Knee pain during menstruation may be caused by muscle tissue laxity, joint inflammation, abnormal hormone levels and other reasons. 1. Muscle tissue laxity: maternal activity is reduced during the period of sitting on the moon, the knee joint movement decreased, resulting in muscle tissue and ligament laxity, which in turn causes joint instability, resulting in knee pain symptoms. 2. Joint inflammation: maternal postpartum resistance is poor, once cold easily caused by joint inflammation such as rheumatoid arthritis, osteoarthritis, etc., the symptoms of knee pain. 3. Hormone level abnormality: postpartum patients with endocrine system changes, the body of a variety of hormone levels fluctuate greatly, which can lead to tissue dysfunction, resulting in pain in different parts of the body symptoms. The knee pain during menstruation can also be caused by calcium deficiency, etc. If the symptoms continue to be unrelieved, the patient should consult a doctor in a timely manner to clarify the cause of the disease and receive professional treatment.