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When should one do a gair assessment?

Enever you are looking and doing a Lower limb assessment, so then the gait is also part of the lower, no?

When you are doing LQ screen you must also be concerned of the gait, because, like we just did say, that it is also part of the LQ.

If a person is falling, that could really really be tied into their gait.

Amd if they habpve neurological issues that needs to be further looked at.


Normal parameters of gait are?

These are all issues of the dimensions that one is to travel physicaly through as they walk.
Base Width, how wide are their feet, x
Step length how far they step, z
Stride length same as step length, z
Lateral pelvic shift , how far thepelvis shifts, straifs to the right or to the left, X
Vertical pelvic shift, this is interesting, is it translational, or is it rotational, translational is just on the X axis and changing it Y, but rotation is changing both the X and Y
Pelvic rotation, here we say it out right at it is rotation, so it is on the Y axis and the x and z change
Normal cadence, how many steps are we to make in a minute, why is he fast, maybe he can not control it unless he is going fast like someone who does not have control in their ice skating so they just go fast, or why are they too slow, why can't they speed up, why are they shuffling.


Base width distance is?

Normal is 2 to 4 inches


Normal step length?

Distance between opposite feet

Normally 14 to 16 inches

Varies with age and height


Stride length?

Is the linear distance in the plane of
progression between successive points of foot to floor contact of the same foot

Normally 27.5 to 32.3 inches


Lateral pelvic shift.

As you walk, you shift your weight, it makes you strafe,

Is the side to side movement of the pelvis during gait

Normally 1 inch


Pelvic rotation

Necessary in order to lengthen the femur
!  Reduces amplitude of displacement
!  Total of 8 degrees of pelvic rotation
◦  4 degrees forward on the swing leg
◦  4 degrees backward on the stance leg
◦  Thorax rotates in the opposite direction for
If you have a higher swing leg rotation, it will make your lumbar
spine more painful.
If your pelvis is rotating the thorax is to counterrotate so that youstay sagittal.


Normal cadence?

Between 30-120 steps per minute

Normal walking speed 3-4 mph


Heel strike/FF

Has alot of forces coming down, and so we need to be able to be calm about it.

Shock absorption with stability


Job of MS?

Stability to allow contra LE to swing through Stable and tall, so that the other leg can travel through.


Job of HO/TO?

Prepare LE for swing phaseTo kick off

Here the heal is taking off and the toes, with a strong plantar flexion, will propel the leg forward, if this is weak, then we will require other compensatory motion to allow the leg to get from its point of origin to its desination.

Think if it now and see if it is what we shall say later..


Job of Acceleration to the Midswing?

Foot clearanceDon't drag the foot.


Job of Midswing to

Step length and foot positioning
To make sure that the foot is in the right place, not
crossing over, to put it back down on the correct place.

You do not want the leg to just go forward and make you fly forward, Thats how chuck norris flies, on his own momentum.



Allows for the smooth forward transition of the tibia on the ankle.


Why does the heel strike have it at pronation, at dorsiflexion, and why does the toe off, plantar flexion, have it at suppination?

At pronation it is softer to absorb shock and at suppination it is stiffer to launch.


At heel strike there is a _________ which needs the _________ to keep the ankle from __________?

Plantarflexion moment,
Just flopping down


At foot flat there is ____________ moment, and so we will need the ___________, so that the tibia will not ___________.

Plantarflexion moment,
Just flop on t


At midstance there is a __________ moment for the ankle, so we will require _________, to keep the tibia from falling ___________.

Dorsiflexion moment,


At the heal off there is a _________ moment,
So we will need the ___________,
to prevent ____________.

Dorsiflexion moment,
the tibia from falling forward.


At kick off there is also a dorsiflexion moment, so we will need the plantarflexors to prevent the tibia from falling forwards.



When the knee has a flexion moment what will you need to make knee from not buckling?

The quadroceps, the knee extensors.



These are the point of the knee undergo various moments, and at the flexion moments wew ill need to make use of the extensors, the quadroceps, to prevent the knee from buckling, and at the extensor moment there really isn't any need for the muscles, the quadroceps.



Heel strike,
Foot flat,
Heel off,
Kick off.

