Which clinical history findings are characteristic of patellofemoral syndrome (PFS)?

Updated: Sep 15, 2020
  • Author: Noel F So, MD, FAAPMR; Chief Editor: Consuelo T Lorenzo, MD  more...
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Answer

Knee pain is the most common presentation of patellofemoral syndrome (PFS). The pain characteristically is located behind the kneecap (ie, retropatellar) and most often manifests during activities that require knee flexion and forceful contraction of the quadriceps (eg, during squats, ascending/descending stairs).

Pain may worsen in intensity, duration, and rapidity of onset if the aggravating activity is performed repeatedly.

Pain may be exacerbated by sitting with the knee flexed for a protracted period of time, such as while watching a movie, hence leading to the terms "theatre sign" and "movie-goer's knee." Patients with this condition often may prefer to sit at an aisle seat, where they may more frequently keep the knee extended.

Symptoms often occur during the activity, shortly thereafter, or sometimes even the following day.

PFS is also known as "runner's knee" or "biker's knee," as PFS is highly associated with running and biking.

Patellofemoral weight bearing increases with knee flexion as follows:

  • Walking - 0.5 times body weight
  • Ascending or descending stairs - 3.3 times body weight
  • Squatting - 6 times body weight

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