Morphological Correlations in Nasolabial Formation After Primary Lip Repair for Unilateral Cleft Lip

We aim to reveal postoperative morphological correlations between the nasolabial components in patients with unilateral cleft lip (UCL). The hypothetical correlations are first, a correlation between the vertical height of the cleft-side alar base and the length of the cleft-side red lip, and second, a correlation between the length of the cleft-side red lip and the vertical position of the cleft-side oral commissure. We explain how these morphological balances are controlled by surgery. Three-dimensional bilateral measurements of the length of the red lip, vertical height of the nasal alar base, and vertical height of the oral commissure were conducted retrospectively on 31 patients with UCL and palate (complete UCL: 26; incomplete UCL: 5) who underwent primary lip plasty at Osaka Women's and Children's Hospital from 2017 to 2019. We found a statistically significant correlation between the vertical height of the cleft-side alar base and cleft-side red lip length (P = .012, r = 0.45); thus, the longer the red lip, the lower was the nasal alar base. The correlation between the cleft-side red lip length and the vertical height of the cleft-side oral commissure also showed a statistical significance (P = .00074, r = 0.57); thus, the shorter the red lip, the higher was the oral commissure. The present results provided objective evidence showing basic morphological relationships between the postoperative nasolabial features of patients with UCL. The results lead to a reasonable approach to define the proposed peak of the Cupid's bow, an unsettled major controversy in cleft lip surgery.