At all places that there is a flexion moment there will be a need to counter that fall forward, so you will need to make use of the hip extensors, the glut maxs, and
When there is an extension give, moment, then you need to counter that extension with the hip flexors, the iliopsoas.


First phase of swing?
Second phase of swing?
Last phase of swing?



At midstance what kind of rotation moment is there at the knee and ankle?

Internal rotation.


At the knee and ankle, during midstance, that there is a huge internal rotation moment, what will limit that internal rotation for botht he knee and ankle?

And once we have this counter force what does it give us?

Popliteus, the hamstrings are secondary and will tire with overuse.

The posterior tibialis, that does eversion, and so it also seems to be able to do external rotation.


Flexor'Synergy allows for?


Because the hip is up,
The knee is flexed,
And the ankle is dorsiflexed.




I guess that when we see the knee and the hip and ankle in extension it just becomes more stiff, more stable.


If you dorsiflex it will cause you to fall forward, and to counter this, you also flex your knee, to make the weight shift
backwards. And if you are stuck in plantarflexion so your weight is shifted to the back and to make the weight shift to thefront, it will extend the knee to shift forward or just because it actually directly causes knee extension.



You need to see where your weight is falling to and...

Counter that with shifting yourself in a position that will make it that the your new weight will be in a opposite direction of the previous moment.

Nothing new.


Lack'of'flexor'synergy?' What do you do to compensate?

You will go and circumvent your leg to gain clearance.



How will you compensate?

Using more muscles, if you have week extensor, you will leanforward, or you will go and use the other knee more.

So if you are falling into knee flexion but have weak quads, so you need that knee to go into extension, so you will lean forward to shift your GRF forward and force your knee into extension.


The plantar flexion will lessen the angle between the heel and the calfs, another way to lessen that angle is to do knee extension, so if the achilie's tendon is out, you will compensate with the quads.



How'can'we'compensate?''•  Ie'pt'can'not'df'during'swing'phase'

•  Compensa 2
If your foot is dragging in the saggital plane, you will circumvent the leg so that it will allow you to get to the end position, but it is using more energy, and you are also hitting things, and the sartorious, which does the hip flexion at external rotation, is not meant repeatedly keep to that motion, and so the sartorious will get tired.


How'can'we'compensate?''•  Ie'pt'can'not'df'during'swing'phase

•  Or'we'don’t'compensate'at'all'And you just drag your foot oryou buckle.


If you cannot do closed chain dorsi flexion, which is pronation, as we did say earlier that pronation at dorsiflexion is softer to be able to absorb the shock, you will go and pronate the ankle in another way. How?

You externaly rotate the hip, and you evert, and you pronate.


What is the heel whip?



Walk at ________ _________ to see if that affects gait

different speeds


Should observe _________, __________, _________ views

anterior, posterior and lateral


Observe _________ to __________ for open chain...

proximal to distal


Observe ________ to ________ for close chain...

distal to proximal


Gait Evaluation 1- Gross analysis

-Gross abnormalities


Gait Evaluation
2- General Qualities

-Stride length
-Step frequency
-Time of walking
-Speed of walking
-Duration of the complete walking cycle


Gait Evaluation
3- Specific analysis by joint



"  Ataxic Gait
"  Hemiplegic gait
"  Parksonian gait
"  Scissors gait
"  Steppage or drop foot gait

Are examples of?

Gross gait analomies.

There are fids of most on youtube.



#  “limping”

#  Due to pain, and the body is self protecting itself
#  The stance phase on the affected leg is shorter
due to remove the pain as quickly as possible

#  The swing phase of the uninvolved leg is
decreased. Why would this decrease? Maybe because you know that you will be stepping on a pained leg, and if the stride length is long then more pressure will be put on it at touch down, so you try to lessen the pressure on the involved leg by making sure that the stride length is short.

If you know of a more correct reason, please let me know.



#  Poor balance and a broad base, to not fall.
#  Cerebellar ataxia includes
!  A lurch or stagger
!  All the movements are exaggerated
!  Slapping of the ground
!  Irregular, jerky and weaving
#  Due to poor sensation or lack of musclecoordination

Parkisonism walk???



#  Swings the paraplegic leg outward and ahead in a circle (circumduction) or pushed ahead
#  The affected limb is carried across the trunk for balance

We spoke of circumvection before. It was used when there was weak flexor syngergies. It just sends the leg forward without having to bend the hip, knee, or ankle. So too here.



