Radiologic Criteria in Patellar Dislocations

Abstract

Imaging of patellofemoral instability allows the recognition of the disturbances of shape and congruence leading to dislocations. The key to adequate imaging is complete evaluation of the underlying factors leading to instability. This chapter discusses the radiographic signs of these factors involved in the genesis of instability, which are trochlear dysplasia, patella alta, abnormal tibial tuberosity-trochlear groove distance, and lateral patellar tilt. Additionally, the acute signs of patellar dislocation are reviewed.