Assessment of facial and cranial symmetry after one-piece fronto-orbital advancement with distraction for isolated unilateral coronal synostosis.

BACKGROUND: The surgical correction of unilateral coronal synostosis (UCS) aims to achieve a long-standing facial and cranial symmetry. We hypothesized that endocranial morphology correction achieved by one-piece fronto-orbital advancement with distraction osteogenesis (FODO) could alleviate facial asymmetry because endocranial morphology is thought to be its major determinant. Thus, this study aimed to quantitatively analyze the changes in supraorbital and midfacial symmetry after FODO.

METHODS: We included 27 UCS patients who underwent FODO between May 2008 and November 2019. The supraorbital, midfacial, and orbital symmetry ratios and the endocranial and midface angles were measured using computed tomography images.

RESULTS: The mean follow-up period was 3.7±1.9 years. The supraorbital shape became symmetric after FODO, as the supraorbital distance ratio changed from 0.88±0.04 to 0.98±0.03 (p<0.001). The endocranial angulation improved from 167.5±5.0° to 174.4±3.4° (p<0.001), and the midface angulation decreased from 6.6±2.2° to 2.6±1.9° (p<0.001). In the long-term follow-up period (5.9 years) analysis, the endocranial angle experienced a slight relapse (- 1.4± 0.9 %) and the supraorbital symmetry noticed a -2.0±3.9 % relapse. The midface angle continued to improve over the follow-up periods, but it was not statistically significant (p=0.121).

CONCLUSIONS: Our observations indicate that FODO produced satisfactory outcomes in correcting supraorbital retrusion and midface asymmetry. In addition, FODO may allow anterior cranial base remodeling and help relieve the midface and skull base angulation. Therefore, FODO can be a good therapeutic strategy for correcting supraorbital and facial asymmetry in patients with UCS.