Gait: intro, ankle, knee Flashcards
What what phase, stance or swing, do we spend most of our time on the limb of focus?
60% of time in stance phase
40% of time in swing
What is the difference between step length and stride length? What are normal values?
- step length = right foot to left foot: 72 cm
- stride length = right foot to right foot: 144 cm
When is the first phase of double-limb support?
loading
How many degrees of foot angle are normal?
5-7 degrees of toe-out
If someone has a greater than normal angle of toe out, what is this called?
duck toe
What is cadence?
number of steps per minute; a temporal descriptor of gait
What are the 3 temporal descriptors of gait?
cadence
step time
stride time
What is gait cycle time also called?
stride time
T/F: Step length = gait cycle step.
false, stride length = gait cycle step
What are normal values for step width?
8-10cm
When increasing walking speed, what happens to stance time and swing time?
With increased walking speed
- stance time decreases
- swing time increases
T/F: Step length increases when we increase walk speed.
true
T/F: With the gait cycle, we start with more concentric activity, and then switch to eccentric activity towards the end of the cycle.
false, we go from eccentric to concentric
What percentage does initial contact consist of in the gait cycle?
0-2%
Where are the ground reaction forces for initial contact?
posterior to ankle
anterior to knee
slightly anterior to hip
When is the first double-limb support period?
loading response of stance
Where are GRFs in loading response?
posterior to knee
posterior to ankle
slightly anterior to hip
How long does loading last for?
from initial contact until the other foot is lifted for swing
What muscles are extremely important in the loading phase?
the knee extensors!! GRF is posterior to knee here, and KEs must eccentrically control this knee flexion
When is the second double stance phase?
preswing
What percentage of the gait cycle is loading?
0-10%
When does the first half of single limb support occur?
midstance
Where is the opposite limb when the stance limb is in midstance?
midswing
What is the position of the limb in early midstance, and then late midstance?
early = knee flexed, hip flexed late = knee extended, hip extended
What two muscles make up 93% of the potential plantar flexor torque?
gastroc and soleus
What muscles preserve the heel rocker?
DFs
At what phase of gait are we in if the foot is in digigrade?
terminal stance
Describe the activity of the plantar flexors during gait cycle.
- most active in beginning during loading and through midstance to eccentrically control DF
- turn on slightly during preswing when the 2nd arc of plantar flexion occurs, but mostly passive recoil is used for push off (from the stretch they just got during DF)
What muscle markedly increases its activity in midstance to control pronation?
tib posterior
When during gait does PF internal torque peak?
at push off, then drops off
Where are GRFs during loading response?
posterior to ankle
posterior to knee
slightly anterior to hip
When does the first arc of ankle PF occur in gait?
during loading response: get a quick 10 degrees as the foot drops to the floor (controlled by DFs)
What should the position of the heel be in at initial contact to activate the heel rocker?
90 degrees
Where are the GRFs at the ankle during midstance?
anterior to ankle, so PFs need to eccentrically control this dorsiflexion happening in midstance
What muscle fixes the first met, and when during gait is this important?
fib longus fixes first met during terminal stance to take advantage of the forefoot rocker
How much sagittal motion is needed at the 1st MTP during gait?
55 degrees: windlass effect must occur
How many degrees of hip flexion do we need in swing?
40 degrees
How many degrees of knee flexion do we need during the stance phase of gait?
20 degrees
When looking at midtarsal motion during gait, what are you looking for?
watch the arch fall or rise abnormally during gait cycle, this is the motion at the midtarsal joint
At what point after loading does recovery of the arch of the foot occur?
with heel rise, so during terminal stance
What motion of the tibia allows for the collapse of the arch? When in gait does this happen?
IR of tibia during loading to early midstance causes the arch to be lost
When during gait is the peak of eversion?
during early midstance
What is the position of the foot during swing?
dorsiflexed and inverted
If a patient has hallux rigidis, what would be compromised in their gait?
preswing is affected: no toe rocker for push off, so you lose momentum
What axes need to be parallel to allow pronation of the foot?
talonavicular and calcaneocuboid
Plantigrade is related to what phase of gait? What kind of support is it called?
midstance: foot flat support
T/F: Medial plantar surface is where weight should be loaded in flat foot support, or plantigrade.
false, should load on lateral side of foot
What muscles do foot inversion?
tib anterior, tib posterior, soleus
When does the tib posterior activity peak?
peaks in LS and mid terminal stance
When does soleus activity peak?
starts in loading, and then rises during midstance and terminal stance
Which is larger, inversion or eversion torque?
inversion is larger -> 20-45% of gait cycle
eversion = 0-20%
What muscles do eversion?
gastroc, fib longus and brevis, EDL, EHL
- activity ranges between LR and TS because they control supination and do pronation
What is the sequence of foot support?
heel -> lateral aspect of foot -> across forefoot -> to 1st met -> push off!
