gait and orthotics Flashcards
prerequisites of normal gait
- stability in stance
- clearance in swing
- pre-positioning of foot in swing
- adequate step-length
- conservation of energy
kinematics
study of positions, angles, velocities, accelerations of body segments and joints during motion
kinetics
study of forces, moments, and powers acting within and on the body
moment =
force x distance
power =
moment x joint angular velocity
initial contact also known as
heel strike
initial contact GRF’s
passes through the heel
- posterior to ankle (ankle neutral)
- anterior to knee (knee extended
- anterior to hip (hip flexed)
initial contact muscles activated
- hip extensors (glute max, hamstrings)
- pre-tibial muscles
loading response is also known as
shock absorption
loading response GRF’s
- posterior to ankle (ankle PF’s from neutral)
- posterior to knee (knee flexes)
- through the hip (hip less flexed; extending)
loading response muscles activated
- pre-tibial muscles (eccentric; control ankle pf)
- quad femoris (eccentric; control knee flexion)
- glut med and adductor magnus (concentric; contralateral pelvis stabilization)
mid-stance is also known as what
extrinsic stability of the knee
mid-stance GRF’s
- anterior to both knee and ankle (restrained df; knee extension)
- posterior to hip (hip stabilization in coronal plane)
mid-stance muscles activated
- soleus and gastroc (eccentric; control tibial forward advancement/df
- glut med (concentric; abductors stabilized pelvis in level posture)
extrinsic stability of the knee during mid-stance is provided by what
eccentric activation of the soleus/achilles tendon
- maintains GRF anterior to the knee > knee extension
during what part of gait does the plantarflexion/knee extension couple happen
mid-stance
terminal stance also known as what
acceleration
terminal stance GRF’s
anterior to knee and posterior to hips > knee and hip extension
terminal stance muscles activated
- gastroc and soleus (eccentric; stabilize tibia at ankle) (concentric; push off)
- tensor fascia lata and iliopsoas (eccentric; restrains hip hyperextension)
pre-swing consists of
- weight transfer to contralateral limb
- unlock stance limb for swing
pre-swing GRF’s
- passes through metatarsals
- posterior to knee
pre-swing muscles activated
- rectus femoris (control excessive knee flexion and hip flexion)
- iliopsoas
- adductor longus (decelerate passive abduction caused by weight transfer to other foot)
swing phase muscles activated
- triceps surae (pre-swing)
- hip flexors (pre and initial swing)
- contralateral hip extensors pull body forward
initial swing consists of
momentum from rapid hip flexion advances femur while tibial inertia from toe-off leads to knee flexion
initial swing muscles activated
- iliopsoas and rectus femoris
- sartorius and gracilis (hip and knee flexion)
- pretibial muscles (ankle df)
mid-swing consists of
transition from knee flexion to knee extension
mid-swing muscles activated
pretibial muscles (ankle df)
terminal swing consists of
deceleration of swing limb
terminal swing muscles activated
- medial and lateral hamstrings (1st half) (restrain hip flexion and prevent excessive knee ext)
- quad femoris (2nd half) (complete knee ext)
- pretibial muscles (foot and toe clearance)
what contracts and lengthens to control forward progression of the tibia over the foot during midstance
gastroc-soleus contracts and achilles tendon lengthens
- directs GRF anterior to knee
- provides extensor moment at knee
first rocker
ankle pf slightly with small df moment produced by eccentric contraction of the ankle df to prevent foot slap
second rocker
ankle df with gradually increasing pf moment as body center of mass moves forward and center of pressure of the GRF moves distally produced by the eccentric contraction of the pf
third rocker
ankle begins to pf with increasing pf moment produced by concentric contraction of ankle pf
drop foot
persistent ankle pf during swing phase, too much pf or too little df
drop foot treatment
external device like e-stim or FES
equinus
one foot is toe walking
knee hyperextension atypical gait
result of overly effective PF/knee extension coupling
- persistent flexion moment at knee
knee flexion atypical gait
- persistent knee flexion through stance and swing
- underperforming or ineffective PF/knee extension couple
knee flexion atypical gait also known as
crouched gait
- usually only in kids
unintended effects of orthotic usage
- limitations in segmental mobility during ambulation
- limitations in higher-level gross motor skills
- long-term changes in soft tissue characteristics (creep)
- skin irritation/breakdown
- psychosocial impact
limitations in segmental mobility during ambulation caused by orthoses examples
- medial/lateral heel whip
- compensatory power generation at hip
limitations in higher-level gross motor skills caused by orthoses examples
- getting up from floor
- stair negotiation
