Patellofemoral disorders: physical and radiographic evaluation. Part II: Radiographic examination

Evaluation of the patient with patellofemoral complaints requires a comprehensive physical and radiologic investigation. The tangential view is most helpful in the evaluation of such patellofemoral disorders as chondromalacia, lateral patellar compression syndrome, and recurrent subluxation or dislocation. Commonly utilized tangential views include those described by Hughston, Merchant, Laurin, and Ficat. Multiple calculations available for quantitation of abnormal tangential views include the sulcus angle, congruence angle, lateral patellofemoral angle, patella index, and patellofemoral index. Lateral radiographic views commonly utilized to evaluate the patellofemoral joint for patella alta or infera include those described by Blumensaat, Labelle and Laurin, and Insall and Salvati. Utilization of all of the available patellofemoral radiographic views and calculations is impractical and unnecessary. However, to ensure diagnostic accuracy, a routine consisting of a reproducible radiographic technique and various, easily performed calculations that aid in diagnosis must be adopted.