The ankle deltoid ligament is located in the medial ankle and is a tough triangular fibrous cord that starts at the tip of the medial ankle and spreads in a fan shape downward to end at the navicular, talus and heel bones. The medial deltoid ligament is tougher and less prone to injury. Ankle sprains can occur during descending hills, slopes and stairs, and most of them are also lateral collateral ligament injuries. In rare cases, the medial deltoid ligament can be injured. Patients with an external rotation injury will have swelling, pain, and limited motion on the medial side of the ankle, and the pain will be more severe when a tear occurs. Surgical ligament reconstruction is required to restore the stability of the medial ankle joint before the clinical symptoms can completely disappear. Usually, attention should be paid to protecting the triangular ligament of the ankle joint, strengthening muscle strength and intensity training, and wearing high-top shoes.