Patellofemoral Pain Syndrome (PFPS)

open chain knee extension -45 to 0 -90 to 45

-45 to 0: joint reaction forces high, caution -90 to 45: joint reaction forces low, okay

closed chain knee extension -90 to 50: -45 to 0:

-90 to 50: joint reaction force high, caution -45 to 0: joint reaction force low, okay

diagnostic criteria: at least 3 positive signs of the following tests

-Noble compression -McConell -Waldron -Zohler's -Clarke's sign -Q angle exceeding 18 degrees -patella in medial or lateral position

medial forces on patella

-VMO -raised lateral facet of intercondylar groove: prevents further lateral movement -medial patellar retinacular fibers

PFPS vs. peripatellar bursitis

-direct trauma to knee -pain with kneeling -swelling -more pain with flexion -different from PFPS because way more painful

compression of patella during knee flexion -effect on surface area: -overall:

-even though the surface area increases with knee flexion, it cannot keep up with the increases joint reaction forces -quads eccentrically firing to lower body towards ground creates compressive force across patella

potential causes: extremes of bony/joint alignment -femur -tibia -Q angle -knee

-femoral anteversion --> genu valgum -external tibial torsion -large Q angle -genu valgum

biomechanical abnormalities in PFPS

-increased Q angle -valgus -pronation

potential causes: excessive stiffness/tightness in periarticular connective tissue or muscle -knee -hip

-lateral patellar retinaculum or ITB -tight hip IR or adductors

surgical treatment for PFPS -lateral retinacular release: -medial retinacular repair -trochleoplasty -realignment of extensor mechanism

-lateral retinacular release: makes structure weaker and allows for laxity -repair of medial retinaculum ligament -trochleoplasty: change of shape of trochlea so patella aligns better -realignment of extensor mechanism: move insertion of quads to change lateral pull

potential causes: excessive laxity in periarticular tissues -knee -ankle

-medial patellar retinaculum and patellofemoral ligament -lax MCL -lax arch in foot = pronation = greater Q angle

prevalence of PFPS -men vs. women -most common in: -assoicated with:

-more common in women than men -common in military recruits -most common in young active people -associated with high training loads and overuse

other diagnostic criteria -palpation -symptoms for how long: -onset -pain level

-pain during patellar palpation -symptoms for at least 1 month with insidious onset -pain level 3 cm/10 cm on visual analog

clinical findings- special tests -positive test: -compression tests: -glides of patella:

-positive patellar apprehension test -increased lateral glide -decreased medial glide -pain with patellar compression tests (Zohler, Clarke, Waldrons)

what muscles should be strengthened as the main way to reduce valgus at the knee?

-prevent femur from collapsing into valgus at the knee -THIS IS THE MAIN WAY TO REDUCE VALGUS -hip abductors and ER's

diagnostic criteria: anterior knee pain with at least 2 of the following activities 1. 2. 3. 4. 5. 6.

-remaining seated -squatting -kneeling -running -climbing stairs** -jumping

potential causes: bony dysplasia

-shallow groove -high patella

lateral forces on the patella

-tight ITB -tight lateral retinacular fibers -overall line of force of quads: bowstring force on patella

potential causes: muscle weakness 1. 2. 3.

-weak quads especially VMO -weak hip ER and abductors --> hip IR and adductors unopposed --> genu valgum -weak tibialis posterior --> pronation --> IR of tibia ???

pathogenesis of PFPS: suspected causes 1. 2.

1. stress intolerance of articular cartilage and underlying subchondral bone 2. associated with abnormal tracking and/or alignment of patella within intercondylar groove

normal gliding of patella

1/3 width of patella

what is the best exercise to start with in PFPS?

SLR -no patella contact in femoral groove -unlikely to increase symptoms

what muscle should be strengthened the most is PFPS?

VMO

what muscle facilitate VMO firing in closed chain?

adductors -mini squat with ball between knees

patellofemoral pain syndrome

anterior knee pain that is aggravated through increases in compressive forces on the patellofemoral joint with repetitive activities

PFPS vs. fat pad

fat pad has pain with SLR -not painful in PFPS because when straight leg patella is superior to groove and not compressed in groove

relationship between Q angle and lateral bowstring affect -affect on force/unit area

increase Q angle= increase lateral bowstring affect -pulls laterally against femoral condyle -same amount of force passing through patella but the force per unit area is increases because the patella is not in as much contact with femur

PFPS has pain at end range ___

knee flexion

Q angle

line from ASIS to midpoint of patella and line through midpoint of patella and tibial tubercle -women: 18 -men: 13

do resistive tests produce pain in PFPS?

no -usually not enough compression

PFPS vs. patellar tendinitis

tendinitis pain with: -running down hill -resistive test -eccentric MOI PFPS: pain with manual patellar compression