Long bone bowing is a congenital condition described by the presence of symmetric or asymmetric angular deformity and shortening of the long bones, particularly the femurs, tibiae and ulnae. Prevalence is unknown. It manifests at radiography as posteromedial bowing with cortical thickening along the concavity of the curvature and, in some cases, diaphyseal broadening. Phenotype analysis of patients with congenital bowing of long bones and otherwise undiagnosable conditions allowed sorting into three major groups: 1) normal bone texture, bowing confined to the femora, relatively thin long bones with no epiphyseal or metaphyseal abnormalities; common associated malformations or CNS abnormalities; 2) osteopenia, more generalized bowing, relatively thick long bones, metaphyseal ossification abnormalities; 3) normal bone texture, relatively thick bones, bowing of the upper and lower limbs, metaphyseal abnormalities. Long bone bowing can share characteristics of the following disorders: campomelic dysplasia, kyphomelic dysplasia, hypophosphatasia, osteogenesis imperfecta, Stuve-Wiedemann syndrome, and several very rare disorders. Radiographic characteristics allow differential diagnosis. Bowing of the long bones can be detected on antenatal ultrasound screening, but it is a nonspecific sign that can be associated with a variety of conditions, whose recognition is important for differentiating those that will resolve spontaneously from those that require surgery or other treatment.
Last update: September 2005