What is Patellofemoral Pain Syndrome?

Patellofemoral pain syndrome (PFPS) is a broad term used to describe discomfort around the knee joint.  Discomfort typically occurs between the kneecap (patella) and thigh bone (femur). Nicknamed ‘Runner’s Knee’, PFPS is classified as an overuse injury, and is particularly common in running activities and sports.   Other activities that can cause PFPS include sitting for a long time, squatting, and jumping [1].

According to multiple studies, up to 33% of all knee injuries associate with patellofemoral pain syndrome [1]. While rehabilitation affords positive outcomes, up to 75% of people with this injury will eventually stop participating in physical activities rather than seek treatment. 

And due to the different bone structures of the hip, females are 2-10 times more likely to experience PFPS.


Why are knees prone to overuse injuries?

Our knees are complex hinge joints, designed to stabilize our legs as we walk, run, climb stairs, kick a ball or squat as we garden. An important component of the knee joint – the patella — provides extra leverage for the quadriceps as the legs straighten. Additionally, this small triangular shaped bone protects the hinge joint, like a shield.

The patella attaches to the lower end of one of the quadriceps muscles that covers the front of the thigh. As the knee bends and straightens, the patella moves, or slides vertically in a shallow groove at the front of the knee.

When the quadriceps muscle is strong, the patella moves smoothly in its groove. However, if the quadriceps muscle is weak, or the direction of pull from the quadriceps muscles changes, the patella’s movement does not conform to the groove. And when the patella becomes “derailed,” the soft tissue between the patella and the knee joint becomes irritated, resulting in pain.

Also, people with muscular imbalances and structural abnormalities (e.g., shallow knee groove, small kneecap dimensions, etc.) are at greater risk of developing patellofemoral pain [2].


What are the main causes of Patellofemoral Pain Syndrome?

1  |  Weakness of the quadriceps muscle

The quadriceps muscle often experiences a weakening following an injury to the knee – such as a meniscal tear, a knee operation (including a total knee replacement) or even a physical impact to the knee. So, due to a weakened quadriceps, the patella may shift out of its groove.

Additionally, the four muscles of the quadriceps group vary in strength. Often, the outer quadriceps, which is stronger, imposes greater directional pull on the patella.

2  |  Weakness around the hip and buttock region

Muscular weakness in the hip or buttock area can alter the biomechanics of the leg, which in turn can change the directional pull of the quadriceps on the patella

3  |  Flat feet (overpronation)

Conditions such as flat feet (when the arches of the foot roll inward or downward when walking) cause the knee to roll inwards and adversely impact the way the patella moves


What are the symptoms of Patellofemoral Pain Syndrome?

Given the large number of structures in the patellofemoral area, symptoms of PFPS vary from person to person. However, the classic symptom of this condition is a dull and achy pain in the front of the knee. Unlike some knee injuries that occur due to a single traumatic event such as a fall, the onset of PFPS is slow and deteriorates over time. As a physiotherapist I have diagnosed and treated hundreds of knee conditions, and PFPS can be the most confounding of these for the patient because it is (1) not associated with a traumatic event and (2) can take time to recover.

Other common symptoms include:

  • Knee pain during repetitive movements which requires the knee to bend and load with body weight (e.g., stairs, running, etc.)
  • Vague pain around the patella (kneecap) and behind the knee (this is less common)
  • Instability of the knee (knee buckling, giving way or locking)
  • Excessive clicking and grinding of the knee whilst moving


How is Patellofemoral Pain Syndrome treated?

Conservative treatment includes:

  • Corrective, strengthening and neuromuscular control exercises
  • Modifying training schedules (e.g., reducing volume, increasing rest durations, etc.)
  • Technique modifications for aggravating activities (e.g., running, squatting, jumping, etc.)
  • Taping, bracing, dry needling and
  • Soft tissue release

Perhaps the most important aspect of rehabilitation is to understand why you experience patellofemoral knee pain and what treatments you can administer at home, including:

  1. Stretches
  2. Exercises aimed at correcting the muscular weakness and imbalance around the knee and hip, ensuring optimal biomechanical alignment
  3. Fitted and supportive shoes with adequate arch support for running, sport and general everyday use



Stretches & Exercises


Overview: While standing, cross one leg behind the other and bend sideways from the hip. Reach arm overhead, feeling a stretch on the outer hip.

  1. While standing, cross the leg to be stretched behind the other leg.
  2. Bending sideways from the hip, lean your body away from the leg you are stretching.
  3. Place the arm, on the side you are stretching, overhead across to the other side.
  4. Push your hips forward to feel a stretch on the outer hip and thigh.
  5. Hold this position



Overview: Standing with feet hip-width apart and arms out in front, bend at the hips and knees, lowering your buttocks into a half squat. Return to standing position.

  1. Stand upright with your feet hip-width apart and your arms outstretched in front of you.
  2. Bend your knees and hips, leaning your chest forward, lowering your thighs to a 45- 60-degree angle. Bend from the hips not the back.
  3. Keep the knee in line with your foot, your weight on your heels, your back straight and look ahead. Do not allow your knees to travel in front of your toes.
  4. At the bottom of the squat, tense your buttocks, and return to a standing position.



Overview: Lying on your side with knees bent, lift and lower your top knee keeping your lower knee grounded, and your feet together.

  1. Lie on your side, legs together and hips bent to 45 degrees and knees to 90 degrees.
  2. Rest your head on your outstretched arm and bend the top arm, placing your hand in front of your chest for stability.
  3. Keeping your feet together, lift the top knee up without rolling your body.
  4. Control the movement as you bring the knee back to start.


[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4458915/

[2]  https://www.physio-pedia.com/Patellofemoral_Pain_Syndrome