biomechanics

Question 1

BK

Total Contact (3)

Answer 1

P= F/A

we want as much residual limb in contact as possible

1-better venous return if total contact

2-dont want distal edema to accumulate

3-it will feel less heavy if there is no gapping

Question 2

BK

Anteriorly Tilt Socket (3)

Answer 2

“flexing the socket” (~5 degrees): get the knee into a more flexed attitude

1. improves WB to tolerant areas: WB infrapatella tendon, less distal stump
2. Promotes Knee Flexion in EARLY STANCE: HS knee extended and then 15-20 degrees flexed at FF
3. accommodates for knee flexion contracture

Question 3

If patient BK has a flexed knee contracture, what to do to adjust the socket

Answer 3

anterior tilt the socket further to acomodate to the contracture = flexing the socket

Question 4

BK anterior tilt socket

1. improves WB to tolerant areas:
2. Promotes Knee Flexion in EARLY STANCE:
3. accommodates for knee flexion contracture

Answer 4

1. infrapatella tendon, less on distal stump
2. HS knee extended and then 15-20 degrees flexed at FF
3. accommodates for knee flexion contracture

Question 5

BK

ankle foot slightly posterior

Answer 5

ankle foot set slightly posterior in relation to the center of the socket

1. promotes knee flexion in EARLY STANCE
2. set heel 1/4 inch slightly posterior

Question 6

BK

ankle foot set slightly medial

Answer 6

1. increases varus moment
2. improves pressure distribution to proximal medial / distal lateral residual limb
   - -not at fibular head

Question 7

BK

what to do if too much pressure proximal and medial

Answer 7

move the ankle foot closer to the center of socket

Question 8

BK

what promotes knee flexion in early stance?

Answer 8

1. anteriorly tilt socket “flexed socket”

2. ankle set slightly posteriorly

Question 9

BK

What improves pressure distribution?

Answer 9

ankle foot slightly posterior

Question 10

BK what accomodates for knee flexion contracture?

Answer 10

BK anterior tilt socket

Question 11

BK

What increases Varus moment?

Answer 11

ankle foot set slightly medial

Question 12

BK

what improves pressure distribution to proximal medial / distal lateral residual limb

Answer 12

ankle foot set slightly medial

Question 13

BK

what improves WB to tolerant areas: WB infrapatella tendon, less distal stump

Answer 13

Anteriorly Tilt Socket

Question 14

AK

Posterior Tilted Socket

Answer 14

“flexing the socket”

1. accommodates for tight hip flexors
2. maintain a better length tension on extensors: lengthen the extensors for more force generation in STANCE
3. help activate the shank/foot position in LATE STANCE: with less need hip extension
4. improve WB tolerance on Ischial Shelf

Question 15

AK

Adduct Lateral Wall

Answer 15

prevent residual limb from going into abduction (for the gluteus medius to be in a good position)

Question 16

AK

TKA line and knee stability

Answer 16

ankle axis posterior to create greater extension moment

Question 17

AK

what accommodates tight hip flexors?

Answer 17

AK posterior tilted socket

Question 18

AK

what to do for a hip flexion contracture?

Answer 18

AK posterior tilt socket

Question 19

AK

what to maintain better length tension on extensors?

Answer 19

AK posterior tilt socket

better length tension on extensors , lengthens the extensors for more force generation in the STANCE phase

Question 20

AK

what to activate the shank / foot position in late stance

Answer 20

AK posterior tilt socket

in late stance the lower leg and foot is back, tilt the socket back to go further back

dont need to do as much hip extension in LATE STANCE to get the prosthesis into a more extended position

need hip extension to get foot back, posterior tilt socket so as come to midstance and heel rise and the hip comes back the lower portion of the prosthesis gets back into terminal stance position

Question 21

AK

what improves WB on ischial shelf?

Answer 21

AK posterior tilt socket

more comfortable instead of sitting straight on shelf

come in at an angle to decrease torque / force around the IT and overlying tissue

Question 22

AK

what prevents residual limb from going into abduction?

Answer 22

AK

adduction of the lateral wall (about 10 degrees)

–for mechanical advantage of gluteus medius

Question 23

TKA line and knee stability

Answer 23

ankle axis is posterior to create a greater extension moment

TROCHANTERIC ANKLE LINE
-center of socket to center of ankle/foot assembly

knee unit is slightly posterior 1/4 inch
for weight line to be further in front to increase extension stability in knee by putting weight in front of the knee (bc axis is further back)

Question 24

AK

what increases extension stability?

Answer 24

TROCHANTERIC ANKLE LINE
-center of socket to center of ankle/foot assembly

knee unit is slightly posterior 1/4 inch
for weight line to be further in front to increase extension stability in knee by putting weight in front of the knee (bc axis is further back)