MRI of ankle sprain: the association between joint effusion and structural injury severity in a large cohort of athletes.

• For ankles exhibiting severe (grade 2) effusion in the tibiotalar joint after sprain, the risk for partial or complete syndesmotic ligament rupture increases more than eightfold. • The presence of effusion in both tibiotalar and talocalcaneal joints is associated with an increased risk for severe ligament injury such as complete ATFL rupture as well as partial or complete syndesmotic ligament rupture. • The presence of effusion in the tibiotalar or talocalcaneal joints after sprain is associated with an increased risk for severe talar osteochondral involvement.