How much knee flexion do we need for swing phase versus stance phase?
need 60 degrees KF for swing, 20 for stance
Terminal stance consists of what percentage of gait?
31-50%`
Mid stance consists of what percentage of gait?
12-31%
In what plane does the knee have most motion?
sagittal = KF and KE
T/F: When limb is in stance, it’s in slight abduction.
true, physiological valgus
What provides shock absorption during gait?
20 deg knee flexion, abduction, plantar flexion
How does the external torque change at the knee as the limb moves forward?
GRFs go from being anterior to the knee to being posterior to the knee
With internal rotation, does this lock or unlock the knee?
IR unlocks the knee, gives knee flexion during loading to midstance
An internally rotated knee means what for the foot position?
foot is pronated
T/F: Knee is mostly in ER during stance.
false, mostly in IR during stance, knee isn’t locked
At what point during gait does the knee move from internal rotation to external rotation?
becomes ER at push off (preswing) to allow foot to be supinated and rigid
When we describe knee rotation, what are we specifically talking about in terms of bones?
rotation of tibia relative to femur
What thigh muscles kick in at IC to ensure knee extension?
vastus medialis and lateralis, gluteus max via IT band, rectus femoris; some slight hamstring activity to prevent hyperextension
What muscle works to counteract adduction during initial contact?
TFL; fires before glut med because it’s smaller
Describe the knee flexor activity throughout the gait cycle.
- eccentrically controls hyperextension during initial contact and then quiets down during midstance
- concentrically fires during preswing and swing phase to flex knee
- eccentrically controls KE during terminal swing also
What is the difference between the biceps femoris short head and long head? Which one activates first?
- short head only does knee flexion, long head does knee flexion and hip extension
- short head activates first for knee flexion
What knee muscle is active through virtually the entire gait cycle?
popliteus
What quad muscle is also active in toe-off while the others quiet down?
rectus femoris to allow hip flexion; other ones do knee extension, and you don’t have that in this phase, you have knee flexion
In initial contact, are the quads concentric or eccentric? What’s their purpose in this phase?
quads concentrically contract in initial contact to provide stable weight bearing
During loading, are the quads concentric or eccentric? What’s their purpose in this phase?
quads eccentrically contract during loading to control knee flexion to 20 degrees, giving shock absorption
When are the quads most active?
during initial contact through loading, then rectus femoris activates during toe off to give hip flexion for swing
How many degrees of total rotation do we get at the knee during gait?
8 degrees of total IR/ER
Describe the locking and unlocking of the knee during gait.
- IC to MS: knee is unlocking
- MS to PS: knee begins to lock for push off
- PS to midswing: knee begins unlocking for swing (b/c it’s in flexion)
- midswing to terminal swing: preparing for IC so it starts to go towards locking
What external moment, ab or adduction, is occuring to the leg in midstance?
adductor moment b/c the GRFs are medial to the knee; this is why TFL must kick in to prevent that
Where are the GRFs in terminal stance?
way anterior to ankle
run through knee
slightly posterior to hip
Maximal knee extension occurs in what phase?
- terminal stance, and then you move quickly into knee flexion and plantar flexion
- allows you to have maximal step length
What muscle slows down the passive knee flexion occuring in preswing?
rectus femoris: GRFs are very posterior to knee in preswing, so rectus femoris has to control that knee flexion
Where are the GRFs for the knee and ankle in preswing?
very anterior to ankle
very posterior to knee
T/F: Gastroc is very active in preswing.
false, only slightly active
- you don’t need it too much for PF due to passive recoil, and you don’t need it for KF too much due to passive KF occuring
What are the roles of rectus femoris?
eccentric control of knee flexion and hip extension
Forward free fall of the body occurs in what phase?
terminal stance
What critical events must happen in terminal stance?
use of forefoot rocker, controlled dorsiflexion by PFs, forward free fall of body with trailing limb
What critical events must occur in preswing?
toe rocker, passive knee flexion
What critical events must happen in initial swing?
knee flexion and hip flexion
Rectus femoris is especially active in what phase?
in preswing because it decelerates the passive knee flexion occuring
What allows for the knee flexion in initial swing?
forward momentum of thigh, biceps femoris short head, gracilis, and sartorius
Describe the sagittal motion of the knee during the entire gait cycle.
- IC = extended to allow stable weight bearing
- loading = flexed to allow shock absorption
- midstance = goes from flexed to extended
- terminal stance = extended
- preswing = passively flexed
- initial swing = flexion via thigh momentum and BFSH, gracilis, sartorius
- midswing = goes into passive knee extention via hip flexion
