Knee

largest

the knee is the _____ joint in the body

tibiofemoral

there are two compartments of _____, patellofemoral, and proximal tibiofemoral joints

hinge

the knee is classified as a _____ joint but its really a special ellipsoid similar to RC joint

foot/ankle

the knee needs to accommodate motions from lumbopelvic/hip and _____/_____

force; shock

slight knee flexion during stance phase of gait cycle allows _____ transmission, conservation of energy, and _____ absorption

concave

the trochlear groove is _____ to accept the convex surface of the patella

larger

the lateral facet of the femur is ____ and more anterior than the medial facet

- helps to stabilize to prevent patellar dislocation

PF

____ syndrome is very common in athletic population

knee extension

medial and lateral grooves of the femur affect arthrokinematics near _____ ______

fibula

does not have a direct function of weight bearing but does serve as attachments of ligaments and muscles of knee and foot/ankle

fibular

______ collateral ligament inserts onto the the proximal fibula

biceps femoris

what muscle inserts onto fibula?

rotation

proximal tib/fib joint dysfunction affects _____ at the knee and foot/ankle mechanics

peroneal

the proximal tib/fib joint may contribute to _____ nerve irritation

full flexion

what is the CPP of the patellofemoral joint?

full extension

what is the OPP of the patellofemoral joint?

patella

triangular bone encapsulated by patellar tendon

posterior surface has thick cartilage

several facets on the posterior surface

175

normal genu valgum is _____ degrees

excessive valgum

knock knee

excessive varum

bow leg

ACL and PCL

what two structures 'check' knee motion in the A-P axis and limit rotation of knee joint?

ROM

the tibial plateaus allows for large knee _____

force

articular cartilage absorbs _____

femur

menisci help maintain that the _____ stays on the joint axis

- they are also susceptible to injury (50% of ACL tears also have meniscal tears)

2-3

walking increases knee joint compression by ____ to ____ times ones body weight

concave; convex

tibia on femur is _____ on ______

convex; concave

femur on tibia is _____ on _____

flexion

the knee will have a ____ moment if 0 degrees of extension is not able to occur

IMA

natural migration of the ML axis during knee movements:

- alters _____ of flexors and extensors

- goniometer readings may be inaccurate

externally; internally

screw home mechanism:

- tibia ______ rotates

- femur _____ rotates

mechanically couple

popliteus

what muscle unlocks the screw home mechanism?

flexes; extends

more rotation occurs in the knee joint when the knee _____

- opposite is true for when the knee _____

45 degrees

about how many degrees of total rotation is there at the tibiofemoral joint?

medial; ACL; quads

three required factors about the screw home mechanism:

- shape of _____ condyle

- tension of ____ ligament

- lateral pull of _____

slacked

during knee flexion the ligaments and capsule are relatively _____

taut; extension

during SHM:

the ACL and MCL become more _____ to stabilize knee and are susceptible to injury in knee _____

full extension

what is the CPP of the tibiofemoral joint?

cruciate ligaments

intracapsular, synovial, poor blood supply

- very strong; can withstand about 400 lbs. tensile force

- resist all extremes of knee joint motion

- most effective at resisting tibiofemoral A-P and P-A shear forces

- oblique orientation also resist forces in frontal/horizontal planes

- guides knee arthrokinematics

- assists with joint proprioception

tensions

knee extension _____ the ACL, posterior capsule, hamstrings, collateral ligaments, and adjacent capsule

quads

what muscle is the ACL antagonist?

70%

what percent of ACL injuries are non-contact?

flexed; valgus; IR; ER

3 main mechanisms to ACL injury:

- ____ knee or extended knee W/ strong quad activation

- _____ collapse

- excessive ____ of femur and excessive ____ of tibia (quad pull)

PCL

less common injury than ACL

- becomes more taut with MORE knee flexion

- most slacked from 0 extension and 30-40 flexion

- usually ruptured with excessive/forceful knee flexion

- prevents anterior translation of femur with deep plyometric squats/jumps

hamstrings

what muscle(s) is an antagonist to the PCL?

