Hidden pain and swelling on one side of the right ankle is considered to be related to sprains, osteoarthritis, lumbar disc herniation and so on. 1. Sprain: If you accidentally twist your ankle during sports or heavy physical labor, it will cause local soft tissue injury, mainly manifested as pain and swelling. 2. Osteoarthritis: Osteoarthritis is a chronic disease that progresses gradually, the cause and mechanism of its development are still unclear, and it is considered to be the result of the joint action of many factors. The main symptoms are pain and pressure in the joints, stiffness of the joints when getting up in the morning, which is relieved by activities, accompanied by swelling or deformity, and so on. 3. Lumbar disc herniation: lumbar disc herniation is the degeneration of intervertebral discs, under the action of strain accumulation and external forces, the nucleus pulposus fibrous ring protrudes backward, and the protruding nucleus pulposus fibrous ring presses on the sciatic nerve, which causes sciatica, and the sciatica will appear as the radiating pain, which mainly radiates from the buttocks along the back of the thighs, and to the backs of the calves and the feet, and it will also cause the pain and swelling of ankle area. The symptoms of vague pain and swelling on one side of the right ankle should go to the hospital for a detailed examination, a clear diagnosis and targeted treatment.