Background: The aim of this study was to determine morphological variations and normal parameters of the cross-sectional tibiofibular syndesmotic anatomy.
Methods: Configurations of syndesmosis, anterior syndesmotic width (ASW), posterior syndesmotic width (PSW), and overlap distance, defined as the overlap of medial fibula with a drawn line from tip of anterior tubercle of incisura fibularis to the posterior tip, were measured on normal computed tomography (CT) scans of 110 cases. Results: Seventy seven male (70%) and 33 female (30%) (left: 50 and right: 60) were assessed. Mean age of the cases was 33 ± 13 (range: 15-80) years. Three different syndesmotic configurations were crescent (55.5%), rectangular (39.1 %), and semicircle (5.4 %). Overall, mean ASW, PSW, and overlap distance were 2.72, 3.98, and 1.02 mm, respectively. Upper limit of normal ASW in crescent, rectangular, and semicircle was 4.80, 4.85, and 3.89 mm, respectively. The maximum of PSW in crescent, rectangular, and semicircle was 6.25, 6.50, and 4.97 mm, respectively. There was not significant difference between syndesmotic configurations based on age (P = .69) and sex (P = .16).
Conclusions: During interpreting axial CT scan to diagnose syndesmotic injuries, the normal range of parameters according to the different configurations of the tibiofibular syndesmosis should be carefully considered.
Level of evidence: Level 4.
Keywords: CT scan; ankle; fibular incisura; syndesmosis; tibiofibular ligament.