Diagnosis: Painful Os Peroneum Syndrome Somewhat of a wastebasket term for lateral sided pain related to either an os peroneum ( a sesamoid bone situated in the peroneus longus tendon at the level of the calcaneocuboid joint) and/or tendinosis and tearing of the peroneus longus tendon. The os peroneum is a common finding said to be present in anywhere from 5-30% of the population. It may be present as a single bone, bipartite structure, or multipartite and can be unilateral or involve both feet. Both an acute injury or chronic inversion stress of the foot can lead to pathology of the os peroneum and the peroneus longus tendon. As the peroneus longus contracts the os peroneum can become compressed against the cuboid and cause stress injuries of the os peroneum, fracture, or diastasis across the components of a bipartite or multipartite os peroneum. Similar forces can lead to tendinosis or tearing of the peroneus longus.
What’s the Diagnosis – Case 137
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