ICL 6.2: Gait Mechanics Flashcards
define gait
the translatory progression of the body as a whole, produced by coordinated, rotary movements of body segments
what are the characteristics of normal gait?
- rhythmic, smooth; not choppy
2. characterized by alternating propulsive and retropulsive motions of the lower extremities
define gait cycle
typically recorded from the time ONE foot strikes the ground until that episode recurs and starts the next, repeating cycle
define stride
segment of distance the body traverses during the gait cycle
so right foot to right foot
define a step
each stride is made of one step by each foot
normally symmetrical in length
right foot to left foot hitting the ground
define cadence
frequency of stepping = steps/minute
define speed
cadence x step length
define stride length
the linear distance from the heel strike of one lower limb to the next heel strike of the same limb
define step length
the linear distance from the heel strike of one lower limb to the next heel strike of the other limb
what is the degree of toe out?
the angle of foot formed by each foot’s line of progression and a line intersecting the center of the heel and the 2nd toe
this decreases as the speed of walking increases in normal adults
what percent of your gait cycle is stance vs. swing phase?
stance = 60%
swing = 40%
what are the two types of variables of gait?
- temporal
stance time, single-limb and double-support time, swing time, stride and step time, cadence, speed
- distance
stride length, step length and width, degree of toe-out
what is the stance phase?
the time period during which limb is in contact with ground
60% of the gait cycle
what is the swing phase?
the time period during which the SAME foot is in the air for limb advancement
40% of the gait cycle
what is single-limb support?
the time period when the opposite foot is lifted for swing phase
it’s the amount of time spent during double-limb support decreases as speed of walking increases
80% of the normal gait cycle
what is double-limb support?
it’s the time period during which both feet are in contact with the floor
both the beginning and the end of the stance phase are considered to be double=support period
20% of the normal gait cycle
what happens to double-limb support during running?
it decreases
what are the traditional stages of the gait cycle?
- Heel Strike
- Foot Flat
- Mid-stance
- Heel off
- Toe off
- Acceleration
- Mid-swing
- Deceleration
what are the new stages of the gait cycle?
- Initial Contact
- Loading Response
- Mid-stance
- Terminal Stance
- Pre-swing
- Initial swing
- Mid-swing
- Terminal swing
what is the first phase of the stance phase?
initial contact/heel strike
this phase begins with initial contact and ends with foot flat
it’s the beginning of stance phase when heel contacts the ground
what is the second phase of the stance phase?
loading response/foot flat
it’s the time period from immediately following initial contact up until contralateral extremity lifted from the ground
weight shift occurs! your foot is completely flat on the ground and you start to shift your weight onto that foot
during which phase of the gait cycle is your center of gravity the lowest?
loading response/foot flat
your foot is completely flat on the ground and you start to shift your weight onto that foot
what is the third phase of the stance phase?
midstance
it’s the time period from lift of contralateral extremity from ground to the point where ankles of both extremities are aligned in frontal plan
your body is directly over the supporting limb
during which phase of the gait cycle is your center of gravity the highest?
midstance
it’s the time period from lift of contralateral extremity from ground to the point where ankles of both extremities are aligned in frontal plane
what is the 4th phase of the stance phase?
terminal stance/heel off
it’s the period from ankle alignment in the frontal plane to just prior to initial contact of the contralateral (swinging) extremity
you’re starting to unload the weight from the foot and this is right before your toe come off the ground
what is the 5th phase of the stance phase?
pre-swing/toe-off
it’s the time interval from initial contact of the contralateral extremity to just prior to lift of the ipsilateral extremity from the ground (unloading weight)
what’s the pneumonic for the phases of the gait cycle?
I like the my tea pre-sweetened in my teapot
- initial contact
- loading response
- midstance
- terminal stance
- pre-swing
- initial swing
- mid-swing
- terminal swing
what is the first step of the swing phase?
initial swing/acceleration phase
lift of the extremity from the ground to position of maximum knee flexion
begins once toe leaves the ground and continues to point at which swinging extremity is directly under the body
what is the second step of the swing phase?
mid-swing
immediately following knee flexion to vertical tibia position
what is the third step of the swing phase?
terminal swing/deceleration
it’s following vertical tibia position to just prior to initial contact
the limb is decelerating in preparation of heel strike
where is your center of gravity?
5 cm anterior to your S1 vertebrae
L4 is at your iliac crest where your hip are so move down a little and you’ll find S1
normally your COG runs anterior to the ankle. through the knee joint, and posterior to the hip join
what are the 6 determinants of gait?
- rotation of pelvis
- pelvic list
- knee flexion
- lateral displacement of pelvis
- foot mechanisms
- knee mechanisms
these all combined together are used to minimize COG movement in vertical and horizontal planes – these are all adjustments made by the pelvis, hips, knees and ankles to reduce energy expenditure and make your gait more efficient
how is the rotation of the pelvis a determinant of gait?
during each step, pelvis rotates forward on side of swinging limb –> your limb also lengthens as it prepares to accept the weight of your body
so your hip rotates in horizontal plane to decrease vertical distance travelled and prevent a sudden drop in COG
this is your pelvis moving forwards and backwards
how is pelvis list a determinant of gait?
pelvis list = trendelenburg motion = virtical displacement
aka pelvis tilt –> your pelvis drops a few degrees on the non-weight bearing side when you walk so the hip of a limb in swing phase is lower than the limb in stance phase
the path is extremely smooth sinusoidal curve
how is knee flexion in stance phase a determinant of gait?
