The deltoid ligament is a strong band of tissue on the inside of the ankle. This ligament has several parts which joint the tibia (leg bone) to the bones of the foot. The function of the deltoid ligament is to provide stability to the ankle. A sprain occurs when this band of tissue is injured during activities such as sports, running downstairs or on uneven surfaces, or in association with an ankle fracture. The pain of deltoid ligament sprain is felt around the medial malleolus (ankle bone). Occasionally, a “pop” may be felt on initial injury. Bursitis, tendinitis, gout and arthritis of the ankle joints may confuse the picture. Tears of the deltoid ligament are organized into type I, type II and type III, with the last being the most severe. X-rays, MRI scans and ultrasound examination can be used to diagnose and classify deltoid ligament sprain. Fractures of the ankle must be suspected and treated if they are found to coexist with ligament injury. Treatment of deltoid ligament sprain begins with conservative modalities such as non-steroidal anti-inflammatory medications, heat, ice, physical therapy and a course of immobilization. Injection around the sprain with a local anesthetic and a steroid may decrease the pain. If deltoid ligament sprain is unresponsive to conservative modalities, surgical intervention may be necessary.