PCL

the ____ is usually not repaired surgically but accelerates knee OA

OKC

does this describe OKC/CKC?

- patella glides ON stationary trochlea

CKC

does this describe OKC/CKC?

- femur glides ON stationary patella

extension

patella loses joint engagement towards knee _____

quadriceps femoris

only knee extensor

multiple head with large CSA

2-3x larger than hamstring CSA

30-75

the maximal amount of knee force that can be produced is between ____ and _____ degrees of knee flexion

90; 0

there is poor force of the knee extensors at greater than _____ degrees and near ____ degrees of flexion

compressive

at 0 degrees of knee extension the IMA is more ______ of the tibiofemoral joint

PF

at 90 degrees of knee flexion the IMA is more compressive of the ______ joint

increases

the patella ____ the IMA of the quads

IMA

the _____ changes during knee motion

- sometimes more stability, sometimes more force and ROM

20

quad weakness results in 0-____ degrees of extensor lag

- very common post knee surgery/trauma

extensor

causes of _____ lag:

- swelling of the knee (intracapsular)

- swelling of the knee (reflexive neurological inhibition)

- inhibits quad

- hamstring resistance

1.3, 2.6, 3.3, 7.8

match the joint compression to the exercise for PF joint:

Gait:

SLR:

stair climbing:

deep squat:

1.3x , 7.8x, 2.36x, and 3.3 x

flexion

the compressive force (CF) is affect by the degree of knee _____

- the deeper the squat, the greater the PF compressive force

Q-angle

degree of angle when measuring from midpatella to ASIS and tibial tubercle. normal q angle is 12 degrees for man and 17 degrees for a woman.

greater Q-angle

leads to less quad force and greater tibia ER

more strain on ankle/foot (ankle sprains)

increased risk for PFS, ACL tears, dislocation, military injuries, and running injuries

superiorly; laterally

the quad pulls the patella _____ and _____ during knee extension

enhances lateral pull of patella

IT band

vastus lateralis

retinacular fibers

internally rotated hip

anterior pelvic tilt

trochlear and patellar facets

enhances medial pull of patella

vastus medialis

PF ligament

medial retinacular fibers

trochlear and patellar facets

VMO

valgus

____ alignment

- excessive lateral pull from quads

- tibia ER, IR femur

- greater valgus force at knee

- stress at MCL and menisci

semitendinosus and semimembranosus

what two hamstrings insert on the medial tibia?

- potential to IR tibia on femur

biceps femoris

what hamstring inserts on the fibular head?

- potential to ER tibia on femur

pes-anserine muscles

flex the knee and IR tibia

0-20

the greatest flexion torque occurs between ____ and ____ degrees of knee flexion

declines

flexion torque _____ rapidly with more knee flexion

90

there is greatest leverage of the hamstrings nearing ____ degrees of knee flexion due to increasing IMA

5-10 degrees

what is the normal amount of valgus at the knee?

- joint force most distributed in menisci

- compresses medial joint space more than lateral

- more medial compartment degeneration than lateral

varum deformity

medial compartment experiences OA

- due to greater varum

loss of joint space and bony hypertrophic changes

after tibial osteotomy (regain joint space and valgus alignment)

valgum deformity

reduced glute med strength

reduced neutral pelvis

reduced kinesthesia/proprioception

reduced overall efficiency, balance

medial structures are tensioned/gapped

lateral knee joint is compression/slack

decreased

more knee flexion = _____ ACL tension

increased

more knee extension = ____ ACL tension

PFS

occurrence in women than men

more in active/athletic population

peripatellar/retro-patellar pain insidious onset

mal-tracking of patella in trochlear groove

associated with hip and lumbopelvic dysfunction

may lead to chondromalacia and dislocation

scientific literature is controversial about best treatment options