Q Angle

The Q angle (Quadriceps Angle) is the angle formed between two lines drawn from:

  • The anterior superior iliac spine (ASIS) to the center of the patella

  • The tibial tubercle (upper part of the shin bone) through the center of the patella
    This biomechanical parameter reflects the alignment of the quadriceps muscle group with the patellar tendon in the frontal plane and is used to assess knee joint alignment and the lateral pull on the patella.

How the Q Angle is Measured

  • The client is usually in a supine or standing position with legs straight and relaxed.

  • A goniometer or ruler is used to form the two lines and measure the angle where they intersect at the patella.

  • Normal values:

    • Men: About 13–15°

    • Women: About 16–18° (due to wider pelvis)

  • Angles less than 13° or greater than 18° are considered abnormal and may be linked to knee dysfunctions.

Clinical Significance

  • Increased Q angle correlates with greater lateral force on the patella, predisposing clients to:

    • Patellofemoral pain syndrome (PFPS)

    • Patellar subluxation and dislocation

    • Chondromalacia patellae

    • Knee osteoarthritis

    • Higher risk of ACL injury

  • Decreased Q angle may be associated with other dysfunctions like patella alta (high-riding kneecap) or altered patellar tracking.

  • The Q angle helps interpret biomechanical risk factors for knee pain, especially in active populations (athletes, runners) or those with persistent anterior knee pain.

Assessment

  • Use the Q angle measurement for clients with anterior knee pain, repeated patellar tracking issues, or biomechanical/postural misalignments.

  • Record whether the Q angle is normal, increased, or decreased, and note side-to-side differences.

  • Consider impact on foot, hip, and pelvic mechanics—Q angle is one piece of the kinetic chain puzzle.

Treatment

  • If Q angle is increased:

    • Avoid excessive lateral mobilization/manipulation of the patella.

    • Focus on myofascial work for IT band, lateral thigh, and hip abductors, and strengthening of the vastus medialis obliquus (VMO) and hip stabilizers to counter excessive lateral pull.

    • Educate about proper squat/knee mechanics and patellar tracking during exercise, and consider referral for bracing, taping, or orthotic intervention if mechanical issues are significant.

  • If Q angle is decreased:

    • Address compensatory movement patterns and any associated patellar tracking or functional limitations.

Safety & Referral

  • Refer for orthopedic or physiotherapy evaluation if abnormal Q angle is associated with severe pain, instability, or failed conservative management.