#  Neck, trunk and knee gaits are flexed
#  Characterized by shuffling or short rapid steps
#  Arms held stiffly and do not have their normal
associated movement
#  May lean forward and walk progressively faster as though they are unable to stop (Festination



#  The result of spastic paralysis of the hip adductor muscles, which causes the knee to drawn
together so that legs can swung forward only
with great effort
#  This is seen in spastic paraplegics and may be
referred to as a neurogenic or spastic gait



#  Pt has a weak df’s resulting in a drop foot
#  In order to avoid dragging the toes against theground
#  The pt lift the knee higher than normal


Second part of the gait analysis?

Once the first step of the gait analysis has been done, the GAP, the gait,a ssymetry, the posture, then the following is supposed to be done.
Then look for
◦  Stride length
◦  Step frequency
◦  Time of walking
◦  Speed of walking
◦  Duration of the complete walking cycle

Before was his beneral idea of looking at them in a general idea, the gait, the posture, the assymetry, they are very much reminiscent of functional level of assesment. The walking, the standing, the symmetry.

But now we are looking at the more specific breakdown of the walking. Its more basic elements.
The bos, how long is the stride length, cadence, and how long it takes to walk.


What ca pn affect step length?

!  Decreased DF of the contralateral wb LE
!  Decreased hip ext on contralateral LE

When my right leg is about to perform heel strike, it makes it that the counterlateral leg needs to be in dorsiflexion, so if it cannot do dorsiflexion, then, the stride length will be diminshed.

And if that leg cannot do extension, then the stride length will again be limited.


How much is a WBOS and what can cause it?

We said a NBOS is 4 inches, so anything wider than a 4" BOS is a WBOS.

And the way that you can get it is :
!  Abductor ms contracture, the abductors pull the person into valgus
Instability, you are unstable so you want to be stable so you walk wide
!  LLD, one leg is longer than another and to allow you to have both legs properly leveled a WBOS will ensue
!  Genu valgum- or just that the legs are wide
!  Fear, fear of falling, so a woder base of support to cause it to be more stable.
!  Cerebellar dysfunction, the person has ataxia of the cerebellum, so they are not smooth, they cannot do last minute moves, and so they will want something that is very stable so that they will not fall.


What would cause a NBOS?

Now it cannot be any real neurological issue of ataxia, because ataxia makes it less coordinateda nd a NBOS is to require more coordination. So it is due to something else.

!  Adductor ms contracture, the muscles bring the person into adduction
Genu varum, the bones are structure into varus.


So we see the functional part, the GAP, the Gait, Assymetry, the Posture, and then the specific details if the walking cycle, and now the third part of the gait annalysis will ask us to look at...

The specific joints.
Ankle, knee, hip, thorso, shoulders, neck.


What would cause a joint to have no flexion?

Either weak flexors, or tight extensors.


Why would you go into hyperextension?

Any reason that would extend the knee and taken to the next step.

Quads that are too tight.

Too tight plantarflexors.

Hip extensors that are too tight.

All of these will bring the knee into extension and if there is too much, Genu Recurvatum.


What frontal plane problems can the knee have?


Valgus and varus.

At valgus, the ankles are hyperpronated

And at varus the ankles are hyper supinated.

Now supination is good at toe off, that it is stiff.
And at heel strike the pronation is good, because it will be soft to allow the shock to be absorbed.


Gait problems at the hip sagital?

!  Excessive flexion, tight flexors, weak extensors
!  Limited flexion, tight extensors, weak flexors
!  Decreased extension, tight flexors, weak extensors
Steppage, to over come the foot drag


Gait problems at the hip frontal?

!  Circumduction
!  Hiking

Hiking is the same as steppage, you flex your hip more, to allow you to not have your other leg drag.


Gait problems at the pelvis sagital?

!  Anterior pelvic tilt
!  Posterior pelvic tilt
!  Increased backward
!  Increased forward rot
Limited backward rot
Limited forward rot

There is not enough or too much


Gait problems at the pelvis frontal?

!  Pelvic drop

Due to weak glut meds are the sode of the grounded leg, that if that glut med is weak that side will hike.


