When the weather is a little cold, the cold inside the kneecap may be caused by physiological cold, knee arthritis, trauma and other reasons. 1. Physiological cold: mostly seen in young people who wear less, when the weather gets cold, local blood vessels and muscle contraction, resulting in transient ischemic damage to local muscles and soft tissues, the patient may feel cold inside the kneecap. 2. Knee osteoarthritis: common in rheumatoid arthritis, rheumatoid arthritis, degenerative osteoarthritis, joint cartilage degeneration, hardening, inflammation and other changes in the weather turns cold, the blood circulation is relatively slow, the patient may feel cold inside the kneecap. 3. Trauma: due to trauma and other violent factors lead to knee meniscus, ligaments and other tissue damage, the patient has not fully recovered, in the weather turns cold, the local blood circulation is not good, the patient may feel cold inside the kneecap. Cold inside the kneecap alone can not accurately determine the cause, but also need to be combined with the characteristics of the medical history, other test results in order to make an accurate judgment, it is recommended to clarify the cause of the disease under the guidance of the doctor.