12: Knee and Ankle - Smith

Question 1

_______ condyle deviates from the femoral midline more

Answer 1

medial

Question 2

longer and narrower condyle

Answer 2

medial femoral condyle

Question 3

which condyle facilitates the screw-home mechanism

Answer 3

longer medial condyle

Question 4

which facet on the tibia is longer?

Answer 4

medial

set a little bit more distally than the lateral facet

Question 5

describe the shape of lateral and medial menisci

Answer 5

medial - c shaped

lateral - complete circle

Question 6

the menisci in cross section are ________ shaped

Answer 6

triangular

- wider around periphery, thinner near middle

Question 7

what are the menisci and what are there function?

Answer 7

• fibrocartilaginous structures attached to tibia between femoral condyles
• shock absorption and spacers within joint

Question 8

in what motion is knee more stable?

Answer 8

extension

Question 9

what type of joint is the knee joint?

Answer 9

ginglymus (hinged) with two degrees of freedom

*actually has six degrees of freedom (flex/extend, int/ext rotation, ab/adduction)

Question 10

describe “roll and glide” of knee

Answer 10

• femur will roll and glide during knee flexion to allow the knee to flex without impinging on post tibial plateau

Question 11

describe “screw-home mechanism”

Answer 11

• external rotation of tibia on femur during last 15-20 degrees of extension OKC
• internal rotation of the femur CKC
• increases osseous stability of the knee joint
• occurs b/c medial femoral condyle has a longer articular surface? (uses it up on lateral side )(also a soft tissue component)

Question 12

name the muscles of the anterior thigh

Answer 12

quadriceps femoris (vastus medialis, vastus intermedius, vastus lateralis, rectus femoris)
sartorius
articularis genu

Question 13

function of the anterior thigh muscles in OKC and CKC

Answer 13

OKC = extend knee
CKC = pull thigh over stationary tibia

Question 14

name the muscles of the posterior thigh

Answer 14

hamstrings (semimebranosus, semitendinosus, biceps femoris)

popliteus

Question 15

posterior thigh muscles function in OKC

Answer 15

• knee joint flexors

- occurs during swing phase

Question 16

name the muscles of the medial thigh

Answer 16

adductor magnus
adductor longus
adductor brevis
gracilis

(function is minimal in gait)
(lateral is tensor fascia lata which is also minimal function)

Question 17

contact phase (knee)

Answer 17

• knee joint flexing to absorb shock
• hamstrings contract to flex knee
• quadriceps contract to keep knee from buckling (counteract hamstrings)

Question 18

midstance phase (knee)

Answer 18

• quads continue contracting and extend knee until body mass passes over the knee joint
• tensor fascia lata externally rotates the tibia on femur during last 20 degrees of knee extension

Question 19

propulsive phase (knee)

Answer 19

• tensor fascia lata continues to externally rotate the tibia as knee continues to extend
• adductors contract during double support
• hamstrings start to flex preparing for swing phase

Question 20

swing phase (knee)

Answer 20

• hamstrings flex to allow foot to clear ground
• knee extends the rest of phase preparing for contact
• quadriceps only needed last 20 degrees of knee extension due to whip like action of hip
• hamstrings contract to counteract the quads and keep knee from fully extending

Question 21

describe the inferior tibiofibular articulation

Answer 21

• fibrous articulation

- strength is increased by interosseous membrane

Question 22

*** when is ankle joint more stable?

Answer 22

dorsiflexed position (the thicker portion of talus is in the ankle joint)

Question 23

which part of the talus is wider?

Answer 23

anterior portion is 25% wider

Question 24

how is the fibula located in relation to tibia?

Answer 24

more distal and posterior to tibia

Question 25

what is the ankle joint axis (degrees)

Answer 25

• 8 from transverse
• 20-30 from frontal plane
• roughly perpendicular to sagittal plane

what does this mean???
mild abduction with ankle dorsiflexion/ mild adduction with ankle plantarflexion

Question 26

what motion occurs at ankle joint with dorsiflexion

Answer 26

mild abduction

mild adduction with ankle plantarflexion

transverse plane motion at ankle reduces amount of frontal plane motion needed at subtalar joint

Question 27

OKC ankle joint

Answer 27

dorsiflexion

plantarflecion

Question 28

CKC ankle joint

Answer 28

dorsiflexion - tibia moves anterior over planted foot

plantarflexion - tibia moves posterior over planted foot

Question 29

ankle joint ROM

Answer 29

dorsiflexion 10 +

plantarflexion 45 +

Question 30

minimum ROM needed at ankle joint

Answer 30

10 dorsiflexion (if less = equinus) 
20 plantarflexion

Question 31

when you repeat ankle dorsiflexion with knee flexed, what do you expect?

Answer 31

• this releases gastroc

- with knee flexed is normally greater than with knee extended

Question 32

if body can’t get enough sagittal plane motion in ankle where will it go for compensation?

Answer 32

1. knee
2. MTJ oblique axis
3. STJ

looking for joints close with sagittal plane motion

Question 33

most common rotational deformity below the knee

Answer 33

tibial torsion “ a change in the axial relationship of foot to thigh”

Question 34

how do you measure rotational deformity below the knee?

Answer 34

• distal tibiofibular axis created by malleoli in relation to axis of knee
• IMPOSSIBLE to measure any amount of actual torsion or twisting of tibia

Question 35

malleolar positioning as you grow

Answer 35

• birth = 0-5 external malleolar position
• 1 yo = 10
• increases by one degree for each year of age until 12/13
• final = 18-23 degrees of external malleolar positioning
• actual amount of tibial torsion = 13-18