Title: Bipartite Patella

Imaging Findings:

Figures Superolateral circumscribed patellar defect (arrows) with plain film findings showing sclerotic, well defined margins differentiating this process from an acute injury.

Figures Not uncommonly encountered on MRI as a cleft of signal alteration (arrows).

Clinical:

Present in 2% of the population and more commonly seen in males. This is almost always bilateral (1). Incidentally discovered or on occasion may present with localized pain (20).

Etiology:

Thought to represent chronic chondro-osseous tensile failure of bone in skeletally immature patients.

References:

1. Weinberg S. Duplication of the patella (“double” patella). Skeletal Radiol 1981; 7:223-224 .
2. Ogden JA, McCarthy SM, Jokl P. The painful bipartite patella. J Pediatr Orthop1982; 2:263-269.