Ch 6 - Prosthetics and Orthotics: Gait Analysis Flashcards
What is stride length?
Distance b/w corresponding successive points of contact of the same foot (distance b/w heel strike to heel strike of same foot)
What is step length?
Linear distance in plane of progression between successive contact points of opposite feet (distance b/w heel strike of one foot with heel strike of opposite foot)
Two phases of the gait cycle and what percentage with normal walking speed is the distribution of time in each one?
Stance phase and swing phase
60% stance, 40% swing
Walking faster dec time in stance
What is the stance phase?
Time period limb is in contact with the ground
What are the subdivisions of stance phase?
"I Like My Tea Presweetened" Initial contact Loading Response Midstance Terminal Stance Preswing
Describe Initial Contact (heel foot strike).
Instant foot contacts ground
Describe Loading Response (foot flat).
Initial contact to lifting of contralateral limb off the ground
Weight shift occurs
Describe Midstance.
Lift of contralateral limb from ground to point where ankles are aligned in frontal (coronal) plane
Describe Terminal stance (heel off).
Ankle alignment in frontal plane to just before initial contact of contralateral (the swinging) limb
Describe Preswing (toe off).
Initial contact of contralateral limb to just prior to ipsilateral limb lifting from ground (unload weight)
When does double-limb support occur?
Beginning and end of stance phase when both feet are in contact with the floor
Describe double-limb support as walking speed increases.
Time in double-limb decreases with increased speed.
No double-limbs support period is considered running
When does single-limb support occur?
When opposite foot is lifted for swing phase
What % of time in a normal gait cycle is spent in single-limb vs double-limb support?
Single-limb: 80%
Double-limb: 20%
What is cadence?
Number of steps per unit of time
Comfortable walking speed = 80 m/min or 3 mph
How is walking speed slowed?
Reducing the cadence or by decreasing step or stride length
Where is Center of gravity (COG) located?
5 cm anterior to the S2 vertebra
How does Center of gravity (COG) change during normal gait?
Displaced 5 cm (less than 2 inches) horizontally and 5 cm vertically during an average adult
male step
When is Center of gravity (COG) lowest?
During loading response
When is Center of gravity (COG) highest?
During midstance
Describe base of support.
Space outlined by the feet and any assistive device in contact with the ground
Normal base of support (distance between heels) = 6 to 10 cm
How is falling avoided?
COG remains positioned over the base of support
What is swing phase?
Time period foot is in air for limb advancement
Describe the subdivisions of swing phase.
“In My Teapot”
Initial Swing
Midswing
Terminal Swing
Describe initial swing.
Lift of the extremity from the ground to position of maximum knee flexion
Describe midswing.
Immediately following knee flexion to vertical tibia position
Describe terminal swing.
Following vertical tibia position to just prior to initial contact
What are the determinants of gait?
- Pelvic rotation
- Pelvic tilt
- Knee flexion in stance phase
- Foot mechanisms
- Knee mechanisms
- Lateral displacement of the pelvis
What do the determinants of gait help to control?
Minimize the excursion of the body’s COG
and help produce forward progression with the least expenditure of energy
What is Trendelenburg Gait?
Hip abductor muscles (gluteus medius and minimus) are weak, the stabilizing effect of these muscles during gait is lost
Describe an uncompensated Trendelenburg gait.
Contralateral pelvis drops because the ipsilateral hip abductors do not stabilize the pelvis to prevent the drop
Describe a compensated Trendelenburg gait.
Patient exhibits an excessive lateral lean in which the
trunk is thrust laterally to keep the COG over the stance leg
Describe function of pelvic rotation in determinants of gait.
Pelvis rotates medially (anteriorly) on the swinging leg side, lengthening the limb as it prepares to accept weight
What does a 4° pelvic
rotation in either direction during double support cause?
Limbs are essentially
lengthened in the would-be lowest point of the gait cycle (preventing a
sudden drop of the COG)
Describe function of pelvic tilt in determinants of gait.
Pelvis on the side of the swinging leg is lowered 4°–5°
This lowers the COG at midstance
Describe function of knee flexion instance in determinants of gait.
Reduces vertical elevation
Lowers COG
Dec energy expenditure
Absorbs shock impact at heel strike by lengthening quad contraction
Describe function of foot mechanisms in determinants of gait.
At heel strike, ankle plantar-flexion smoothes the curve of the falling pelvis
Describe function of knee mechanisms in determinants of gait.
After midstance, the knee extends as the ankle plantar flexes and the foot
supinates to restore the length to the leg and diminish the fall of the pelvis at opposite heel strike
Describe function of lateral displacement of the pelvis in determinants of gait.
Displacement toward the stance limb so net COG of the body lies above the base of support (the stance foot)
Describe muscles that should be strengthened in crutch walking.
– Latissimus dorsi – Triceps – Pectoralis major – Quads – Hip extensors – Hip abductors
Which muscles are active during initial contact?
Glut max Glut medius Hamstrings Quadriceps Pretibial muscles *All eccentric
Which muscles are active during loading response?
Glut medius Hamstrings Quadriceps Pretibial muscles *All eccentric
Which muscles are active during midstance?
Glut medius
Calf muscles
*All eccentric
Which muscles are active during terminal stance?
Eccentric: Glut medius
Concentric: Iliopsoas, Calf muscles
Which muscles are active during preswing?
Eccentric: quadriceps
Concentric: Iliopsoas, Calf muscles
Which muscles are active during initial swing?
Eccentric: hamtrings, quadriceps
Concentric: Iliopsoas, pretibial muscles
Which muscles are active during midswing?
Eccentric: hamtrings
Concentric: Iliopsoas, pretibial muscles
Which muscles are active during terminal swing?
Eccentric: hamtrings
Concentric: pretibial muscles
What are causes of foot slap during initial contact?
Moderately weak dorsiflexors (grade 3/5)
What can cause gait pathology during initial contact through midstance?
– Genu recurvatum – Excessive foot supination – Excessive trunk extension – Excessive trunk flexion
What can cause gait pathology during initial contact through preswing?
– Excessive knee flexion – Excessive medial femur rotation – Excessive lateral femur rotation – Wide base of support – Narrow base of support
What can cause gait pathology during loading response through preswing?
– Excessive trunk lateral flexion (compensated Trendelenburg gait)
– Pelvic drop (uncompensated Trendelenburg gait)
– Waddling gait
What causes Excessive trunk lateral flexion (compensated
Trendelenburg gait)?
Ipsilateral gluteus medius weakness
Hip pain
What can cause gait pathology during midstance through preswing?
– Excessive foot pronation – Bouncing or exaggerated – Insufficient push-off – Inadequate hip extension
What can cause gait pathology during swing phase?
– Steppage gait/foot drop
– Circumduction
– Hip hiking
What is the increased metabolic cost above normal ambulation for a Syme’s amputation?
15%
What is the increased metabolic cost above normal ambulation for a Traumatic TT BKA?
25%
(Short BKA—40%
Long BKA—10%)
What is the increased metabolic cost above normal ambulation for a Traumatic Bilateral BKA?
41%
What is the increased metabolic cost above normal ambulation for a Traumatic TF AKA?
60% to 70%
What is the increased metabolic cost above normal ambulation for a Traumatic Bilateral AKA?
> 200%
What is the increased metabolic cost above normal ambulation for a Traumatic BKA and AKA?
118% net cost
What is the increased metabolic cost above normal ambulation for a Vascular TF BKA?
40%
What is the increased metabolic cost above normal ambulation for a Vascular TF AKA?
100%
