Foot and Ankle Biomechanics

Question 1

What happens to foot during weight acceptance?

Answer 1

foot pronates to absorb shock

Question 2

What happens to the foot during mid stance

Answer 2

pronation ends

Question 3

What happens to the foot during terminal stance?

Answer 3

foot moves into supination

Question 4

ROM necessary for gait? DF, EV, INV? how much does the foot need to pronate and supinate from neutral position?

Answer 4

10 degrees DF
4-6 degrees EV
8-12 degrees INV
pronate and supinate 6-8 degrees from neutral position

Question 5

What happens during gait of the STJ is stiff?

Answer 5

There is excessive pronation –> excessive mobility–> can’t go into rigid lever (axes can’t cross) –> get propulsion from 1st ray OR by rotating LE and compensating with hip and knee.

Question 6

What’s Dutton’s definition of SINGLE PLANE?

Answer 6

single plane: leg, foot, and ankle
FRONTAL PLANE
HORIZONTAL PLANE
SAGITTAL PLANE

Question 7

What is in and happens in the FRONTAL PLANE?

Answer 7

Motion of the foot- anterior/posterior axis

inversion and eversion

Question 8

What is in and happens in the HORIZONTAL PLANE?

Answer 8

Motion of the forefoot- superior/inferior axis

abduction and adduction

Question 9

What is in and happens in the SAGITTAL PLANE?

Answer 9

movements at the ankle and midtarsal joint- medio-lateral axis

plantar flexion and dorsiflexion

Question 10

What is TRIPLANE movement and where does it occur in the foot/ankle?

Answer 10

movement about an obliquely oriented axis through all three body planes

talocrural, subtalar, midtarsal joints, 1st ray, 5th ray

Question 11

Describe OKC and CKC motions at the subtalar joint.

Answer 11

Triplanar Motion

OKC

• pronation = calcaneal eversion/abduction and dorsiflexion
• supination= calcaneal inversion/adduction and plantarflexion

CKC

• pronation= calcaneal eversion with adduction and plantar flexion of the talus
• supination= calcaleal inversion, abduction and dorsiflexion of the talus

Question 12

Sub-Talar Neutral (STJN)

Answer 12

mid position of the sub-talar joint = range at which STJ should act to prevent dysfunction

Measured as an angle between the bisection of the distal portion of lower leg and line that bisects calcaneus

Should be 0-3 degrees or mathematically position of 2:1 inversion to eversion.

Question 13

What should you see in a posterior view of the foot/ankle during normal gait?

Answer 13

Heel strike: rear foot inverted

Midstance: rearfoot perpendicular

Heel rise: rearfoot inverted

Question 14

What would you see in a posterior view of an excessively pronated foot during gait?

Answer 14

Heel strike: inverted

Midstance: everted

Heel rise: everted

Question 15

What would you see in a posterior view of an excessively supinated foot during gait?

Answer 15

Heel strike: inverted

Midstance: Inverted

Heel rise: inverted (maybe everted)

Question 16

What are some intrinsic causes of excessive supination? are they compensated or uncompensated?

Answer 16

plantar flexed first met (compensated)

forefoot valgus (compensated)

uncompensated rearfoot and forefoot varus

Question 17

What are some extrinsic causes of excessive supination? are they compensated or uncompensated?

Answer 17

femoral retroversion (compensated)

uncompensated tibial varum

neurological disorders

leg length discrepency

Question 18

What are some intrinsic causes of excessive pronation? are they compensated or uncompensated?

Answer 18

forefoot varus (compensated)

rearfoot varus (compensated)

Question 19

What are some extrinsic causes of excessive STJ pronation? are they compensated or uncompensated?

Answer 19

compensation for limited DF during gait

compensation for excessive tibial varus

achilles tightness

weak peroneus longus or ankle/STJ invertors (posterior tibialis, FDL, FHL; anterior tibialis, EHL) arch laxity

compensation for increased LE IR secondary to femoral anteversion or muscle strength imbalance of hip internal: external rotators

Question 20

At the STJ, what would you expect to see at the in the gait cycle in a foot with forefoot valgus?

Answer 20

supination when forefoot becomes plantargrade ( need enough mobility in forefoot in order to do this)

Question 21

According to Dutton, how much rearfoot varus is normal?

Answer 21

3 degrees rearfoot varus

Question 22

At the STJ, what would you expect to see in the gait cycle of a foot with rearfoot varus?

Answer 22

early and prolonged pronation of mobile adapter

Question 23

At the STJ, what would you expect to see in the gait cycle of a foot with forefoot varus?

Answer 23

excessive pronation in stance

pt can’t push off and will probably compensate (i.e. push off with knee –> patella femoral symptoms)

Question 24

Genu vara can cause excessive ____________ at the foot/ankle.

Answer 24

supination

Question 25

Genu valga can cause excessive _______ at the foot/ankle.

Answer 25

pronation

Question 26

Coxa vara can cause excessive ______ at the foot/ankle.

Answer 26

pronation

Question 27

Coxa valga can cause excessive _______ at the foot/ankle.

Answer 27

supination

Question 28

Excessive lateral tibial torsion can cause excessive _____ at the foot/ankle.

Answer 28

pronation

Question 29

Excessive medial tibial torsion can cause excessive _______at the foot/ankle.

Answer 29

supination

Question 30

Leg length discrepency can cause _______ in the long leg’s foot and ________ in the short leg’s foot.

Answer 30

pronation; supination

Question 31

medial hamstring tightness can cause excessive _______ in the foot/ankle.

Answer 31

pronantion

Question 32

Tigh calves can cause excessive ______ in the foot/ankle.

Answer 32

pronation