Skeletal analysis of craniofacial asymmetries in plagiocephaly (unilateral coronal synostosis).

Why do the craniofacial bones grow asymmetrically in patients with plagiocephaly (unilateral coronal synostosis)? We obtained three-dimensional skeletal replicas of two patients with the condition and analysed the deformities of the facial bones. From this analysis we deduced that the asymmetric deformation of the facial bones in these patients was caused by a combination of three rotations: rotation of the calvaria toward the affected side because of premature synostosis of the coronal and sphenofrontal sutures; rotation of the facial bones on the horizontal plane toward the unaffected side caused by anterior displacement of the TM (temporomandibular)-joint on the affected side; and downward rotation of the facial bones toward the unaffected side caused by inferior displacement of the TM-joint on the affected side.