Determination of Novel, Cranium-Based Relationships for Construct Placement in Microtia Reconstruction for Hemifacial Microsomia Patients.

Objective: Determine if the ideal location of the construct in microtia reconstruction for hemifacial microsomia (HFM) can be more accurately derived from measurements on the cranium.

Design: High-resolution computerized tomography (CT) images were analyzed through craniometric linear relationships.

Setting: Our tertiary care institution from 2000 to 2021.

Patients/participants: Patients diagnosed with HFM and microtia, who had high-resolution craniofacial CT scans, yielding 36 patients accounting for 44 CT scans.

Main Outcome Measure(s): First, the integrity of the posterior cranial vault among HFM patients was determined. If proven to be unaffected, it could be used as a reference in the placement of the construct. Second, the position of the ear in relation to the cranium was assessed in healthy age-matched controls. Third, if proven to be useful, the concordance of these cranium-based relationships could be validated among our HFM cohort.

Results: The posterior cranial vault is unaffected in HFM ( > .001). Further, craniometric relationships between the tragus and the Foramen Magnum, as well as between the tragus and the posterior cranium, have been shown to be highly similar and equally precise in predicting tragus position in healthy controls ( > .001). These relationships held true across all age groups ( > .001), and importantly among HFM patients, where the mean absolute difference in predicted tragus position never surpassed 1.5 mm.

Conclusions: Relationships between the tragus and the cranium may be used as an alternative to distorted facial anatomy or surgeon's experience to assist in pre-operative planning of construct placement in microtia reconstruction for HFM patients.