Knee pain for no reason may be caused by physiological reasons such as overwork, or it may be caused by pathological reasons such as trauma, knee joint disease, lumbar spine disease, and so on. 1. Overexertion: For over exertion leading to muscle spasm or lactic acid accumulation in the knee muscles, tendons and other tissues, the patient may have symptoms of knee pain for no reason. 2. Trauma: commonly seen in excessive exercise such as dancing or trauma resulting in knee injury, patients may experience knee pain for no apparent reason. 3. Knee diseases: such as osteoarthritis, rheumatoid and rheumatoid arthritis, infections, tuberculosis, tumors and other diseases, can cause knee pain for no reason. 4. Lumbar spine disease: common in lumbar disc herniation, lumbar spinal stenosis and other lumbar degenerative diseases, caused by nerve compression in the lower limbs, the patient may appear knee pain for no reason. Knee pain for no reason may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, give targeted treatment or treatment.