Background: Talus secundarius is a very rare accessory bone at the lateral border of the foot. It is attached via a synchondrosis or small synostosis to the lateral aspect of the talar body and has additional facets to the tip of the lateral malleolus and the superior aspect of the calcaneus.
Methods: Over a period of 8 years, we have seen 5 patients with 6 cases of talus secundarius with an average age of 17 years at first presentation to the senior author. One ossicle was an incidental finding and completely asymptomatic. In the other 5 cases, the average duration of symptoms was 21 months at that time. In 3 cases, additional accessory bones were seen around the talus.
Results: The average size of the ossicles was 18 × 12 × 8 mm. Complete removal resulted in considerable pain reduction without further functional restriction in 4 cases. Two cases (1 asymptomatic, 1 with mild intermittent symptoms) were treated nonoperatively. The average Foot Function Index improved from 22.6 to 4.8 in all patients and from 31.0 to 4.5 in the patients treated with excision for symptomatic talus secundarius (P < .01).
Conclusion: The knowledge of accessory bones at the foot is important, as missed diagnosis may lead to prolonged course of pain and unnecessary protection in the affected patients. Resection of symptomatic ossicles substantially reduces pain, but patients have to be counseled that some symptoms may prevail in a congenital deformity.
Level of evidence: Level IV, prospective case series.
Keywords: accessory; excision; lateral process; nonunion; talus.