20: Foot Function during Gait - Vardaxis

Question 1

how do the following parameters change with increasing speed?**

• ankle dorsiflexion
• ankle plantarflexion
• maximum heel elevation
• heel elevation at contralateral heel strike
• maximum toe elevation
• vertical excursion of head
• lateral excursion of head

Answer 1

• increases
• increases
• increases
• increases
• increases
• increases
• decreases * only decreasing parameter with speed

Question 2

effect of low-dye taping on arch deformation during gait using MLA

Answer 2

• taping decreases the deformation of the arch (doesn’t flatten as much)
• support disappears after 48 hrs

Question 3

measuring MLA during gait

Answer 3

• MLA increases through stance phase (arch becomes flatter)

- at toe off - becomes more cavus - because plantar fascia is tightened

Question 4

single segment foot model rockers during stance phase of gait [system of pivots in the foot during the stance phase, allowing for smooth advancement)

Answer 4

1st rocker - heel: heel contact point acts as fulcrum while foot and shank rotate to full contact [ankle plantarflexion]

2nd rocker - ankle: the foot is in full contact w/ ground. body advances due to forward momentum pivoting at the ankle [ankle dorsiflexion]

3rd rocker: forefoot: as center of pressure moves forward towards the met heads, the pivot pt becomes the MPJ joint [metatarsophalangeal]

Question 5

Tulchin 2009

Answer 5

• used n=24 individuals
• single rigid body model at different speeds versus the multi-segment models
• single showed: peak dorsiflexion LESS with increasing speed; amount of plantarflexion increased with speed
• hindfoot showed: time effect only, dorsiflexion happened earlier with increasing speed
• forefoot showed: dorsiflexion motion is peaked earlier with more plantarlexion
• the maximum hindfoot dorsiflexion is correlated to maximum forefoot dorsiflexion, should we look at them separately? maybe because not related in all foot morphologies. structure described less than 25% of mobility.

Question 6

forefoot deformation during the stance phase of Gait

Answer 6

• the transverse arch angle become smaller as we progress through stance phase (becomes higher)
• different between bases and heads (changes quicker in heads)
• during push of third rocker at heads becomes rigid (highest arch)
• speed has effect on rigidity of foot (faster more rigid)

Question 7

stance phase _______ with increased speed

Answer 7

decreases

Question 8

how do the rockers change with increasing speed?

Answer 8

heel rocker no change
ankle rocker faster
toe rocker longer