Chapter 13
Gait and posture analysis
Overview
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It is not clear whether gait is learned
or is pre-programmed at the spinal
cord level. However, once mastered,
gait allows us to move around our
environment in an efficient manner,
requiring little in the way of conscious
thought, at least in familiar
surroundings.
The Gait Cycle
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Walking involves the alternating action of
the two lower extremities
The walking pattern is studied as a gait
cycle
– The gait cycle is defined as the interval of time
between any of the repetitive events of walking.
Such an event could include the point when the
foot initially contacts the ground, to when the
same foot contacts the ground again
The Gait Cycle
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The gait cycle consists of two periods:
stance and swing
– The stance period
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Constitutes approximately 60% of the gait cycle
Describes the entire time the foot is in contact with the
ground and the limb is bearing weight
Begins with the initial contact of the foot on the
ground, and concludes when the ipsilateral foot leaves
the ground
The stance period takes about 0.6 sec during an
average walking speed
The Gait Cycle
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Swing period
– Constitutes approximately 40% of the
gait cycle
– Describes the period when the foot is not
in contact with the ground
– Begins as the foot is lifted from the
ground and ends with initial contact with
the ipsilateral foot
Stance Period
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Within the stance period, two tasks
and four intervals are recognized
The two tasks include weight
acceptance and single limb support
The four intervals include loading
response, mid stance, terminal stance
and pre-swing
Stance Period
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Weight acceptance
– The weight acceptance task occurs during
the first 10% of the stance period
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The loading response interval begins as one
limb bears weight while the other leg begins
to go through its swing period. This interval
may be referred to as the initial double stance
period and consists of the first 0-10% of the
gait cycle
Stance Period
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Single Leg Support
– The middle 40% of the stance period is divided
equally into mid stance and terminal stance
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The mid stance interval representing the first half of
the single limb support task, begins as one foot is
lifted, and continues until the body weight is aligned
over the forefoot
The terminal stance interval is the second half of the
single limb support task. It begins when the heel of
the weight bearing foot lifts off the ground and
continues until the contralateral foot strikes the ground
Stance Period
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Limb Advancement
– Pre-swing. This interval begins with initial
contact of the contralateral limb and ends
with ipsilateral toe-off. As both feet are
on the floor at the same time during this
interval, double support occurs for the
second time in the gait cycle.
Swing Period
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Within the swing period, one task and
four intervals are recognized
The task involves limb advancement
The four intervals include pre-swing,
initial swing, mid-swing, and terminal
swing
Swing Period
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Limb Advancement
– Pre-swing. In addition to representing the final
portion of the stance period and single limb
support task, the pre-swing interval is
considered as part of the swing period
– Initial swing. This interval begins with the lift of
the foot from the floor and ends when the
swinging foot is opposite the stance foot.
Swing Period
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Limb Advancement
– Mid-swing. This interval begins as the
swinging limb is opposite the stance limb,
and ends when the swinging limb is
forward and the tibia is vertical
– Terminal swing. This interval begins with
a vertical tibia of the swing leg with
respect to the floor, and ends the
moment the foot strikes the floor
Gait parameters
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Cadence
– Cadence is defined as the number of
separate steps taken in a certain time
– Normal cadence is between 90 and 120
steps per minute
The cadence of women is usually 6-9 steps
per minute slower than that of men
 Cadence is also affected by age, with cadence
decreasing from the age of 4 to the age of 7,
and then again in advancing years
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Gait parameters
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Stride length
– Step length is measured as the distance
between the same point of one foot on
successive footprints (ipsilateral to the
contralateral foot fall).
