Of the more than 200 species of primates and more than 4,000 species of mammals, there is only one that walks exclusively on two feet according to Dr. Craig Stanford, an anthropologist at the University of Southern California.
At 5,000 steps per day and an average life expectancy of near 80, that is close to 150 million steps in a lifetime. It is that clear we should be focused on understanding how to keep our lower extremities healthy in an effort to remain mobile. The Q-angle, or quadriceps angle, can potentially affect structures in the hip and knee joints and should be considered when pain is at either location.
How is Q angle measured?
The Q-angle is the intersection of two lines drawn from the midpoint of the patella; one line connects to the anterior superior iliac spine (ASIS) 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 patellofemoral joint mechanics. Q-angle may also be useful for predicting the severity of hip labrum tears.
Q-angle has been shown to be reliable when measured in sitting or supine. To measure the Q-angle, a standard goniometer is used. The anatomical landmarks of anterior superior iliac spine, midpoint 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 midpoint of the patella to ensure proper alignment of the goniometer during measurement. Using this method, Horton and Hall reported excellent consistency between and among testers which demonstrates this is an easy, accurate test that can be used by novices and experts alike.
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 the ease of using this measure.
A study of more than 500 college students found significant differences in the Q-angles of males vs. females and supine vs. standing. It is worth noting that the differences in Q-angle from supine to standing 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. It is suggested that this increase occurs in weight bearing due to other anatomical variations such as foot position. It seems that measuring in supine and standing is the most complete method for assessing Q-angle so that all biomechanical implications associated with weight bearing may be considered.
Changes in tibial or femoral rotation can also influence the magnitude of 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.
At the femur, internal rotation moves the patella medial to the ASIS and/or tibial tuberosity which increases the Q-angle. Conversely, femoral external rotation decreases the Q-angle by creating a resultant line of action that is closer to the ASIS and tibial tuberosity.
What is considered the “normal” values of the 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. A study of 50 men and 50 women measured the Q-angle from a standing position and found the average Q-angle was nearly 16 degrees in women and 11 degrees in men.
Also measured in standing, a different set of researchers found the Q-angle 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 notion. A study of 22 women with patellofemoral pain syndrome was unable to find any correlation between the Q-angle and pain intensity, functional capacity, or dynamic knee valgus.
Excessive Q-angle measurements are often thought to be associated with dynamic knee valgus (the angle formed by the anatomical axes of the femur and tibia measured when the patient actively moves into knee flexion) because of the medial positioning of the knee relative to the instep of the foot, 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.
Despite conflicting evidence on its role, the Q-angle is often implicated in 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 patellofemoral pain syndrome. A study of 34 elite athletes who performed a supervised, weight-bearing exercise program over an eight-week period found that at the end of the program, both dynamic Q-angles (measured with digital images) and pain decreased significantly. This suggests that closed kinetic chain exercises—that is, exercises done with your feet in contact with the floor like squats and lunges rather than leg raises and clam shells—should be incorporated into rehabilitation programs for patients with knee pain when Q-angle is a possible cause of the dysfunction.
Q angle and knee pain
Knee mechanics are often described using a ‘train on the tracks’ analogy, but it would seem we may have been blaming the train when the track was the problem. 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’ 2003 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 be slow to abandon this theory is that the idea is in-line with in vivo analysis of patellar forces where higher Q-angles have been shown to increase compressive forces to a potential injury or knee pathology.
Hvid and Andersen’s findings may be the most likely to represent the real-world implications of bony anatomy and soft tissue structures. They investigated Q-angle and hip internal rotation in 20 patients with knee pain and found both measures to be higher in women with patellofemoral pain. This relationship between Q-angle and hip internal rotation is likely explained by associated changes in the anatomy of the femur that leads to compensatory changes at the tibia as well. 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.
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.
There is no direct link between Q-angle and hip injuries, but there is evidence that there is a link between femoral version and Q-angle and femoral version and femoroacetabular impingement Intraoperative findings from a cohort of 204 symptomatic hips found that femoral anteversion greater than 15 degrees was associated with larger labral tears (about 1.5 inches).
Patients with less than five degrees of retroversion had the smallest tears (about one inch) and those between five 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.
The researchers also found slightly higher anteversion angles in patients who required psoas release, which they hypothesized to be a consequence of psoas impingement caused by the more anterior positioning of the femoral head.
Genu valgum, often referred to as “knock-kneed,” is an abnormality typically identified 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 overweight or obese.
In fact, a cross-sectional study of more than 1,000 children and adolescents, 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 discovered that the tibiofemoral angle (the valgus angle formed by the anatomical axes of the femur and tibia measured statically) and femoral anteversion were strongly associated with greater Q-angles in men and women.
Their work revealed that changes in tibiofemoral angle have a greater impact on 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.
This work suggests that anatomical deviations that affect the frontal plane potentially have a greater impact on the Q-angle than those in the transverse plane. The same study found that structural increases in femoral anteversion and tibiofemoral angle were associated with greater Q-angle found in men and women, which provides an alternative to the widely-believed, but rarely demonstrated, hypothesis that an increased Q-angle is a result of a wider pelvis.
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. 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 extremity injuries.
Genu recurvatum is a sagittal plane deviation characterized by hyperextension at the knee joint, where the knee extension is greater than 5 degrees. A study of 130 female athletes who were evaluated for several lower-body alignment conditions (e.g. navicular drop, Q-angle, genu recurvatum, tibiofemoral angle, dorsiflexion, hip internal and external rotation) was unable to establish a relationship between genu recurvatum and Q-angle.
The relationship of lower extremity alignment and knee injuries has been a major focus of research for quite some time, however, the role these variables play in general knee function and risk of injury remains controversial. Lower extremity alignment findings should be considered when examining causes of knee pain but must be correlated to subjective history and additional clinical findings when determining the cause of injury or pathology.
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 higher Q-angle results in lateralization of the patella which may lead to soft tissue restrictions in vastus lateralis and the lateral retinaculum.
Higher Q-angles are also associated with femoroacetabular impingement, which could result in tissue changes to the psoas muscle. To address the tissue changes associated with a higher Q-angle, massage therapists should focus on reducing lateral tension at the knee through muscle bending of the quadriceps.
Different massage techniques to the anterior and posterior thigh muscles and myofascial release to the lateral aspect of the thigh can also be used. Additional consideration should be given to psoas, as this muscle has been found to be related to femoral anteversion which can lead to labral tears at the hip.
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 on the involved side will also allow for some hamstring work but a transition to prone may be necessary for deeper strokes.
If the supine position is intolerable over longer periods of time, the patient can alternate between side-lying with a pillow between the knees for work on the lateral structures of the knee and supine for anterior hip and quadriceps work.
Although the relationships are often difficult to fully define, it is evident that the development of pathological conditions is rarely linked to a single cause. Awareness of the implications of the Q-angle on hip and knee function can assist in fitness planning, guide lifestyle modifications, and direct massage therapy treatment so that you can keep your patients healthy and on two feet.