Patellofemoral Pain Syndrome (PFPS)

PFPS causes, prevention and risk factors, plus rehabilitation exercises and stretches.

by Brad Walker | Updated June 1, 2025

Note: The term Patellofemoral Pain Syndrome (PFPS) is often mistakenly used as an umbrella term to refer to a number of different knee injuries. PFPS specifically refers to pain experienced on or above the patella (kneecap): Not pain below the patella, which is Patellar Tendinitis, or Jumper’s Knee. And not pain behind the patella, which is Chondromalacia Patellae, or Runner’s Knee.

Anatomy of Patellofemoral Pain Syndrome

To understand PFPS we first need to understand the anatomy of the patellofemoral joint.

The bones that make up the knee joint are the Femur, Tibia, Fibula and Patella. The femur has a groove that the patella sits in, called the patellofemoral groove. The patella moves within the patellofemoral grove of the femur.

One of the common misconceptions is that the patella only moves in an up and down direction. But in fact, it tilts and rotates, so there are various points of contact between the undersurface of the patella and the femur.

Ligaments hold the knee joint together, while the medial and lateral meniscus work as a shock absorber for the femur and the tibia so that they don’t collapse onto each other.

The muscles that affect PFPS are the Quadriceps in the front of the thigh, the Hamstrings at the back of the thigh, and Planter flexor muscles of the lower leg.

Causes of PFPS

Literature suggests that the etiology of patellofemoral pain syndrome is multifactorial. Many theories have been proposed to explain patellofemoral pain, and these include:

Muscular Imbalance and Disfunction

The potential muscular causes of patellofemoral pain can be divided into weakness and tightness. Or, lack of strength and lack of flexibility.

Weakness of the quadriceps muscles is a common area of concern. The quadriceps muscles include the vastus medialis, vastus intermedius, vastus lateralis and the rectus femoris. Weakness of any of these muscles may adversely affect the patellofemoral mechanism. The muscle that is most commonly the weakest is vastus medialis (sometimes referred to as vastus medialis oblique or VMO). Weakness of the vastus medialis allows the patella to track too far laterally, which changes the Q angle. When the Q angle is changed it can cause the patella to move out of the patellofemoral groove, causing pain around the kneecap. The VMO is difficult to isolate and may need specific strengthening exercises to strengthen the muscle.

Inflexibility (tight muscles) can also be a problem that affects the patellofemoral mechanism. A tight iliotibial band can place excessive lateral force on the patella and externally rotate the tibia, which can upset the balance of the patellofemoral mechanism. While hamstring muscles flex the knee, tight hamstrings can place more posterior force on the knee, which causes pressure between the patella and the femur to increase. Adductor muscles play a role in the stability of the pelvis, which can cause an external rotation that may result in compensatory foot pronation. Tight calf muscles can lead to compensatory foot pronation, and like the hamstrings they can increase the posterior force on the knee.

Biomechanical Problems

When looking at biomechanical problems, there has been more than one factor identified as a primary cause of patellofemoral pain.

Flat foot and foot pronation cause compensatory internal rotation of the tibia or femur, which upsets the patellofemoral mechanism. Arch supports or custom orthotics can help with the internal rotation of the tibia in patients with patellofemoral pain due to flat feet.

A high arch foot provides less cushioning for the leg when it strikes the ground. This places more stress on the patellofemoral mechanism, particularly when a person is running. Proper footwear, such as running shoes with extra cushioning and an arch support can be helpful.

Overuse

Bending the knee increases the pressure between the patella and various point of the femur, hence why patellofemoral pain syndrome is often classified as an overuse injury. However, a more appropriate term may be overload, because the syndrome can also affect inactive people.

Repeated weight bearing impact may be a contributing factor, particularly in runners. Steps, hills, and uneven surfaces tend to make patellofemoral pain worse. After the pain has developed, even sitting for lengthy periods can be painful, because of the extra pressure between the patella and the femur during knee flexion.

Patellofemoral Pain Syndrome Treatment

The initial treatment for patellofemoral pain syndrome is the same as most other soft tissue injuries. This involves the application of R.I.C.E.R. (R) rest, (I) ice, (C) compression, (E) elevation and obtaining a (R) referral for appropriate medical treatment. It is critical that the R.I.C.E.R. regimen be implemented for at least the first 48 to 72 hours. Doing this will give you the best possible chance of a complete and full recovery. The following two points are of most importance.

During the first 48 to 72 hours after an injury like PFPS, be sure to avoid any form of heat at the injury site. This includes heat lamps, heat creams, spas, Jacuzzi’s and saunas. Avoid all movement and massage of the injured area. Also, avoid excessive alcohol. All these things will increase the swelling and pain of your injury.

Patellofemoral Pain Syndrome Prevention

Although it is important to be able to treat Patellofemoral Pain Syndrome, prevention should be your first priority. So here are some things you can do to help prevent PFPS.