Transcript Chapter 12 Textbook Gait

Chapter 12
Fundamentals of Human Gait
Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc.
Gait Cycle
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Describes important events occurring between two
successive heel contacts of same limb
Gait cycle is described as occurring between 0% and
100% and includes stance phase and swing phase
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Stance Phase
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Heel contact
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Foot flat
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Lower limb contacts ground (0% of gait cycle)
Entire plantar aspect is on ground (8% of gait cycle)
Mid stance
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Body’s weight passes directly over supporting lower
extremity (30% of gait cycle)
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Stance Phase – cont’d
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Heel off
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Toe off
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Heel comes off ground (40% of gait cycle)
Toe leaves ground (60% of gait cycle)
Push off
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Describes combined actions of heel off and toe off, when
stance foot is literally “pushing off” toward next step
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Swing Phase
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Early swing
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Mid swing
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Period from toe off to mid swing (65% of gait cycle)
Period when foot of swing leg passes next to foot of stance
leg (75% of gait cycle)
Late swing
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Period from mid swing until heel contacts ground (85% of
gait cycle)
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Additional Terminology of Gait
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Stride
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Events that take place between successive heel contacts of
same foot
Stride length
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Distance traveled in one stride—two consecutive heel
contacts of same foot
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Additional Terminology of Gait – cont’d
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Step
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Step length
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Events occurring between successive heel contacts of
opposite feet
Distance traveled in one step
Step width
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Distance between heel centers of two consecutive foot
contacts
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Additional Terminology of Gait – cont’d
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Cadence
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Also called step rate, defined as number of steps
Walking velocity
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Speed at which an individual walks
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Stance Phase: Heel Contact
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Gait cycle beginning, when heel first contacts ground
Center of gravity of body is at its lowest point
Ankle is held in neutral dorsiflexion
Ankle transitions toward foot-flat stance and
dorsiflexor muscles are eccentrically activated to
lower ankle into plantar flexion
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Stance Phase: Heel Contact – cont’d
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Knee is slightly flexed, positioned to absorb shock of
initial weight bearing
Quadriceps are eccentrically active to allow a slight
“give” to flexed knee and help prevent knee from
buckling
Hip extensors are isometrically active to prevent trunk
from jackknifing forward
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Stance Phase: Foot Flat
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Point in which entire plantar surface of foot contacts
ground
Loading-response phase of gait
Muscles and joints of lower limb assist with shock
absorption, as lower extremity continues to accept
increasing amounts of body weight
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Stance Phase: Foot Flat – cont’d
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Ankle has just rapidly moved into 5-10 degrees of
plantar flexion
Knee continues to flex to about 15 degrees, acting as
a shock absorbing “spring”
Quadriceps continue to function eccentrically, and hip
extensors guide hip toward increasing extension
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Stance Phase: Mid Stance
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Occurs as leg approaches vertical position
Leg is in single-limb support, as other limb is freely
swinging forward
Dorsiflexor muscles are inactive; plantar flexor
muscles are eccentrically active, controlling rate at
which lower leg advances over foot
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Stance Phase: Mid Stance – cont’d
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Knee reaches near-fully extended position
Hip abductors play important role in stabilizing pelvis
in frontal plane, preventing opposite side of pelvis
from dropping excessively
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Stance Phase: Heel Off
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Occurs just after mid stance as lower leg and ankle
begin “pushing off,” continuing to propel body forward
Begins as heel breaks contact with ground
Plantar flexor muscles and Achilles tendon stretch in
preparation for propulsion
At heel off, plantar flexor muscles have switched their
activation from eccentric to concentric
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Stance Phase: Heel Off – cont’d
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Extended knee prepares to flex, usually driven by
short burst of activity from hamstring muscles
Hip continues to extend, ending in about 10 degrees
of extension
Eccentric activation of hip flexors, particularly
iliopsoas, helps control amount of hip extension that
occurs
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Stance Phase: Toe Off
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Final event of stance phase of gait
Toe off ends when toes break contact with ground
Toes are in marked hyperextension at
metatarsophalangeal joints, supported by activation
of intrinsic foot muscles
Ankle continues plantar flexing through concentric
activation of plantar flexor muscles
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Stance Phase: Toe Off – cont’d
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At toe off, knee is flexed 30 degrees, but hamstrings
are only minimally active
Most knee flexion arises as a result of inertia
produced, as hip is pulled into flexion
In final stage of toe off, hip is in nearly-neutral
position, with thigh nearly perpendicular to ground
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Swing Phase: Early Swing
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Leg begins to accelerate forward
Plantarflexed ankle begins to dorsiflex, clearing
ground as it is advanced forward
Knee continues to flex, and hip flexors continue to
contract, pulling extended thigh forward
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Swing Phase: Mid Swing
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Midpoint of swing phase
Contralateral leg is mid stance, supporting body
weight
Ankle is held in neutral position
Knee is flexed about 50-60 degrees, helping advance
lower limb
Hip approaches 35 degrees of flexion, continuing to
be pulled forward through concentric hip flexor
activation
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Swing Phase: Terminal Swing
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Limb begins to decelerate in preparation for heel
contact
Leg is placed well in front of body, preparing for
transition to accept body weight
Ankle dorsiflexors are activated isometrically,
positioning foot for heel contact