Gait dysfunction at the trunk sagital

!  Excessive trunk forward bending


Gait dysfunction at the trunk frontal

!  Excessive trunk lateral flexion


What is the main job of gait?

to move the body properly through space with the least amount of energy


what are the two major aspects of gait?

the weight-bearing is present at all times, but we have single leg stance and double leg stance. the single leg stance is the majority of the time. But we also want there to be safe control of the movement so that the person walking is not kicking his leg in front of him, nor is the walker not able to do it smoothly.


One gait cycle =

all the events that occur from the time of initial
ground contact of one extremity (heelstrike) to the time when that SAME extremity contacts the ground again. Ex: left HS to Left HS


What percentage of a gait cycle is that one leg i. stance and that same leg in swing phase?

60% in stance and 40% in swing.


In gait when do we have double leg stance?

twice, during the heel strike and the contralateral leg's heel off.


Double leg stance happens for what percentage of the entire gait cycle?

22% of the entire time, but it is 11% for each leg.


Two Sets of Terminology, what are they?

Traditional, and Ranchos Los Amgios


Difference between the RLA and the Traditional?

RLA is movement period, and tradition is a specific time period.

So Tradition has the heel strike as the exact time that there is strike of the heel on the floor and RLA can have it as the moments prior/during/after the heel strike.


Stance- (RLA terminology)
Phase 1: Initial Contact
The moment when the foot just touches the floor.
Phase 2: Loading Response
The double stance period beginning when the foot contacts the floor and continuing until the other foot is lifted for swing.
Phase 3: Mid Stance
The first half of the single limb support interval. It begins with the lifting of the back foot and continues until body weight is aligned over the supporting foot.
Phase 4: Terminal Stance
The body continues to move forward over the foot even further and this phase then begins when the heel rises and continues until the heel of the swing leg hits the ground.
Phase 5: Pre-Swing
The second double stance interval in the gait cycle. It begins with the initial contact of the swing foot and ends with toe-off of the stance leg.



Swing is divided into how many parts?



What are these three parts of the swing phase of gait?

Acceleration, once we’ve left the ground,
Midswing where the limb is directly
beneath the body, and
Deceleration where it passes in front of the body and the knee is extending for the
next HS.


SWING ( RLA terminology)

Phase 6: Initial Swing
Begins when the foot is lifted from the floor and ends when the swinging foot is opposite the stance foot.
Phase 7: Mid Swing
Continues from the end point of the initial swing and continues until the swinging limb is in front of the body and the tibia is vertical.
Phase 8: Terminal Swing
Begins when the tibia is vertical and ends when the foot touches thefloor.


At midstance, RLA, the tibia is in fact vertical, but the way that I did it I saw that I was having my tibia vertical, not directly when my swing leg is opposite my stance leg, but slight more anterior.



Stride length is ...

the linear distance between two
successive HS of the same extremity. It can be two
successive TO’s or anything else, but HS is the most common. So in one gait cycle, we have traveled one stride length.


Step length is ...

the linear distance form the point of HS ofone leg to the point of HS of the CONTRALATERAL leg. If the right and left step lengths are different lengths, we get an asymmetrical gait.


Width of the base of support is ...

the linear distance from the midpoint of one heel to the midpoint of the otherheel. Anywhere from 1 - 5 inches is WNL. Obviously wider bases are seen when we need more balance.


Stance time =

the amt of time elapsed during one stance phase


Single support time =

amt of time in single leg stance


Double support time =

is just what it sounds like! This time varies inversely with the speed of walking ie the slower we go the more double leg stance time, and as we get faster this gets smaller until it actually disappearswith running. And we get a new phase of zero limb
support. We see that horses at full gallop have moments that they are fully in the air.


Stride duration is ...

the time it takes to complete onestride, or one gait cycle. 1 - 2 seconds is typical.


Step duration is...

the amt of time to take go one step
length. (measured in seconds per step.) ex if we limp,one LE’s step length is a lot faster than the other.


Cadence is?

# of steps per minute. For men its approx 110 steps/min. (100 - 120)Women, ~116steps/min.(105 - 125) At ~180, we start to run. We said that stride duration is 1-2 seconds, so if we look at 60/2=30, so how do we get 120 steps per minute.


What amount of toe out is normal?

