Patellofemoral Pain Syndrome (PFPS) is a very common condition affecting both athletes and non-athletes alike. It is a very common running injury, with approximately 25% of runners experiencing PFPS at some point. In fact, it is so frequently associated with runners that it is often called “runner’s knee”. People with PFPS present with a dull pain in the front (anterior) part of the knee. It usually improves with rest and worsens with exercise, especially those that include lots of running or jumping. Pain is usually brought on when the knee is loaded in a flexed position (bent), such as when squatting or climbing stairs. Someone with PFPS can also experience clicking of the knee (crepitus), may feel the knee is weak or likely to give way, and sometimes have mild swelling of the area.
Sometimes people use the term “Chondromalacia Patella” as a synonym for PFPS despite this not strictly being correct. Chondromalacia Patella is the name given to a specific condition that causes anterior knee pain of the patella where the cartilage on the inside surface of the patella (articular surface) has softened and/or become damaged. PFPS does not include any softening or damage to the cartilage, thus setting these two conditions apart. Apart from this, they have almost exactly the same presentation and causes, leading some to suggest that the distinction is a theoretical one, not a practical one. Since PFPS is diagnosed clinically without any diagnostic imaging, it is highly likely that some (but only some) individuals diagnosed with PFPS will actually have Chondromalacia Patella. Conservative treatments for both conditions will be more or less the same. Severe Chondromalacia Patella may require surgery, while PFPS will not.
The biomechanical causes of PFPS include: tight quadriceps or hamstring muscles, tight iliotibial band (ITB), weak or delayed onset of vastus medialis oblique (VMO), gluteus maximus, or gluteus medius, or an imbalance in the muscles making up the quadriceps, and poor foot, ankle, or lower limb biomechanics.
It is believed that these can lead to PFPS because the patella not tracking properly through the groove in the knee behind it, called the “trochlear groove of the femur”. See the image below:
As the knee bends, the patella should glide smoothly along this groove with very little friction. As mentioned above, a lack of proximal control from the muscles of the thigh and hip (weakness), an imbalance in the muscles of the quadriceps, or poor lower leg biomechanics can lead to mal-tracking of the patella along the groove, leading to PFPS.
Other causes of PFPS can be cumulative loads placed on the knee that are more than the tissues can handle without injury. We call this a “training load error” as it is often due to the tissues not being prepared for the sudden increases in load through correct training. It can also result from injury to the knee, such as a fall. And finally, it may be due to a developmental issue in which the knee has not formed correctly. For the sake of this article, we will be dealing only with the biomechanical aspects causes of PFPS.
The important distinction to make in cases of PFPS is whether the mal-tracking is due to lack of proximal control and/or muscles imbalances, or if it is due to poor biomechanics of the foot and ankle, or both. This can be done in clinic using standard muscle tests and podiatric biomechanical assessments. If the issue is entirely proximal, then orthoses are not recommended, as evidence has suggested this can actually make the problem worse. In this case, a set of therapeutic exercises can be prescribed alongside changes in activity and training. However, if the foot and ankle are the cause, or if they are blocking the muscles of the hip and thigh from being able to function normally, then foot orthoses are not only recommended, but essential for treatment.
Acupuncture and electroacupuncture, as well as NSAIDs and “RICE” (rest, ice, compression, elevation) can be used to manage pain during recovery, while strapping and devices that offer structural support to help you do the exercises you need in order to recover.