Patellofemoral Instability in Children: What the Pediatric Orthopaedic Surgeon Wants to Know from the Radiologist

The clinical spectrum of patellofemoral instability (PFI) includes nonspecific anterior knee pain to acute and/or chronic patellofemoral dislocation. The role of the radiologist should go beyond binomial identification of acute or chronic PFI, to identify the underlying pathophysiologic cause and treatment-relevant findings based on both radiography and cross-sectional imaging. The purpose of this review is to detail the imaging findings of PFI in children from the perspectives of alignment, patellofemoral morphology including underlying dysplasia, and intra-articular pathology.