Up to seven degrees.


What is toe out?

you look at the direction that the foot is moving, and hopefully the foot is moving at the correct path directly in front of the person, but there are circumductions that take place, this will not have the leg going straight in front of the person. So if the leg is traveling straight in front of the person, you measure from the heel to the second toe and see if that line is within seven degrees of the the straight line in front.


What is the normal range of vertical dosplacement?

2 inches


Why is there vertical displacement?

Because when the stance leg gets straightened out from toe off to midstance, this all contributes to the added height, and when the stance leg is getting into extension during the terminal stance of the contralateral leg, or the heel strike of the contralateral leg, the body needs to drop down to allow the heel to hit the ground without needing to bend the knee as much, so there is extension of the swing leg, but the right stance leg drops down from the extension and perhaps from the knee bending, so we have stance leg hip extension and stance leg knee flexion and swing leg knee extension.


Pelvic rotation is utilized when?

to allow the swing leg to come in front without the body dropping to low, because if not for the pelvic rotation, to allow for heel strike/initial contact, the body would need to go lower.


Why is it that if the person cannot perform plantar/dorsiflexion properly they will carry out a more dramatic pelvic rotation?

I went and tried this, it seems that if there is a lack of dorsi/plantar flexion as when the person will wear an ankle/foot orthosis, they will attempt to go into heel off and toe off, but these require an amount of plantar flexion, and if plantar flexion is not had, then they will rotate their pelvis to be able to achieve that hip "extension".


How does one lower the COM of the body during a stride, besides knee flexion of the stance leg and knee extension of the swing leg?

The swing leg will have hip drop and the stance leg will have hip hike, but the focus is really in the swing leg's hip drop, to bring the foot closer to the ground, although this will shorten the stride length, but it will also lessen the shifts of the COM so that less energy consumption.


Determinants of Gait : knee

Physiologic valgus of the knee
Prevents COM from going too High.
AND prevents COM from displacing too far laterally.
Genu Varus would also allow the COM to not go too high, but will Varus not allow for lateral displacement?
Something about keeping the COM central is key.


During heel strike the foot is in dorsiflexion and it is everted, so it is pronated, this makes it softer and more able to take the shock.

Dorsi out, pronate.

at toe off, the foot is plantar flexed, inverted, which is suppinated, to become harder to allow for a better transmission of energy.

Plant in, suppinate.




Lower limb is orthosis and upper limb is a
brace, but the names are interchangeable.





TLSO'Thoraco lumabo sacral'Orthosis




!  Aluminum'
!  Plastic'
!  steel'components''Steel is not used alot.
Common for people who have polio.



the goal of the orthosis.


!  Assist'movement'(Semiflexible,'Springs)'!  Cushion'(Flexible)'
!  Properties'of'the'materials'




!  Polyethylene'foams'! 
Pelite, lite, they are squishy
!  Plastazote, like plastic
!  PPT',
!  Spenco, like spandex


Function)of)the)Materials), the foams

!  Absorbs'pressure'
!  HeatMmoldable'(not'PPT)'
! Rebounds'to'former'shape'under'intermittent'loading'conditions'



!  High'temperature'thermoplastic'polymers'
!  Polypropylene'*******
!  Closer'fit'
!  lightweight'
!  Resins'combine two different materials to make it hard.
!  Metals'
!  Steel'Uprights'Joints'
!  Longevity'and'fatigue'resistance'(especially'
!  Heat'moldable'and'rebound'
!  aluminum'alloys'
!  carbon'fiber'composites'
can custom make them, but it become very expensive.



)!  Leather'
!  Cork'
!  Thinned'rigid'materials'!  Cork'with'latex'for'
heat moldable'matieral'
!  Thinned'polypropylene'and'carbon'composites'

we had said earlier that polypropylene was rigid, but here it is thinned, so it is semirigid, it is somewhat more malleable.


