Objective:​ Our objective was to describe the MRI findings associated with acute and chronic distal tibiofibular syndesmosis injury.

Materials and methods:​ Ninety-four 1.5-T MRIs of ankles of 90 individuals with histories of severe sprain were assessed by two musculoskeletal radiologists for syndesmosis injury (acute, edema of the syndesmosis;​ chronic, disruption or thickening of the syndesmosis without edema). We examined associated MRI findings, including anterior talofibular ligament injury (scar, chronic injury;​ edema, acute injury), bone bruise, osteochondral lesion, tibiofibular joint congruity, tibiofibular recess height, and osteoarthritis. The Fisher's exact test and analysis of variance test were used to evaluate the significance of the associations.

Results:​ In 94 ankles, syndesmosis injury was seen in 63% (n = 59;​ 23 acute;​ 36 chronic). Anterior talofibular ligament injury (acute or chronic) was seen on MRIs in 74% (n = 70;​ 49 with syndesmosis injury;​ 21 without;​ p = 0.03). Bone bruises were present in 24% (n = 23;​ 18/23 acute;​ 4/36 chronic;​ 4/35 no injury;​ p < 0.0001). Of these, talar dome osteochondral lesions were present in 28% (n = 26;​ 11/23 acute;​ 14/36 chronic;​ 1/35 no injury;​ p = 0.0001;​ 13 medial;​ 13 lateral). The tibiofibular joint was incongruent in 33% (n = 31;​ 6/23 acute;​ 21/36 chronic;​ 4/35 no injury;​ p < 0.0001). The tibiofibular recess (mean ± SD) was 1.2 ± 0.92 cm in acute cases, 1.4 ± 0.57 cm in chronic cases, and 0.54 ± 0.68 cm in cases with no syndesmosis injury (p < 0.0001). Osteoarthritis was present in 10% (n = 9;​ 1/23 acute;​ 7/36 chronic;​ 1/35 no injury;​ p = 0.06).

Conclusion:​ Injury to the distal tibiofibular syndesmosis has a significant association with a number of secondary findings on MRI, including anterior talofibular ligament injury, bone bruises, osteochondral lesions, tibiofibular joint congruity, and height of the tibiofibular recess.