Quantification of patellar tracking using kinematic MRI.
The purpose of this study was to describe a method to quantify dynamic patellar tracking using kinematic MRI (KMRI). Twelve normal females and three patients with patellofemoral pain participated. Imaging was performed with a 1.5-T/64-MHz MR system using a fast spoiled gradient-recalled acquisition in the steady state (GRASS) pulse sequence. A nonferromagnetic positioning device permitted active, bilateral knee extension against resistance (15% bwt) from 45 degrees knee flexion to full extension. Subjects were instructed to extend their knees at a rate of 9 degrees per second, which allowed images to be obtained at 45 degrees, 36 degrees, 27 degrees, 18 degrees, 9 degrees, and 0 degrees. All images were assessed for medial/lateral patellar displacement, patellar tilt, and sulcus angle using a computer-aided system. Normal patellar motion was characterized by medial movement from 45 degrees to 18 degrees, followed by a reversal toward lateral displacement from 18 degrees to full extension. The results for patellar tilt revealed a tendency toward decreasing lateral tilt as the knee extended. Sulcus angle measurements indicated that the patella was moving to a more shallow portion of the trochlear groove (superiorly) during extension.
Powers
C M
CM
Department of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles 90033, USA.
Shellock
F G
FG
Pfaff
M
M
D000328:Adult; D001696:Biomechanical Phenomena; D004867:Equipment Design; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D007537:Isometric Contraction / Q000502:physiology*; D007593:Joint Instability / Q000175:diagnosis / Q000503:physiopathology; D007718:Knee Injuries / Q000175:diagnosis / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D010329:Patella / Q000293:injuries / Q000503:physiopathology*; D012680:Sensitivity and Specificity