it’s a shock absorbing mechanism at beginning of stance at foot strike (15 degrees)
it helps maintain momentum and reduces energy lost to stopping and re-starting the gait cycle
it also reduces the height of hip joint in med-stance
how is lateral displacement of the pelvis a determinant of gait?
aka swaying of the hips –> the pelvis and trunk move to stance side to balance the COM of the trunk above the stance foot
as you walk faster you have less lateral displacement of the pelvis
walking base is narrowed by natural valgus of the knee and shift in the body’s position over the stance limb allowing for reducing the lateral displacement of the pelvis during the gait cycle and reduction of horizontal curve as well
how are foot mechanisms determinants of gait?
rolling-like mechanisms of the foot during stance phase preserves momentum
controlled plantar flexion smoothens the curve of the falling pelvis
how are knee mechanisms a determinant of gait?
after midstance, the knee extends as ankle plantar flexes
the foot supinates to restore the length to the leg and diminish the fall of the pelvis at opposite heel strike
all of the following adjust the center of gravity in the vertical place except:
A. pelvis rotation
B. pelvis list
C. knee flexion in stance phase
D. pelvis lateral displacement
E. foot mechanics
F. knee and ankle mechanics
D. pelvis lateral displacement
what are some of the causes of abnormal gait?
- pain
- neurological disturbance
ex. muscle paralysis, cerebellar dysfunction, kinetic dysfunction and basal ganglia dysfunction
what is antalgic gait?
it’s a compensatory gait pattern secondary to pain –> it’s done to remove or diminish discomfort caused by pain in the lower limb or pelvis
characteristics:
- decreased duration of stance of affected limb
- lack of weight shift laterally over the stance limb
- decrease stance phase in affected limb will result in decrease swing phase of unaffected limb
what is hemiplegic gait?
- patient usually stands with unilateral weakness on the affected side
their arm will be flexed, adducted and internally rotated –> the leg on the same side is in extension with plantar flexion of the foot and toes
- when walking the patient will hold arm to one side and no reciprocal arm swing
they will then drag the affected leg in a semicircle because there’s weakness of distal muscles = foot drop
with mild hemiparesis, loss of normal arm swing and slight circumduction may be the only abnormalities
so like a lot of times, stroke patients toes are plantar-flexed and they will swing their legs out of hike their hip up to try and compensate so their toes don’t drag
what is diplegic gait?
the patient walks with an abnormally narrow base, dragging both legs and scaling the toes
it’s seen in some forms of cerebral palsy
it’s usually due to extreme rightness of hip adductors which can cause legs to cross the midline
a lot of them have increased lumbar lordosis to try and compensate and not fall forward
scissoring gait and diplegia gait are basically synonymous
what is steppage gait?
seen in patients with foot drop
the patients attempt to lift the leg high enough during walking so that the foot does not drag on the floor
ex. slapping gait
ex. drop foot gait
how does steppage gait and and hip-hike differentiate?
during steppage gait, the patient can flex their knee while in hip-hike they can’t
what is the Trendelenberg gait?
the individual shifts trunk over the affected side during stance phase
this is a pelvis listing problem!!
gluteus medius weakness causes the pelvis on the contralateral side to drop because the ipsilateral hip abductors do not stabilize the pelvis to prevent the drop
during compensated trendelenberg gait, the patient will swing their body over the affected side to compensate for the contralateral drop and to keep their COG over the stance leg
what is the gluteus maximus gait?
aka extensor lurch or rocking horse gait
their extensor muscle is very weak and they don’t want to fall forward so instead they throw themselves back and hip thrust because their gluteus maximus muscle isn’t extending his leg for him
what is the quadriceps gait?
if you have weak quads your knees will buckle while walking
so lots of times the patients will put their hand on their thigh and push while walking to compensate for weak quads
what is genuflects recurvatum gait?
hamstring weakness
so during stance phase the knee will go into excessive hyperextension (EXCESSIVE)
during swing phase without your hamstring to slow down the swing forward of the lower leg and will snap into extension
what is parkinsonian gait?
parkinson’s patients are right so they have a hard time moving and are slow; lots of them just get stuck and can’t move forward especially with floor changes
they tend to lean forward when walking but we think it’s because they have bad balance and lean backwards which is why they lean forward to try and compensate
overall, their head is stooped and neck is forward and their knees are flexed but fingers are usually extended
what is marche a petits pas?
walk of little steps associated with parkinson’s gait
it’s shuffling gait to keep their COG stable
what is festination?
accelerating steps associated with parkinson’s gait
there’s a loss of voluntary control over movement and a loss of balance that causes them to walk faster as if they’re chasing their COG
what is ataxic gait?
described as clumsy, staggering movements with a wide-based gait
while standing still, the patient’s body may swagger back and forth and from side to side, known as TITUBATION
not able to walk from heel to toe or in a straight line - like a drunk person!
gait of acute alcohol intoxication will resemble the gait of cerebellar disease
what is sensory gait?
as your feet touch the ground, propioreceptive information to the brain will tell you their location normally but with sensory ataxic gait, there is loss of proprioreceptive input so the patient will purposely stomp their feet so they can tell where it is
a key to this gait involves its exacerbation when patients cannot see their feet (i.e. in the dark)
in its severe form, can cause an ataxia resembling cerebellar ataxic gait
what commonly causes sensory gait?
- dorsal columns disorders (B12 deficiency or tabes dorsalis)
- diseases affecting the peripheral nerves (uncontrolled diabetes)
what is the ground reactive force?
ground reactive force is a line drawn from the ground up to the center of gravity
it is important for determining flexion or extension moments at the joints
