What is a Q angle within the human body?

What is a Q angle within the human body?
The Q-angle is the angle of the femur as it enters the hip socket.
http://moon.ouhsc.edu/dthompso/namics/qa...
The Q angle which is formed by a file drawn from the anterosuperior iliac spine through the center of the patella and a line drawn from the center of the patella to the center of the tibial tubercle, should be measured subsequent. In women, the Q angle should be less than 22 degree with the knees in extension and smaller number than 9 degrees next to the knee surrounded by 90 degrees of flexion. In men, the Q angle should be smaller amount than 18 degrees near the knee contained by extension and less than 8 degree with the knees in 90 degree of flexion.
As an addendum to Mercury's answer, "Q angle" stands for quadriceps angle. It influences the volatility of the lower extremity and knee stability.