The Role of Computed Tomography with External Rotation and Dorsiflexion in Decision Making for Acute Isolated Posterior Malleolar Fractures Bartoníček and Rammelt Type II: A Cross-Sectional Study

Abstract

Category: Ankle; Sports Introduction/Purpose: A ligament-centered analysis is currently incorporated in the assessment of joint stability in malleolar fractures. Although several imaging tests are available, in the setting of acute isolated non-displaced posterior malleolar fractures Bartoníček/Rammelt types II and IV diagnosing syndesmotic instability remains challenging. The objective of this multi-center cross- sectional study was to evaluate the syndesmotic and fracture instability using conventional ankle CT with external rotation and dorsiflexion in the setting of acute, isolated non-displaced Bartoníček and Rammelt type II posterior malleolar fractures. Methods: Between March 2018 and September 2022, a consecutive sample of 123 individuals with an ankle sprain were assessed for eligibility. In total, 33 participants met the inclusion criteria. All participants underwent a CT scan (CTSM), comprising a first phase with the ankles in a neutral position, then a stress phase with the ankles in external rotation and dorsiflexion and semiflexed knees. Investigators used the patterns of ligament tear found at MRI and instability at CTSM to classify all participants into West Point grades I, IIA, IIB, or 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. Results: In MRI reading parameters two patterns of syndesmotic ligament injury predominated. A completely torn AITF and IO ligaments and a completely torn AITF was combined with a partially torn IO. Regarding the deep layer of the deltoid ligament, participants were classified as normal, strained and partially torn. In CT scan reading parameters in the neutral phase, the median difference of 0.2 mm in d measurements between injured and uninjured syndesmoses was not statistically significant (P = 0.057). During the stress phase, the injured and uninjured syndesmoses had distinct behavior, and the 2.3 mm median difference for d measurement was statistically significant (P < 0.0001). Conclusion: The conventional computed tomography with external rotation and dorsiflexion represent a reproducible and accurate diagnostic option for the detection of syndesmosis instability and fracture instability in acute isolated posterior malleolar fractures Bartonícek and Rammelt type II.