Optimizing Aesthetic Outcomes in Unilateral Cleft Lip Repair: Three-Dimensional Anthropometric Analysis of the Modified Onizuka Technique

Abstract

This study evaluates anthropometric outcomes of a modified Onizuka technique for unilateral cleft lip (CL) repair using 3-dimensional (3D) photogrammetry, with emphasis on anatomic subunit reconstruction without preoperative numerical measurements. A prospective cohort study was conducted at a tertiary craniofacial center. Sixty-one patients with unilateral CL and/or palate who underwent CL repair using the modified Onizuka technique were enrolled. The technique relocates key landmarks to the footplate of the medial crus, preserves an 80° angular design at the peak of Cupid’s bow, and uses a V-Y advancement flap for frenulum reconstruction. Concurrent primary rhinoplasty and gingivoplasty were performed. Anthropometric symmetry was assessed via 3D imaging at ≥1-year follow-up, including nostril width, columellar height, central and medial lip height, lateral lip height and length, and hemi-Cupid’s bow width. The cohort comprised 60.7% males, with 70.5% having left-sided clefts and 67.2% having complete clefts. Median age at surgery was 5.0 months. All intraclass correlation coefficient values exceeded 0.75, indicating good to excellent reliability. No statistically significant differences were observed between cleft and noncleft sides (all P>0.05). Mean differences were <0.2 mm, below the threshold of human visual perception. The modified Onizuka technique achieves symmetric outcomes in unilateral CL repair, validated by objective 3D metrics. Its emphasis on anatomic subunit reconstruction without preoperative numerical marking offers a versatile, reproducible approach for diverse cleft phenotypes.