Transcript Gait and orthotics - VCU Physical Medicine & Rehabilitation

Lower limb orthotics
Jeff Ericksen, MD
VCU/MCV Dept. of PM&R
Goals
Gait review
Key muscles, joint mechanics
Common conditions for orthotics
Lower limb orthotic approach
Examples
Normal gait = progression of
passenger unit through
space with stability and
minimal energy output.*
 Keep center of gravity in tightest spiral
Most efficient CG path = line, only with wheels
Perry, J Atlas of Orthotics
Initial
Contact
Loading
Response
Weight Acceptance
Mid
Stance
Terminal
Stance
PreSwing
Single Limb Support
Stance Phase
Initial
Swing
MidSwing
Terminal
Swing
Limb Advancement
Swing Phase
Terminology
Gait Cycle: Sequence of events from
initial contact of one extremity to
the subsequent initial contact on the
same side
Gait terminology
 Stride length: Distance from initial contact
of one extremity to the subsequent initial
contact on the same side (x= 1.41 m)
 Step length: Distance from initial contact
of one extremity to the initial contact on
the opposite side (x= 0.7 m)
Terminology
Cadence: The step rate per minute
(x= 113 steps per min)
Velocity: The speed at which one
walks
(x= 82 m/min)
Normal Gait
Classic Gait Terms:
1) Heel Strike
2) Foot Flat
3) Midstance
4) Heel Off
5) Toe Off
6) Initial Swing/ Midswing/ Terminal Swing
Gait Events
Phases:
1) Stance Phase: 60%
2) Swing Phase: 40%
Periods:
1) Weight Acceptance
2) Single Limb Support
3) Limb Advancement
Gait Events (Perry)
1.
2.
3.
4.
5.
6.
7.
8.
Initial Contact
Loading Response
Mid Stance
Terminal Stance
Pre-Swing
Initial Swing
Mid Swing
Terminal Swing
Progression
Mostly from forward fall of body
mass as it progresses in front of
loaded foot, ankle moves into DF with
rapid acceleration as heel rises
Swing limb generates second
progressional force as stance limb
goes into single support phase, must
occur to prepare for forward fall
Energy consumption
Acceleration & deceleration needs
Swinging mass of leg must be
decelerated by eccentric contraction
of extensors and counterforce
(acceleration) of body
Forward falling body must be
decelerated by shock absorption at
initial contact = heel strike
Eccentric energy
consumption is high
Pretibial and quadriceps contraction
at initial contact with eccentric
control of tibial shank in loading
phase on stance leg.
Results in 8:5 ratio for energy in
deceleration or control activity vs.
propulsion activity
Determinants of gait
Foot, ankle, knee and pelvis
contributions to smoothing center of
gravity motion to preserve energy
Inman APMR 67
Determinants
1) Pelvic Rotation
2) Pelvic Tilt
3) Lateral pelvic motion
4) Knee flexion in midstance
5) Knee motion throughout gait cycle
6) Foot and ankle motion
Determinants
 Pelvic rotation 4 degrees
saves 6/16 vertical drop
 Pelvic tilt 5 degrees,
saves 3/16 vertical
excursion
 Knee flexion 15 degrees
lowers CG 7/16
total savings = 1 inch
per leg
 Foot & ankle motion
Smooths out abrupt
changes in accel/decel
& direction of body
motion
Knee contributes also
Converts CG curve into
smooth sine wave < 2
inch amplitude
 CG horizontal translation
reduced by leg alignment
reduces side to side
sway for stability by >
4 inches
Muscle activity in gait cycle*
Muscle activity*
Energy costs and gait*
Forearm crutch use
Normal subjects
Joint stability in gait
Determined by relationship between
muscle support, capsule & ligamentous
support, articular relationships and
lines of force
Gait deviations
Structural bony issues
Joint/soft tissue changes
Neuromuscular functional changes
Leg length difference
 < 1.5 in, see long side shoulder
elevation with dipping on short leg
side
Compensation with dropping pelvis on
short side
Exaggerated hip, knee, ankle flexion on
long side
 > 1.5 in, different compensation such
as vaulting on short leg, trunk lean to
short side, circumduct long leg
ROM loss or ankylosis will
show proximal compensation
with or without velocity
changes.
Other orthopedic problems
affect gait*
Foot equinus gives steppage gait to clear
the relatively longer leg
Calcaneal deformity changes push off and
initial contact
Gait changes from
orthopedic issues
Joint instability gives unstable motion
and fear, reduced stance phase
Pain reduces stance typically
Spine pain may reduce gait speed to
reduce impact
Hemiplegia gaits
Extensor synergy allows ambulation
Hip & knee extension, hip IR, foot & toe
PF and foot inversion
Difficulty in loading phase or clearing
the “longer” plegic limb gives step-to
gait.
