Mechanical Strain of the Nasal Bilobed Transposition Flap-Graduated Changes in Skin Thickness Superiorly Displace the Location of the Pivot Point

BACKGROUND: The bilobed transposition flap recruits the relatively thinner and laxer skin of the nasal dorsum and sidewall to reconstruct defects of the more sebaceous nasal tip and alae. There have been no studies performed to quantify how the material properties of skin alter the bilobed flap's performance during nasal reconstruction. OBJECTIVE: To determine the effects of skin thickness and stiffness on bilobed flap mechanics to help guide flap design principles and optimize surgical outcomes. MATERIALS AND METHODS: Two-dimensional artificial silicone skin models of varying thickness were created. The bilobed flap was incised, transposed, and secured in standard fashion. Digital image correlation was used to translate model deformation and displacement into local stress and mechanical strain forces within the bilobed flap pedicle. RESULTS: Qualitatively, the center of rotation of the bilobed flap rotates superiorly up the flap pedicle as model skin thickness increased. CONCLUSION: Location of the bilobed flap's pivot point may be dependent on local tissue characteristics-oversizing of the primary lobe can be considered in stiff, immobile tissue such as highly sebaceous Zone II nasal skin.