Hemilaterally symptomatic bipartite patella associated with bone erosions arising from a gouty tophus: a case report.

Symptomatic bipartite patella in adults is rare. We have treated an unusual case of a bipartite patella in an adult, which became symptomatic in association with cystic degeneration localized to the patella and a gouty tophus. Although the patient had bilateral bipartite patellae, multiplanar reformation with computed tomography (CT-MPR) clearly demonstrated that the bipartite portion of the patella was malaligned at the junction of the accessory bone and patella in the symptomatic knee. Bone erosions were present both in the bipartite fragment and adjacent portion of the patella. After surgical excision of the bipartite fragment, the patient's symptoms have improved. This case illustrates that cyst formation associated with inflammatory arthritis may be a rare cause for a bipartite patella in an adult to become symptomatic.