Os Navicularis Syndrome-MRI

Os naviculare is a large ossicle adjacent to the medial side of the navicular bone. The tibialis posterior tendon often inserts with a broad attachment onto the ossicle. Most cases are asymptomatic but in a small proportion it may cause a painful tendinosis due traction between the ossicle and the navicular. Such changes are best seen on MRI as in our case with marrow and soft tissue edema on STIR images in relation to the bony ossicle.