Which type of osteogenesis imperfecta presents with bowing of long bones, possible fractures, a normal head size, and wrinkled bones?

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

Answer: (A)

Osteogenesis imperfecta varies in severity, and the pattern of bone fragility plus growth and skull involvement helps distinguish the types. A presentation with bowing of the long bones, fractures, a normal head size, and bones that look wrinkled or fragile on imaging fits a mild form of the disease. This is Type I, the mildest and most common form. In this form, fractures occur but deformities are not severe, growth is typically normal, and the skull is not affected, so head size stays normal. Wrinkled or fragile-appearing bones come from the underlying collagen defect that's enough to cause fractures but not extensive skeletal deformity or cranial involvement. The more severe types show significant deformity, short stature, and skull or chest abnormalities (Type II is lethal at birth; Type III has progressive deformity and short stature; Type IV has moderate deformity).