Biomechanical Analysis Midterm

what are the phases of gait in order?

Closed chain: muscles are working to stabalize

1. Initial contact

2. Loading response

3. Mid stance

4. Terminal stance

Open chain: muscles are working to swing the leg forward

1. Pre Swing

2. Initial Swing

3. Mid Swing

4. Terminal Swing

what is the initial contact phase of gait?

the instant the foot contacts the ground

what is the loading response phase of gait?

begins with foot contact and ends with contralateral limb toe off

what is the mid stance phase of gait?

begins with contralateral limb toe off and ends with ipsilateral heel rise

what is the terminal stance phase of gait?

begins with ipsilateral heel rise and ends with contralateral limb foot contact

what is the pre swing phase of gait?

begins with contralateral limb foot contact and ends with ipsilateral toe off

what is the initial swing phase of gait?

begins with ipsilateral toe off and ends when the medial malleoli are aligned

what is the mid swing phase of gait?

begins when the medial malleoli are aligned and ends when the ipsilateral tibia is perpendicular to the ground

what is the terminal swing phase of gait?

begins when the ipsilateral tibia is perpendicular to the ground and ends when the ipsilateral foot strikes the ground

what is the cyclical process of observational gait analysis?

1. Identify deviations

2. Develop hypotheses for probable causes that are informed by the patient (ICF)

3. Plan and perform the examination

4. Examination findings plus patient and family context informs treatment

5. Reevaluate—measure effectiveness of treatment

how can we identify deviations when observing gait?

• watch the individual in both the sagittal and frontal planes to have a more complete picture of the patient. movement in the transverse plane is inferred based on what you see in other planes

• use technology to help support what you observe and provide data that can’t be seen

what are primary deviations?

a deviation due to an impairment local to the area in question

ex: decreased DF during the swing phase due to stiff plantar flexors

what are secondary deviations?

due to an impairment that is at adjacent joint or further away

ex: excessive hip flexion during the swing phase to compensate for lack of DF

how can we develop a hypothesis using primary and secondary deviations?

we would want to assess/examine the areas where we see deviations. for ex, if we see decreased DF during the swing phase, we would assess the ankle and hip. if the hip has no impairments then we can assume it is a primary deviation like stiff plantar flexors.

how do we plan our examination of gait?

we have our examination priorities made up of red flags and SINNS, identifying deviations, and patient context

what are our objective and subjective gait measurements we can use to reevaluate gait?

subjective: observations— keep in mind there is bias in this

objective:

• walking speed

• 10 meter walk test (10MWT)

• timed up and go test (TUG)

• 6 minute walk test (6MWT)

• functional gait assessment (FGA)

what are the components that make up walking speed?

walking speed/velocity is the distance travelled during a specific period of time (m/sec or m/min). the components that make it up are…

• cadence: the number of steps taken during a specific time period (steps/min)

• stride length: the linear distance between 2 successive events on the same limb. so basically the distance between initial contact on the R limb until initial contact again on the R

the larger the stride length, the faster the gait speed

how do we calculate walking speed?

velocity= distance/time

cadence= steps/time

stride length= walking speed/ ½ cadence

what are the noermative values for the 10 meter walk test in individuals ages 20-59?

velocity: W 1.32 m/sec (79.3 m/min); M 1.36 m/sec (82.1 m/min)

cadence: W 121 steps/min; M 111 steps/min

stride length: W 1.32 m; M 1.48 m

what are the components of the 10 meter walk test?

1. instruct patient to walk at their normal walking speed begining at a point 2 meters before the intended start time

2. record the length of time it takes for the lead foot to cross the start line and finish line

3. repeat for a total of 3 times and average them up

what are the components of the timed up and go test?

1. patient is given one chance

2. patient may use any assistive device they normally use

3. on the word go patient stands up and walks 3 meters, turns around the cone, and walks back to the chair and sits back down

4. timer stops when the patients back is resting against the back of the chair

what are the components of the 6 minute walk test?

1. test should be done in an enclosed 30 meter walkway

2. give encouragment in standardized intervals like 30 sec or two minutes and record to maintain retest quality

3. participant should be told to walk at a comfortable pace

4. in patient with pulmonary or cardiac dysfunction, vital signs should be monitored at regular intervals to seem how the body responds

5. if they cannot walk 6 minutes, use the distance they ended at. they can also take breaks but the timer does not stop.

what is instrumented gait analysis?

the objective, quantitative measurement of human walking using specialized technology

what are the differences between instrumental gait analysis (IGA) and observational gait analysis (OGA)?

IGA

• quanitative

• objective

• reliant on technology

• high cost

• takes time to set up

• only in research or specialty clinics

IGA

• qualitative

• subjective

• may use technology to support such as filming someone

• low cost

• can be done quickly

• can be used in almost any clinic setting

what 3 categories of data collected make up instramental gait analysis?

temporal spatial, kinetics, kinematics

stance accounts for how much of the gait cycle?

just over half

swing accounts for how much of the gait cycle?

swing

the majority of the gait cycle is spend in what?

single leg support

what spatial characteristics can IGA tell us?

stride and step length

step width— wider in someone with impaired balance which leads to more frontal plane side to side movement

foot progression angle— when heel strikes the ground, do toes go out to the side, the middle, or stay with the angle of the heel

what are the main kinematic movements we could see using IGA?

translational movements (linear displacement)— COM

rotationanl movements (angular displacement)— joint angles

why is limiting COM displacement important?

more vertical and lateral displacement leads to less efficiencly, taking away the energy needed to move forward

discuss vertical displacement

• normal is around 5cm

• highest during mid-stance

• lowest during loading response and pre-swing

discuss lateral displacement

• normal lateral displacement is around 3.5cm

• maximum excursion during mid-stance

what are the types of rockers during gait?

heel rocker: occurs during initial contact through loading response

ankle rocker: occurs during stance phase when the body pivots over the talocrural joint

forefoot rocker: occurs during terminal stance when the body pivots over the MTP joints

toe rocker: fulcrum off great toe MTP joint

what are ground reaction forces?

the effect forces from the ground have on our body. they can predict an external moment which are the effect of the GRFs on our joint

what are external moments?

• calculated based on the position of the joints in space relative to the forces of ground reaction forces and acceleration of hte body limbs

• if our muscles did nothing, this is where our body would want to go