Presentation
Incidental finding in a case of right ankle inversion injury.
Patient Data
An extra-structure with muscle echopattern located posterior-lateral to the peroneal tendons. It starts in the distal leg and ends at the retrotrochlear eminence of the calcaneum.
The anterior talofibular ligament shows laxity and mild thinning. The calcaneofibular ligament is thickened. Small effusion in the anterior ankle joint recess. Normal anterior inferior tibiofibular ligament.
A short-axis cine-loop runs from the proximal to the distal direction. Similar extra-structure is present on the asymptomatic side.
Case Discussion
The patient with a history of recent right ankle inversion shows anterior talofibular ligament injury and calcaneofibular ligament sprain with anterior ankle joint recess effusion.
Incidental finding of accessory muscle in the peroneal compartment on both sides. It is known as the peroneus quartus muscle.