Patellofemoral Pain Syndrome Flashcards
What is patello-femoral pain syndrome?
pain around or behind the patella - which is aggravated by at least one activity which loads the PFJ during weight-bearing on a flexed knee
What is the mechanism of pain in PFPS?
Consistent overloading of the articular cartilage results in increased metabolic activity and water content of the subchondral bone - increases the pressure within the PFJ - stimulating the pressure-sensitive nociceptors in the patella
What is a moment arm?
the distance of the knee joint from the line of gravity
What is the impact of the moment arm on joint stress?
The longer the moment arm, the higher the stress on the joint - i.e. in a squat - the knee joint moves forwards away from the line of gravity
What is the effect of open chain exercises on PFJ stress?
When a weight is applied to the ankle, and the knee extends, the line of gravity moves as the ankle moves further from the knee joint - thus increasing PFJ stress
What is the effect of cable/theraband exercises on PFJ stress?
point of force remains relatively constant and so the line of gravity and length of the moment arm remains fairly constant - reducing PFJ stress
why is pain greater in knee flexion for people with PFPS?
As the knee flexes, the contact area between the patella and the trochlea of the femur is increased = increased pressure in the joint = increased pain
What are the non-mechanical traits of PFPS?
anxiety, depression, fear of movement, family & friends, work & education, income situation
- cause sensitization of the nociceptive system so that stimuli which would not normally be painful cause pain
Who does PFPS effect?
females and adolescents more common
high baseline levels of activity - e.g. athletes and military personnel
quadriceps weakness
high isometric hip abduction
What are the signs of PFPS?
Gradual onset of pain - around or behind the patella
Aggravated by PFJ loading (e.g. squatting or running)
Pain with prologued sitting (theatre sign)
Pain when straightening the knee after sitting
What are the objective signs of PFPS?
AKP when squatting
May have crepitus, small effusion, and tenderness over patella facets
