Lecture 15: Gait biomechanics

Question 1

how does the pelvis move during gait and what are the axes of movement

Answer 1

2-4 deg ant/post pelvic tilt

some movement with ML and AP axis

Question 2

how does the pelvis tilt through the different phases of gait

Answer 2

heel strike neutral-loading = posterior

single limb support - midstance = anterior

toe off = posterior

early-mid swing = anterior

late swing = posterior

Question 3

how does the hip move in the sagittal plane during gait

Answer 3

heel contact = 30 deg flexion

before toe off = 10 deg ext

loss of ext found with anterior tilt/lordosis

Question 4

how does the knee move in the sagittal plane with gait

Answer 4

heel contact = 5 deg; goes to 10-15 deg with loading

extension then occurs until heel off

then flexes until toe off into mid swing

extends toward heel contact

Question 5

sagittal plane kinematics of ankle motion during gait

Answer 5

heel contact = slight PF

stance = 10 deg DF

after heel off = PF to max 15-20 deg

neutral in swing

Question 6

limited ankle PF can cause what

Answer 6

abnormal pattern

decreased push off and shorter step length

limited DF early heel off

genu recurvatum

Question 7

how much ext is needed at 1st MTP between heel off to just before toe off

Answer 7

45 deg ext

without = less efficient push off

Question 8

frontal plane movement of pelvis during gait (degrees)

Answer 8

10-15 deg total excursion

Question 9

how does the hip move with gait

Answer 9

pelvic on femoral movement

possibly some femoral on pelvic with motion at knee

Question 10

motion present in frontal plane at the knee

Answer 10

miminal and inconsistent

stance = 3 deg-5 deg at end

swing = 5 deg abd

Question 11

frontal plane motion at foot and subtalar joint during gait

Answer 11

pronation and supination via subtalar and transverse tarsal

2-3 deg inversion at heel contact

rapid eversion at calcaneus through midstance

reverses to inversion when neutral is reached at heel off

6 deg of inversion before toe off

Question 12

horizontal plane motion at the pelvis during gait

Answer 12

R heel contact = R ASIS forward compared to L

L advances during the rest of R LE stance and R ER where R ASIS is behind toe off

3-4 deg in each direction
; increases with speed

Question 13

horizontal motion present at femur, tibia, knee and hip during gait

Answer 13

femur = IR first 20% after heel strike; then reverse til toe off; 6-7 deg each direction

tibia = same as femur but 8-9 deg each way

hip = ER at heel strike and IR motion; max at 50% of cycle

knee = variable

Question 14

how does the trunk/UEs move during gait

Answer 14

provide balance and minimize energy use

spinal motions dampen force

rotational excursion = 7-9 deg of shoulder girdle

shoulder
-amplitude increases with speed
-ant/post delts
-when hip ext, shoulder flexes

elbow = 20 deg flexion at heel contact

Question 15

how is the COM displaced throughout the gait cycle

Answer 15

vertical = oscillates up and down 2 full sine waves per cycle; minimum at double support and max at single (5cm total)

side to side = 4 cm total

Question 16

what is the most metabolically efficient gait speed

Answer 16

1.33 m/sec

Question 17

notable muscle activities during gait (erector spinae, abdominals, hip flexors/extensors)

Answer 17

erector spinae contract at lumbar region before heel contact

rectus abdominis = firing corresponds to hip flexor activity but is variable/minimal

glut max = late swing as hip ext and weigth acceptance at midstance

eccentric hip flexors as hip is extending and then concentric for swing

Question 18

hip adductor/abductor actions during gait

Answer 18

abductors
-stabilize pelvis in frontal plane
-end of swing prepare for heel contact
-SLS to control pelvis drop
-control femur ADD

ADD
-heel contact
-just after toe off
-

Question 19

knee extensor/flexor activity during gait cycle

Answer 19

quads eccentric from late stage swing into heel contact; concentric from midstance

flexors before and after heel contact, swing phase, and with hip ext

Question 20

when does tibialis anterior activate during gait

Answer 20

heel contact eccentrically

can help decelerate pronation and swing phase

Question 21

when do EDL and EHL activate during gait

Answer 21

heel contact

decelerate swing

Question 22

when do peroneals activate during gait

Answer 22

5% until just before toe off

works vs posterior tib and holds 1st ray down for foot rigidity

Question 23

function of foot intrinsics during gait

Answer 23

mid stance to toe off

stabilize foot and lift arch

help with foot rigidity

Question 24

function of plantar flexors during gait

Answer 24

most of stance phase eccentric to control DF

concentric near heel off into push off

Question 25

function of tibialis posterior durign gait

Answer 25

supinator throughout stance phase

decelerates after heel strike

concentrically supinates midstance to toe off

overused with overpronators

Question 26

describe the forces (vertical, AP, and ML) the body experiences throughout the gait cycle

Answer 26

vertical = perpendicular to ground; peak twice during cycle; slightly greater than BW

AP = shear forces; parallel to floor; posterior force at heel contact; 20% BW

ML = small; 5% BW

Question 27

during the early part if stance the line of action promotes what joint movements

Answer 27

ankle PF, knee flexion, and hip flexion

Question 28

throughout much of stance the GRFs create what type of torque on knee

Answer 28

varus

Question 29

describe how individuals with a PF contracture move

Answer 29

make initial contact with ground in the forefoot region

midstance - bringing heel to ground will result in knee hyperextension

fwd lean of trunk occurs in terminal stance to maintain fwd progression of center of mass

Question 30

weak ankle dorsiflexors may result in what

Answer 30

foot drop during swing phase

requires excessive hip and knee flexion for toes to clear ground

Question 31

how might a pt compensate for limited functional shortening of the affected swing limb

Answer 31

vaulting through excessive PF of the unaffected stance limb

Question 32

weak quads leading to anterior trunk lean moves the COM where

Answer 32

anterior to the axis of rotation of the knee

Question 33

knee flexion contracture results in what

Answer 33

crouched gait of the stance limb

to clear toes during swing the unaffected contralateral side must compensate with exaggerated knee and hip flexion

Question 34

hip circumduction during swing is used to compensate for what

Answer 34

inability to shorten the swing limb because of the inadequate knee flexion or DF