The Q-angle is a measurement that gives an indication of the likelihood of excessive forces tending to pull the patella over to the outer (lateral) side.

Page updated November 2023 by Dr Sheila Strover (Clinical Editor)

Image showing the way the q-angle is calculated
The q-angle gives an idea of the alignment of the forces through the patella.



What does the Q-angle measure?

The bigger the Q-angle, the greater the force trying to pull the patella to the outer side. Normally, when the knee is straight (extension) the kneecap sits at the shallow section of the trochlea. As the knee flexes ('bends'), it is pulled into the deeper part of the trochlea at about 30 degrees of flexion, then runs centrally in the trochlear groove during the rest of bending. If the Q-angle is high, the soft tissue restraints and the trochlear groove are not always sufficient to keep the patella where it should be.

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Peer-reviewed papers

  • Quote:

    "The Q angle's enigmatic nature is caused by...the lack of methodological clarity.....While women show a higher mean Q angle value than men, the underlying causes of the difference are not immediately apparent."

    Citation: Sharma R, Vaibhav V, Meshram R, Singh B, Khorwal G. A Systematic Review on Quadriceps Angle in Relation to Knee Abnormalities. Cureus. 2023 Jan 29;15(1):e34355. doi: 10.7759/cureus.34355. PMID: 36874732; PMCID: PMC9974941.

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Quadriceps angle
Q angle

Dr Sheila Strover (Editor)
BSc (Hons), MB BCh, MBA

See biography...



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