Hypothesis-Generating Magnetic Resonance Imaging (MRI) Observation of Maisonneuve Fractures With Discontinuous Interosseous Membrane Injury: A Three-Case Series.

Maisonneuve fractures, proximal fibular fractures with concomitant distal tibiofibular disruption and either medial malleolus fracture or deltoid ligament injury, represent ~5% of ankle fractures and are uncommon pronation-external‑rotation ankle injuries whose interosseous‑membrane (IOM) damage is widely believed to be continuous from the ankle to the proximal fibular fracture. However, this hypothesis was proposed in the literature prior to the widespread use of magnetic resonance imaging (MRI). This study aimed to describe MRI patterns of IOM injury in Maisonneuve fractures from a small three-case series and to reconsider the traditional assumption of a full‑length IOM rupture. We reviewed MRI scans and defined IOM disruption as loss of the continuous low‑signal band between the tibial and fibular cortices with corresponding high signal on short tau inversion recovery (STIR). Distal (A), proximal (B), and intact mid‑segment (C) lengths were measured on coronal images. All cases demonstrated distal and proximal IOM injury with a preserved mid‑segment. Recognition of this discontinuous injury pattern on MRI challenges the concept of full‑length IOM rupture.