Clinical features

Knee pain is the most common presentation of patellofemoral syndrome

• pain characteristically is retropatellar) and most often manifests during activities that require knee flexion and forceful contraction of the quadriceps (eg, during squats, ascending/descending stairs)
  • may worsen in intensity, duration, and rapidity of onset if the aggravating activity is performed repeatedly
  • may be exacerbated by sitting with the knee flexed for a protracted period of time, such as while watching a movie
    • leading to the terms "theatre sign" and "movie-goer's knee" where a patients with this condition often may prefer to sit at an aisle seat, where they may more frequently keep the knee extended
• knee pain often occurs during the activity, or may occur later after the activity has been completed
  • occasionally symptoms manifest as late as the next day.

Clinical examination:

• usual physical findings are localized around the knee
  • tenderness often is present along the facets of the patella
    • facets are most accessible to palpation by manipulation of the patella while the knee is fully extended and the quadriceps muscle is relaxed
      • manual positioning of the patella medially, laterally, superiorly, and inferiorly allows for palpation of the respective facets
  • an apprehension sign may be elicited by manually fixing the position of the patella against the femur and having the patient contract the ipsilateral quadriceps
  • there may be crepitus present
    • however if present in isolation, crepitus does not allow for definitive diagnosis
• Q-angle may be calculated by measuring the angle between the tibia and femur
  • use the attachment of the patella to the patellar tendon as the intersection point
• examination of gait may demonstrate excessive foot pronation, excessive knee valgus, or an antalgic gait pattern
• knee pain may be reproduced by repetitive squatting