Gait and posture analysis

1
Chapter 13

• Gait and posture analysis

2
Overview

• 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.

3
The Gait Cycle

• 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

4
The Gait Cycle

• The gait cycle consists of two periods stance
  and swing
• The stance period
• 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

5
The Gait Cycle

• 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

6
Stance Period

• 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

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Stance Period

• Weight acceptance
• The weight acceptance task occurs during the
  first 10 of the stance period
• 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

8
Stance Period

• Single Leg Support
• The middle 40 of the stance period is divided
  equally into mid stance and terminal stance
• 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

9
Stance Period

• 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.

10
Swing Period

• 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

11
Swing Period

• 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.

12
Swing Period

• 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

13
Gait parameters

• 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

14
Gait parameters

• 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
• A stride is one full lower extremity cycle
• Two step lengths added together make the stride
  length

15
Characteristics of Normal Gait

• 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

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Normal Gait

• 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

17
Center of Gravity (COG)

• During the gait cycle, the COG is displaced both
  vertically and laterally

18
Joint Motions in Gait

• Trunk and Upper Extremities
• During the gait cycle
• 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

19
Joint Motions in Gait

• Pelvis
• For normal gait to occur, the pelvis must both
  rotate and tilt

20
Joint Motions in Gait

• 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

21
Joint Motions in Gait

• 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

22
Joint Motions in Gait

• Hip
• Hip motion occurs in all three planes during the
  gait cycle
• Knee
• The knee flexes twice and extends twice during
  each gait cycle once during weight bearing and
  once during non-weight bearing

23
Joint Motions in Gait

• Foot and ankle
• Ankle joint motion during the gait cycle occurs
  primarily in the sagittal plane
• 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

24
Muscle Actions in Gait

• 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

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Muscle Actions in Gait

• 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

26
Muscle Actions in Gait

• 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

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Muscle Actions in Gait

• 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

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Muscle Actions in Gait

• 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.

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Muscle Actions in Gait

• 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

30
Muscle Actions in Gait

• 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

31
Muscle Actions in Gait

• 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

32
Muscle Actions in Gait

• 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

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Influences on Gait

• Pain
• Posture
• Flexibility and the amount of available joint
  motion
• Endurance - economy of mobility
• Base of Support
• Interlimb coordination
• Leg-length
• Gender
• Pregnancy

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Influences on Gait

• Obesity
• Age
• Lateral and vertical displacement of the COG
• Properly functioning reflexes
• Vertical Ground Reaction Forces
• Medial-Lateral Shear Forces
• Anterior-Posterior Shear Forces

35
Specific Deviations of Individual Joints

• Hip
• Inadequate power
• Inadequate or inappropriate range of motion
• Malrotation

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Specific Deviations of Individual Joints

• 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

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Specific Deviations of Individual Joints

• 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

• 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

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Abnormal Gait Syndromes

• 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

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Abnormal Gait Syndromes

• 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

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Abnormal Gait Syndromes

• 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

42
Abnormal Gait Syndromes

• 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

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Abnormal Gait Syndromes

• Spastic Gait
• A spastic gait may result from either unilateral
  or bilateral upper motor neuron lesions
• 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)

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Abnormal Gait Syndromes

• Ataxic Gait
• The ataxic gait is seen in two principal
  disorders cerebellar disease (cerebellar ataxic
  gait) and posterior column disease (sensory
  ataxic gait)

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Abnormal Gait Syndromes

• 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

46
Abnormal Gait Syndromes

• 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

47
Abnormal Gait Syndromes

• 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

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Abnormal Gait Syndromes

• 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

49
Posture

• 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

50
Posture

• 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