Q Angle
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.
The Q angle is 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.
Measurement[edit | edit source]
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
