Treatment of posterior malleolar (PM) ankle fractures remain controversial. Despite increasing recommendation for small PM fragment fixation, high quality evidence demonstrating improved clinical outcomes over the unfixated PM is limited. We describe the medium-to-long term clinical and radiographical outcomes in younger adult patients with PM ankle fractures managed without PM fragment fixation. A retrospective cohort study of patients aged 18–55 years old admitted under our orthopaedic unit between 1st of April 2009 and 31st of October 2013 with PM ankle fractures was performed. Inclusion criteria were that all patients must mobilise independently pre-trauma, have no pre-existing ankle pathologies, and had satisfactory bimalleolar and syndesmotic stabilisation. Open fractures, talar fractures, calcaneal fractures, pilon fractures, subsequent re-injury and major complications were excluded. All PM fragments were unfixated. Clinical outcomes were evaluated using Foot and Ankle Ability Measure (FAAM) with activities of daily living (ADL) and sports subscale, visual analogue scale (VAS) and patient satisfaction ratings. Osteoarthrosis was assessed using modified Kellgren-Lawrence scale on updated weightbearing ankle radiographs. 61 participants were included. Mean follow-up was 10.26 years. Average PM size was 16.19±7.39%. All participants were evaluated for clinical outcomes, demonstrating good functional outcomes (FAAM-ADL 95.48±7.13; FAAM-Sports 86.39±15.52) and patient satisfaction (86.16±14.42%), with minimal pain (VAS 1.13±1.65). Radiographical outcomes were evaluated in 52 participants, showing no-to-minimal osteoarthrosis in 36/52 (69.23%), mild osteoarthrosis in 14/52 (26.92%) and moderate osteoarthrosis in 2/52 (3.85%). Clinical outcomes were not associated with PM fragment size, post-reduction step-off, dislocation, malleoli fractured or syndesmotic injury. PM step-off and dislocation were associated with worse radiographical osteoarthrosis. Other published medium-to-long term studies reported overall good outcomes, with no differences after small fragment fixation. The unfixated smaller posterior malleolus fragment demonstrated overall satisfactory clinical and radiographical outcomes at 10-year follow-up and may be considered a valid treatment strategy.
