How do you measure a Q angle?
- If you cut a pizza into four big slices, each slice makes a 90° angle
- If you cut a pizza into four big slices and then cut each of those slices in half, you get eight pieces, each of which makes a 45° angle
- If you cut the original pizza into 12 slices, each slice makes a 30° angle
What is a normal Q angle?
What is the normal Q angle? The normal q angle measured in standing is about 15 degrees and anything more than that is considered a risk factor for knee injuries. Ladies tend to have a wider Q angle due to their wider pelvis compared to their males. From some studies, 13.5 ± 4.5° is considered as a normal Q angle for healthy subjects between the ages of 18 and 35 years.
What does the angle Q represent?
What does the angle of Q represent? The Q angle, which is also known as quadriceps angle, is defined as the angle formed between the quadriceps muscles and the patella tendon.
What is the Q angle?
The quadriceps angle (Q angle), formed between the quadriceps muscles and the patella tendon, is considered clinically as a very important parameter which displays the biomechanical effect of the quadriceps muscle on the knee, and it is also regarded a crucial factor for the proper posture and movement of the knee patella.
What is the normal angle of a Q-angle?
The intersection of these two lines is the Q-angle; the normal value for this angle is 13 to 18 degrees. Men tend to have Q-angles closer to 13 degrees, and women usually have Q-angles at the high end of this range. Because the Q-angle is a measure of bony alignment, it can be altered only through bony realignment surgical procedures.
What is the Q angle of a male?
The Q angle in males is typically between 8° and 14° , whereas that in females ranges from 11° to 20°. The Q angle typically increases a degree with weightbearing owing to a valgus adaptation of the knee. In general patients with Q angles greater than 14° are vulnerable to patellar conditions, particularly abnormal tracking and instability.
What is the Q angle of the quadriceps?
The quadriceps or Q angle describes the vector of pull exerted by the quadriceps muscles on the patella. The components of the quadriceps complex attach at the anterior superior and anterior inferior iliac spines (ASIS and AIIS) of the pelvis and converge to form the patellar tendon. The Q angle is measured by dropping a plumb-line through the tibial tubercle and middle of the patella and another from the ASIS to intersect with the first line at the mid-patella. The angle created by the intersecting lines is the Q angle. With growth the pelvis widens, displacing the ASIS and AIIS laterally in relation to the knee. This places a lateral pull on the patellar tendon. During puberty the pelvis widens more in girls than boys owing to hormonal influences. The wider gynecoid structure results in Q angles that are greater in females than in males. The Q angle in males is typically between 8° and 14°, whereas that in females ranges from 11° to 20°. The Q angle typically increases a degree with weightbearing owing to a valgus adaptation of the knee. In general patients with Q angles greater than 14° are vulnerable to patellar conditions, particularly abnormal tracking and instability. The Q angle can be functionally increased in genu varum, genu recurvatum and over-pronation of the subtalar joint.
How is the Q angle influenced?
The Q angle can be influenced proximally through motions of the femur. As described previously, increased femoral medial rotation results in a larger Q angle, because the patella is moved medially with respect to the ASIS and tibial tuberosity (see Figure 22-21, B ).
What causes a Q angle to be higher?
Foot pronation (pes planus or flat feet) and limb internal rotation both increase the Q-angle. The range of normal for the Q-angle varies in the literature, and there is controversy whether the wider pelvic anatomy in women contributes to a greater Q-angle. The reported values of normal Q-angles are 10 degrees for men and 15 degrees for women.
What is the angle created by intersecting lines?
The angle created by the intersecting lines is the Q angle. With growth the pelvis widens, displacing the ASIS and AIIS laterally in relation to the knee. This places a lateral pull on the patellar tendon. During puberty the pelvis widens more in girls than boys owing to hormonal influences.
What angle is the patella?
A high Q-angle (intersection formed by lines drawn from the anterior superior iliac spine to the center of the patella and from the center of the patella to the tibial tuberosity; normally 13 degrees in males and 18 degrees in females) predisposes the patella to sublux laterally. With the addition of a loose retinaculum, patella alta, and a weak or dysplastic vastus medialis obliquus muscle, the patella can easily sublux in the first 30 degrees of knee flexion. With a flattened lateral femoral condyle, the patellofemoral joint becomes unstable, even though the patella is seated in the trochlear groove.
What is the Knee Q Angle Definition?
