Which structures are responsible for patellar stability at 0 to 30 degrees of knee flexion?

The answer identifies the medial patellofemoral ligament (MPFL) and the secondary vastus medialis oblique (VMO) as the structures responsible for providing stability to the patella during the initial range of knee flexion from 0 to 30 degrees.

At full extension (0 degrees) and early flexion (up to 30 degrees), the patella is primarily stabilized by soft tissue structures rather than by bony congruity. The MPFL, being a critical ligament, aids in restraining lateral displacement of the patella during movement. In conjunction with the MPFL, the VMO contributes by creating a medial pulling force on the patella, which helps to maintain its proper alignment in the trochlear groove of the femur.

These structures are particularly important because they counteract the tendency for lateral tracking of the patella, which is a common issue that can lead to patellar instability and related pain. The dynamic stability provided by the VMO and the passive stability from the MPFL are crucial for proper knee function and stability during activities that require knee motion.

The other options do not adequately address the specific stability dynamics at this range of motion. For instance, while the quadriceps tendon is essential for knee extension and