Unit 2 - Knee

Question 1

stability of the knee

Answer 1

ligaments, accessory structures, muscles that control varus/valgus, rotation

Question 2

genu recurvatum

Answer 2

hyperextension >5 degrees

Question 3

rotation of tibiofemoral joint

Answer 3

position dependent (greater in knee flexed, max at 90 deg flex)
named by tibial tuberosity motion

Question 4

coupled motion of the knee

Answer 4

sagittal and frontal plane, due to oblique orientation of axis
extension with valgus
flexion with varus

Question 5

screw home mechanism

Answer 5

locking of knee in last 30 degrees of knee extension
lateral rotation of tibia on femur due to 3 factors:
1. lateral pull of quads
2. tension in ACL
3. shape of medial condyle

Question 6

patellar motion with tf flexion

Answer 6

patella moves medially from a lateral position and glides inferiorly/rotates down intercondylar groove

Question 7

patellar motion with tf extension

Answer 7

patella glides superiorly/rotates up and around condyles

Question 8

arthrokinematics of tf extension

Answer 8

-taut pcl and anterior meniscus facilitates posterior glide of femur and anterior glide of tibia

Question 9

arthrokinematics of tf flexion

Answer 9

taut ACL and posterior meniscus facilitate posterior glide of tibia and anterior glide of femur
semimembranosus (medially) and popliteus (laterally) pull on the meniscus which also facilitates posterior glide of tibia

Question 10

arthrokinematics of tf rotation

Answer 10

about a longitudinal axis that tends to be on the medial tibial condyle
-distorts the meniscus

Question 11

bundles of ACL and PCL

Answer 11

ACL: anteromedial and posterolateral
PCL: anterolateral and posteromedial

stressed at different knee angles

Question 12

what resists anterior tibial translation

Answer 12

ACL
posterior meniscus
MCL
ITB
hamstrings
gastroc and soleus in wb

Question 13

what resists posterior tibial translation

Answer 13

PCL (is stressed most during 75-90 degrees of knee flexion)
anterior meniscus
quads
popliteus
gastroc

Question 14

what resists valgus forces at the knee

Answer 14

MCL
lateral meniscus
ACL, PCL
posterio-medial capsule
semimembranosus tendon
medial gastroc

Question 15

what resists varus force at knee

Answer 15

LCL
posterior lateral capsule and popliteus tendon
ITB
biceps femoris tendon
medial meniscus
ACL, PCL
lateral gastroc

Question 16

what resists medial rotation of the tibia

Answer 16

ACL, PCL
posterior-medial capsule
meniscus
biceps femoris

Question 17

what resists lateral rotation of the tibia

Answer 17

posterior lateral capsule
MCL, LCL
popliteus
sartorius/gracilis
medial hamstrings
meniscus

Question 18

what resists genu recurvatum

Answer 18

ACL
posteromedial capsule/lig
posterolateral capsule/lig

Question 19

how does the contact area of the patella change during tf movement

Answer 19

full extension: inferior pole
during flexion: moves inferiorly and medially
full flexion: lateral and odd facet only

Question 20

laterally directed forces on the patella

Answer 20

ITB
bowstring force of the patella
lateral patellar retinacular fibers
overall line of quad force is slightly lateral

Question 21

medially directed forces on the patella

Answer 21

medial patellar retinacular fibers
raised lateral facet of intercondylar groove
VMO

Question 22

q- angle

Answer 22

angle of pull of the quads
asis to midpoint of patella
tibial tuberosity to midpoint of patella
should be around 10-15 degrees
increase in angle--increase in lateral force

Question 23

what increases q-angle

Answer 23

structurally: femoral anteversion
lateral tibial torsion
valgus
dynamic: femoral medial rotation, tibial lateral rotation, valgus (as flexion occurs)

Question 24

compression of pf joint

Answer 24

increases with increasing tf flexion angle (25-50% of bw while walking, 5-6x while running)

Question 25

adaptations to reduce stress of pf joint

Answer 25

increase contact area up to 90 degrees flexion
increase MA of quad up to 90 degrees
hyaline cartilage: medial facet>lateral facet

Question 26

knee flexors and tibial translation

Answer 26

hamstrings: posterior shear peaks around 75-90 degrees knee flexion

Question 27

why does posterior capsule resist knee rotation

Answer 27

capsule fibers are oriented at an angle from a to p