The Knee Q angle (also known as Quadriceps Angle) is defined as the angle between the quadriceps muscle (primarily the rectus femoris) and the patellar tendon.
How to Measure Knee Q Angle?
A line is drawn from the anterior superior iliac spine to the midpoint of the patella, corresponding to the quadriceps’ tensile direction.
Quadriceps Angle Assessment
Normally the Knee Q angle is 13° for men and 18° for women when the knee is straight.
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What does Q stand for in a thigh?
With ‘Q’ standing for Quadriceps (the muscles on the front of the thigh). The wider the hips, the greater the Q angle will be, with the thighs effectively angling in more steeply towards the knees.
Why do knees have a Q angle?
Because they have wider hips. You may have been introduced to the term Q Angle. And been told that because your angle is greater, your knees are put under more strain. You may have been told that your knees are out of alignment (pointing the wrong way). Or ‘maltracking’ (moving in the wrong direction).
Why does a greater Q angle cause more strain on the knees?
The commonly held conception is as follows: a greater Q angle will put more strain on the knees. Because the quadriceps muscles end up pulling the knee cap (patella) away from its natural ‘groove.’. This patella maltracking is thought to cause friction against structures under the knee.
What is the Q angle?
The Q angle is the angle between the quadriceps muscle (primarily the rectus femoris) and the patellar tendon. 1 It provides useful information regarding the alignment of the knee in the frontal plane. A measurement is made of the angle formed by the quadriceps muscle’s pull from the pelvis to the patella, and the patellar tendon’s pull on ...
How to measure Q angle?
First, place the center axis of a long-arm goniometer over the center of the patella. Next, palpate the proximal tibia and align the lower goniometer arm along the patellar tendon to the tibial tubercle.
What is the normal range of Q angle?
Normal ranges. When measured standing, the Q angle should fall between 18° and 22°. 4 Males are usually at the low end of this range, while females (because of their wider pelvis) tend to have higher measurements.
Does foot pronation affect Q angle?
The effects of excessive pronation on the Q angle also deserve attention, since controlling foot pronation can often reduce the detrimental effects of an abnormal Q angle.
Background
Normative Values
- In women, the Q angle should be less than 22 degrees with the knee in extension and less than 9 degrees with the knee in 90 degrees of flexion. In men, the Q angle should be less than 18 degrees wi...
Measuring Q Angle
- Position: Patient supine with knee extended. The therapist stands next to patient. Application: When measuring ensure that the lower extremity is at a right angle to the line joining each ASIS. The foot should be placed in a neutral position relative to supination and pronation with the hip in neutral position relative to medial and lateral rotation. Draw a line from ASIS to the midpoint of p…
Problems with Measuring 'Q' Angle
- A Problem with using the Q angle as a measure of the lateral pull on the patella is that the line between the ASIS and the mid-patella is only an estimate of the line of pull of the quadriceps and...
- If a substantial imbalance exists between the vastus medialis and vastus lateralis muscles in a patient, the Q angle may lead to an incorrect estimate of the lateral force on the patellabecau…
- A Problem with using the Q angle as a measure of the lateral pull on the patella is that the line between the ASIS and the mid-patella is only an estimate of the line of pull of the quadriceps and...
- If a substantial imbalance exists between the vastus medialis and vastus lateralis muscles in a patient, the Q angle may lead to an incorrect estimate of the lateral force on the patellabecause the...
- Furthermore, a patella that sits in an abnormal lateral position in the femoral sulcus because of imbalanced forces, will yield a smaller Q angle because the patella lies more in line with the ASIS...
Factors Affecting 'Q' Angle
- Increase in Q angle is associated with: 1. Femoral anteversion 2. External tibial torsion 3. Laterally displaced tibial tubercle 4. Genu valgum: increases the obliquity of the femur and concomitantly, the obliquity of the pull of the quadriceps
Clinical Importance
- An understanding of the normal anatomical and biomechanical features of the patellofemoral joint is essential to any evaluation of knee function. The Q angle formed by the vector for the combined p...
- Any alteration in alignment that increases the Q angle is thought to increase the lateral force on the patella.
- An understanding of the normal anatomical and biomechanical features of the patellofemoral joint is essential to any evaluation of knee function. The Q angle formed by the vector for the combined p...
- 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 dislocate over the femoral sulcus when the quadriceps muscle is activated on an extended knee.