Among the 200-plus species of primates and more than 4,000 species of mammals, there’s only one that walks exclusively on two feet: humans, according to Dr. Craig Stanford, an anthropologist at the University of Southern California.
At about 5,000 steps per day and an average life expectancy of almost 80 years, that’s close to 150 million steps in a lifetime. It’s clear that we should be focused on understanding how to keep our lower extremities healthy in an effort to remain mobile.
Thus, the Q-angle—or quadriceps angle—can potentially affect the structures of the hip and knee joints and should be considered when pain is at either location.
How to measure the Q-angle
The Q-angle is the intersection where two imaginary lines are drawn from the midpoint of the patella; one line connects to the anterior superior iliac spine (ASIS) of the pelvis and the other to the tibial tubercle.
This angle represents the line of pull of the quadriceps muscle and can play a major role in knee mechanics. The Q-angle may also be useful for predicting the severity of hip labrum tears.
The Q-angle has been shown to be reliable when it’s measured in a sitting or supine position. To measure the Q-angle, a standard goniometer is used and the ASIS, the middle of the patella, and the tibial tuberosity are identified first.
After the landmarks have been found, a string can be stretched from the ASIS to the middle of the patella to ensure proper alignment of the goniometer.
How reliable is the Q-angle measurement?
Using this method in the late 1980s, Horton and Hall reported excellent consistency between and among testers, which demonstrates this is an easy and accurate test that can be used by novices and experts.
Another study on the reliability of the Q-angle measurement examined 20 subjects without a history of anterior knee pain using the same methodology described above. These researchers found that inexperienced testers were able to accurately reproduce Q-angle measurements with minimal training which reinforces how easy it is to measure.
A study of more than 500 college students found significant differences in the Q-angles of males vs. females and supine vs. standing. The differences in the Q-angle were quite small and likely not clinically or practically relevant, even though they were statistically significant (1.2 degrees in females, 0.9 degrees in males).
The study found larger Q-angles in standing than supine, which is consistent with other research. This increase occurs in weight bearing due to other anatomical variations, such as foot position.
It seems that measuring in supine and standing positions is the most complete method for assessing the Q-angle so that all biomechanical implications associated with weight bearing may be considered.
Changes in the shape of the bones of the lower leg (tibia and femur) can influence the size of the Q-angle. When the lowermost bone (tibia) is rotated to the outside, the Q-angle is increased.
When the tibia is rotated to the inside, the Q-angle is decreased. In the upper leg bone (femur), the opposite is true. Rotation to the outside makes for a smaller Q-angle and rotation to the inside creates a larger Q-angle.
Changes in tibial or femoral rotation can also influence the magnitude of the Q-angle.
External rotation of the tibia moves the tibial tuberosity laterally and increases the Q-angle, while tibial internal rotation displaces the tibial tuberosity medially and decreases the Q-angle.
Larger Q-angles are typically associated with the conditions that lead to knee pain, but this isn’t always the case.
What is a “normal” Q-angle?
The normal Q-angle falls between 14 and 16 degrees for men and 16 and 18 degrees for women and are reported in countless research studies. However, they seem to be somewhat arbitrary.
For example, researchers measured the Q-angles of 50 men and 50 women from a standing position and found the average Q-angle was nearly 16 degrees in women and 11 degrees in men.
Also, when measured in a standing position, different researchers found the Q-angle’s average to be 9 degrees in men and 13.5 degrees in women. These inconsistent findings may suggest a wider range of Q-angles than has been previously reported.
The Q-angle and dynamic knee valgus may be related, however, research does not support this idea. A study of 22 women with patellofemoral pain syndrome (PFPS) was unable to find any correlation between the Q-angle and pain intensity, functional capacity, or dynamic knee valgus.
Large Q-angles are generally thought to be associated with the “knock-knee” position, but this is not supported by the research. Pantano and colleagues found that people with Q-angles greater than 17 degrees did not have a greater knee valgus angle during a single-leg squat than those with Q-angles less than 8 degrees.
