The two most severe complications of single-stage, porous polyethene microtia reconstruction are flap necrosis/framework exposure and frontal nerve paralysis. To reduce these risks, require a temporoparietal fascia (TPF) flap that includes both the parietal and frontal branches of the superficial temporal artery (STA) while sparing the nerve. We propose a classification that helps minimize said complications.

Fifty-five TPF flaps of 54 microtia patients who underwent single-stage auricular reconstruction from May 2018 to July 2021 were studied. Flaps were harvested using endoscopic techniques. The parietal and frontal branch characteristics and measurements were obtained using a microscope/endoscope.

The frontal artery might have 1 to 4 branches. If they were close to Pitanguy's line (≤5 mm), there would be a high risk of nerve damage. Parietal (P) and frontal (F) artery diameters <0.5 mm were risk factors for partial flap necrosis. Based on this observation, we proposed 0.5 mm as the diameter threshold to determine whether an arterial branch is hypoplasia or sufficient.

From this study, a new classification of STA branching pattern was proposed with five types: PF1 (23.6 %), PF2 (43.6 %), pF1 (3.6 %), pF2 (12.8 %), and Pf (16.4 %); where P/F indicates sufficient branches, p/f indicates absent or hypoplasia ones, and the number indicates single or multiple frontal artery branching.

The risk of flap necrosis and frontal nerve damage is due to abnormalities of the frontal artery of the STA in the TPF flap. Understanding the anatomical classification with clear visualization during flap harvest ensures a successful outcome.