Osteogenesis imperfecta is described as having a wrinkled appearance of bones with bowing; which type matches this description with a normal head size?

• A. Type I
• B. Type II
• C. Type III
• D. Type IV

Answer: (A)

Osteogenesis imperfecta shows a spectrum from very mild to lethal, and the key differences lie in how fragile the bones are and how much they deform, along with overall body proportions such as head size. The description of wrinkled or irregularly surfaced, bowed long bones with a normal head size points to the milder end of the spectrum. In the mildest form, bones fracture easily but the overall skeleton remains relatively well proportioned, and the head size is normal. Radiographs can show osteopenia with healed fractures that give the bones a somewhat wrinkled or irregular look, and bowing of the long bones is common. In more severe forms, there are extensive deformities, significant short stature, or perinatal lethality, and head size can be affected by the degree of skeletal involvement. So the combination of bowing with a normal head size best fits the mildest form.