Ten year outcomes after non-fixation of the smaller posterior malleolar fragment: A retrospective cohort study

Introduction

Treatment of posterior malleolar (PM) ankle fractures remains 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 long term clinical and radiographical outcomes in younger adult patients with PM ankle fractures managed without PM fragment fixation.

Material and methods

A retrospective cohort study was performed on PM ankle fracture patients aged 18–55 years old admitted under our orthopaedic unit between 1st of April 2009 and 31st of October 2013. Inclusion criteria were ASA 1 and 2, independent mobility pre-trauma, no pre-existing ankle pathologies, with 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 visual analogue scale (VAS) for pain, Foot and Ankle Ability Measure (FAAM) with activities of daily living (ADL) and sports subscale for function, and patient satisfaction ratings. Osteoarthritis was assessed using modified Kellgren-Lawrence scale on follow-up weightbearing ankle radiographs.

Results

Sixty-one participants were included. Mean follow-up was 10.26 years. Average PM size was 16.2 ± 7.39%. All participants were evaluated for clinical outcomes. Mean score of FAAM-ADL was 95.5 ± 7.13, FAAM-Sports 86.4 ± 15.5, patient satisfaction 86.2 ± 14.4% and pain score 1.13 ± 1.65. Radiographical outcomes were evaluated in 52 participants, showing no-to-minimal osteoarthritis in 36/52 (69%), mild osteoarthritis in 14/52 (27%) and moderate osteoarthritis in 2/52 (4%). Pain and functional scores were independent of PM fragment size, post-reduction step-off, dislocation, malleoli fractured or syndesmotic injury. PM step-off more than 1 mm and traumatic dislocation/subluxation were associated with worse radiographical osteoarthritis.

Conclusion

After controlling for confounders, the unfixated smaller posterior malleolus fragment at 10-year follow-up demonstrated largely satisfactory clinical outcomes with some radiographical progression of osteoarthritis.

Level of evidence

Level III – Retrospective cohort study