COMPONENTS of orthosis

!  Foot'plate'MM'Shoes'!  Joints'
!  Locks'
!  Assists'and'Stops'
!  Uprights'
!  Shells'
!  Straps'
!  Other'



!  Shoes'
!  Stirrups'
!  Full'length'
!  Heel'M'toe'
!  ¾'Length'
!  proximal'to'
!  Sulcus'length'
!  distal'to'metatarsals'



Hinge'and'multiMaxial'!  Offset'



! Ring'with'retention'button'! Bail'Lock'(Swiss'lock)''
! Spring'loaded'
! Offset'Joint'
! Adjustable'
!  Limited'motion'






!  Used'to'control'excessive'knee'flexion'
! Drop'lock'with'an'attached'ring'located'midMthigh'
!  This'lock'us'used'when'a'









!  Locks'in'one'place'Or'in'a'range'of'motion



Leaf'springs'(DF'assist)'! Coil'(metal)'spring'(DF'assist,'KE/HE'assist)'



!  Adjustable'stop'
!  BiCAAL:'BiChannel'
Adjustable'Ankle'Locks'!  Posterior'Stop'
!  Overlap'joint'(PF'stop)'
!  Strap'(DF'stop)'



!  BiCAAL:'BiChannel'Adjustable'Ankle'Locks'!  aka:'Double'action'ankle'joint'
!  aka:'Double'Klenzak'joint'
!  Anterior/Posterior'channel'
!  Can'add'springs'for'motion'assist'



degrees'of'plantarflexion'!  Can'be'posterior'pin,'



!  PF'stop'
!  Orthosis'must'be'



•  DF'stop'
•  Independent'of'ankle'joint.'
•  Adjustable'



!  One'plane'of'control'
!  Medial'&'Lateral'
(extremities'and'trunk)'!  Anterior'&'Posterior'



!  Shells'(plastic)'
!  MultiMplane'of'control'! 



!  Typically'Velcro'or'Leather'
!  Attach'orthosis'to'limb''
!  Links'components'(uprights)'
!  Can'provide'suspension'


3 Point Pressure System, so how is it realted to Orthotics?

lets say we are looking at a knee, where, and how many points, and what direction on this knee, and its leg area, are we supposed to place pressure to achieve knee extension?

The patella needs to go posterior, while the tibia and femur go anterior.

So that is it, the one point will push the patella area posterior and the other two points will push the tibia and the femur anterior.


3 point system for the thoracic.

you want the upper chest to go posterior and the lower back to go anterior and the pubic area to go posterior, all of this bringing the person from kyphosis into neutral and also there is the point of bringing about more lordosis in the lower spine.


If the individual is in need to promote inversion since their foot is going more into eversion, besides the Richie brace, that it cups the heel, where will the three point pressure system need to be?

so we want inversion, we want the lateral distal side of the foot to go medial, we want the ankle to go lateral, and we want the tibia to go medial, because we want the distance to become less between the medial aspect of the tibia and the lateral aspect of the foot.


Three point positioning for eversion.

because we want the lateral aspect of the tibia to come closer to the lateral aspect of the foot, so there needs to be lateral pressure on the tibia, and lateral pressure on the medial aspect of the foot, and also medial pressure on the area of the ankle that is where the malleolli are. This will promote ankle eversion


At heel strike, not after, where is the GRF for the Hip for the knee and for the ankle?

Anterior, anterior, posterior


If the GRF is anterior to the Hip, knee, ankle, or posterior to the hip, knee, ankle, how ill it move the joint?

Hip: flexion give, needs hip extensor to maintain position.
Knee: extension give, but usually this is very stable.
Ankle: dorsiflexion, so they will need the plantar flexors to not move the tibia over the ankle.


Hip: hip extension give, will need the hip flexors to maintain
Knee: knee flexion give, will need the quadriceps to maintain the extension and not allow the knee to buckle
Ankle: plantar flexion give, so dorsiflexors will need to be active so that there will not be a foot flat.


Why at foot flat does the GRF move to the back of the knee?

Because we are basically in the same position as that of the heel strike, but now the knee flexes, and so the GRF also moves to the posterior of the knee, which further causes the knee to flex, which now we are in a strong need to make use of the quadriceps to prevent the knee from buckling.


Why is midstance to have the ankle GRF anterior and the hip posterior?

Lets look at the midstance from the perspective of the heel strike.
Now midatance looks just like heel strike but with some few alterations.

The ankle is more dorsiflexed, so that will have the line brought anterior and the hip is taken from flexion to more neutral, this will push it posterior.

Ankle was neutral and was at the posterior then it changed to DF and it became anterior.

