The Körner septum as a reliable reference point in temporal bone surgery: clinical-morphometric relationship with the facial nerve and surrounding structures.

PURPOSE: The Körner septum (KS) represents a critical anatomical pitfall that may mimic the medial wall of the antrum, potentially leading to surgical disorientation and iatrogenic injury. This study aims to quantify its prevalence and topographical variations while evaluating the morphometric impact of its presence on vital temporal bone landmarks to enhance surgical safety. METHODS: The study included CT images of 942 temporal bones which were divided into two groups according to KS presence; KS + cases were further subdivided according to anatomical localization (malleus head, superior semicircular canal, and tympanic sinus levels). Mastoid pneumatization (MP) and mastoid antrum (MA) volumes as well as linear distances of the KS to the malleus, facial nerve canal, and Cog were measured. RESULTS: KS prevalence was 39.6% and was uninfluenced by sex or laterality. It was most prevalent at the level of the HM (54.2%), followed by the SSC (27.3%) and TS (18.5%). Although most parameters, including MP and MA volumes, tubotympanic angle, Eustachian tube length, and distances to key surgical landmarks, showed no significant difference between the three localizations, a significant difference was found in KS thickness (p-value < 0.05. Despite reassuring mean values, extreme anatomical configurations revealed critical risk corridors as narrow as 2.14 mm, underscoring the necessity of individualized radiological mapping. CONCLUSION: Our results demonstrate that the KS should not merely be regarded as an anatomical variant but as a radiologically quantifiable surgical landmark defining critical safety corridors in mastoid surgery.