– Stride length, on the other hand, is the distance
between successive points of foot-to-floor
contact of the same foot
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A stride is one full lower extremity cycle
Two step lengths added together make the stride
length
Characteristics of Normal
Gait
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Gait involves the displacement of body
weight in a desired direction utilizing a
coordinated effort between the joints of the
trunk and extremities and the muscles that
control or produce these motions
Any interference that alters this relationship
may result in a deviation or disturbance of
the normal gait pattern
Normal Gait
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Five priorities of normal gait:
– Stability of the weight bearing foot throughout
the stance period
– Clearance of the non-weight bearing foot during
the swing period
– Appropriate pre-positioning (during terminal
swing) of the foot for the next gait cycle
– Adequate step length
– Energy conservation
Center of Gravity (COG)
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During the gait cycle, the COG is
displaced both vertically and laterally
Joint Motions in Gait
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Trunk and Upper Extremities
– During the gait cycle:
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The swing of the arms is out of phase with the legs
As the upper body moves forward, the trunk twists
about a vertical axis
The thoracic spine and the pelvis rotate in opposite
directions to each other to enhance stability and
balance
The lumbar spine tends to rotate with the pelvis
The shoulders and trunk rotate out of phase with each
other during the gait cycle
Joint Motions in Gait
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Pelvis
– For normal gait to occur, the pelvis must
both rotate and tilt
Joint Motions in Gait
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Sacroiliac Joint
– As the right leg moves through the swing period,
the position of the right innominate changes
from one of extreme anterior rotation at the
point of pre-swing to a position of posterior
rotation at the point of initial contact
– As the right extremity moves through the
loading response to mid stance, the ilium on that
side begins to convert from a posteriorly rotated
position to a neutrally rotated position. From
mid stance to terminal stance, the ilium rotates
anteriorly, achieving maximum position at
terminal stance
Joint Motions in Gait
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Sacroiliac Joint
– The sacrum rotates forward around a
diagonal axis during the loading
response, reaching its maximum position
at mid stance (e.g., right rotation on a
right oblique axis at right mid stance),
and then begins to reverse itself during
terminal stance
Joint Motions in Gait
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Hip
– Hip motion occurs in all three planes
during the gait cycle
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Knee
– The knee flexes twice and extends twice
during each gait cycle: once during
weight bearing and once during nonweight bearing
Joint Motions in Gait
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Foot and ankle
– Ankle joint motion during the gait cycle occurs primarily in
the sagittal plane
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At initial contact with the ground the ankle is dorsiflexed
During the loading response interval, plantar flexion occurs
at the talocrural joint, with pronation occurring at the
subtalar joint
At the end of the mid stance interval, the talocrural joint is
maximally dorsiflexed, and the subtalar joint begins to
supinate
From the mid stance to the terminal stance interval the foot
is in supination
Once the ankle is fully close-packed, the heel is lifted by a
combination of passive force and contraction from the taut
gastrocnemius, and the soleus
Muscle Actions in Gait
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Spine and pelvis
– During the swing period, the semispinalis,
rotatores, multifidus, and external oblique
muscles are active on the side toward which the
pelvis rotates
– The erector spinae and internal oblique
abdominal muscles are active on the opposite
side
– The psoas major and quadratus lumborum help
to support the pelvis on the side of the swinging
limb, while the contralateral hip abductors also
provide support
Muscle Actions in Gait
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Knee
– During the swing period, there is very little
activity from the knee flexors
– The knee extensors contract slightly at the end
of the swing period prior to initial contact.
During level walking the quadriceps achieve
peak activity during the loading response
interval (25% maximum voluntary contraction)
and are relatively inactive by mid stance as the
leg reaches the vertical position and ‘locks’,
making quadriceps contraction unnecessary
Muscle Actions in Gait
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Hip
– During the early to mid portion of the swing
phase, the iliopsoas is the prime mover with
assistance from the rectus femoris, sartorius,
gracilis, adductor longus, and possibly the tensor
fascia latae, pectineus, and the short head of the
biceps femoris during the initial swing interval
– In terminal swing, there is no appreciable action
of the hip flexors when ambulating on level
ground. Instead the hamstrings and gluteus
maximus are strongly active to decelerate hip
flexion and knee extension
Muscle Actions in Gait
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Hip
– The adductor magnus muscle supports hip
extension and also rotates the pelvis externally
toward the forward leg
– In mid stance, coronal plane muscle activity is
greatest as the abductors stabilize the pelvis.
The muscle activity initially is eccentric as the
pelvis shifts laterally over the stance leg. The
gluteus medius and minimus remain active in
terminal stance for lateral pelvic stabilization
Muscle Actions in Gait
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Knee
– Hamstring involvement is also important
to normal knee function. The co
activation of the antagonist muscles
about the knee during the loading
response aid the ligaments in maintaining
joint stability, by equalizing the articular
surface pressure distribution, and
controlling tibial translation.
Muscle Actions in Gait
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Foot and ankle
– During the beginning of the swing period,
the tibialis anterior, extensor digitorum
longus (EDL), extensor hallucis longus
(EHL), and possibly the peroneus tertius
contract concentrically with slight to
moderate intensity tapering off during the
middle of the swing period
Muscle Actions in Gait
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Foot and ankle
– At the point where the leg is
perpendicular to the ground during the
swing period, the tibialis anterior, EDL
and EHL group of muscles contract
concentrically to dorsiflex and invert the
foot in preparation for the initial contact
Muscle Actions in Gait
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Foot and ankle
– Following initial contact, the anterior tibialis
works eccentrically to lower the foot to the
ground during the loading response interval
– Calcaneal eversion is controlled by the eccentric
activity of the posterior tibialis, and the anterior
movement of the tibia and talus is limited by the
eccentric action of the gastrocnemius and soleus
muscle groups as the foot moves towards mid
stance
– Pronation occurs in the stance period to allow
for shock absorption, ground terrain changes,
and equilibrium
Muscle Actions in Gait
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Foot and ankle
– The triceps surae become active again from mid
stance to the late stance period contracting
eccentrically to control ankle dorsiflexion as the
COG continues to move forward
– In late stance period the Achilles tendon is
stretched as the triceps surae contracts and the
ankle dorsiflexes
– At this point the heel rises off the ground and
the action of the plantar flexors changes from
one of eccentric contraction, to one of concentric
contraction
Influences on Gait
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Pain
Posture
Flexibility and the amount of available joint motion
Endurance - economy of mobility
Base of Support
Interlimb coordination
Leg-length
Gender
Pregnancy
Influences on Gait
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Obesity
Age
Lateral and vertical displacement of the COG
Properly functioning reflexes
Vertical Ground Reaction Forces
Medial-Lateral Shear Forces
Anterior-Posterior Shear Forces
Specific Deviations of
Individual Joints
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Hip
– Inadequate power
– Inadequate or inappropriate range of
motion
– Malrotation
Specific Deviations of
Individual Joints
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Knee
– The common problem at the knee during
the stance period is excessive flexion.
