Patient 1 has a fracture of the superior pole of the patella, involving the articular surface. There is associated joint effusion and intra-articular gas, raising the possibility of an open patellar fracture. This patient had a deep cut on the anterior knee and subsequently underwent emergent joint washout with ORIF of the patella.
Patient 2 has a developmental variant, a bipartite patella, due to an unfused accessory ossification centre at the superolateral aspect. A bipartite patella is often confused with a fracture; it is bilateral in approximately 50% of the cases.