Patellofemoral knee pain

Question 1

What is patellofemoral knee pain?

Answer 1

also called ‘anterior knee pain’ or ‘runners knee’

“Pain around or behind the patella, which is aggravated by at least one activity that loads the patellofemoral joint (PFJ) during weight bearing on a flexed knee (e.g. squatting, stairs, running)”

Question 2

What is the mechanical model for the cause of pfp?

Answer 2

→ PFP occurs when the load applied to the joint exceeds the joint’s load capacity
→ Nociceptors trigger signals that alert the brain to potential or actual tissue damage
→ Articular cartilage (no nociceptors)
→ Increased metabolic activity and water content in the underlying (subchondral) bone, stimulating pressure sensitive receptors in the patella. Patella NOT cartilage provides nociceptive signals.

Answer 3

The longer the external moment arm, the harder the quadriceps have to work, and the greater the patellofemoral joint contact force.