Q Angle: Difference between revisions
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== Clinical Importance == | == Clinical Importance == | ||
<div>An understanding of the normal anatomical and biomechanical features of the patellofemoral joint is essential to any evaluation of knee function. One important concept in patellofemoral joint function is the quadriceps femoris muscle angle,better known as the "Q angle." This angle, which has been defined by Hungerford and Barryas the acute angle formed by the vector for the combined pull of the quadriceps femoris muscle and the patellar tendon, | <div>An understanding of the normal anatomical and biomechanical features of the patellofemoral joint is essential to any evaluation of knee function. One important concept in patellofemoral joint function is the quadriceps femoris muscle angle,better known as the "Q angle." This angle, which has been defined by Hungerford and Barryas the acute angle formed by the vector for the combined pull of the quadriceps femoris muscle and the patellar tendon, is important because of the lateral pull it exerts on the patella.<ref>Horton MG, Hall TL. Quadriceps Femoris Muscle Angle:Normal Values and Relationships with Gender and Selected Skeletal Measures. Phy Ther 1989; 69: 17-21</ref> Any alteration in alignment that increases the Q-angle is thought to increase the lateral force on the patella. This can be harmful because an increase in this lateral force may increase the compression of the lateral patella on the lateral lip of the femoral sulcus. In the presence of a large enough lateral force, the patella may actually sublux or dislo-cate over the femoral sulcus when the quadriceps mus-cle is activated on an extended knee.<ref name="norkin" /><br></div><div></div><div></div> | ||
== References == | == References == | ||
Revision as of 17:35, 7 December 2013
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Background[edit | edit source]
The direction and magnitude of force produced by the quadriceps muscle has great influence on patellofemoral joint biomechanics. The line of force exerted by the quadriceps is lateral to the joint line mainly due to large cross-sectional area and force potential of the vastus lateralis. Since there exists an association between patellofemoral patholgy and excessive lateral tracking of the patella, assessing the overall lateral line of pull of the quadriceps relative to the patella is a meaningful clinical measure. Such a measure is referred to as the Quadriceps angle or Q angle.
Measurement[edit | edit source]
The knee is fully extended, but not hyper-extended,during measurements.
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.
Normative Values[edit | edit source]
Factors affecting 'Q' Angle[edit | edit source]
Increases in q-angle are associated with [1]:
- Femoral anteversion
- External tibial torsion
- Laterally displaced tibial tubercle
- Genu valgus
Clinical Importance[edit | edit source]
An understanding of the normal anatomical and biomechanical features of the patellofemoral joint is essential to any evaluation of knee function. One important concept in patellofemoral joint function is the quadriceps femoris muscle angle,better known as the "Q angle." This angle, which has been defined by Hungerford and Barryas the acute angle formed by the vector for the combined pull of the quadriceps femoris muscle and the patellar tendon, is important because of the lateral pull it exerts on the patella.[2] Any alteration in alignment that increases the Q-angle is thought to increase the lateral force on the patella. This can be harmful because an increase in this lateral force may increase the compression of the lateral patella on the lateral lip of the femoral sulcus. In the presence of a large enough lateral force, the patella may actually sublux or dislo-cate over the femoral sulcus when the quadriceps mus-cle is activated on an extended knee.[3]
References[edit | edit source]
- ↑ 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
- ↑ Cite error: Invalid
<ref>tag; no text was provided for refs namednorkin
