Computed Tomography Assessment of Os Trigonum in the Omani Population and Its Clinical Relevance

Background: Os trigonum (OT) is an accessory ossicle that develops from the failure of the secondary ossification center of the posterior talar process fusion. It is clinically significant due to its association with posterior ankle pain and impingement syndromes. Despite its tremendous clinical relevance, limited data exist on the frequency of OT in Middle Eastern populations. Objectives: This study aimed to determine the frequency, morphological variations, and dimensions of OT in Omani subjects using computed tomography (CT) imaging and to evaluate the sex and laterality differences in its occurrence. Methods: A retrospective cross-sectional study of 352 foot and ankle CT scans were conducted to assess the OT at Sultan Qaboos University Hospital. OT presence, dimensions, and classification along with patient demographics, including age and sex, were recorded. Descriptive statistical analysis and the chi-square test were employed to present the data. Results: The overall prevalence of OT was 10.2%, with a frequency of 11.2% on the left side and 8.9% on the right side. Type IIA was the most prevalent subtype in both feet (41.2% right, 44.4% left). The average minor-axis and macro-axis dimensions were 7.88 ± 2.998 mm and 10.76 ± 4.280 mm on the right side, while they were 8.06 ± 2.600 mm and 11.50 ± 4.997 mm on the left side. No statistically significant sex or laterality differences were observed with regard to the OT frequency (p > 0.05). Conclusions: This study provides the first detailed evaluation of OT in the Omani population, highlighting its frequency and morphological variability. These findings emphasize the importance of CT imaging in identifying OT and guiding clinical management. Future studies should explore OT's clinical correlations to enhance its diagnostic and therapeutic implications.