Lateral patella dislocations: History, physical exam, and imaging

Acute lateral patellar dislocations occur primarily in the second decade of life, affecting young active individuals. Concomitant injuries to the knee, including medial patellofemoral ligament injuries, are common, occurring in up to 90 % of patients. Recurrent instability episodes may occur in up to 44 % of patients and are dependent on the patient’s anatomy, particularly patellar position and trochlear morphology. A careful history and physical exam will help establish the diagnosis, with specific imaging studies often used to confirm the diagnosis and define the spectrum of concomitant injuries. Advanced imaging studies are also used to define objective measurements, patellar position, and trochlear shape, in order to determine recurrent instability risk and help guide surgical treatment.