Predicting need for and effect of external fixation in closed ankle fractures: a retrospective case–control study

OBJECTIVES: To compare outcomes between planned and delayed ex-fix and identify predictors for requiring external fixation for closed ankle fractures. METHODS: Design: Retrospective case-control study. SETTING: Single trauma centre. Patient selection criteria: Skeletally mature patients with closed ankle fractures, with or without dislocation, temporised in cast or external fixation (ex-fix) (< 24 versus > 24 h), treated with open reduction/internal fixation. Outcome Measures and Comparisons: Planned (≤ 24 h from admission) or delayed (> 24 h) patients were compared in terms of time to definitive fixation, length of stay (LOS), and complications. A control cohort of cast-only patients with identical AO/OTA fracture patterns was identified to evaluate predictors of requiring ex-fix. Initial radiographs were analysed for talar displacement, posterior malleolar fragment (PMF) size, and number of reduction attempts. RESULTS: Seventy-one patients underwent external fixation (25 planned, 46 delayed). Planned ex-fix was associated with significantly shorter time from admission to definitive fixation (7.8 vs 11.7 days, p < 0.0001) and reduced LOS (11.2 vs 16.6 days, p = 0.0037) compared with delayed ex-fix. Complication rates did not differ significantly between groups. Compared with controls, patients requiring delayed ex-fix demonstrated greater talar displacement on AP and lateral radiographs (p = 0.02 and p = 0.001, respectively). A PMF size ≥ 23% (OR 5.74, p = 0.0002) and two or more reduction attempts (OR 4.68, p = 0.0022) were independently associated with the need for external fixation. CONCLUSIONS: Planned external fixation in closed ankle fractures is associated with shorter hospital stay and earlier definitive fixation compared with delayed application. Significant talar displacement, larger posterior malleolar fragments, and multiple failed reduction attempts may help identify fractures that would benefit from planned external fixation. LEVEL OF EVIDENCE: Therapeutic and Diagnostic Level III.