Os Peroneum Fracture-Plain Film

An adult patient presents with acute trauma to lateral foot with tenderness near cuboid. X ray shows  irregular, fragmented and possibly spread out appearance of osperoneum with Soft tissue swelling in the vicinity  with spurring at cuboid peroneal groove location- comminuted fracture of os-peroneum with peroneus longus tendon rupture is possible. MRI  would help.

Teaching points by Dr MGK Murthy

·         Os-peroneum is round or oval  accessory ossicle located at calcaneocuboid junction level in the distal peroneus longus tendon substance

·          Peroneus longus originates from lateral tibial condyle and head of fibula, travels along the retromalleolar groove of fibula protected by superior peroneal  retinaculum (SPR), and inserts in to 1^st MT base  and medial cuneiform (brevis  comes from mid 1/3 leg and goes to  base of 5th MT)

·         Seen in 26% of feet , though some differ from these figures

·         Fractures can occur due to direct trauma or indirect stress due to forced dorsiflexion of foot

·         Fragments spread along the  longus tendon and are often accompanied by tendinopathy or rupture

·         Differentials include more common bipartite os-peroneum, and degenerative process of the ossicle