In vivo tracking of the human patella using cine phase contrast magnetic resonance imaging

Improper patellar tracking is often considered to be the cause of patellar- femoral pain. Unfortunately, our knowledge of patellar-femoral-tibial (knee )joint kinematics is severely limited due to a lack of three-dimensional, n oninvasive, in vivo measurement techniques. This study presents the first l arge-scale, dynamic, three-dimensional, noninvasive, in vivo study of nonim paired knee joint kinematics during volitional leg extensions. Cine-phase c ontrast magnetic resonance imaging,vas used to measure the velocity profile s of the patella, femur and tibia in 18 unimpaired knees during leg extensi ons, resisted by a 34 N weight. Bone displacements were calculated through integration and then converted into three-dimensional orientation angles. W e found that the patella displaced laterally, superiorly, and anteriorly as the knee extended. Further, patellar flexion lagged knee flexion, patellar tilt was variable, and patellar rotation was fairly constant throughout ex tension.