OBJECTIVE: To compare posterior malleolar fracture morphology in ankle fractures compared with those with tibial shaft fractures. SETTING: Level 1 trauma center. DESIGN: Retrospective cohort study. PATIENTS/PARTICIPANTS: Fifty-four patients with tibial shaft fractures and 61 patients with ankle fractures. MAIN OUTCOME MEASUREMENTS: Posterior malleolar fractures in ankle fractures versus tibial shaft fractures were classified by type and pathomorphology analyzed. RESULTS: Posterior malleolar fractures were significantly larger when associated with tibial shaft fractures (32% cross-sectional area) as compared to ankle fractures (15% cross-sectional area) (P < 0.001). The distribution of posterior malleolar fracture type differed between tibial shaft fractures and ankle fractures. In addition, 47% of the type II posterior malleolar fractures in tibial shaft fractures had an additional fracture line oriented in the sagittal plane, a fracture pattern unique to these injuries that were not observed in the ankle fracture cohort. CONCLUSIONS: Posterior malleolar fracture morphology varied significantly between tibial shaft fractures and rotational ankle fractures. Posterior malleolar fractures in tibial shaft fractures were over twice the size of posterior malleolar fractures that occur with rotational ankle fractures and more likely to involved the medial malleolus. This information emphasizes the importance of recognizing that large posterior malleolar fractures are associated with tibial shaft fractures. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.
OBJECTIVE: To compare posterior malleolar fracture morphology in ankle fractures compared with those with tibial shaft fractures. SETTING: Level 1 trauma center. DESIGN: Retrospective cohort study. PATIENTS/PARTICIPANTS: Fifty-four patients with tibial shaft fractures and 61 patients with ankle fractures. MAIN OUTCOME MEASUREMENTS: Posterior malleolar fractures in ankle fractures versus tibial shaft fractures were classified by type and pathomorphology analyzed. RESULTS: Posterior malleolar fractures were significantly larger when associated with tibial shaft fractures (32% cross-sectional area) as compared to ankle fractures (15% cross-sectional area) (P < 0.001). The distribution of posterior malleolar fracture type differed between tibial shaft fractures and ankle fractures. In addition, 47% of the type II posterior malleolar fractures in tibial shaft fractures had an additional fracture line oriented in the sagittal plane, a fracture pattern unique to these injuries that were not observed in the ankle fracture cohort. CONCLUSIONS: Posterior malleolar fracture morphology varied significantly between tibial shaft fractures and rotational ankle fractures. Posterior malleolar fractures in tibial shaft fractures were over twice the size of posterior malleolar fractures that occur with rotational ankle fractures and more likely to involved the medial malleolus. This information emphasizes the importance of recognizing that large posterior malleolar fractures are associated with tibial shaft fractures. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.