Injury and Trauma
Sometimes trauma and injury to the nail can also cause a deformity to occur. This occurs when a heavy object falls on the nail, or the nail gets crushed by getting caught between two doors, for example. This causes damage to the nail root. If the trauma is too severe, it can lead to permanent damage and cause the nail to continue forming that way, even though the injury might have healed. The trauma could also lead to the clotting of blood and lead to an infected toenail.