The depression below the ankle usually refers to below the tip of the inner (outer) ankle. Pain in this area is considered to be soft tissue injury, synovitis, ankle joint instability, osteophytes, etc. 1. Soft tissue injury: long-term walking, sports or ankle sprains can lead to damage to the ankle muscles and ligaments, and then cause pain. 2. Synovitis: Ankle trauma, cold and repeated injury can lead to aseptic inflammation of the synovial membrane of the ankle joint, and synovitis of the ankle joint can lead to synovial effusion, localized redness, swelling and heat pain. 3. Ankle joint instability: It is common in old ankle joint injury, which leads to laxity of ankle joint ligaments, and then produces ankle joint instability and pain in the ankle depression after walking. 4. Osteomalacia: trauma leading to ankle fracture or osteoarthritic degeneration can cause osteomalacia, which can irritate the surrounding soft tissues and cause pain after activity. There are many reasons for the pain in the depressed area below the ankle joint, and it is recommended to consult a doctor to clarify the cause of the pain and treat it under the guidance of the doctor.