Biomechanics Final

Gait

The manner in which a person walks

Stride length

The distance you travel during the gait cycle; its between two heel strikes on the same foot (ex: starts at the first heel strike of the R leg and ends at the second heel strike of the R leg)

Gait cycle

Also called stride, the activity that happens between the time one foot touches the ground and the time the same foot touches the ground again

Step length

Distance between the first heel strikes on both feet ex: distance between the 1st heel strike of the R foot to the 1st heel strike of the L foot

Stance phase

The phase of gait when the foot is in contact with the ground

Swing phase

The phase of gait when the foot loses contact with the ground and the lower limb swings

Heel strike

A phase of the gait cycle when the heel comes into contact with the ground

Foot flat

A phase of the gait cycle when the entire foot is on the ground

Midstance

A phase of the gait cycle when your body passes over your weight-bearing foot; your COG is aligned with you stance leg

Heel-off

A phase of the gait cycle when the heel rises off the floor

Toe off

Signals the end of the propulsion and stance phases of the gait cycle

Acceleration

Speeding up in the forward direction

Deceleration

Slowing speed in the forward direction

Waddling gait

Shoulder behind the hips; arms back with the legs forward

Entire side of the body swings together

Minimal trunk/pelvis rotation and increased lordosis

Trendelenburg Gait

Atypical gait pattern due to dysfunction of hip abductors, the hip drops on the non-weight bearing side (the swing leg) and there is a lateral lean of the trunk

Genu recurvatum

Hyperextension of the knees; trunk leans anteriorly

Antalgic gait

Limping

Festinating gait

Shuffling gait that involves ‘freezing’ when a person stops or reaches a doorway; seen in Parkinson’s disease

Equinus gait

Atypical gait where the ankle is held in plantar flexion, preventing the heel from touching the ground normally

Foot slap gait

Atypical gait where the dorsiflexor muscles (Tibialis anterior) are unable to support a person’s body weight, leading to an uncontrolled descend of the foot; it creates a slapping noise

Foot drop

Atypical gait in with a person is unable to dorsi flex the ankle as the leg swings; involves hiking the hip to clear the foot

Dysfunction of the Tibialis anterior

Steppage gait

Atypical gait where an individual raises their knee higher than usual to ensure their foot clears the ground as it swings

Gluteus Maximus lurch

Hip flexes during heel strike, hyperextends at mid-stance; involves rocking of the trunk; moves COG over pelvis to keep balance

Dysfunction of the gluteus Maximus

Bell-clapper gait

Atypical gait due to a fused hip, the lumbar spine and pelvis compensates for this by being the prime movers of the swing phase on the affected side; results in decreased lumbar lordosis and a posterior pelvic tilt

Vaulting

Atypical gait due to decreased knee flexion and extension, it involves and individual rising up on their toes

Circumducted gait

Atypical gait where the leg begins at midline during toe off but it swings out during the swing phase before returning to midline for the heel-strike

Ataxic gait

Atypical gait due to damage to the cerebellum, it is uncoordinated, lacking balance, and causes jerking motions during gait; the individual also uses a wide base of support to compensate

Crouch gait

Hip and knees in chronic flexion; ankles in chronic dorsi flexion

Limited strength, ROM, high tone, extreme lateral arm swing

Hemiplegic gait

Hip extended, Adducted, and medially rotated; knee extended, ankle inverted

Flexion of affected arm with no arm swing

What does the PD gait look like during early stage PD?

Reduced arm swing

Reduced step length

Reduced axial rotation

Slower speed in general

What does PD gait look like during late stage PD?

Bilateral arm swing or no arm swing

Reduced step length

Slow movements

Shuffling gait

Reduced postural control

Fragmentation of movements

Freezing

Scissor gait

Knees and toes are turned inward; knees and thighs can touch and even cross

Flexion at waist, hips, and knees; excessive adduction due to tight adductors and weak abductors; internal rotation

What does gait require and involve?

Movement or stabilization of nearly every body joint

Body performing in the safest, most efficient manner

Repeated losing of and regaining of balance

Gait is a __________ progression of the whole body, produced by coordinated, _________ movements of body segments

Translatory, rotary

Gait involves alternating __________ and ___________ motions

Propulsive, retropulsive

What is the percentage of gait is the stance phase?

60%

What percentage of gait is the swing phase?

40%

What are the subdivisions of the stance phase?

1. Heelstrike

2. Foot flat

3. Midstance

4. Heel off

5. Toe off

What are subdivisions of the swing phase?

1. Acceleration

2. Mid swing

3. Deceleration

What are the sub phases of the stance phase?

Initial contact

Mid-stance

Push-off phase

What is the initial contact phase?

This is a component of the stance phases, it is begins when the foot first makes contact and ends with the foot flat; its the loading response/weight acceptance phase

What is the mid-stance phase?

It’s a component of the stance phase, it is begins at foot flat and ends with heel off; the terminal stance where COG moves from behind the stance leg to the front

What is the push-off phase?

A component of the stance phase, begins with heel off and ends with toe off; provides propulsion

What phase of stance is the R LE in?

Heelstrike

What part of the stance phases is the R LE in?

Foot flat

What stage of the stance phase is the R LE in?

Mid-stance

What stage of the stance phase is the R LE in?

