Q Angle
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Background[edit | edit source]
Measurement
[edit | edit source]
The Q angle is acute angle formed between:
- A line representing the resultant line of force of the quadriceps, made by connecting a point near the ASIS to the mid-point of the patella
- A line representing a long axis of the patellar tendon, made by connecting a point on the tibial tuberosity with the mid-point of the patella.
Traditionally, Q-angle has been measured with the knee at or near full extension (but not hyperextension)with subjects in supine and quadriceps relaxed because lateral forces on the patella may be more of a problem in these circumstances. With the knee flexed, the patella is set within the intercondylar notch, and even a very large lateral force on the patella is unlikely to result in dislocation. Furthermore, the Q-angle will reduce with knee flexion as the tibia rotates medially in relation to the femur.[1] This is regarded as the 'traditional' or 'conventional' method. The Q angle has also been assessed on standing.
Normative Values [edit | edit source]
Factors affecting 'Q' Angle[edit | edit source]
Increases in q-angle are associated with [2]:
- Femoral anteversion
- External tibial torsion
- Laterally displaced tibial tubercle
- Genu valgus
Clinical Importance[edit | edit source]
References[edit | edit source]
- ↑ 1.0 1.1 Levangie, P.K. and Norkin, C.C. (2005). Joint structure and function: A comprehensive analysis (4th ed.). Philadelphia: The F.A. Davis Company.
- ↑ http://moon.ouhsc.edu/dthompso/namics/qangle.htm
- ↑ Horton MG, Hall TL. Quadriceps Femoris Muscle Angle:Normal Values and Relationships with Gender and Selected Skeletal Measures. Phy Ther 1989; 69: 17-21