Bone cortical defect may be caused by fracture, poor bone fiber structure, tumor and so on. 1. Fracture: usually caused by indirect violence or direct violence, when external violence acts directly on the bone, exceeding the capacity of the bone, it usually damages the local bone, causing the patient to have bone cortical defects, and also causing pain, impaired movement and other symptoms. 2. Skeletal fiber dysplasia: usually also known as abnormal proliferation of bone fibers, the specific cause of the disease is still unclear, may be caused by trauma or infection, may also be caused by endocrine disorders. Poor bone fiber structure can lead to symptoms such as narrowing of the nasal cavity, displacement of the eyeballs, tearing, etc. It can also lead to the phenomenon of bone cortical defects. 3. Tumor: if the patient has a local tumor, the tumor may stimulate the bone cortex, making the body’s bone cortex defect phenomenon, and may cause local discomfort, impaired movement and other symptoms. Bone cortical defects may also be caused by other factors, it is recommended to consult a doctor in time to clarify the cause of the disease and give targeted treatment.