Patellofemoral Pain Syndrome (PFPS), also known as runners’ knee, chondromalacia patellae, anterior knee pain, or patellofemoral joint syndrome, is a generic term used to describe pain that is felt behind the kneecap, where the patella (kneecap) articulates with the thigh bone (femur). PFPS occurs mainly due to excessive pressure at the patellofemoral joint from poor kneecap alignment, which in time affects the joint surface behind the kneecap. Runners, jumpers and other athletes such as skiers, cyclists and soccer players frequently experience PFPS.

Causes of patellofemoral pain syndrome

PFPS causes include:

  • Patellar misalignments – These are an abnormal muscle imbalance and poor biomechanical control
  • Overuse – In many cases, patellofemoral pain syndrome is caused by vigorous physical activities that put repeated stress on the knee, such as jogging, squatting and climbing stairs
  • Repeated trauma – this causes an increase in retropatellar joint forces, which can lead to kneecap pain, joint irritation, and eventually degeneration of the patella joint surface
  • Sudden change in physical activity

Symptoms of patellofemoral pain syndrome

The most common symptom of PFPS is a dull, aching pain in the front of the knee. Other common symptoms include:

  • Knee pain, especially when sitting with bent knees, squatting, jumping or using the stairs (especially going down stairs)
  • Occasional knee buckling
  • Pain related to a change in activity level or intensity, playing surface or equipment
  • Popping or crackling sounds in the knee when climbing stairs or when standing up after prolonged sitting
  • Catching or grinding sensation during walking or moving the knee