KNEE JOINT KINEMATICS Medial and Lateral rotation RIMT

KNEE JOINT KINEMATICS: (Medial and Lateral rotation) RIMT University Department of Physiotherapy Prepared by: Dr Navkara Singh

Medial & Lateral Rotations: • Medial and lateral rotation of the knee joint are angular motions that are named for the motion (or relative motion) of the tibia on the femur. • These axial rotations of the knee joint occur about a longitudinal axis that runs through or close to the medial tibial intercondylar tubercle.

The medial condyle acts as the pivot point while the lateral condyles move through a greater arc of motion, regardless of the direction of rotation.

• As the tibia laterally rotates on the femur, the medial tibial condyle moves only slightly anteriorly on the relatively fixed medial femoral condyle • whereas the lateral tibial condyle moves a larger distance posteriorly on the relatively fixed lateral femoral condyle.

• During tibial medial rotation, the medial tibial condyle moves only slightly posteriorly, whereas the lateral condyle moves anteriorly through a larger arc of motion. • During both medial and lateral rotation, the knee joint’s menisci will distort in the direction of movement of the corresponding femoral condyle and, therefore, maintain their relationship to the femoral condyles just as they did in flexion and extension.

• E. g: As the tibia medially rotates (femur laterally rotates on the tibia), the medial meniscus will distort anteriorly on the tibial condyle to remain beneath the anteriorly moving medial femoral condyle, and the lateral meniscus will distort posteriorly to remain beneath the posteriorly moving lateral femoral condyle. • In this way, the menisci continue to reduce friction and distribute forces without restricting motion of the femur, as more solid or rigidly attached structures would do.

1. Axial rotation is permitted by articular incongruence and ligamentous laxity. 2. Therefore, the range of knee joint rotation depends on the flexion/extension position of the knee. 3. When the knee is in full extension, the ligaments are taut, the tibial tubercles are lodged in the intercondylar notch, and the menisci are tightly interposed between the articulating surfaces; consequently, very little axial rotation is possible.

• As the knee flexes toward 90 degree , capsular and ligamentous laxity increase, the tibial tubercles are no longer in the inter- condylar notch, and the condyles of the tibia and femur are free to move on each other. The maximum range of axial rotation is available at 90 degree of knee flexion. The magnitude of axial rotation diminishes as the knee approaches both full extension and full flexion.

• At 90 degree, the total medial/lateral rotation = 35 degree (approx. ) 1. Range for lateral rotation being slightly greater = 0 to 20 degree 2. Range for medial rotation = 0 to 15 degree

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