5. patella Q angle and dislocation

What usually causes a patellar fracture?

Direct trauma to the knee

In a patellar fracture, what pulls the proximal patellar fragment?

Quadriceps tendon

In a patellar fracture, what pulls the distal patellar fragment?

Patellar ligament

What is the Q-angle?

The angle between the pull of the quadriceps and the patellar tendon/tibia

What is the normal Q-angle?

Around 12–17 degrees

Increased Q-angle is more common in which population and why?

Adult females due to a wider pelvis

What is genu valgum?

Knock-knee; associated with a large Q-angle and lateral knee stress

What is genu varum?

Bowleg; associated with a small Q-angle and medial knee stress

What direction do most patellar dislocations occur?

Lateral

Why do most patellar dislocations occur laterally?

The pull of the quadriceps creates a lateral vector

What structures normally resist lateral patellar displacement?

Vastus medialis and the lateral patellar lip

Which quadriceps muscle is especially important for stabilizing the patella medially?

Vastus medialis