Evaluating Relapse Following Fronto-Orbital Advancement for Metopic and Unilateral Coronal Synostosis: The Lateral Brow Projection Angle

Abstract

Background: Fronto-orbital advancement (FOA) expands intracranial volume and provides esthetic correction for patients with metopic (MS) and unilateral coronal synostosis (UCS). We present a simple, reproducible method for analyzing these conditions called the lateral brow projection angle (LBPA). Purpose: Assess the FOA LBPA percent advancement maintained at 2-years post-operatively in MS and UCS. Methods: An IRB-approved retrospective review of patients treated with FOA for MS or UCS between 2012 and 2019 with pre-operative, immediate post-operative, and 2-year follow-up CTs were included. LBPA was defined as the angle between a line perpendicular to the mid-sagittal plane passing the anterior-most point of the glabella and a line from this point to the maximal lateral orbit rim inflection point. Percent advancement maintained was calculated. Two-year postoperative LBPAs were compared to 20 age-matched controls. Results: Twenty-two MS and 17 UCS were included. For MS, the mean LBPA bilaterally was 18.9° (SD 3.1) pre-op, 6.5° (SD 3.5) immediately post-op, and 13.2° (SD 3.2) at follow-up. Average percent advancement maintained was 43.6% (SD 31.5). For UCS, the mean LBPA on the affected side was 15.1° (SD 3.6) pre-operatively, 5.1° (SD 1.7) post-operatively, and 12.5° (SD 2.1) at follow-up. Average percent advancement maintained was 19.7% (SD 32.6). The control group average LBPA was 12.8° (SD 0.5) at 39.8 months mean age. Mean 2-year post-operative LBPAs of patients with MS and UCS compared to controls did not demonstrate a significant difference (P = .29 and .24, respectively). Conclusions: Utilizing a simple, reproducible method of measurement, we determined significant correction followed by relapse in these populations, however despite relapse, we are able to restore the dysmorphia to a comparable measurement to normative controls. LBPA may additionally be used preoperatively as a determination of severity for cross center studies.