Open reduction and internal fixation of the posterior malleolus fragment frequently restores syndesmotic stability.

Abstract

Comparison of unfixed, CRIF, and ORIF of the posterior malleolus fragment (PMF) regarding the frequency of trans-syndesmotic fixation and quality of reduction in trimalleolar (equivalent) fractures. Retrospective registry study. Patients with a trimalleolar (equivalent) ankle fractures were identified within the departments' fracture database. General demographics, treatment details, and fracture specific details (CT-scans) were assessed. Patients were grouped per the PMF treatment: not addressed, CRIF, ORIF. 236 patients (53.0 ± 18.3 (range: 18-100) years), 58.1% female were eligible. The mean size of the PMF was 21.4 ± 10.4% (range: 2.7-55.9%), 71.6% were ≤25% of the tibial plafond. PMF fixation: Untreated 48.3%, CRIF 18.6%, ORIF 33.1%. ORIF of the PMF significantly (p < 0.001) reduced the frequency of trans-syndesmotic fixation (25%) compared to CRIF (61%) or untreated PMF (63%) with no significant influence of the PMF size (≤25%/>25%). ORIF resulted in a significantly (p < 0.001) better quality of reduction (1.2 ± 1.1 mm (range: 0-5 mm)) compared to CRIF (2.5 ± 2.1 mm (range: 0-8 mm)) and untreated PMF (2.5 ± 2.3 mm (range: 0-20 mm)). Neither the frequency of trans-syndesmotic fixation nor the quality of reduction differed significantly between untreated PMF and CRIF. All posterior malleolus fragments, independent of their size, should be treated by ORIF, as this restores syndesmotic stability significantly more often than untreated PMF or CRIF.