Knee has moved from flexed position of mid swing to
almost full extension
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Swing Phase: Terminal Swing – cont’d
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Hamstrings are active eccentrically at this time to
slow rapidly extending knee
Hip flexor muscles become inactive in terminal swing
Hip extensors decelerate forward leg progression leg
through eccentric activation
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Muscle and Joint Interactions
in Frontal Plane
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Abductor muscles play important role in frontal plane
hip stability
Without activation of hip abductors on stance leg,
opposite side of pelvis would drop under force of
gravity, known as positive Trendelenburg sign
Activation of stance leg’s hip abductors holds pelvis
level
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Muscle and Joint Interactions
in Frontal Plane – cont’d
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Strong medial and lateral collateral ligaments of knee
provide natural stability to knee in frontal plane
Loss of this stability may lead to issues such as genu
valgus, potentially altering normal gait mechanics
Instability of knee may arise from impairments at hip
or foot
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Muscle and Joint Interactions
in Frontal Plane – cont’d
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While walking, subtalar and transverse tarsal joints
cooperate to transform foot from pliable platform at
early stance to more rigid platform at late stance
Position of supination arranges bones of foot to their
most stable position, forming rigid lever for push-off
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Muscle and Joint Interactions
in Horizontal Plane
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Much of lower limb control within horizontal plane
during walking occurs at hip and foot
During walking, pelvis rotates in horizontal plane
about a vertical axis of rotation through hip joint of
stance leg
Because trunk remains relatively stationary during
walking, lumbar spine must rotate slightly to decouple rotating pelvis from thorax
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Foot Slap
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On heel strike, foot quickly drops into plantar flexion,
producing a slapping sound as forefoot impacts
ground
Impairment
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Weakness of dorsiflexors
May follow injury to common peroneal nerve or hemiplegia
Reason for deviation
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Inadequate strength in dorsiflexor muscles to slowly control
plantar flexion following heel contact
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High Stepping Gait
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Individual appears to be stepping over an imaginary
obstacle; initial foot contact is typically made with
forefoot or entire plantar surface of foot
Impairment
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Marked weakness of dorsiflexors—resulting in “foot drop”
Possibly following injury to common peroneal nerve or
hemiplegia
Reason for deviation
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In order to clear foot from ground, hip and knee must be
excessively flexed to advance leg
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Hip Circumduction
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Swing leg is advanced in semi-circle arc
Impairment
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Inability to “shorten” swing leg, possibly due to reduced
active or passive hip or knee flexion or as a result of wearing
a “straight-leg” brace at knee
Reason for deviation
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Circumduction creates extra clearance to advance
functionally “long leg”
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Hip Hiking
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Excessive elevation of pelvis on “swing” side
Impairment
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Inability to functionally “shorten” swing-leg
Possibly due to weak hip flexor muscles
Reason for deviation
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Elevating or “hiking” pelvis provides extra clearance for
advancing leg
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Weak Gluteus Maximus Gait
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Backward lean of trunk during foot-flat phase
Impairment
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Weakness of hip extensors—gluteus maximus
Reason for deviation
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Leaning backward during stance phase shifts body’s line of
gravity posterior to hip, reducing need for active hip
extension torque
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Walking with Hip
and/or Knee Flexion Contracture
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Flexed position of hip and knee during stance phase
of gait, often referred to as a “crouched gait”
Impairment
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Hip or knee flexion contracture
Reason for deviation
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Increased tightness in tissues that allow hip and knee
extension
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Weak Hip Abductor Gait
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During single-limb support, pelvis and trunk lean
excessively to same (uncompensated) or opposite
(compensated) side as weak hip abductor muscles
Impairment
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Weakness of hip abductor muscles
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Weak Hip Abductor Gait – cont’d
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Reason for deviation
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“Uncompensated” response: hip abductors of stance leg are
unable to produce enough force to hold pelvis level
“Compensated” response: purposely leaning trunk and pelvis
to same side as weak muscles shifts line of gravity closer to
stance hip
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Vaulting
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Individual rises up on toes of stance foot while
swinging contralateral leg forward
Impairment
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Any impairment of lower extremity that reduces ability to
functionally reduce length of limb
Reason for deviation
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Standing on tiptoes creates extra clearance for contralateral
leg to clear ground during swing
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Weak Quadriceps Gait
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Knee remains fully extended throughout stance,
combined with excessive forward lean of trunk
Impairment
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Weakness or avoidance of activation of quadriceps muscle
Reason for deviation
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Forward lean of trunk shifts line of gravity anterior to mediallateral axis of knee
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Genu Recurvatum
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Excessive hyperextension of knee during stance
phase of gait
Impairment
 A: Quadriceps and/or knee flexor paralysis
 B: Plantar flexion contracture
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Genu Recurvatum:
Reasons for Deviation
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A: Overstretched posterior capsule of knee and/or
paralysis of muscles that cross posterior side of knee
(hamstrings) fail to limit knee extension
B: Leg deviates posteriorly relative to ankle and
forces knee into hyperextension, eventually
overstretching posterior capsule
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Summary
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Gait training is vital component of physical therapy
Individual’s level of independence and length of stay
is often determined by ability to safely ambulate from
one place to another
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