Associations of Bartoníček Classification and Fragment Size With Treatment Selection and Reduction Quality in Posterior Malleolar Fractures.

BACKGROUND: Posterior fragment size has traditionally guided treatment decisions for posterior malleolar fractures, whereas computed tomography has emphasized fracture morphology. PURPOSE: This study evaluated the associations of the Bartoníček classification and posterior fragment size with fracture characteristics, treatment selection, and postoperative reduction quality. STUDY DESIGN: Retrospective multicenter study. METHODS: We reviewed surgically treated ankle fractures involving the posterior malleolus from 2020 to 2022. Fractures were classified using the Bartoníček classification on preoperative computed tomography. Fracture morphology, fragment size, preoperative articular displacement, fixation procedures, and postoperative reduction quality were evaluated. Malreduction was defined as residual articular step-off or gap >1 mm. RESULTS: Among 638 surgically treated ankle fractures, 206 met the inclusion criteria. Bartoníček type was associated with posterior fragment size, preoperative sagittal articular gap, and treatment selection, but not postoperative reduction quality. In patients without posterior malleolar fixation, malreduction increased with fragment size: 19%, 36%, and 61% in the <10%, 10%-25%, and ≥25% groups, respectively (p = 0.013). In exploratory multivariable analysis of the non-fixation cohort, fragment size ≥25% was independently associated with malreduction (OR 6.36, 95% CI 1.66-24.50). CONCLUSIONS: The Bartoníček classification reflected morphology and treatment selection, whereas fragment size was related to malreduction when the posterior malleolus was not fixed. Computed tomography-based morphology and fragment size provide complementary information.