Cold knees may be caused by lumbar spinal stenosis, osteoarthritis, synovitis and other diseases. 1. Lumbar spinal stenosis: Lower back pain, lumbar leg pain is a common manifestation of this disease in the early stage, which can be accompanied by lower extremity numbness, cold and other symptoms. In addition, sensory disturbances may occur in the innervated area of the affected nerves. There may also be sciatica, intermittent claudication, limited lumbar activity and other symptoms. 2. Osteoarthritis: It occurs in knee joints, hip joints, spine and distal interphalangeal joints, etc., which are heavily loaded. When the knee joint is changed, it can show symptoms such as knee pain, stiffness and swelling. It can cause insufficient blood supply, resulting in always cold knees. 3. Synovitis: This disease mainly manifests as swelling and pain in the knee joint. If the disease continues to progress, it can lead to joint adhesion and restriction of knee joint movement, which has a serious impact on knee joint function. It can lead to insufficient blood supply to the knee joints, resulting in conditions such as cold knees. In addition to the above factors, cold knees may also be due to inadequate warming measures, rheumatoid arthritis, lumbar disc herniation and other factors. It is important to seek timely medical treatment to avoid adverse effects on daily life.