The Q-angle

The Q-angle (or "quadriceps angle) is formed in the frontal plane by two line segments: from tibial tubercle to the middle of the patella from the middle of the patella to the ASIS The q-angle in adults is typically 15 degrees. Increases or decreases in the q-angles are associated in cadaver models with increased peak patellofemoral contact pressures (Huberti & Hayes, 1984). Insall, Falvo, & Wise (1976) implicated increased q-angle, along with patella alta, in a prospective study of patellofemoral pain.

Increases in q-angle are associated with:

• femoral anteversion
• external tibial torsion
• laterally displaced tibial tubercle
• genu valgus

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References:

Huberti, H.H., & Hayes, W.C. (1984). Patellofemoral contact pressures: The influence of Q-angle and tendofemoral contact. Journal of Bone and Joint Surgery, 66A, 715-724.

Insall, J., Falvo, K.A., & Wise, D.W. (1976). Chondromalacia patellae: A prospective study. Journal of Bone and Joint Surgery, 58A, 1-8.

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