Week 11: Pathologic Gait & Outcome measures

What is gait?

-Gait: moving from one place to another

-Dynamic Balance Activity- series of losses and recoveries of balance

How is normal gait characterized?

Normal gait is a series of controlled falls followed by controlled stopping of a fall.

What happens when the center of mass moves beyond the base of support?

It causes the opposite leg to step in order to prevent a fall.

What is the importance of ankle mobility in gait?

Ankle motion is crucial for contralateral stepping, mainly dorsiflexion (DF) for the contralateral stepping.

What are the three essential components for normal gait?

1. Progression, 2. Stability, 3. Adaptability.

What does the component 'progression' refer to in gait?

It refers to basic reciprocal and rhythmic patterns of muscle activation and movement synergy.

What does the component 'stability' entail during gait?

It involves maintaining equilibrium during propulsive movement and upright posture during perturbations.

What does the component 'adaptation' entail during gait?

-To behavioral goals and external constraints and environmental demands

-Ability to change direction

Control Mechanisms for Gait

-Sensory

-Supraspinal

-Spinal Cord CPG

Activation of the corticospinal tract includes the

motor cortical circuitry, segmental interneurons and their influence on the alpha motor neuron

What is the role of the Central Pattern Generator (CPG) in gait?

The CPG is a neuronal network in the lumbrosacral spinal cord that can produce basic locomotor patterns without brain or sensory input.

What happens to de-afferent cats regarding rhythmic movements?

They can still produce rhythmic movements of their hind legs despite not receiving sensory information.

spinal preparation

a surgical preparation in which the spinal cord is severed at an anterior level in order to isolate it from the rest of the CNS

What is the significance of supraspinal input in human gait?

Humans are more dependent on supraspinal input compared to animals for walking.

What happens when the CPG is stimulated

they generated an oscillating efferent output the generates the flexor and extensor muscles

Human research with CPGs

-Individuals with complete SCIs can be stimulated to produce these patterns

-However strength of contractions are too weak to support body weight

-Humans are more dependent on supraspinal input compared to animals

supraspinal input

brainstem

What role does the brainstem play in gait?

The brainstem initiates walking and controls speed through the Mesencephalic region

reticulospinal tract in gait

-Responsible for postural control and locomotion

-Connects brainstem to lumbosacral cord

What is the function of the cerebellum in locomotion?

The cerebellum is responsible for error detection, correction, and fine-tuning of walking.

Senses are critical to regulate and adapt gait to the environment

Postural control is maintained via Reactive Strategies and Anticipatory Strategies

muscle spindle during gait

-Activated when leg goes into terminal stance and hi[p flexor is stretched activating the 1-a afferent causing a hip flexor muscle burst during pre-swing to assist with initiation of swing

-Extensor muscle gets inhibited during this

GTO during gait

-During gait the GTO excites agonist activity assisting in extensor support of the leg during stance

-As the leg makes initial contact, the 1-b afferents activate causing ipsilateral activation of the extensors

What are the two phases of the gait cycle?

Stance Phase (60-62% of gait) and Swing Phase (38-40% of gait).

What is the significance of the Loading Response phase?

-It is the phase of greatest muscle activity

-Controlled ankle plantarflexion (heel rocker)

-Controlled weight transfer to stance limb

-begins with IC and ends with Contralateral toe off

-First period of double limb support

-Controlled knee flexion (shock absorption)

What is the Mid Stance phase characterized by?

-Single limb support and controlled progression of the center of mass (COM) from behind to in front of the ankle.

-starts with contralateral toe off and ends when COG is over stance foot

- Controlled closed chain dorsiflexion/rate of tibial advancement

What happens during the Terminal Stance phase?

-The body progresses forward over the stance limb as the COM moves anterior to the foot.

-begins when COG is over stance foot and ends when the contralateral foot touches the ground, body progresses over stance limb

What happens during the Preswing phase?

-Ankle Plantarflexion (only toe contact with ground)

-Hip & Knee flexion based on momentum vs muscle activity

What happens during the initial swing phase?

-begins at toe off and continues until knee flexion of 60º

-Knee flexion for toe clearance

-Hip flexion

What happens during the mid swing phase?

-Hip flexion to continue advancing thigh

-Ankle dorsiflexion to neutral

-period of max knee flexion until tibia is vertical to ground

What happens during the terminal swing phase?

-tibia starts vertical to ground, ends at initial contact

-Deceleration of hip flexion and knee extension

Which phase of gait has the most muscle activity

LR

Ankle isometric DF occurs during

MsW-TsW

Eccentric gastroc during gait occurs during

MsT-TsT

spatial gait characteristics

-Stride length

-step length

-step width

Stride length

-distance from initial contact to initial contact of the same foot

-Norm 1.42 meters.

