The role of computed tomography with external rotation and dorsiflexion in decision making for acute isolated non-displaced posterior malleolar fractures Bartoníček and Rammelt type II: a prospective study

Our objective was to evaluate the syndesmotic and fracture instability using conventional ankle computed tomography (CT) with stress maneuvers. A consecutive sample of 123 individuals with an ankle sprain was assessed for eligibility. In total, 33 patients met the inclusion criteria. All patients underwent a magnetic resonance imaging (MRI) and CT scan with stress maneuvers (CTSM). The patterns of ligament tears f were classified using West Point grades I, IIA, IIB, III. Mann–Whitney test was used to test the differences in the numerical variables between injured and uninjured syndesmoses. The Spearman correlation tested the strength of the association between the tibial joint surface involved in posterior malleolus fracture and syndesmotic instability. In MRI, two patterns of syndesmotic ligament injury predominated. A completely torn anterior inferior tibiofibular (AITFL) and interosseous tibiofibular ligaments (ITFL) and a completely torn AITFL were combined with a partially torn ITFL. In the neutral phase CTSM and during the stress phase the median difference of the narrowest tibiofibular distance between injured and uninjured syndesmoses was 0.2 mm (P = 0.057) and 2.3 mm (P < 0.0001), respectively. There was no association between the percentage of involvement of the posterior tibial joint surface in the posterior malleolar fracture and syndesmotic instability as measured with CTSM. The conventional computed tomography with external rotation and dorsiflexion represents a reproducible and accurate diagnostic option for detecting syndesmosis instability and fracture instability in acute isolated non-displaced posterior malleolar fractures Bartoníček and Rammelt type II. Level of Evidence: Prospective study among consecutive patients (Diagnosis); Level of evidence, 2.