Os supranaviculare contributing to anterior ankle impingement: a case report

The os supranaviculare is a rare accessory ossicle of the midfoot, typically considered asymptomatic. We report a case of chronic dorsal midfoot and anterior ankle pain in which the os supranaviculare likely contributed to an anterior ankle impingement mechanism with associated tibiotalar synovitis and extensor hallucis longus tenosynovitis. Dynamic ultrasound was essential in demonstrating mechanical interaction during dorsiflexion and in guiding targeted treatment. This case suggests that the os supranaviculare may play a clinically relevant role within the spectrum of anterior ankle impingement and should be considered in the differential diagnosis of chronic dorsal midfoot pain. Level of Evidence IV; Case report.