Tarsal Tunnel Syndrome Associated With a Bipartite Talus

Abstract

Background: Talus bipartitus is a rare skeletal anomaly that may be mistaken for an os trigonum, a relatively common accessory ossicle found posterior to the talus. Both are believed to be formed similarly with the failed fusion of the talus with a second ossification center. Os trigonum is often diagnosed incidentally or found on radiographs obtained in symptomatic patients with signs of os trigonum syndrome, which presents with posterolateral ankle pain. A bipartite talus may also present with similar symptoms but may be differentiated through its articular involvement.

Case: In this article, we describe the rare presentation of tarsal tunnel syndrome in a patient caused by a bipartite talus. The patient underwent surgical decompression with the removal of the posterior fragment.

Conclusion: A bipartite talus is a rare entity that may be mistaken for an os trigonum, a common accessory ossicle. In this article, we describe an outcome of a bipartite talus fragment removal due to tarsal tunnel syndrome and illustrate a rare pathological consequence of a bipartite talus. We further highlight the importance of early surgical management in patients presenting with an identifiable structure contributing to tibial nerve compression.

Figure 1

Lateral, AP, and oblique radiographs of the left ankle demonstrating the posterior fragment of the bipartite talus (white arrow) and degenerative changes at the left tibiotalar joint.

Figure 2

T1-weighted MRI of the left ankle in the sagittal, coronal, and axial planes. Red asterisk (*) denotes the posterior fragment of the bipartite talus, and the red arrow denotes the neurovascular bundle of the and posterior tibial artery and tibial nerve.