Morphometric investigation of the infraorbital canal and determination of its “suspended” variant: a multidetector computed tomography study

OBJECTIVES: The aim of this Multidetector Computed Tomography (MDCT) study was to investigate the morphometry and variations of the Infraorbital Canal (IOC), including the "suspended" (Type 3) variant, to highlight its clinical importance in preventing iatrogenic nerve injury during sinonasal surgeries. METHODS: In this retrospective analysis, 600 IOCs were analyzed using MDCT images obtained from 300 patients (18-82 years old, equal gender distribution). IOCs were classified into three types according to maxillary sinus protrusion: Type 1 (no protrusion), Type 2 (partial) and Type 3 (complete/suspended). The presence of Haller cell was also evaluated. RESULTS: The prevalence of type 3 IOC was 13%. Haller cells were observed in 21.2%. Type 3 IOCs exhibited significantly larger D1 (distance from the infraorbital rim to the infraorbital foramen) and D2 (maximum length of the IOC) lengths and were found in younger patients. There was a weak negative correlation between age and D1/D2. Although women were older, IOC measurements did not show a significant gender difference in Type 3 cases, except that right-sided D3 (length of the bony septum extending into the maxillary sinus) was larger than left-sided D3. CONCLUSIONS: Type 3 IOC is a common anatomical variation, often associated with Haller cells, that increases the risk of infraorbital nerve injury in maxillary sinus surgery. Preoperative multidetector CT imaging of these variants is crucial to improve surgical safety.