Step length

-IC of one foot to IC of the other

- Norm 0.71 meters.

temporal gait factors

-cadence

-velocity

What is the normal cadence for women and men?

Women: 118 steps/min; Men: 108 steps/min.

What is the normal walking speed for men and women?

Women: 1.3 m/s; Men: 1.37 m/s (approximately 3 mph).

What are common gait deficits associated with excessive plantarflexion?

Decreased shock absorption, poor position for heel rocker during loading response, and extension moment at the knee.

gait speed times

-Community ambulator: >0.8 m/s, >1.79 mph

-Limited community ambulator: 04.-0.8 m/s 0.89-1.79 mph

-Household ambulatory:

vertical displacement during gait

- center of mass normally lies anterior to S2

- as we walk, the center of mass will be vertically and horizontally displaced

- vertical displacement of center of mass will make two full sine waves in one gait cycle

- minimum displacement of height will occur at the middle of both periods of double limb support

- maximum height of the wave will occur at the mid point of both periods of single limb support [MIDSTANCE]

- normal vertical displacement during the gait cycle is about 5 cm between the high and low points

medial and lateral displacement during gait

- one sinusoidal pattern occurring the in the horizontal plane during one gait cycle

- center of mass causing the medial-lateral displacement alternates between right and left lower limbs

- maximum position of the center of mass to the right occurs during mid stance on the right

- maximum point of the center of mass to the left occurs at mid stance on the left

- normal medial-lateral displacement in 4 cm.

- displacement is increased if the base of support is increased

energy efficiency during gait horizontal pelvic rotation

Pelvis rotates 5º in the horizontal plane to increase relative leg length and minimize downward displace of COG

energy efficiency during gait lateral pelvic tilt

Occurs in frontal plane during midstance at the contralateral pelvis which minimizes upward displacement of the COM

energy efficiency during gait Knee flexion

-Stance: Limits max vertical excursion of the COM

-Swing: Shorten length of leg allowing foot to clear

energy efficiency during gait Ankle DF/PF

-IC: Calcaneus contacts the floor and elongates the leg

-TsT: PF elongates the leg

-Stance: downward displacement is minimized

energy efficiency during gait Lateral pelvic/hip motion

-Reduces step width and minimized m/L displacement of the COM

-Increase in step width increases stability but reduces energy efficiency

Biomechanical subcomponents of gait

stance control, limb advancement, propulsion, postural stability

Postural Stability

Balance- maintaining upright in the sagittal and frontal planes, keeping COM within the BOS

stance control

Maintenance of a vertical limb and prevention trunk collapse during stance

Propulsion

Ability to move COM in a specific direction (forward, backward, etc) during stance, separate from limb advancement

Lim swing

Limb advancement with adequate foot clearance and a positive step length

Energy Expenditure of each subcomponent

-Propulsion 48%

-Stance control 28%

-Limb advancement 10%

-Postural stability 6%

Excessive PF during stance significance

-Decreased shock absorption (limited knee flexion)

-Decreased progression of tibia

-Poor position for heel rocker during LR

-Forces extension moment at knee for wt acceptance

Excessive PF during stance causes

-Heel/Ankle pain

-Excessive knee flexion in terminal swing disrupts ability to have the heel contact the floor resulting in a foot flat initial contact

-Compensation for weak quads: Progressing into SLS causes extension moment at the knee disrupting quad function during stance

-Plantarflexors contracture/hypertonicity results in forefoot or foot flat IC forcing person to hyperextend knee and flex trunk and hips to keep balance

Excessive PF during swing significance

-Only need neutral DF during swing

-Poor foot clearance compensation- steppage gait:

steppage gait

-Excessive hip and knee flexion

-Typically from damage to deep peroneal/fibular nerve

Excessive PF during swing Causes

-Weak pretibial muscles

-Plantarflexor contracture or hypertonicity

-Lack of selective DF control during terminal swing

Excessive PF can cause major deviations in every phase except

except preswing

What compensatory mechanisms might occur due to excessive plantarflexion during swing?

Excessive hip and knee flexion to achieve foot clearance.

What is the significance of knee flexion during stance?

It limits maximum vertical excursion of the center of mass.

What does neuroplasticity refer to in gait control?

The CNS's ability to adapt and change, impacting functional recovery for walking.

Where is the central pattern generator located?

In the lumbosacral spinal cord.

What is the critical event during terminal stance?

Controlled forward progression of the COM beyond the area of support.

What happens during the pre-swing phase?

Rapid unloading of the limb occurs, marking the second period of double limb support.

