The Role of the Q Angle in Anterior Knee Pain
Postural distortions can lead to numerous soft-tissue disorders. Clients with these postural challenges often look to the massage therapist to help with the pain or biomechanical challenges that result.
In the lower extremity, a large quadriceps angle, more commonly called the Q angle, is a postural distortion involving patellofemoral biomechanics. An exaggerated Q angle can lead to knee pain and knee pathologies, as well as compensations in other regions of the body.
The degree of the Q angle is determined by measuring two lines superimposed on the lower extremity. One line begins at the tibial tuberosity and continues in a superior direction through the midpoint of the patella. A second line connects the anterior superior iliac spine (ASIS) with the midpoint of the patella. The angle between these two lines is the Q angle (Figure 1).
There is a disagreement in the research literature about what constitutes an exaggerated Q angle. Some sources say a Q angle as small as 10 degrees can be a problem, while others say it is not an issue until the angle is greater than 20 degrees.2 A challenge with evaluating the Q angle’s role is it’s not easy to accurately measure the angle. However, repeated investigations have shown people with a larger Q angle have a greater likelihood of developing numerous knee complaints.
To understand how the Q angle contributes to knee pathologies, it’s helpful to look at the anatomical relationships in the region. The patella is embedded in the quadriceps tendon. There is a ridge on the underside of the patella that must fit in the trochlear groove between the two condyles of the femur (Figure 2). The patella moves superiorly and inferiorly in this groove during knee flexion and extension.
The patella’s ability to track straight in the trochlear groove is determined by the quadriceps’ angle of pull. When the Q angle is greater, the quadriceps pull the patella in a more lateral direction. The unequal pull on the patella causes increased tensile stress on soft tissues around the knee. Too much lateral pull on the patella also can drag it against the lateral femoral condyle and eventually cause degeneration of the cartilage on the underside of the patella – a condition known as chondromalacia patellae. Problems associated with the patella and its correct movement during flexion and extension are referred to as patellar tracking disorders. In addition to patellar tracking disorders, a larger Q angle also can be a major factor in patellar subluxation or dislocation, as well as anterior cruciate ligament sprains.
There is an increased incidence of these knee disorders in women and individuals with genu valgum. The Q angle is greater in women due to the wider pelvis, which places the ASIS farther away from the patellar midline, thereby increasing the Q angle. The Q angle also is greater in people who have the genu valgum postural distortion, more commonly known as knock-knees.
Because certain aspects of bony structure, such as a wide pelvis, determine the Q angle, it’s difficult to alter the angle with soft-tissue work alone. However, treatments such as massage are helpful for addressing some of the factors that aggravate Q angle problems. For example, an imbalance in tightness between the vastus lateralis and vastus medialis muscles can contribute to patellar tracking disorders. If the vastus lateralis is too tight, it can pull the patella farther in a lateral direction. This situation often occurs in people with a larger Q angle. Comprehensive massage treatment of the vastus lateralis can reduce the distance it pulls the patella in a lateral direction.
There are numerous causes of anterior knee pain. Several of these can be related to an excessive Q angle. It’s not necessary to pull out the protractor and determine the exact Q angle. However, a visual estimation of the Q angle can give important clues about the role this postural distortion plays in a variety of pain complaints. In those cases, massage treatment of the quadriceps muscle group and the retinacular fibers around the patella greatly helps reduce the detrimental results of a large Q angle.