Ligamentous Injuries in Stable Ankle Fractures: An MRI-Based Study.

Abstract

Background: Ankle fractures are common orthopaedic injuries, and their management is primarily determined by fracture stability. The Lauge-Hansen classification system categorizes fractures according to mechanism of injury and ligaments involved. Supination external rotation (SER) type 2 fractures correspond to stable weber B fractures and are traditionally treated nonoperatively, whereas SER 3 and SER 4 fractures, characterized by syndesmosis disruption, typically require surgical intervention. We hypothesize that some apparently stable injuries may involve additional structures, challenging the conventional treatment approach. This study aims to determine the prevalence of SER 3 and SER 4 ankle injuries among radiographically stable SER 2 fractures.

Method: The study used baseline data from a longitudinal cohort conducted at Gold Coast Hospital and Health Service (GCHHS). Patients attending the GCHHS fracture clinic with radiographically stable SER 2 fractures were invited to participate. Those meeting the eligibility criteria underwent ankle magnetic resonance imaging (MRI) to evaluate the integrity of syndesmotic and ankle ligaments.

Results: Fifty-six participants were recruited, 38 (68%) female and 18 (32%) male, with a mean age of 47.2 years. All had stable syndesmoses on radiographic assessment and diagnosed with stable SER 2 ankle fractures. MRI scans revealed that 71% (n = 40) met the criteria for SER 2 injuries, 25% (n = 14) for SER 3 injuries with complete ruptures of posterior inferior tibiofibular ligament (PITFL), and 4% (n = 2) for SER 4 injuries with PITFL and deltoid ligament (DL) ruptures. These results challenge the assumption that radiographically stable SER 2 fractures are consistently stable in terms of additional structures involved.

Conclusion: The study highlights that a considerable proportion of seemingly stable ankle fractures involve more structures than previously thought. This suggests the management of SER 3 and SER 4 injuries could include nonoperative treatment.

Level of evidence: Level III, cohort study.