The Q-angle is the measured angle between the patellar tendon and the alignment of which of the following structures?

The Q-angle, also known as the quadriceps angle, is the angle between the quadriceps tendon and the patellar tendon. This angle is measured in degrees and is used to assess the alignment of the knee joint.

Here are the steps to measure the Q-angle:

1. The person being measured should be in a standing position with the knees in extension (straightened).

2. Identify the following anatomical landmarks: the anterior superior iliac spine (ASIS), the center of the patella (kneecap), and the tibial tuberosity (a prominent bony point located on the upper part of the tibia, just below the knee).

3. Draw an imaginary line from the ASIS to the center of the patella. This represents the line of pull of the quadriceps muscle.

4. Draw a second imaginary line from the center of the patella to the tibial tuberosity. This represents the line of the patellar tendon.

5. The angle formed by the intersection of these two lines is the Q-angle.

So, to answer your question, the Q-angle is the measured angle between the patellar tendon and the alignment of the quadriceps muscle (from the ASIS to the center of the patella).