Persistent congenital isolation of the suprapatellar pouch mimicking patellofemoral disease

A patient with congenital isolation of the suprapatellar bursa presented with pain suggestive of patellofemoral joint disease. At arthroscopy, injection filled only the bursa. The diagnosis of congenital isolation of the suprapatellar bursa was made by the injection of radiopaque material into the bursa. Excision of the bursa eliminated the symptoms. This case is instructive, as it documents an unusual congenital anomaly that can complicate arthroscopic technique and can be a rare cause of knee pain.