Osteogenisis Imperfecta is also known as Fragililis ossium, idiopathic osteopsathyrosis and periostealdysplasia. It is characterized by bony fragility, blue sclera, deafness, and joint laxity. It is a congenital hereditary pain caused by hypoplasia of mesenchymal tissue and impaired collagen formation. Etiology】The etiology is unknown, and it is a congenital developmental disorder. The incidence is equal in males and females. It can be divided into congenital type and late type. The congenital type refers to the onset of the disease in utero, and can be subdivided into fetal type and infant type. The disease is severe and most of them die, or die within a short period of time after delivery. It is autosomal recessive, while the late-onset form is milder and can be divided into pediatric and adult forms. The majority of patients can survive for a long time and are autosomal dominant. 15% of patients have a family history. Clinical manifestations: (a) Increased bone fragility can cause fractures with minor injuries and spontaneous fractures in severe cases. The congenital type has multiple fractures at birth. Most of the fractures are cyanotic, less displaced, less painful, faster healing, and rely on subperiosteal osteogenesis to complete, thus often going unnoticed and causing malunion. The long bones and ribs are the preferred sites. The deformity caused by multiple fractures further reduces the length of the bone. After puberty, the tendency to fracture gradually decreases. (ii) Blue sclera accounts for about 90% or more. This is due to the fact that the patient’s sclera becomes translucent and the color of the choroid beneath it can be seen. There is no abnormality in the thickness and structure of the sclera, and its translucency is due to a change in the nature of the collagen fibrous tissue. (c) Deafness often appears from 11 to 40 years of age, accounting for about 25% of cases. It may be due to sclerosis of the ear canal and fixation of the stapedial pedicle attached to the oval window due to bony ankylosis, but it is also thought to be due to pressure on the auditory nerve as it exits the skull base. (d) Excessive joint laxity, especially in the wrist and ankle joints. This is due to impaired development of the collagenous tissue of the tendons and ligaments. There can also be knee valgus and flat feet. Sometimes there is habitual shoulder dislocation and radial head dislocation. (v) Weak muscles. (F) Severe cranial dysostosis, the skull has a dermatomal sense at birth. Later, the skull is broad, the parietal and occipital bones are prominent, the two temporal bulbs are bulging, the frontal bone is protruding, the ears are pushed down, and the face becomes an inverted triangle. Some patients have hydrocephalus. (vii) Dental dysplasia The teeth do not develop well and both the milk teeth and permanent teeth can be involved. The teeth are yellow or blue-gray in color and are prone to caries and early loss. (H) Dwarf. This is due to slightly shorter development than normal, combined with multiple fracture malformations of the spine and lower extremities healing. (ix) Increased width of skin scars, which is also due to defective collagen tissue.