Typical-Atypical Gait and the Impact of Orthotics Flashcards
Prerequisites of normal gait
*Stability in stance
*Clearance in swing
*Pre-positioning of the foot in
swing
*Adequate step-length
*Conservation of energy
Kinematics
Kinematics: Study of positions, angles, velocities, accelerations of
body segments and joints during motion
Kinetics
Study of the forces, moments, and
powers acting within and on the body
Moments (or Torques)
moment (Nm) = Force x distance
Force is origin, direction, and magnitude
Power
Power (W) = moment x joint angular velocity
Initial Contact
- Heel strike
- GRF passes through the heel
- Posterior to ankle –> Ankle neutral
- Anterior to knee –> Knee extended
- Anterior to hip –> Hip flexed ~30°
- 1st ankle (heel) rocker –into LR
initial contact - muscle activation
- Hip extensors (G. maximus, hamstrings)
- Pre-tibial muscles
Loading Response
- Shock absorption
- GRF passes:
- Posterior to ankle –> Ankle plantarflexes from neutral ~10°
- Posterior to knee –> Knee flexes
- Through the hip –> Hip less flexed; extending
loading response muscle activation
- Pretibial muscles –> Eccentric; control ankle plantarflexion
- Quadriceps femoris –> Eccentric; control knee flexion
- G. medius & Adductor magnus –> Concentric; contralat pelvis stabilization
Midstance
- Extrinsic stability of the knee
- GRF passes:
- Anterior to both ankle and knee –> Restrained ankle dorsiflexion and Knee extension
- Posterior to the hip –> Hip stabilization in coronal plane
- Critical site for dynamic stability shifts from knee to ankle
midstance muscle activation
- Soleus & Gastrocnemius –> Eccentric; control tibial forward advancement / dorsiflexion
- Gluteus medius –> Concentric; abductors stabilize pelvis in level
posture
Midstance - lower leg progresses over foot
- Extrinsic stability of knee is provided by eccentric activation of the soleus / Achilles tendon –maintains GRF anterior to the knee →knee extension
- Plantarflexion / Knee extension
couple (PF-KE) - Relieves the quadriceps; reduces the work of walking
terminal stance - acceleration
- Active ankle plantarflexion & heel rise
- Free forward fall of the body
Terminal stance GRF
- Anterior to knee & posterior to hips→Knee & hip extension
Terminal stance muscle activation
- Gastrocnemius & Soleus –> Eccentric; Stabilize tibia at the ankle then Concentric; Propulsive force for push off
- Tensor fascia lata (ant) & Iliopsoas –> Eccentric: restrains hip hyperextension
Preswing
- Weight transfer to contralateral limb
- Unlock the stance limb for swing
- Ankle plantarflexion ~20°
- Knee flexion ~40°
- Hip flexes to neutral
Preswing GRF
GRF passes through metatarsals
* Posterior to the knee
Pre swing Muscle activation
Rectus femoris –> Control excessive knee flexion; Hip flexion
* Iliopsoas
* Adductor longus –> Decelerate passive abduction caused by weight
transfer to other foot
Swing phase, 40% of gait cycle
- Swing limb as a pendulum
- The hip, knee, and ankle must flex
sufficiently for clearance
Muscles provide adequate power to
propel the limb into swing & energy
transfer between body segments:
- Triceps surae (pre-swing)
- Hip flexors (pre- & initial swing)
- Contralateral hip extensors pull
the body forward
Initial Swing
- Knee flexion ~60°
- Hip flexion ~20°
- Ankle reduces 10° of plantarflexion
What does initial swing need?
- Sufficient knee flexion for foot clearance
- Continuation of pre-swing knee flexion
- Momentum from rapid hip flexion advances femur while tibial inertia from toe push-off leads to knee flexion
Initial swing muscle activation
Iliopsoas & Rectus femoris
* Sartorius & gracilis –hip & knee flexion
* Pretibial muscles –ankle dorsiflexion
Mid swing
- Transition from knee flexion to extension
- Hip flexion to ~30
- Knee flexion decreases to ~30
- Active ankle dorsiflexes to neutral
What 2 things does midswing have
- Passive hip flexion –> Continuing flexion momentum from initial swing
- Pendular knee motion:
- Knee extension is purely passive
- Momentum of hip flexion balances out the pull of
gravity on the tibia
mid swing muscle activation
Pretibial muscles –ankle dorsiflexion
Terminal swing
deceleration of the swing limb
what 2 things does terminal swing do
Transition from swing to stance:
* Hip flexion maximal
* Knee continues to extend to neutral
* Ankle maintained in dorsiflexion
Passive hip flexion:
* Continuing flexion momentum from initial swing
terminal swing muscle activation
- Medial & lateral hamstrings –1st half of TSw –> Restrain hip flexion, Prevent excessive knee extension
- Quadriceps femoris (Vastii) –2nd half of TSw –> Complete knee extension
- Pretibial muscles –> Foot and toe clearance
look at all the graphs from joe
plantar flexion extension couple
- Midstance
- Tibia advances over stationary foot
- Stance stability & conserve energy
normally, with stable foot in line of progression:
- Gastroc-soleus contracts & Achilles tndn lengthens to control forward progression of the tibia over the foot
→directs GRF anterior to knee
→provides extensor moment at knee
→reducing demand on quadriceps
look at more joe graphs
look at all of the atypical patterns of gait
unintended effects of orthotic usage - Limitations is segmental mobility during ambulation
- Medial/Lateral heel whip
- Compensatory power generation at the hip
unintended effects of orthotic usage - Limitations in higher-level gross motor skills
- Getting up from floor
- Stair negotiation
unintended effects of orthotic usage- Long-term changes in soft tissue characteristics (Creep)
- Posterior ankle/lower leg
- Results in increased motion at other, adjacent, segments
unintended effects of orthotic usage - skin irritation/breakdown
typically do not prescribe an orthosis to “correct” a deformity