This suggests that variations in bony anatomy alone are not necessarily cause for concern when it comes to painful or debilitating conditions at the knee.
Despite conflicting evidence on its role, the Q-angle is often blamed for knee and lower extremity injuries. Q-angles outside of the normal reported ranges (greater than 15 degrees in men, greater than 20 degrees in women) are considered an anatomical risk factor for development of overuse injuries in the knee.
Those with large Q-angles can benefit from therapeutic exercise to modulate the pain associated with PFPS. A study of 34 elite athletes, who performed a supervised, weight-bearing exercise program over an eight-week period, found that both dynamic Q-angles (measured with digital images) and pain decreased significantly at the end of the program.
This suggests that closed kinetic chain exercises—that is, exercises done with your feet in contact with the floor, such as squats and lunges, rather than leg raises and clam shells—should be used in rehab programs when the Q-angle is a possible cause of the knee pain.
Q angle and knee pain
The relationship of the patella to the quadriceps tendon is such that the femur can move beneath them independently. In fact, Powers et al. found that femoral internal rotation, not malalignment of the patella, was the primary contributor to lateral patellar tilt and displacement in participants with patellar pathology.
Despite Powers’ findings, the Q-angle is still generally believed to be larger in those with knee pain compared to their asymptomatic counterparts. One reason manual therapists may hang on to this idea is that it’s been demonstrated time and again that forces at the knee—and therefore, potential for injury—are higher when the Q-angle is larger.
Hvid and Andersen’s findings may be the most likely to represent the real-world implications of bony anatomy and soft tissue structures. The old song “the knee bone connected to your thigh bone” has never been more true than in these lower extremity relationships as changes to hip anatomy will affect the knee and foot, and vice versa.
They investigated the Q-angle and hip external rotation in 20 patients with knee pain and found both measurements to be higher in women with patellofemoral pain.
The relationship between the Q-angle and hip external rotation may be best explained by the bony relationships of the leg.
When the thigh bone is anatomically rotated (femoral torsion), a compensation occurs within the joint in the opposite direction. This compensation serves to optimize stability and muscle function.
In the case of internal femoral torsion or retroversion (the femoral shaft is rotated inward compared to the femoral head), the femur externally rotates (“toes-out”) to find a better position in the joint.
Conversely, when the femur is anteverted (the femoral shaft is rotated outward relative to the femoral head), the person will “toe-in” to find a better position for stability.
Q angle and hip pain
The shape of the femur has the potential to affect Q-angle and hip pain. “Version” is typically further described as “ante-” or “retro-”, depending on which direction the femoral head faces.
In people with femoral retroversion, the head and neck of the femur are rotated backward relative to the knee, which can cause their toes to point out when they walk.
In femoral anteversion, the head and neck are rotated forward relative to the knee, which tends to cause hip internal rotation. People with this condition may walk with their toes pointing inward while they try to gain stability.
For example, a study of 204 painful hips found that femoral anteversion greater than 15 degrees was associated with larger labral tears (about 1.5 inches).
Patients with less than 5 degrees of retroversion had the smallest tears (about one inch), and those between 5 and 15 degrees had moderate size tears (about 1.33 inches). Patients with greater than 15 degrees of anteversion were twice as likely to have anterior tears.
Those with more anteversion tended to have larger labral tears and needed surgical release of the psoas muscle to decrease symptoms and improve function.
In terms of real-world hip pain management, these patients may present with more complex surgical considerations. Rehab professionals should be clear on the details and extent of the surgical procedures.
Genu valgum, often referred to as “knock-kneed,” is an abnormality that’s often found during childhood. The prevalence of genu valgum was reported between 5 to 10% in a sample of nearly 50,000 Israeli army recruits. There is also a clear association with being female and being overweight or obese.
