Patellar tracking patterns during active and passive knee extension: evaluation with motion-triggered cine MR imaging

Area of Science:

• Orthopedics
• Radiology
• Biomechanics

Background:

• Patellofemoral maltracking is a common cause of knee pain.
• Accurate diagnosis is essential for effective treatment.
• Static imaging may not fully capture dynamic joint abnormalities.

Purpose of the Study:

• To compare dynamic (motion-triggered cine) and static MRI for evaluating patellofemoral joint motion.
• To assess the diagnostic value of active versus passive knee extension in patellar tracking analysis.
• To identify critical differences in patellar tracking between patients with maltracking and healthy subjects.

Main Methods:

• Motion-triggered cine MRI and static MRI were performed during active knee extension (30° flexion to full extension).
• 13 patients with patellar maltracking and 15 healthy controls were studied.
• Key parameters analyzed included patellar tilt angle, bisect offset, and lateral patellar displacement.

Main Results:

• Statistically significant differences in patellar tracking parameters were observed between active and passive knee motions in both patient and control groups.
• Actively extended knees showed significant differences in all parameters between patients and controls, unlike passively extended knees.
• Dynamic MRI during active extension proved more effective in differentiating maltracking from normal tracking.

Conclusions:

• Dynamic patellar motion studies using motion-triggered cine MRI are vital for diagnosing patellofemoral maltracking.
• Active knee extension provides more diagnostic information than passive extension for patellar tracking assessment.
• This dynamic approach enhances the accuracy of diagnosing patellofemoral joint abnormalities.