National Physical Therapy Examination (NPTE) Practice Exam

Which structure does not serve as a secondary restraint to the posterior cruciate ligament (PCL)?

1. Lateral collateral ligament (LCL)

2. Medial collateral ligament (MCL)

3. Iliotibial band (ITB)

4. Popliteus tendon

The correct answer is: Iliotibial band (ITB)

The iliotibial band (ITB) does not serve as a secondary restraint to the posterior cruciate ligament (PCL) because its primary role is to stabilize and support the lateral aspect of the knee joint, particularly in relation to movements that involve hip abduction and flexion. While the ITB does provide some lateral stability, it is not directly involved in the posterior stabilization of the knee, which is primarily the function of the PCL. On the other hand, the lateral collateral ligament (LCL), medial collateral ligament (MCL), and popliteus tendon all play significant roles in supporting the posterior aspect of the knee and can assist in stabilizing the joint against posterior translation of the tibia. Specifically, the LCL provides lateral stability, the MCL provides medial stability, and the popliteus tendon aids in knee flexion while providing a dynamic stabilization mechanism for the posterior aspect of the knee. Therefore, the iliotibial band's role does not overlap with the secondary restraining function of these other structures concerning the PCL's stability.