In fact, a cross-sectional study of more than 1,000 children and teens found the likelihood of genu valgum increased 6 and 75 times, respectively, in children who were overweight and obese when compared to their thinner counterparts.
A study of 218 men and women examined the relationships between alignment of the lower extremity and Q-angle. Researchers found that the tibiofemoral angle and the femoral anteversion were strongly associated with greater Q-angles in men and women.
This work revealed that changes in the tibiofemoral angle have a greater impact on the Q-angle than femoral anteversion as every one degree change in the tibiofemoral angle predicted a 0.60 degree change in the Q-angle. Every one degree change in anteversion predicted 0.18 degree change in the Q-angle of males and females.
Anatomical deviations that can be seen from the front view (ie. knock-kneed) potentially has a greater impact on the Q-angle than rotations at the hip or knee joint do.The same study found that increased femoral anteversion (toe-in) and the associated tibiofemoral external rotation were associated with greater Q-angles in men and women.
Several research studies have shown Q-angle to be a largely frontal plane measurement which, alone, may not be sufficient for examining its role in lower extremity injuries. Clinicians must take into account muscle strength and range of motion when examining a patient for existing or potential injury or pathology.
Currently, clinicians cannot accurately measure static posture and dynamic knee function in both the frontal and transverse planes, which leaves most injury risk assessments to be only hypothetical.
Future research into the role of transverse plane movements of the femur and tibia may represent important factors for understanding lower-limb injuries.
Genu recurvatum is where the knee hyperextends in the sagittal plane; this means the knee gets so straight to the point where it may even appear to bend in the opposite direction.
A study of 130 female athletes who were evaluated for several lower-body alignment conditions was unable to establish a relationship between genu recurvatum and the Q-angle.
The relationship of the lower extremity alignment and knee injuries has been a major focus of research for quite some time, but the role these variables play in general knee function and risk of injury remains controversial.
Along with the patient’s history and other clinical findings, the position of the bones of the lower body should be considered when looking for causes of knee pain.
Can you fix the Q-angle?
There are very few simple answers when it comes to our body. Whether the Q-angle can or even needs to be fixed is dependent on each person’s presentation.
A large Q-angle without pain or symptoms is not a cause for concern. In fact, trying to change something that isn’t currently a problem can lead to problems that would have otherwise been avoided.
In those with knee pain and symptoms, rather than trying to change Q-angle, clinicians should focus on restoring muscle function, strength, and joint range of motion.
Once these musculoskeletal factors have been addressed, attention turns to proper form with exercise and activities of daily living. The Q-angle may change throughout the process, but this change is not often a goal of treatment.
Q-angle and massage therapy
Although massage therapists do not regularly measure Q-angles, an understanding of how this condition changes the angle of pull of the muscles that cross the hip and knee joint is critical. A greater Q-angle will cause the kneecap to sit more toward the outside of the leg which allows the soft tissues—specifically the vastus lateralis and the lateral retinaculum—to get tight.
Higher Q-angles are also associated with femoroacetabular impingement, which may change the tissues of the psoas muscle. To address such tissue changes, massage therapists should focus on reducing lateral tension at the knee through muscle bending of the quadriceps.
Different massage techniques to the front and back of the leg can also be used, and the technique used should reflect on the patient’s preference. The patient should be positioned in supine to allow easy transitions between work at the anterior hip, lateral thigh, and quadriceps muscle belly. Bending the knee will also allow some hamstring work, but a transition to prone may be necessary for deeper massage strokes.
If the patient cannot lie on their back for a long time, they can alternate between side-lying with a pillow between the knees so the therapist can work on the lateral knee and supine for anterior hip and quadriceps work.
Although the relationships are often difficult to define, it’s evident that knee pain and other conditions are rarely linked to a single cause. Being aware of the relationship between the Q-angle and hip and knee functions can assist in exercise planning, guide lifestyle changes, and direct massage therapy treatment.