Os peroneum syndrome

Case contributed by Dr Sinéad Culleton


Right ankle pain.

Patient Data

Age: 60 years
Gender: Male

1 cm intratendinous os peroneum in the peroneus longus lateral and plantar to the calcaneocuboid joint.


There is prominent marrow oedema with a 7 mm intratendinous os peroneum within the proximal plantar aspect of the peroneal longus. There is adjacent soft tissue oedema.The remainder of the plantar aspect of the peroneal longus tendon is normal.

Case Discussion

Painful os peroneum syndrome is an important differential in lateral foot pain. This may be secondary to trauma in the acute setting, causing a fracture or diastasis of a multipartite os. In the chronic setting foot pain may be attributed to a chronic frature or diastasis with callus formation. This can result in partial or complete rupture of the peroneus longus tendon or tenosynovitis. A large peroneal tubercle can also can entrapment of the tendon causing symptoms 1,2. This accessory os should not be confused with an os vesalianum.

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Case information

rID: 40637
Published: 3rd Nov 2015
Last edited: 5th Nov 2015
Inclusion in quiz mode: Included

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