The knee feels cold for several common reasons: 1. Cold knee: The low temperature of the surrounding environment and the lack of attention to warmth can easily cause the knee to become cold. The patient will feel the symptoms of a cold knee joint, accompanied by pain and transient joint movement restrictions. 2. Osteoarthritis: If an elderly patient has osteoarthritis, the clinical symptoms of cold knee joints are accompanied by joint pain, limited movement and, in severe cases, deformity of the bone joints. The narrowing of the joint space and joint osteophytes can be detected by X-ray examination, and functional exercise and surgical treatment can relieve the clinical symptoms.3. Lumbar spine lesions: If the spinal canal is narrowed and the nerves are stimulated by a herniated disc, the patient may have clinical symptoms of cold knee joints. Therefore, the cold knee joint should be diagnosed and treated early so that the clinical symptoms can be relieved as soon as possible.