During the swing period, the most
common error is due to inadequate
motion
Specific Deviations of
Individual Joints
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Foot and ankle
– There are three broad types of errors of
the foot and ankle in the stance and
swing periods:
Malrotation
 Varus or valgus deformity
 Abnormal muscle moments
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Abnormal Gait Syndromes
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In general gait deviations fall under
four headings:
– Those caused by weakness
– Those caused by abnormal joint position
or range of motion
– Those caused by muscle contracture
– Those caused by pain
Abnormal Gait Syndromes
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Antalgic Gait
– The antalgic gait pattern can result from
numerous causes including joint inflammation or
an injury to the muscles tendons and ligaments
of the lower extremity
– The antalgic gait is characterized by a decrease
in the stance period on the involved side in an
attempt to eliminate the weight from the
involved leg and use of the injured body part as
much as possible
Abnormal Gait Syndromes
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Equinus Gait
– Equinus gait (toe-walking), one of the
more common abnormal patterns of gait
of patients with spastic diplegia, is
characterized by forefoot strike to initiate
the cycle and premature plantar flexion in
early stance to midstance
Abnormal Gait Syndromes
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Gluteus maximus Gait
– The gluteus maximus gait, which results from
weakness of the gluteus maximus, is
characterized by a posterior thrusting of the
trunk at initial contact in an attempt to maintain
hip extension of the stance leg
– The hip extensor weakness also results in
forward tilt of the pelvis, which eventually
translates into a hyperlordosis of the spine to
maintain posture
Abnormal Gait Syndromes
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Quadriceps Gait
– Quadriceps weakness can result from a
peripheral nerve lesion (femoral), a spinal berve
root lesion, from trauma, or from disease
(muscular dystrophy)
– Quadriceps weakness requires that forward
motion be propagated by circumducting each
leg. The patient leans the body toward the
other side to balance the center of gravity, and
the motion is repeated with each step
Abnormal Gait Syndromes
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Spastic Gait
– A spastic gait may result from either unilateral or
bilateral upper motor neuron lesions
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Spastic hemiplegic (hemiparetic) gait. This type of gait
results from a unilateral upper motor neuron lesion
and is frequently seen following a completed stroke
Spastic paraparetic gait. This type of gait results from
bilateral upper motor neuron lesions (e.g., cervical
myelopathy in adults and cerebral palsy in children)
Abnormal Gait Syndromes
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Ataxic Gait
– The ataxic gait is seen in two principal
disorders: cerebellar disease (cerebellar
ataxic gait) and posterior column disease
(sensory ataxic gait)
Abnormal Gait Syndromes
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Steppage Gait
– This type of gait occurs in patients with a foot
drop
– A foot drop is the result of weakness or paralysis
of the dorsiflexor muscles due to an injury to the
muscles, their peripheral nerve supply, or the
nerve roots supplying the muscles
– The patient lifts the leg high enough to clear the
flail foot off the floor by flexing excessively at
the hip and knee, and then slaps the foot on the
floor
Abnormal Gait Syndromes
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Trendelenburg Gait
– This type of gait is due to weakness of the hip
abductors (gluteus medius and minimus)
– The normal stabilizing affect of these muscles is
lost and the patient demonstrates an excessive
lateral list in which the trunk is thrust laterally in
an attempt to keep the center of gravity over the
stance leg
Abnormal Gait Syndromes
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Parkinsonian Gait
– The parkinsonian gait is characterized by a
flexed and stooped posture with flexion of the
neck, elbows, metacarpophalangeal joints, trunk,
hips, and knees
– The patient has difficulty initiating movements
and walks with short steps with the feet barely
clearing the ground. This results in a shuffling
type of gait with rapid steps
Abnormal Gait Syndromes
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Hysterical Gait
– The hysterical gait is non-specific and bizarre
– It does not conform to any specific organic
pattern with the abnormality varying from
moment to moment and from one examination
to another
– There may be ataxia, spasticity, inability to
move, or other types of abnormality
– The abnormality is often minimal or absent when
the patient is unaware of being watched or
when distracted
Posture
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Good posture is a subjective term
reflecting what the clinician believes to
be correct based on ideal models.
Generally speaking muscles can be
subdivided into:
– Postural muscles
– Phasic muscles
Posture
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The ability to main correct posture is
related to a number of factors, which
includes but is not limited to:
– Energy cost
– Strength and flexibility
– Structural deformities
– Disease
– Pain