Heel off

What stage of the stance phases is the R LE in?

Toe off

Early swing portion of the swing phase-

From toe off to mid-swing

Initial swing phase or acceleration phase

Mid-swing portion of the swing phase-

lower limb under the hip

Last swing portion of the swing phase-

Limb deceleration phase or terminal swing phase

What stage of the swing phase is the R LE in?

Acceleration

What stage of the swing phase is the R LE in?

Midswing

What stage of the swing phase is the R LE in?

Deceleration

Double limb support

Occurs at the initial contact and again at toe off

What represents 20% of the gait cycle?

Double limb support

Double limb support _________ as gait speed increases and often _________ as balance and stability decreases

Decreases, increases

Single limb support

Occurs during stance phases and throughout the swing phase

What makes up 40% of the gait cycle?

Single limb support

What is the average step length?

72 cm

Step width

Lateral measurement between two heels

Foot angle

Angle between body progression and long axis of the foot (are the toes point forward, in, or out?)

What possible conditions could result in an asymmetrical stride length?

Foot pain

What condition might result in an person increasing the step width?

Aging (Older or younger)

Being pregnant

What proximal bony alignment could contribute to a decrease in the foot angle or a “toeing- in”?

Tight hamstrings

Weakened glute muscles

Step time

Time to complete one right or left Stroop

Cadence

Step rate

Number of steps per minute

Stride time

Time to complete one full gait cycle

Walking or gait speed

Distance covered in a given amount of time

posture is influenced by…

Fitness levels, strength, balance, age, height, weight

Decreased gait speed is associated with increased risk for…

Falls

What is the COG displacement during gait?

Forward linear displacement

Vertical displacement- up and down

Lateral displacement- shifts to line up with the stance leg

Smooth sinusoidal curve

Peaks at double support

Low point at the heel strike

Joint kinematics during gait

Linear progression of the body with angular movements of the joints of the extremities

What limit is vertical rise of the COG?

Lateral pelvic tilt in the frontal plane

Knee flexion

Knee interactions

Ankle interactions

How do you limit vertical drop of the COG?

Pelvic rotation in the transverse plane

What limits lateral motion of the COG?

Valgus of the knee

When does posterior pelvic tilt occur?

During double limb support (assists with deceleration or breaking)

When does anterior pelvic tilt occur?

During single leg support (assists with propulsion)

When does the pelvis rotate in the frontal plane (laterally)?

During weight acceptance

To unload the weight the ASIS rotates forward in the horizontal plane

What degrees of flexion is the hip at when making initial contact?

30

What is the joint positioning the knee goes through?

Initial contact: 5 degrees of flexion that changes to about 10 - 15 degrees

Flexion of the knee serves as what (during initial contact)?

A shock absorber

How is the knee positioned during heel off and mid-swing?

35 degrees of flexion

60 degrees of flexion

How is the ankle positioned during initial contact, foot flat, and heel and toe off?

Talocrural joint- plantar flexion 0-5 degrees Dorsiflexors- eccentrically lower the foot

Tibia translates forward, 10 degrees of dorsi flexion

15 - 20 degrees of plantar flexion

How is the subtalar joint positioned during initial contact, mid-stance, and heel off?

2 - 3 degrees of inversion

Everts to about 2 degrees

Reverses to its neutral position

What is the role of the first tarsometatarsal (TMT) joint during gait?

Assist with flexibility of longitudinal arch

Has small degrees of plantar flexion and dorsi flexion

What is the role of the first metatarsophalangeal (MTP) joint during gait?

Initial contact- slight extension to neutral

Push-off- extends to 45-55 degrees of closed-chain extension

What is the role of the upper extremities during gait?

Have rhythmic pattern opposite lower extremities

Balance rotation of the trunk

What is the role of the trunk during gait?

Rotates small amount in horizontal plane

Contributes to efficient gait pattern via arm swing and trunk rotation

What is the role of the hamstrings and gluteus maximus during gait?

Extend hip to prepare for weight acceptance

Prevent uncontrolled trunk flexion

What is the role of the hip flexors during gait?

Lift leg during initial swing phase

What is the role of the hip abductors during gait?

Stance leg eccentrically lowers contralateral pelvis

Concentrically control frontal plane alignment of femur

What is the role of the quadriceps during gait?

Assist with shock absorption at initial contact

Eccentrically control knee flexion on stance limb during weight transfer

Concentrically extend knee during stance phase

What is the role of the dorsiflexors during gait?

Eccentrically lower the foot during initial contact

During the swing phase it produces ankle dorsi flexion to clear the toes

What is the role of the plantar flexors during gait?

Eccentrically control forward movement of tibia and fibula over the ankle

Provide push-off during heel off with forward propulsion of body

What is the role of the Tibialis posterior during gait?

Acts as a supinator to decelerate pronation during initial contact and foot flat

Concentrically supinates foot from mid-stance to to off

What muscle is prone to an overuse injury?

Tibialis posterior

What are the roles of the fibularis longus and brevis during gait?

Act as pro actors

Anchors first ray

Stabilize the foot

Support medial longitudinal arch

What contractions occur during heel strike?

Isometric contraction during deceleration (hip extensors, knee flexors, plantarflexors)

Concentric contraction for positioning (hip flexors, knee extensors)