Preservation Rhinoplasty: Assessment of Anatomical Safe Boundaries on Computed Tomography.

[BACKGROUND] Nasal dorsum reconstruction is a crucial step of the rhinoplasty. For avoiding complications, techniques that preserve natural dorsal anatomy becomes popular recently. In preservation techniques, ethmoidal bone surgery may take part in the vast majority of defined techniques. Therefore, detailed anatomical knowledge is essential to avoid severe complications, especially cerebrospinal fluid leakage. Based on these, this study aimed to investigate anatomical safe boundaries of preservation techniques based on the measurements on computed tomography.

[METHODS] A total of 100 patients who underwent paranasal computed tomography were enrolled in this retrospective study. Five groups were selected based on the age distribution. The distance of the dorsal osteotomy line to cranial base, amount of cartilaginous/bony septum overlaps under nasal bones, cartilaginous/bony septum length anterior and posterior to the nasal hump starting point, and anteroposterior distance of perpendicular plate was measured.

[RESULTS] The mean distance between the starting point of the nasal hump and the cribriform plate was 29.5 mm. The amount of bony overlap above the cartilaginous septum was 10.9 mm in females and 10.5 mm in males. The length of septal cartilage posterior to nasal hump was 0 mm in 39 of 100 patients (39%) and the mean value was 2.38 mm in all populations. The mean distance from the starting point of the perpendicular plate to the cribriform plate was 28.17 mm.

[CONCLUSIONS] Perpendicular plate may take part in the constitution of the nasal hump. Therefore, delicate surgery with appropriate tools needed for avoiding the risk of skull base injury.

[LEVEL OF EVIDENCE] Level of Evidence: 3 (Therapeutic).