Posture and Gait Flashcards
Define Base of Support
area bounded posteriorly by the tips of the heels and anteriorly by a line joining the tips of the toes
Define Center of Gravity
also called COM
point where mass of body is centered
Define postural control
maintenance of COM over BOS to control body’s orientation in space and stabilize head w/respect to vertical to orient gaze
what 2 responses enable postural control?
reactive (compensatory) response
proactice (anticipatory) response
what are reactive (compensatory) responses?
responses that occur as reactions to external forces that displace the body’s COM
what are proactive (anticipatory) responses?
responses that occur in anticipation of internally generated destabilizing forces
how much postural sway is normal?
7 mm during quiet stance
COP can be mapped to determine sway
what is the clinical relevance of postural sway?
increased sway = increase fall risk due to COM nearing/getting outside of BOS
what is the difference between sensory and mechanical perturbations?
sensory = may be caused by altering visual input
mechanical = displacement causing changes in the relationship of the body’s COM to BOS
what are muscle synergies/strategies (pertaining to postural control)?
centerally organized patterns of muscle activity that occur in response to perturbations of standing postures
what is the pattern for an ankle strategy? Hip strategy?
ankle = distal-to-proximal pattern
hip = proximal-to-distal pattern
what are 2 changes in support stategies?
- stepping strategies
- grasping strategies
what is the goal of changes in support strategies?
move/enlarge the body’s BOS so that it remains under the COM
it is the only strategy that is successful with large perturbations
how can you define equilibrium with respect to internal/external forces?
sum of internal and external forces equal to zero
what occurs if the line of gravity (LoG) passes through a joint axis?
no torque is created around the joint
what occurs if the LoG passes at a distance from the joint axis?
external gravitation moment
this results in rotation around the joint axis unless it is opposed by a counterbalancing internal moment/muscle contraction
Direction depends on the ________ of the ________ in relation to the ___________
location
LoG
joint axis
if the LoG is anterior to the joint axis, the external moment will cause what?
anterior motion of the proximal segment supported by that joint
what are 3 keys to a successful postural assessment?
- assess from multiple angles
- remove obstructive clothing
- observe more than the area of complaint
Long-term deviation of the LoG passing through/around joint axis will result in __________
structural changes
Describe the Ideal Standing Posture
ideal alignment palce the LoG:
- through external auditory meatus
- midway through shoulder
- slightly posterior to center of hip joint
- slightly anterior to axis of knee joint
- slightly anterior to lateral malleolus
As the LoG passes anterior to the lateral malleolus, what are the external and internal moments?
external = pulling into dorsiflexion
internal = coutner w/plantarflexion (no passive structures contribute, active contraction of solues and gastro)
as the LoG passes anterior to the knee joint, what are the external and internal moments?
external = pull into extension
internal = counter w/flexion
(prevent knee hyperextension by passive tension of posterior joint capsule and associated ligaments and active contraction of hamstrings and gastroc)
as the LoG passes posterior to the hip joint, what are the external and internal moments?
external = pull into extension
internal = counter w/flexion
(passive tension of hip ligaments and active contraction of hip flexors)
what is the ideal posture at the lumbosacral joint?
LoG passes through the body of the L5 causing a slight extension moment
creates shear force rather than a true torque
opposed by anterior longitudinal ligament, iliolumbar ligament, facet joint approximation
As the LoG passes through the external auditory meatus and anterior to the axis of the head, what are the external and internal moments?
external = flexion of cervical spine
internal = extension of cervical spine
(passive tension of ligamentum nuchae, tectorial membrane, and posterior facet joint capsules)
(active contraction of cervical extensors)
Describe the ideal standing posture from the posterior view
- Midline
- head
- spine
- feet evenly spaced
- Shoulder and scapulae
- scapulae lie flat on thorax
- approximately between T2-T7
- approximately 4 inches apart
describe the ideal standing posture from the anterior veiw
- alignment of knees
- patellae face directly forward
- slight physiological valgus
- alignment of ankles
- neutral, neither supinated nor pronated
- alignment of feet
- heels separated by ~3 inches
- out-toeing 8-10 degrees
what is the difference between a step and a stride?
stride = distance between 2 successive heel contacts of the same foot
step = distance between 2 successive heel contacts of 2 different feet
define degree of toe-out
angle between line of progression of the body and a line intersecting the center of the heel and 2nd toe
normal = 5-7 degrees
what are the 3 temporal descriptors of gait?
- stride time
- step time
- cadence
what is considered a normal cadence for men and women?
men = 108 steps/min
women = 118 steps/min
what is our spatiotemporal descriptor for gait?
gait speed/velocity
T/F: gait speed is a very functional measurement of an individual’s walking ability?
TRUE
often called the 6th vital sign
An individual’s gait speed can be predictive of what?
