Dislocation of an enlarged fabella as uncommon cause of knee pain: a case report.

The fabella is a sesamoid bone that can very occasionally act as a source of atypical knee pain, often mistaken for a more common cause of clinical symptoms, such as an intra-articular loose body or an osteophyte. We report a case of symptomatic dislocation of an osteoarthritic, enlarged fabella, 4 years after total excision of the patella for a comminuted fracture, that was primarily overlooked and led to repeated diagnostic arthroscopy of the knee. A thorough history and physical examination of the joint as well as appropriate roentgenographic studies could have spared this patient an unnecessary arthroscopy and indicated the correct therapy.