Association Between Isolated Fibular Fracture Displacement and Deep Deltoid Injury: A Comparative Analysis of Arthroscopic and Radiographic Assessments.

Abstract

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. To determine whether distal fibular fracture displacement is a reliable indicator of fracture stability based on arthroscopic assessment of deep deltoid ligament integrity. 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. 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. 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). 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 3, retrospective cohort.