Anatomical Variations in Keystone Area in Nepalese Noses: A Descriptive Cross-sectional Study.

Introduction: The keystone area, a crucial part of the nasal dorsum that maintains its structural stability, is known to have anatomical variations. This study aimed to evaluate these anatomical variations in Nepalese noses.

Methods: This was an observational, analytical study done at a tertiary center after taking ethical approval {208(6-11)E2-077/078}. Thirty-one cadaveric noses consisting of 26 males and five females aged 24 to 70 years were dissected. The shape of the caudal margin and the overlap pattern of the nasal bone over upper lateral cartilage were assessed. The proportion of overlap was calculated. The lengths of the lateral and dorsal keystone and dorsal quadrangular cartilage were measured.

Results: The most common shape of the nasal bone caudal margin was curvilinear 15 (48.39%) followed by paramedian retractions 8 (25.81%). Elongated midline was the least commonly seen in 1 (3.23%) female only. The length of the dorsal keystone ranged from 1-12 mm (mean 6.97±2.57) whilst the lateral keystone measured 1-4 mm (mean 2.22±1.20). The dorsal quadrangular cartilage measured 21-39 mm (mean 29.77±4.6). The mean overlap proportion was 23.82±7.33 (11 - 40)%.

Conclusions: Anatomical variations in the structural components of the keystone area in Nepalese was seen in the study.