Arthroscopic removal of separated bipartite patella causing snapping knee syndrome

The bipartite patella is a developmental osseous variant that is found in approximately 2% to 6% of the population, and is bilateral in 50%. The proposed etiologies include old nonunion, osteochondritis, and congenital growth defect. It is often found incidentally around the inferior pole, lateral margin, or superolateral border of the patella. It is usually asymptomatic, but may be related to anterior knee pain. However, separation of the bipartite patella is rare, with 9 cases reported in the literature. The symptomatic snapping knee syndrome may be caused by multiple intra-articular and extra-articular pathology including discoid meniscus, tumors, iliotibial band, popliteus, gracilis, semitendinosus, or biceps femoris tendon. However, no reports exist on separated bipartite patella as the feasible cause of the snapping knee syndrome in the orthopedic literature. This article presents a case of snapping knee syndrome due to separated bipartite patella. The accessory bone was removed by arthroscopy, which has rarely been described in the literature.