• BACKGROUND
    • Isolated distal fibular fractures can often be successfully treated without surgery. Fracture stability is largely dependent on an intact deep deltoid ligament, yet methods of determining ligament integrity remain a clinical challenge. Recently, fibular fracture displacement on radiographs has been used to predict deep deltoid disruption.
  • PURPOSE
    • To determine whether distal fibular fracture displacement is a reliable indicator of fracture stability based on arthroscopic assessment of deep deltoid ligament integrity.
  • STUDY DESIGN
    • This retrospective study evaluated isolated fibular fracture displacement on radiographs in 85 patients at a single medical center. All patients underwent surgical repair of the fracture and arthroscopic evaluation of the deep deltoid.
  • METHODS
    • Anterior to posterior fibular fracture displacement (APD) and lateral fracture displacement (LFD) were measured and correlated with deep deltoid integrity at each millimeter (mm) of displacement.
  • RESULTS
    • Fifty-seven (67%) patients had an intact deep deltoid, with a median APD of 0.8 mm (range 0.0 - 3.7 mm). Twenty-eight (33%) patients had a ruptured deep deltoid, with a median APD displacement of 1.85 mm (range 1.05 - 2.7 mm). The deep deltoid was intact over a wide range of fracture gap measurements. The APD was significantly greater in patients with a ruptured deep deltoid (p < 0.001).
  • CONCLUSION
    • Although there was a significant increase in fracture displacement when the deep deltoid was compromised, large APD gap distances did not consistently correlate with a deep deltoid rupture. Anterior to posterior fracture gap distance is not a reliable indicator of deltoid ligament integrity in isolated distal fibula fractures.
  • LEVEL OF EVIDENCE
    • Level 3, retrospective cohort.