The hip was at flexion and anterior and now the hip became more neutral so the GRF became posterior.

And at heel strike the GRF for the knee was anterior when the angle of the knee was neutral, but when the knee flexed it became posterior, and when the knee again came closer to neutral, the GRF of the knee came anterior again.


Why is it that at heel off the GRF of the ankle is anterior even though until now the GRF of the ankle at neutral, like by heel strike and at midstance, not by foot flat, since by foot flat the ankle is at PF, was posterior, and this heel off's GRF is at the anterior, which does make it harder to push off, because the ankle wants to pull more into DF but the person needs to PF?

because they are so moved forward, that most of their HAT is anterior, so it shifts the COG anteriorly, and shifting the COG anteriorly will shift the LOG anteriorly, and shifting the LOG anteriorly will bring the GRF of the ankle anteriorly, even though at heel off the angle of the ankle os at neutral.


What will happen to the knee if the ankle is at zero during the loading response, foot flat?

because at the loading response the ankle wishes to go into PF but cannot since the orthosis is blocking it, so to be able to get the entire foot flat, because the foot will and it will become flat, so the tibia will move forward as well, and if the tibia is moving forward and the femur is not moving forward, this is in fact what sheering is. So to prevent the forward movement of the tibia, the ACL will consistently be called into play, and if that ligament is consistently being called into play, then it will be damaged.


Ankle zero degrees and now at midstance, what will happen?

At midstance the foot is at zero, so since the AFO causes the ankle to be at zero, then there not be any issue to be of concern.


At midstance to heel off, what is the issue if the AFO causes the ankle to be stuck at zero?

because during this phase the ankle wishes to go into dorsiflexion but the AFO does not allow it, so the foot will be stuck at zero and it will cause the knee to hyper extend. And hyperextension of the knee will bear pressure on the PCL, because the tibia is sheering posteriorly and the job of the PCL is to limit posterior sheer of the tibia.


What will happen at heel strike if the ankle is stuck at 5 degrees of PF?

At the heel strike we want the heel to be at zero, but our scenario the heel is at 5 degrees of PF. If at 5 degrees the heel is still more distal than the toes, so the person will just go and heel strike. But if at 5 degrees of PF the person is not able to get their heel to hit the floor without the toes touching the floor, so then, they must get their heel in the floor and to do that they will increase their stride length, and if their stride length is long enough, then the knee will be in hyper extension and hyperextension is a cause for PCL sprain.


If the person is stuck at 5 degrees of PF what will happen at their knee from the heel strike to the loading phase?

So now that they somehow got their heel on the floor, either because it touched or because they hyperextended their knee, depending on the point that I made earlier, so now their ankle wants to come into further PF here at the loading phase, but the AFO does not allow it, so now it will be the same as when the ankle was stuck at 0, but now the tibia is more posterior than when the ankle was at zero, so there is no need for the tibia to come anterior as much as it had when the ankle was stuck at zero degrees, so the tibia will move forward, albeit not as much as when the ankle was stuck at zero, and the knee will flex, albeit not as much as when the ankle was stuck at zero, but to prevent this anterior sheer of the tibia the ACL will be called into play, consistently, and it will cause damage.


5 degrees of of and now going from loading phase to Midstance, how ill the kinematics be affected?

So we are at the loading response phase and the entire foot is flat on the floor, since this is what must happen at this stage, and it will happen with knee flexion and increased ACL sheer, so now we are at the foot flat, and we want to bring the ankle into DF, but the orthosis will not allow us to come into the desired position of the ankle, which is our zero degrees of ankle for the midstance. Earlier we said that if the ankle is stuck at zero, this should not cause a problem for the midstance, but it would cause a problem for the heel off, which that is something which we hope to tackle next.
So to get into the zero degrees, which is further DF, and we cannot, the femur will come forward, this will cause the knee to go into further hyper extension and it will cause the PCL to be damaged.


We are at midstance and which to get into heel off but the AFO is restraining us at 5 degrees of PF, how will this affect the kinematics of the knee?

So from midstance of a 5 degree PF we have a hyper extension of the knee to allow for the femur to come up over the ankle.
And now we want further, even more movement into DF, but the AFO does not allow.

So it will cause even more knee hyperextension, and this will place even more stress in the PCL.