Tibiofibular relationships of the normal syndesmosis differ by age on axial computed tomography-Anterior fibular translation with age.

INTRODUCTION: This study aimed to assess the tibiofibular relationships of normal syndesmosis on axial computed tomography (CT) images and evaluate the measurement differences by gender, age, and body sides.

PATIENTS AND METHODS: The cases of 120 volunteers who underwent bilateral ankle CT were retrospectively reviewed. Volunteers were divided into three groups of 40 (20 men and 20 women) as follows: 20-40, 40-60, and 60-80 years old. Radiographic evaluation included the anterior tibiofibular clear space (ATFCS), posterior tibiofibular clear space (PTFCS), anterior tibiofibular interval (ATFI), length of incisura (LI), depth of incisura (DI), and fibular width (FW). Each measured parameter was compared based on gender, age, and body sides. To calibrate anatomical variations among the volunteers, ATFCS, PTFCA, and ATFI were expressed as ratios of FW.

RESULTS: PTFCS and ATFI were significantly larger in the men (p = 0.001, 0.001). LI and FW were significantly smaller in the women (p <0.001, <0.001). Calibrated ATFCS, PTFCS, and ATFI did not differ between the genders. ATFCS, PTFCS, and ATFI were significantly different among the age groups (p = 0.001, 0.001, and <0.001, respectively). These calibrated parameters showed significant differences according to age (p = 0.009, 0.006, and <0.001, respectively). There were no significant differences between sides. All CT measurements, except DI, showed high intra- and inter-observer reliabilities.

CONCLUSIONS: Axial CT images of the normal syndesmosis showed significant differences according to gender and age, but not between sides. In light of the anatomical variation, narrowing of the syndesmotic joint due to anterior translation of the fibula following aging may represent the most significant finding.

LEVEL OF EVIDENCE: Level IV, case series.