Patellofemoral Pain Syndrome


The structures in your lower body are designed to work in a coordinated sequence to produce uninhibited movement. When correctly aligned, your knee cap facilitates smooth gliding at the knee as your powerful leg muscles contract to propel you forward and upward.

Pain occurring at the front of the knee and around the kneecap can signal a serious problem that, if ignored, may grow worse over time, especially if you are an athlete or are physically active. Patellofemoral pain syndrome (PFPS), also known as runner’s knee, is an umbrella term that covers a range of knee issues commonly found in runners and athletes.

Knee Anatomy

Your knee is the most complex joint in your body, responsible for transferring huge force loads during physical activity. Its structures include four bones: the patella (knee cap), the femur (thigh bone), and the tibia and the fibula of the lower leg. The knee is stabilized by muscles, tendons, ligaments, cartilage and menisci.

As a hinge joint, your knee enables you to stand, sit, walk run and jump. Synovial fluid within the joint capsule lubricates the knee to help it glide smoothly during flexion and extension. Two types of cartilage, meniscus and articular, provide shock absorption and help the bones to move smoothly against one another with minimal friction.

Incidence of PFPS

PFPS is the most common type of knee pain, with its locus in the area surrounding and underneath the knee cap. The syndrome is most common in runners and cyclists, but it can occur in anyone who is physically active, and even in people who sit too much. In professional cyclists, the incidence of PFPS is as high as 40 percent, but it is even more prevalent in runners, ranking as the number one running injury.

Causes of PFPS

Knee injuries are common in athletics, especially strains, sprains, and tears of the ligaments and menisci. But the most common cause of knee pain is overuse, where repetitive motion leads to wear and tear. PFPS is a type of overuse injury.

Common factors contributing to PFPS include:

  • Muscle imbalances that cause the knee to track less efficiently
  • Tight inflexible muscles that inhibit movement
  • Faulty movement mechanics that place excessive stress on the structures of the knee
  • Poor gait mechanics when walking and running
  • Repetitive overuse with inadequate recovery
  • Sudden changes in type, duration, frequency or intensity of physical activity
  • Worn or poorly fitting footwear
  • Sedentary lifestyle with excessive sitting

Often there are multiple factors at play in cases of PFPS. Most non-traumatic knee pain can be resolved with conservative treatment methods.

Diagnosis of PFPS

At NYDNRehab, we use dynamic diagnostic ultrasound to locate and visualize the structures of the knee. During diagnosis, both patient and clinician are able to view the images on the monitor, and the patient is able to provide feedback. Ultrasound imaging allows us to view the knee in motion, in real time, to identify the source of pain. Because diagnostic ultrasound give us immediate results, we can quickly proceed to devise an individualized treatment plan.


After a thorough clinical evaluation, we create an individualized treatment strategy that may include a combination of some or all of the following:

  • Gait and jumping analysis using 3D motion capture force plate technology
  • Manual release techniques to restore knee alignment and patellar gliding
  • C.A.R.E.N (Computer Assisted Rehabilitation Environment), a multi-sensory virtual reality environment used to train motor control
  • Sophisticated video feedback with surface EMG for runners and athletes
  • Training on our antigravity AlterG treadmill
  • Force-plate video feedback training
  • Extracorporeal shockwave therapy (ESWT)

The sports medicine professionals at NYDNRehab take a holistic approach to treatment, with the end goal of restoring pain-free function and enhancing athletic performance.


In this instance, an athlete was originally diagnosed with minor quadriceps muscle strain and was treated for four weeks, with unsatisfactory results. When he came to our clinic, the muscle was not healing, and the patients’ muscle tissue had already begun to atrophy.

Upon examination using MSUS, we discovered that he had a full muscle thickness tear that had been overlooked by his previous provider. To mitigate damage and promote healing, surgery should have been performed immediately after the injury occurred. Because of misdiagnosis and inappropriate treatment, the patient now has permanent damage that cannot be corrected.

The most important advantage of Ultrasound over MRI imaging is its ability to zero in on the symptomatic region and obtain imaging, with active participation and feedback from the patient. Using dynamic MSUS, we can see what happens when patients contract their muscles, something that cannot be done with MRI. From a diagnostic perspective, this interaction is invaluable.

Dynamic ultrasonography examination demonstrating
the full thickness tear and already occurring muscle atrophy
due to misdiagnosis and not referring the patient
to proper diagnostic workup

Demonstration of how very small muscle defect is made and revealed
to be a complete tear with muscle contraction
under diagnostic sonography (not possible with MRI)


Complete tear of rectus femoris
with large hematoma (blood)


Separation of muscle ends due to tear elicited
on dynamic sonography examination

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