The pain of straightening the foot is considered ligament strain, gout, osteoarthritis and other reasons. 1. Ligament strain: When ligament injury occurs during exercise or walking, localized swelling and pain when the foot is straightened. This condition requires rest and braking for a period of time. 2. Gout: acute attack, localized redness, swelling and pain, limitation of activities, with obvious symptoms at the synovial membrane of the joint. Laboratory tests of uric acid can make a clear diagnosis. Attention should be paid to a low purine diet, and those with obvious symptoms can take oral uric acid-lowering drugs, such as febuxostat. 3. Osteoarthritis: caused by degeneration of the joints, osteophytes, narrowing of the joint space, pain when the foot is straightened. There may be other causes of pain when the foot is straightened, such as aseptic necrosis of the talus and bone tumors, etc. It is recommended to consult a doctor in time for examination and treatment under the guidance of the doctor.