement, and in severe cases, significant joint weakness, pain and difficulty moving. If mild pain is a sign, then severe pain is a demon. Some patients may be unable to stand or walk during the day and have difficulty sleeping at night due to pain. To date, we do not know the exact cause of osteoarthritis, except that its occurrence is related to many factors such as age, obesity, inflammation, trauma, and genetics, and the treatment guidelines of each country list numerous treatment options to facilitate clinicians to select the appropriate measures to arrange the appropriate treatment for the local situation. In our clinical practice, we have found that knee warmth has a unique role in the prevention and treatment of osteoarthritis of the knee. Moreover, in modern lifestyles, keeping the knee warm in winter is not a problem, as thick winter clothing already “incidentally” keeps the knee joint warm; however, in summer, many people crave the pleasure of air conditioning and electric fans, and the exposed knee joint often bears the brunt, especially for young women in revealing clothing. To make matters worse, because of the widespread use of air conditioning, people move from one place to another, in fact, from one air-conditioned area to another, so that our precious bodies frequently “enjoy” the high and low external temperatures; many people are also accustomed to sleeping with the air conditioning on all night. In this way, the vulnerable knee joint is constantly exposed to this so-called “coolness”, which gradually becomes an important factor in the development of osteoarthritis over time. On the other hand, in many patients with clearly diagnosed OA, they follow the advice of their doctors and pay great attention to the warmth of the knee while actively treating it, achieving good results. Usually, patients are advised not to expose their knee joints directly in an air-conditioned environment, to avoid direct blowing of air conditioning and electric fans on the knee joints, to avoid wearing skirts and shorts as much as possible, and to wear long pants instead, and preferably to add thin, warm knee pads for summer. Here, please note the difference between thermal knee pads and sports knee pads. Sports knee pads sold in sporting goods stores are shorter and tighter to protect you during exercise, but wearing them for long periods of time can affect blood flow and cause swelling in the lower legs, and they are shorter and easier to slip out of. The warm knee pads are longer and generally need to be around 30cm to protect a larger area and not slip off easily, preferably in different sizes to suit different thicknesses of knee profile, and with a wider fixation area at both ends so that they do not form a striped compression. The winter type is thicker and usually uses warm materials such as wool, while the summer type is thinner and usually made of cotton, which facilitates ventilation and sweat absorption. As the ancients used to say, “prevention is better than cure”, and so is the prevention of osteoarthritis. In the heat of summer, it is still important to pay attention to the warmth of the knee and not to let the knee “catch a cold”. For patients who have been diagnosed with OA, it is even more important to keep the knee warm in the summer, which is an extremely important part of the overall treatment plan.