- future health status
- functional decline
- hospitalization rate
- mortality rate
what are the 2 phases of the gait cycle?
stance phase (60%)
swing phase (40%)
how much time in the gait cycle is spent in single-limb support?
80%
(double limb support = 20%)
what system is used to describe the individual phases/parts of the gait cycle?
Rancho Los Amigos Terminology
what are the stages of the stance phase of gait?
- initial contact
- loading response
- midstance
- terminal stance
- preswing
what are the stages of the swing phase of gait?
- initial swing
- mid swing
- terminal swing
what occurs in the Stance Phase: Initial contact (IC)?
the instant the foot hits the ground
critical event = heels first contact
what is occuring on the opposite limb during stance phase: initial contact?
TSt and PSw
(terminal stance
what are the relative joint positions during the Stance Phase: Initial contact?
- Hip = 20° flexion,
- Knee = 0-5° flexion
- Ankle = 0°
What occurs in the Stance phase: Loading Response (LR)?
shock is absorbed as forward momentum is preserved. A flat foot position is achieved
critical event = hip stability, controlled knee flexion, and ankle PF
What is occuring on the opposite limb during stance phase: loading response (LR)?
PSw
pre-swing
what are the relative joint positions for the Stance Phase: loading response?
- Hip = 20° flexion
- Knee = 15° flexion
- Ankle = 5° PF
Initial contact and loading response combine for what functional task?
weight acceptance, shock absorption, and providing a stable base for the body to progress over
absorb impact of GRF
period of dual-limb support
What occurs in the stance phase: midstance (MSt)?
the body progresses over the foot in a controlled manner. First instance of single limb support
critical events = controlled tibial advancement
What is occuring on the opposite leg during stance phase: midstance (MSt)?
ISw - MSw
(Initial swing to Midswing)
what are the relative joint positions for stance phase: midstance?
- Hip = 0°
- Knee = 5° flexion
- Ankle = 5° dorsiflexion
what occurs during stance phase: terminal stance (TSt)?
progression over the stance limb continues past the forefoot. Body is ahead of stance limb
critical events = controlled ankle DF with heel raise
what is occuring on the opposite limb during stance phase: terminal stance (TSt)?
TSw
(terminal swing)
what are the relative joint positions for stance phase: terminal stance?
- Hip = 20° extension
- Knee = 5° flexion
- Ankle = 10° dorsiflexion
What occurs during stance phase: pre swing (PSw)?
rapid unloading of the limb with weight transfer to opposite limb, starting the second period of double limb support
critical events = passive knee flexion to 40°, Ankle PF, 60° of MTP extension
what is occuring in the opposite limb during stance phase: pre swing (PSw)?
IC → LR
initial contact into loading response
what are the relative joint positions for stance phase: pre-swing (PSw)?
- Hip = 10° extension
- Knee = 40° flexion
- Ankle = 15° plantarflexed
what occurs during swing phase: initial swing (ISw)?
the thigh begins to advance as the foot leaves the floor
critical events = hip flexion, knee flexion
what is occuring at the opposite limb during swing phase: initial swing (ISw)?
LR → MSt
(loading response into midstance)
what are the relative joint positions during swing phase: initial swing (ISw)?
- Hip = 15° flexion
- Knee = 60° flexion
- Ankle = 5° plantarflexion
what occurs during swing phase: mid swing (MSw)?
thigh continues to advance, knee begins to extend as foot clearance is maintained
critical events = continued hip flexion, foot clearance
What is occuring in the opposite limb during swing phase: mid swing (MSw)?
MSt
midstance
what are the relative joint positions for swing phase: mid swing (MSw)?
- Hip = 25° flexion
- Knee = 25° flexion
- Ankle = 0° dorsiflexion
what occurs during swing phase: terminal swing (TSw)?
the leg reaches out to achieve step length
critical events = knee extension
What is occuring on the opposite limb during swing phase: terminal swing (TSw)?
TSt
terminal stance
what are the relative joint positions during swing phase: terminal swing (TSw)?
- Hip = 20° flexion
- Knee = 5° flexion
- Ankle = 0° dorsiflexion
What are the 3 functional tasks of gait?
- Weight acceptance
- Single limb support
- Swing limb advancement
When does weight acceptance occur within the gait cycle and what are it’s goals?
Occurs during: IC and LR
Goals:
- forward progression
- stability
- shock absorption
when does single limb support occur within the gait cycle and what are the goals of this task?
occurs in: MSt and TSt
Goals:
- stability
- forward progression
When does swing limb advancement occur within the gait cycle and what are the goals of this task?
occurs in: PSw, ISw, MSw, and TSw
Goals:
- foot clearance
- limb advancement
What are some general tips to take into consideration when performing a gait analysis?
- Big picture first
- Avoid tunnel vision
- Do not let classification of gait dictate your treatment
- Take your time, get it right
- Understand what you are seeing before you try to fix it
- Use anatomical and standard terminology
- Let the patient choose their walking speed
