A checkrein deformity can occur after a distal tibiofibular fracture. Usually, a checkrein deformity due to a dysfunction of the extensor hallucis longus muscle is rarer than that of the flexor hallucis longus. Only a few related studies have been reported. The authors encountered an extensor hallucis longus checkrein deformity due to extensor retinaculum syndrome while managing a triplane fracture. In magnetic resonance imaging, an increase in the heterogeneous signal was observed on the T2-weighted images suggesting muscle necrosis or ischemic changes in a part of the extensor hallucis muscle. Postoperative great toe motor weakness, unintentional movement, sensory changes, and weakness improved spontaneously during the follow-up.

A checkrein deformity can occur after a distal tibiofibular fracture. Usually, a checkrein deformity due to a dysfunction of the extensor hallucis longus muscle is rarer than that of the flexor hallucis longus. Only a few related studies have been reported. The authors encountered an extensor hallucis longus checkrein deformity due to extensor retinaculum syndrome while managing a triplane fracture. In magnetic resonance imaging, an increase in the heterogeneous signal was observed on the T2-weighted images suggesting muscle necrosis or ischemic changes in a part of the extensor hallucis muscle. Postoperative great toe motor weakness, unintentional movement, sensory changes, and weakness improved spontaneously during the follow-up.