What is the effect of excessive ankle plantarflexion during initial contact?

It can lead to foot-flat contact or forefoot contact

flatfoot contact effects

-Ankle 15º PF

-Knee fully extended

-Still initiated with heel but foot almost parallel to the floor

-Decreased heel rocker

-Decreased knee flexion thrust

forefoot contact

-Ankle equinas

-Knee flexion

What is the effect of excessive ankle plantarflexion during LR?

Foot slap or foot flat contact

Forefoot contact 3 results

-Foot drops in heel while tibia is vertical (ankle mobility must be good)

-Person stays on the ball of the foot (heel off)

-Tibia is driven backward as heel drops to floor (rigid PF)

What is the impact of excessive ankle plantarflexion during midstance?

It inhibits tibial advancement, affecting gait efficiency.

What compensatory strategies may occur due to excessive plantarflexion in midstance

-Premature Heel Off:: To push over the flat foot onto the forefoot quickly

-Knee Hyperextension: Most common compensation, occurs if ligaments lax (increases stress on posterior knee structures) Femur rolls over immobile tibia

-Forward trunk lean and anterior tilt: Used to maintain balance over the PF foot (not so much for progression), Slow gait

What is the impact of weak gastrocnemius on gait?

It may cause knee flexion during stance due to inadequate tibial advancement.

What happens to the femur during knee hyperextension?

The femur rolls over an immobile tibia.

What happens if forward tibial progression does not occur during walking?

The knee may hyperextend and hip flexion compensates.

Excessive Ankle Plantar Flexion - TSt and Swing

-Excess heel rise

-Increased hip flexion

-Toe drag

excess heel rise in stance

Occurs if the pt is able to roll onto forefoot

What occurs if there is no heel rise during late stance

advancement is limited to the amount of knee hyperextension, trunk lean or pelvic rotation that contributes to forward reach of the contralateral limb

What is a common substitution to clear the foot during swing?

Increased hip flexion.

What is toe drag and how does it affect gait?

It inhibits limb advancement and can terminate swing prematurely.

What compensations can prevent toe drag?

Circumduction, lateral trunk lean, contralateral vaulting, and steppage gait.

What is the significance of excessive dorsiflexion during weight acceptance and SLS

-increases demands of hip and knee extensors to stop knee from bending

-Decreases step length of contralateral lower extremity

Excessive DF during Weight acceptance and SLS causes

-Excessive hip or knee flexion

-Weak Plantarflexors: esp gastric which doesn't allow the tibia to stay back thus making it progress excessively forward

Excessive Ankle Dorsiflexion -IC, LR

Ankle fixed at neutral: Tibia advances at the same rate as foot falls to floor increasing heel rocker so increased demand on quads

Excessive Ankle Dorsiflexion MsT

-Too much tibial advancement increases ankle rocker

-Prolonged contact of heel due to very fast DF

-Quads act to advance femur but pulls whole COG forward so knee cannot extend

Excessive Ankle Dorsiflexion TsT

-Prolonged heel contact (no heel off) 2' increased anterior displacement of tibia

-Increased knee flexion with heel rise can compensate for the extra tibial advancement

Excessive Ankle Dorsiflexion PsW

-Prolonged heel contact with excess DF because tibia will not stop moving forward until full ankle ROM has been reached

-C/L limb takes a shorter tha normal step

What is the impact of excessive hip flexion on gait?

Increases demands on hip and knee extensors and decreases stability.

Excessive inversion significance: weight acceptance and SLS

-Poor foot position for weight acceptance as weight will be born on lateral border of the foot

-Decreased shock absorption during IC and LR

-Instability during SLS

-High arch

Excessive inversion significance: Swing

Inversion causes supination and PF reducing ability to foot clearance

What are the potential causes of excessive inversion of the foot?

-Tibialis ant, posterior or soleus over-activity/hypertonia

-Weak peroneals

-Contracture

What is the significance of excessive eversion during gait?

It strains the midfoot and knee and impairs forefoot rocker.

Causes of excessive eversion in stance

-Weak tibialis post or soleus

-Valgus deformity

-Flat feet

-Increasing eversion/pronation can be used to gain DF

Causes of excessive eversion in swing

-Weak tibialis anterior

-Peroneal hypertonicity

Hammer toes

Description: Hyperextension of the MTP & DIP joints and flexion of the PIP joint of the lateral 4 toes.

claw toes

hyperextension of the MTP joint and flexion of the DIP and PIP joints

significance of hammer and claw toes

-Affects forward progression by shortening foot lever

-Decrease step length of contralateral limb

Causesof hammer and claw toes

-Compensation for weak plantarflexors

-Hypertonicity

-Intrinsic muscle imbalance