Long Bone Bowing

The degree of long-bone curvature should be examined. Campomelic (bent-bow) dysplasia is characterized by ventral bowing of the long bones. Thanatophoric dysplasia and osteogenesis imperfecta also have bowed extremities.

Fig 1, Fig  2

The major differential diagnoses are as follows:

• Campomelic dysplasia (bowing but no shortening)
• Osteogenesis imperfecta type II (related to fracture and callus formation)
• Thanatophoric dysplasia (severe shortened long bones)
• Achondrogenesis
• Hypophosphatasia

Fig 1:  Campomelic dysplasia   Longitudinal scan of tibia: anterior bowing of well ossified tibia

Fig 2:  Osteogenesis imperfecta type IIB  Irregular and angular fracture of long bones (arrow) but rather well-ossified