Lecture 15: Gait biomechanics Flashcards
how does the pelvis move during gait and what are the axes of movement
2-4 deg ant/post pelvic tilt
some movement with ML and AP axis
how does the pelvis tilt through the different phases of gait
heel strike neutral-loading = posterior
single limb support - midstance = anterior
toe off = posterior
early-mid swing = anterior
late swing = posterior
how does the hip move in the sagittal plane during gait
heel contact = 30 deg flexion
before toe off = 10 deg ext
loss of ext found with anterior tilt/lordosis
how does the knee move in the sagittal plane with gait
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
sagittal plane kinematics of ankle motion during gait
heel contact = slight PF
stance = 10 deg DF
after heel off = PF to max 15-20 deg
neutral in swing
limited ankle PF can cause what
abnormal pattern
decreased push off and shorter step length
limited DF early heel off
genu recurvatum
how much ext is needed at 1st MTP between heel off to just before toe off
45 deg ext
without = less efficient push off
frontal plane movement of pelvis during gait (degrees)
10-15 deg total excursion
how does the hip move with gait
pelvic on femoral movement
possibly some femoral on pelvic with motion at knee
motion present in frontal plane at the knee
miminal and inconsistent
stance = 3 deg-5 deg at end
swing = 5 deg abd
frontal plane motion at foot and subtalar joint during gait
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
horizontal plane motion at the pelvis during gait
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
horizontal motion present at femur, tibia, knee and hip during gait
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
how does the trunk/UEs move during gait
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
how is the COM displaced throughout the gait cycle
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
what is the most metabolically efficient gait speed
1.33 m/sec
notable muscle activities during gait (erector spinae, abdominals, hip flexors/extensors)
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
hip adductor/abductor actions during gait
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
-
knee extensor/flexor activity during gait cycle
quads eccentric from late stage swing into heel contact; concentric from midstance
flexors before and after heel contact, swing phase, and with hip ext
when does tibialis anterior activate during gait
heel contact eccentrically
can help decelerate pronation and swing phase
when do EDL and EHL activate during gait
heel contact
decelerate swing
when do peroneals activate during gait
5% until just before toe off
works vs posterior tib and holds 1st ray down for foot rigidity
function of foot intrinsics during gait
mid stance to toe off
stabilize foot and lift arch
help with foot rigidity
function of plantar flexors during gait
most of stance phase eccentric to control DF
concentric near heel off into push off
function of tibialis posterior durign gait
supinator throughout stance phase
decelerates after heel strike
concentrically supinates midstance to toe off
overused with overpronators
describe the forces (vertical, AP, and ML) the body experiences throughout the gait cycle
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
during the early part if stance the line of action promotes what joint movements
ankle PF, knee flexion, and hip flexion
throughout much of stance the GRFs create what type of torque on knee
varus
describe how individuals with a PF contracture move
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
weak ankle dorsiflexors may result in what
foot drop during swing phase
requires excessive hip and knee flexion for toes to clear ground
how might a pt compensate for limited functional shortening of the affected swing limb
vaulting through excessive PF of the unaffected stance limb
weak quads leading to anterior trunk lean moves the COM where
anterior to the axis of rotation of the knee
knee flexion contracture results in what
crouched gait of the stance limb
to clear toes during swing the unaffected contralateral side must compensate with exaggerated knee and hip flexion
hip circumduction during swing is used to compensate for what
inability to shorten the swing limb because of the inadequate knee flexion or DF
