Assessment of tibial rotation and meniscal movement using kinematic magnetic resonance imaging

Objective: This work aimed to assess tibial rotations, meniscal movements, and morphological changes during knee flexion and extension using kinematic magnetic resonance imaging (MRI). Methods: Thirty volunteers with healthy knees were examined using kinematic MRI. The knees were imaged in the transverse plane with flexion and extension angles from 0 degrees to 40 degrees and 40 degrees to 0 degrees, respectively. The tibial interior and exterior rotation angles were measured, and the meniscal movement range, height change, and side movements were detected. Results: The tibia rotated internally (11.55 degrees +/- 3.20 degrees) during knee flexion and rotated externally (11.40 degrees +/- 3.0 degrees) during knee extension. No significant differences were observed between the internal and external tibial rotation angles (P > 0.05), between males and females (P > 0.05), or between the left and right knee joints (P > 0.05). The tibial rotation angle with a flexion angle of 0 degrees to 24 degrees differed significantly from that with a flexion angle of 24 degrees to 40 degrees (P < 0.01). With knee flexion, the medial and lateral menisci moved backward and the height of the meniscus increased. The movement range was greater in the anterior horn than in the posterior horn and greater in the lateral meniscus than in the medial meniscus (P < 0.01). During backward movements of the menisci, the distance between the anterior and posterior horns decreased, with the decrease more apparent in the lateral meniscus (P < 0.01). The side movements of the medial and lateral menisci were not obvious, and a smaller movement range was found than that of the forward and backward movements. Conclusion: Knee flexion and extension facilitated internal and external tibial rotations, which may be related to the ligament and joint capsule structure and femoral condyle geometry.