The importance of magnetic resonance imaging in a symptomatic "bipartite" os peroneum: a case report.

Although well reported in the literature, fractures of the os peroneum are uncommon and can be difficult to differentiate from symptomatic multipartite sesamoids. The location of the os peroneum within the tendon of peroneus longus can make it difficult to excise without compromising or sacrificing the tendon, and, subsequently, necessitating reconstruction or tenodesis to peroneus brevis. In this article, we describe the case of an adult female who presented with a fractured os peroneum that radiographically appeared bipartite, and necessitated excision with reconstruction of the peroneus longus. In retrospect, with the benefit of histology and careful review of the preoperative magnetic resonance image scans, simple excision of the medial fragment of the ossicle may have obviated the need for tendon reconstruction by maintaining the integrity of the peroneus longus tendon.