Comminuted Suprasyndesmotic Ankle Fractures are Associated with a High Rate of Anterolateral Plafond Involvement

Objectives: This study aimed to identify the rate at which the anterolateral tibial plafond is affected in comminuted suprasyndesmotic ankle fractures (AO/OTA 44C2) and to assess how its involvement affects clinical outcomes. Methods: Design : Retrospective review Setting: Level 1 Trauma Center Patient Selection Criteria: Patients with a pre-operative computed tomography (CT) treated surgically for AO/OTA 44C2 fractures from January 2005 to December 2021. Outcome Measures and Comparisons: The primary outcome measure was the prevalence of anterolateral plafond impaction or a displaced Tillaux-Chaput fracture. Secondary outcome measures included reoperation rate (excluding hardware removal), rate of new-onset ankle osteoarthritis, rate of ankle osteoarthritis progression, Single Assessment Numeric Evaluation (SANE) score, and the Olerud Molander Ankle Score (OMAS). Results: Fifty-three patients met inclusion criteria. The average age was 50 years (range 18-100), and 53% were female. The anterolateral plafond was involved in 26 patients (49%), with anterolateral plafond impaction in 11 patients (21%) and a displaced Tillaux-Chaput fragment in 15 patients (28%). Five patients (19%) received independent fixation of the anterolateral plafond, and three of these patients had anterolateral plafond impaction addressed. Thirty-eight patients (72%) had clinical follow-up of at least 6 months. Patients with anterolateral plafond impaction had a higher rate of reoperation (excluding hardware removal) compared to those without any anterolateral plafond involvement (HR = 8.3, 95% CI: 1.4-15.3, p=0.022) as well as a higher rate of new-onset ankle osteoarthritis (83% vs 23%, p=0.013). There was no difference in the rate of reoperation (11% vs 9%, p=0.748) or new-onset osteoarthritis (63% vs 23%, p=0.078 when comparing those with a displaced Tillaux-Chaput fracture to those without anterolateral plafond involvement. There were no differences in SANE (75% vs. 78% vs. 85%, p = 0.661) or OMAS (70 points vs. 69 points vs. 81 points, p=0.517) scores when comparing those with anterolateral plafond impaction, those with Tillaux-Chaput fragments, and those with no anterolateral plafond involvement. Conclusion: CT evaluation is recommended in patients with comminuted suprasyndesmotic fibula fractures (AO/OTA 44C2) given their high association with anterolateral plafond impaction and Tillaux-Chaput fracture. Patients with anterolateral plafond impaction have a higher reoperation rate and new-onset ankle osteoarthritis compared to those without anterolateral plafond involvement. Level of Evidence: Level IV