We have previously discussed three common sources of knee pain including; knee arthritis, meniscus tears, and patellofemoral pain syndrome in this article. Due to the overwhelmingly large amount of people affected by knee pain, we will be dissecting those common causes of knee pain with more depth. This article will focus on PFPS (patellofemoral pain syndrome.) PFPS is characterized by pain along the front of the knee with no known reason or traumatic event.
There are many factors that contribute to patellofemoral pain such as; patellar hypermobility (too much movement), hip and thigh weakness, muscle and soft tissue tightness, overpronation, and recent changes in exercise routine (1). These factors can lead to impaired tracking of the knee cap, causing irritation, pain, and snapping or cracking noises of the patella (knee cap) and surrounding tissues.
Blame The Hip
Females are nearly twice as likely as males to experience PFPS which is partially due to their hip anatomy. Females with patellofemoral pain have increased hip internal rotation (leading to inward collapse of the knee), decreased hip strength, and differences in muscle recruitment (2). It is believed the angle of the thigh bone due to hip structure (known as the Q-Angle) plays a large role in knee function. The Q-angle is the angle between an imaginary line from the front of the hip and mid line through the patella (knee cap) (Figure C, reference 5). The angle is 10-14 degrees for males and 14.5-17 degrees for females with anatomical differences in the pelvis explaining the gender differences (3).
Weakness of the hip muscles (specifically the glutes) can also lead to an increased dynamic Q-angle, or decreased control of hip rotation when moving. One study showed individuals with patellofemoral pain had a greater dynamic Q -angle (A.K.A hip weakness) than those without knee pain when climbing stairs (2). Combine large anatomical Q-angle with hip weakness and it is a recipe for poor function at the knee.
Don’t Forget the Foot
We can’t blame the hip for everything, let’s get the foot involved too. Foot overpronation is another contributing factor to the potential onset of patellofemoral pain. Pronation is a naturally occurring biomechanical process by which your ankle rolls inward. A typical gait pattern starts with contact on the outside of the heel, followed by the foot rolling inwards during weight bearing, and finishing on the outside of the forefoot when pushing off (1). This process is essential to absorb forces from the ground to protect your body for impact and injury.
Overpronation occurs when the ankle rolls inward and stays inward during the push off portion of gait. The rolling in of the foot and ankle can cause a domino effect that causes the knee to rotate and fold inwards resulting in a malalignment of the kneecap. This overpronation can be caused by genetic changes in the feet with either flat feet (collapsed arches) or rigid feet (excessively high arches). Foot and ankle weakness will also lead to overpronation.
Patellofemoral pain can be a chronic condition when not managed properly. Previous treatment protocols focused mainly on quadriceps (thigh) strengthening. However, in health care we are constantly learning and changing. Current research supports focusing on foot, ankle, and hip impairments instead. Along with an appropriate strengthening program, adjustments to sport and exercise training routines can help to reduce the incidence of patellofemoral pain. The use of an orthotic may also improve patellofemoral pain when foot overpronation is a cause (1,4).
While there is little we can do about your genetics (thanks mom and dad), there is plenty that can be done with improve your foot, ankle, and hip strength. Optimal strength, stability, and flexibility of the hip and ankle will help control the forces placed on the knee. Less force on the knee equals less pain.
If you are interested in learning more about how to exercise with knee pain, click the link below to schedule your free discovery visit with a physical therapist.
1. Dutton RA, Khadavi MJ, Fredericson M. Patellofemoral Pain. Phys Med Rehabil Clin N Am. 2016;27:31-52.
2. Souza RB, Powers CM. Differences in Hip Kinematics, Muscle Strength, and Muscle Activation Between Subjects With and Without Patellofemoral Pain. J Orthop Sports Phys Ther. 2009;39:12-19.
3. Silva DO, Briani RV, Pazzinatto MF, et al. Q-angle static or dynamic measurements, which is the best choice for patellofemoral pain? Clinical Biomechanics. 2015;30:1083-1087.
4. Fredericson M, Powers CM. Practical Management of Patellofemoral Pain. Clin J Sport Med. 2002:12:36-38.
5. Austin, William M. “Women in Sports, Q Angle, and ACL Injuries.” Dynamic Chiropractic 21.21 (2003): n. pag. Web.