Closed injuries are those where the skin barrier is intact but internal structures can be damaged, such as closed fractures, closed craniosynostosis, closed liver rupture, closed spleen rupture, and gastrointestinal injuries. Patients will have internal structural damage and have clinical symptoms such as pain, limited movement, swelling, and even the formation of a hematoma, which can lead to life-threatening hemorrhagic shock. Therefore, after a closed injury occurs, prompt diagnosis and treatment should be provided to confirm the severity of the injury and to treat the different injuries accordingly so that the patient’s life can be ensured and the local injury can be restored, and great attention should also be paid to the recovery of the subcutaneous tissues because even a closed injury may lead to serious damage to the subcutaneous tissues.