PAINFUL OS-PERONEUM SYNDROME - A SPECTRUM OF CONDITIONS RESPONSIBLE FOR PLANTAR LATERAL FOOT PAIN

Plantar lateral foot pain may be caused by various entities and the pa inful os peroneum syndrome (a term coined by the authors) should be in cluded in the differential diagnosis. Painful os peroneum syndrome res ults from a spectrum of conditions that includes one or more of the fo llowing: (1) an acute os peroneum fracture or a diastasis of a multipa rtite os peroneum, either of which may result in a discontinuity of th e peroneus longus tendon; (2) chronic (healing or healed) os peroneum fracture or diastasis of a multipartite os peroneum with callus format ion, either of which results in a stenosing peroneus longus tenosynovi tis; (3) attrition or partial rupture of the peroneus longus tendon, p roximal or distal to the os peroneum; (4) frank rupture of the peroneu s longus tendon with discontinuity proximal or distal to the os perone um; and/or (5) the presence of a gigantic peroneal tubercle on the lat eral aspect of the calcaneus which entraps the peroneus longus tendon and/or the os peroneum during tendon excursion. Familiarity with the v arious clinical and radiographic findings and the spectrum of conditio ns represented by the painful os peroneum syndrome can prevent prolong ed undiagnosed plantar lateral foot pain. Clinical diagnosis of the pa inful os peroneum syndrome can be facilitated by the single stance hee l rise and varus inversion stress test as well as by resisted plantarf lexion of the first ray, which can localize tenderness along the dista l course of the peroneus longus tendon at the cuboid tunnel. Radiograp hic diagnosis should include an oblique radiograph of the foot for vis ualization of the os peroneum and, if indicated, other imaging studies . Recommended treatment ranges from conservative cast immobilization t o surgical approaches including: (1) excision of the os peroneum and r epair of the peroneus longus tendon, and (2) excision of the os perone um and degenerated peroneus longus tendon with tenodesis of the remain ing remnant of peroneus longus to the peroneus brevis tendon.