Ankle Fractures Involving the Posterior Malleolus: 7-Year Results in 100 Cases

Abstract

Category:Ankle; TraumaIntroduction/Purpose:The presence of a posterior malleolar (PM) fragment has a negative prognostic impact in ankle fractures. The best treatment is still subject to debate and new concepts continue to emerge. The aim of this study was to assess the medium- to long-term clinical and functional outcome of ankle fractures with a PM fragment in a larger patient population treated with an individualized treatment approach.Methods:One hundred patients with ankle fractures involving the PM were identified retrospectively and reevaluated at an average follow-up of 7.0 years. Fixation of the PM was tailored to the individual fracture pattern. Bartoníček-Rammelt type I PM fractures (extraincisural shell-like fragments) were not fixed surgically. Displaced Type II (posterolateral fragments) and type III PM fractures (two-part with medial extension) were mostly fixed with direct posterior screw or plate fixation. Intercalary joint fragments were fixed with lost K-wires or resorbable pins. Type IV PM fractures (large triangular fragments) were treated with either posterior screw / plate fixation or indirect anteroposterior screw fixation with direct transfibular control of reduction, if feasible.Results:Internal PM fragment fixation was negatively correlated with the need for syndesmotic screw placement at the time of surgery (p=0.010). At 7 years, the mean Foot Function Index was 16.5, the Olerud Molander Ankle Score averaged 80.2 and the American Orthopaedic Foot & Ankle Society ankle/hindfoot score averaged 87.5. The physical (PCS) and mental health component summary (MCS) scores of the SF-36 averaged 47.7 and 50.5, respectively. Range of motion was within 3.4 degrees of the uninjured side. The size of the PM fragment had no prognostic value. There was a trend to lower outcome scores with anterior or posterior shift of the distal fibula of 1 mm within the tibial incisura. Patients who underwent primary internal fixation had significantly superior SF-36 MCS than patients who underwent staged internal fixation (p=0.031). Two patients (2%) needed secondary ankle fusion following deep infection.Conclusion:With an individualized treatment protocol, tailored to the CT-based assessment of PM fractures, favorable medium and long-term results can be expected. The mere size of the PM fragment is just one of the factors guiding treatment, other important criteria are fragment displacement, impaction of the tibial plafond and incisura involvement. PM fixation provides direct bone-to-bone fixation of the syndesmosis and significantly reduces the need for additional transsyndesmotic fixation with a screw or flexible implant.