Hemiplegia
1) Asymmetric Gait
2) Step length shortened on the plegic side
3) Decreased knee and hip flexion on swing
phase
4) Shortened stance phase
5) Upper extremity held in flexion and
adduction
Lower motor neuron gaits
Hip extensor weakness gait
Trunk & pelvis posterior after heel
strike
Glut medius limp
pelvis drops if uncompensated
trunk shift if compensated
Hip flexor weakness
Leg swung by trunk rotation pulling leg
on hip ligaments
Lower motor neuron gaits
Quadricep weakness: forcible extension
using hip flexors, heavy heel strike and
forward lean over heel to keep force
anterior to knee joint.
Gastroc/soleus weakness: poor control of
loading phase DF >> compensation is delay
with resulting knee bending moment and
more quad extensor needs. Reduced
forward progression of limb with push off
into swing*
Lower motor neuron gaits
Dorsiflexor weakness gives steppage
gait
Foot slap in fast walk with mild weakness
and if some strength, may be noticable
with fatigue as eccentric TA activity
fails
Forefoot = initial contact point if no
strength for DF present
LE Orthotics
Weakness
Skeletal & joint insufficiency
Leg joint alignment orthoses
Use with & without weight bearing
features
Most common in knee support for RA
induced ligamentous loss
Form fitting shells better than bands
Alignment of knee joint is key
Typically use single axis knee joints for
these orthoses
LE weakness orthoses
 AFO’s
Double metal
upright
Plastic
Molded
off shelf
VAPC
 KAFO’s
Many designs for
band configurations
Metal vs. plastic
 HKAFO’s
 Reciprocating Gait
Orthosis
 Functional
Electrical
Stimulation (FES)
AFO’s
Most common orthotic
Stabilizes ankle in stance
Helps clear toe in swing
Gives some push off in late stance to
save energy
Remember effects on knee!!
AFO’s
Double metal upright allows for
anterior and posterior stops and
spring assist for DF & PF force
generation.
Hinged molded AFO can be similar
Mediolateral stability is good but can
be enhanced with T-straps
Knee effects of PF stops
PF stop helps weak DF & swing
clearance but stops PF of foot at heel
strike, force line behind knee
destabilizes.
Minimal PF stop or just spring assist to
pick toe up in swing should be used for
flaccid paralysis and only few degrees of
DF position for PF stop in spastic
paralysis.
Posterior PF stop should
allow adequate toe clearance
in swing but not excessive
DF to increase knee bending
moment at heel strike.
Contact & loading phase knee effects of
AFO’s
Heel adjustments can help knee*
Effects of DF stops
Anterior DF stop (plus sole plate in shoe)
enables push off and propulsion of limb
and pelvis
Normal forces if DF stop in 5o PF
Use for PF weakness, restores step length
on opposite side and knee moments
normalize.
Spring doesn’t help
Too much PF angle gives genu recurvatum
Stabilizes knee with absent gastroc/soleus
eccentric knee extension help in stance
Push off knee effects of AFO’s
Single upright orthoses
Reduces interference with
contralateral orthoses or medial
malleolus
Not useful for mediolateral stability
problems
Plastic AFO’s
Similar biomechanical analysis
Trim lines of posterior vertical
component influence ankle rigidity
Plastic AFO components
Plastic AFO considerations
Light weight
Variable shoes can effect
performance
Skin irritation very real risk
Contraindicated in diabetic neuropathy
or poorly compliant patient with skin
checks
Minimal help for PF weakness, mostly
for DF weakness
Can help with arch support
VAPC dorsiflexion assist orthosis
Knee orthoses
Commonly used for genu recurvatum
Swedish knee cage
3 way knee stabilizer
Medial/lateral laxity
Joint system with thigh & calf cuffs
Axial derotation braces
Axial rotation control plus angular
control in sagittal and frontal planes
Knee extension control
Knee locks
KAFO’s used in SCI, conus or
cauda equina injuries
T10 is often cutoff level, use swing to
gait with locked knees, considerable
energy expenditure
Knee stability added when
AFO not able to control knee
Continue to utilize rigid foot plate
and DF stop to help push off and PF
stop to clear toe in swing
Knee stability via 3 force
application
Anterior force to stop knee buckling
2 posterior counterforces at thigh &
1 at calf
Shoe level counterforce keeps lower
leg from posterior motion in closed
chain loading
HKAFO’s
Rarely used, indicated for hip
extensor weakness
Pelvic band often necessary for
stabilization and suspension
Hip orthotics for dislocation
risks
Adults
Pediatrics
Scottish Rite
Pavlik Harness
Reciprocation Gait Orthosis
Releasable hip joint & knee joint for
sitting
Cable coupling of hip flexion to
contralateral hip extension
Questions