Three-dimensional image analysis of facial skeletal changes after monobloc and bipartition distraction

Both monobloc and facial bipartition distraction are important tools for correcting functional and aesthetic problems in patients with syndromic craniosynostosis. Three-dimensional computed tomographic reconstructions have become increasingly useful in planning and analyzing surgical results. This study measured the differential deformation of the facial skeleton following distraction osteogenesis with the rigid external distractor frame, looking especially at correction of the midface concavity. Correction of the midface concavity aims to not only improve the appearance but also increase the upper airway volume.

Ten children with syndromic craniosynostoses were studied. Seven children with Crouzon syndrome underwent monobloc distraction and three with Apert syndrome underwent facial bipartition distraction using the rigid external distractor frame. The patients' ages ranged from 4 months to 15 years. The medial advancement and the lateral advancement of the facial skeleton were compared by landmarking three-dimensional computed tomographic reconstructions using the sella turcica as the fixed point. To compare the shape of the monobloc segment from the preoperative to postoperative scans, a color map was generated.

Of the seven patients who underwent monobloc distraction, the mean medial advancement of the face was 4.9 mm greater than the lateral advancement. With the bipartition distraction, the mean central area advancement was 11.4 mm farther than the lateral aspect of the facial skeleton.

Both monobloc and in particular the facial bipartition distraction differentially advance the central part of the face more than the lateral areas. This bending of the face appears to have both cosmetic and functional advantages.