Q-Angle Measurement: Assessing Patellofemoral Alignment

The Q-Angle (Quadriceps Angle) is an important clinical measurement used to assess the overall alignment of the knee. It measures the angle of pull of the quadriceps muscle on the patella and is a key indicator for patellar tracking issues.

[Image of Q-Angle measurement landmarks]

1. Purpose

The primary purpose of the Q-Angle (Quadriceps Angle) Measurement is to **assess the alignment** of the quadriceps muscle pull relative to the patella. It helps evaluate patellofemoral mechanics and risk factors for conditions like Patellofemoral Pain Syndrome (PFPS), subluxation, or chondromalacia.

2. How to Perform

1. The patient is positioned in supine with the knee fully extended and quadriceps relaxed.
2. Identify three anatomical landmarks: the Anterior Superior Iliac Spine (ASIS), the midpoint of the patella, and the Tibial Tuberosity.
3. Draw an imaginary line from the ASIS to the midpoint of the patella.
4. Draw a second imaginary line from the Tibial Tuberosity to the midpoint of the patella.
5. Use a goniometer to measure the angle formed where these two lines intersect.

3. Normal & Abnormal Values

Normal Values:
Females typically have a larger Q-angle due to a wider pelvis.

• Males: Approximately 13 degrees.
• Females: Approximately 18 degrees.

Abnormal Findings:

• Increased Q-Angle (>18-20 degrees): Associated with Genu Valgum ("knock knees"), lateral patellar tracking, and increased risk of ACL injury or patellar dislocation.
• Decreased Q-Angle (<10 degrees): Associated with Genu Varum ("bow legs").