Heel drop can be caused by Achilles tendon contracture, clubfoot and nerve injury. 1. Contracture of Achilles tendon: Contracture of Achilles tendon may be caused by trauma or chronic degenerative diseases. Contracture of the Achilles tendon is caused by the shortening of the Achilles tendon, resulting in the heel not being able to touch the ground. 2. Horseshoe inversion of foot: Horseshoe inversion of foot can be caused by poliomyelitis and congenital or birth injury, because of the muscle imbalance of the lower limbs, resulting in the phenomenon of the heel not to the ground. 3. Nerve injury: Nerve injury includes lumbar disc herniation and intracranial cerebral thrombosis, etc. The cranial nerves and nerves innervating the muscles of the lower limbs are compressed, resulting in the inability to ensure the balance of the limbs, and the patient’s lower limbs lose the point of gravity, which leads to the phenomenon of the heel not touching the ground. It is recommended that patients go to the hospital in time to follow the doctor’s instructions for examination and treatment after the symptoms appear.