Gait 2.1 (Oct 8th)

Requirements for successful walking?

• Efficiency

• Forward progression

• Stability

• Adaptability

• Shock absorption

Kinematics

Describes joint motion + position

Underlying forces eliminated

Features:

• 1 point on curve= position of joint @ specific time in cycle

• Direction of slope= joint movement direction

• Slope of curve= rate of movement (speed)

Kinetics

Forces acting on body

COM

Point @ centre of TOTAL BODY MASS

Mass distributed evenly in all directions [equal weight distributed in all directions]

• Under the belly button in anatomical position

COG

Point where effects of gravity are balanced

Primary COM displacement in gait

Forward progression path

When does walking start and stop?

Start: Forward momentum carries COM beyond BOS, fall prevented by take step

Stop: Foot placement stops forward momentum, balance over static BOS

COM Vertical displacement greatest/lowest when?

Sine wave

~5 cm displacement (depends on height)

Max: Mid single limb support (30%, 80%)

Min: mid double leg support (5%, 55%)

Is COM directly over BOS?

NO! It’s never.

Body goes over foot

COM side-side displacement greatest/lowest when?

Max: midpoint R single limb support 30%

Min: midpoint L single limb support 80%

1 full sine wave/cycle

Total displacement= ~4 cm

Do peak vertical & side-side displacement occur @ same time?

Yes

What happens to COM displacement w/ wider BOS gait?

More displacement side-side

Hip @ Heel Contact (0%)

Position: 30 deg flexion

Speed: Slow-no movement

Why: To initiate gait cycle

Hip @ 0-10% stance

Position: Hip still flexed

Speed: Slow movement

Why: Preparing for extension

Hip during double support (10-50%)

Position: Hip is going from flexion → neutral → extension

• Moving to extension

Speed: slow - medium

Why: To propel COM forward; body moving over foot

Hip @ 55% terminal stance

Position: Peak 10 deg extension

Speed: no movement/slow

Hip @ 60% push off

Position: hip extension (moving to neutral)

Speed: Fast to flexion

Why: swing, forward progression

Hip during 60-70% early swing

Position: Hip extended moving to flexion

Speed: fast

Why: bring leg forward for next step

Hip @ 85% late swing

Position: Hip flexion

Speed: slowing down

Why: prepare for heel contact, deceleration, bring leg forward for next step

Degree of peak hip flexion in gait + when?

35 degrees

Right be4 put foot down @ end of swing

Hip @ 100% of gait cycle [Heel contact]

Position: 30 deg flexion [extending]

Speed: slow

Why: Prepare for weight acceptance

Phases of gait

1. Heel contact

2. Foot flat

3. Stance: extending moving sorta fast

4. Mid stance

5. Terminal stance: PEAK hip extension

6. Push off

7. Toe off

8. Early swing

9. Late swing: peak hip flexion

10. Heel contact

Pathologic gait patterns are result of…

Effort to preserve walking fxn by adapting

Body wants to keep walking by finding a way to compensate

At a cost

• Overload joint

• Shortening already shortened mm

What should be included in gait observation

Joint + side?

Deviation?

When in gait cycle?

Does this follow a pattern? Why is this happening?

Antalgic gait

Limping after leg day

Avoid WB on painful leg

Shorter swing of good foot, ↓ rom, step length, stance time on painful side

Lateral Trunk Lean - general

• Due to pain [common in knee OA]

↓ knee loading, MORE horizontal displacement

• Lean towards painful leg in stance to remove stretch

• Modify load on knee by change COM location, change ground rxn force

Lateral Trunk lean components

a) Knee ADDUCTION moment

b) Toe out - shift CoP laterally to shorten lever arm

c) Lateral trunk lean - shift COM laterally to shorten lever arm

ALL TO OFFLOAD PAINFUL KNEE (smaller torque)

↓ ROM due to______ (deviation for normal kinematic pattern)

Less ROM due to…

• Mm tightness

• Contracture

• Abnormal joint structure

↓ strength due to______ (deviation for normal kinematic pattern)

Atrophy

Peripheral nerve injury

Deviation on 1 side of joint =

Compensation in 1+ surrounding joints

Compensation on OTHER SIDE

Underlying impairment

Problem in body fxn + structure

Significant deviation or loss

i.e. R knee flexion contracture

Primary gait deviation

Change from expected gait kinematics/kinetics due to impairment

i.e. Excessive knee flexion in R stance phase

Secondary Compensation

Change from expected gait kinematics/kinetics to adjust for primary deviations

i.e. L leg circumducted during swing