Kinematic CT and MR imaging of the patellofemoral joint

Anterior knee pain is a frequently encountered orthopedic symptom and is of ten associated with patellofemoral malalignment: which may cause chondromal acia of the patella. The difficulty in determining the pate position betwee n 0 degrees and 30 degrees of knee flexion with a conventional axial radiog raphic examination is well known. The introduction of computed tomography ( CT) and magnetic resonance (MR) imaging for the diagnosis of knee joint abn ormalities has enabled assessment of the patellar position in this critical range. More recently, emphasis has been placed on dynamic visualization of patellar motion to detect an abnormal tracking pattern. The important infl uence of the quadriceps muscle on the patellar tracking pattern is well kno wn and has been examined during active knee extension by the use of ultrafa st CT, and motion-triggered and ultrafast MR imaging. This article provides an overview of the current status of kinematic CT and MR imaging in the di agnosis of patellofemoral alignment, its clinical implications, and future directions.