[Pathology of the anterior peroneus tendon and that of the intermetatarsal bone]

The inconstant peroneus tertius is the fourth muscle in the antero-lateral aspect of the leg. Its tendon crosses the fourth tendon of the extensor hallucis brevis on the dorsal aspect of the cuboïdo-metatarsal joint. If an impingement occurs it may provoke a painful condition and a typical synovial cyst. The anatomy and the pathology of the condition are described. The treatment is very simple: the inconstant tendon should be removed when it produces symptoms. An accessory bone, the intermetatarsal bone, located at the proximal part of the first intermetatarsal or intercuneiform space, may have various shapes. It can provoke pain in the first space when pressure is exerted on capsulo-ligamentous structures or on neuro-vascular elements. The treatment is excision of the accessory bone.