Endoscopic-assisted versus open fronto-orbital distraction for unicoronal craniosynostosis: morphometric and technique considerations

Abstract

Introduction: In an effort to maximize benefit and minimize morbidity when performing fronto-orbital distraction osteogenesis (FODO) for unilateral coronal synostosis (UCS), we have transitioned to an endoscopic-assisted approach ("endo-FODO"). This study compares photogrammetric outcomes of patients who underwent FODO via an endoscopic-assisted versus open approach.

Methods: We retrospectively reviewed patients treated for UCS from 2013 to 2023. Photogrammetric outcomes at one to three years postoperatively were compared between patients who underwent endo-FODO and age- and sex-matched controls who underwent open FODO. Differences between pre- and postoperative periorbital symmetry ratios, canthal tilt symmetry, and orbital dystopia angle (ODA) were calculated.

Results: Twenty patients (ten per group) underwent surgery at a mean age of 6.1 ± 1.8 and 5.4 ± 1.1 months (p = 0.426) and were photographed at 1.6 ± 0.9 and 1.8 ± 0.9 years (p = 0.597) postoperatively in the endo-FODO and open FODO groups, respectively. Patients who underwent endo-FODO demonstrated significant improvements in margin-reflex distance 1 (MRD1) symmetry ratio (p = 0.004), palpebral height symmetry ratio (p = 0.004), canthal tilt symmetry (p = 0.020), and ODA (p = 0.009). Patients who underwent open FODO likewise demonstrated significant improvements in MRD1 symmetry ratio (p = 0.004), palpebral height symmetry ratio (p = 0.033), and ODA (p = 0.004). All postoperative measurements as well as degrees of improvement were similar between groups (p > 0.05).

Conclusions: Endo- and open FODO were associated with significant and comparable improvements in soft tissue periorbital symmetry and orbital dystopia at nearly two years postoperatively. While continued follow-up until cranial maturity is needed to assess the durability of aesthetic results, these data support a minimally invasive, endoscopic alternative to fronto-orbital distraction.

Keywords: Endoscopic; Fronto-orbital distraction osteogenesis; Minimally invasive; Unilateral coronal synostosis.

Fig. 1

Illustration of our minimally invasive, endoscopic-assisted approach to fronto-orbital distraction osteogenesis, which demonstrates a critical view through the pterional window that serves as the predominant working portal for the sphenoid wing and orbital roof osteotomies (Copyright © 2024 Meagan Wu)

Fig. 2

Intraoperative photographs of a female patient with right unicoronal synostosis undergoing internal distractor placement for open fronto-orbital distraction osteogenesis via a coronal incision

Fig. 3

All soft tissue parameters are demonstrated on the preoperative frontal photograph of a male patient with left unicoronal synostosis who underwent fronto-orbital distraction osteogenesis at five months of age. Periorbital measurements included margin-reflex-distance 1, pupil-to-brow distance, palpebral fissure height and width, and canthal tilt angle. MRD1 margin-reflex-distance 1, PTB pupil-to-brow distance, PH palpebral height, PW palpebral width, ODA orbital dystopia angle

Fig. 4

A female patient with right unicoronal synostosis is shown before undergoing endoscopic-assisted fronto-orbital distraction osteogenesis at five months of age (top row) and three years postoperatively (bottom row)

Fig. 5

A female patient with left unicoronal synostosis is shown before undergoing open fronto-orbital distraction osteogenesis at four months of age (top row) and at two years postoperatively (bottom row)