Typical-Atypical Gait and the Impact of Orthotics

Question 1

Prerequisites of normal gait

Answer 1

*Stability in stance
*Clearance in swing
*Pre-positioning of the foot in
swing
*Adequate step-length
*Conservation of energy

Question 2

Kinematics

Answer 2

Kinematics: Study of positions, angles, velocities, accelerations of
body segments and joints during motion

Question 3

Kinetics

Answer 3

Study of the forces, moments, and
powers acting within and on the body

Question 4

Moments (or Torques)

Answer 4

moment (Nm) = Force x distance
Force is origin, direction, and magnitude

Question 5

Power

Answer 5

Power (W) = moment x joint angular velocity

Question 6

Initial Contact

Answer 6

• 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

Question 7

initial contact - muscle activation

Answer 7

• Hip extensors (G. maximus, hamstrings)
• Pre-tibial muscles

Question 8

Loading Response

Answer 8

• Shock absorption
• GRF passes:
• Posterior to ankle –> Ankle plantarflexes from neutral ~10°
• Posterior to knee –> Knee flexes
• Through the hip –> Hip less flexed; extending

Question 9

loading response muscle activation

Answer 9

• Pretibial muscles –> Eccentric; control ankle plantarflexion
• Quadriceps femoris –> Eccentric; control knee flexion
• G. medius & Adductor magnus –> Concentric; contralat pelvis stabilization

Question 10

Midstance

Answer 10

• 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

Question 11

midstance muscle activation

Answer 11

• Soleus & Gastrocnemius –> Eccentric; control tibial forward advancement / dorsiflexion
• Gluteus medius –> Concentric; abductors stabilize pelvis in level
  posture

Question 12

Midstance - lower leg progresses over foot

Answer 12

• 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

Question 13

terminal stance - acceleration

Answer 13

• Active ankle plantarflexion & heel rise
• Free forward fall of the body

Question 14

Terminal stance GRF

Answer 14

• Anterior to knee & posterior to hips→Knee & hip extension

Question 15

Terminal stance muscle activation

Answer 15

• Gastrocnemius & Soleus –> Eccentric; Stabilize tibia at the ankle then Concentric; Propulsive force for push off
• Tensor fascia lata (ant) & Iliopsoas –> Eccentric: restrains hip hyperextension

Question 16

Preswing

Answer 16

• Weight transfer to contralateral limb
• Unlock the stance limb for swing
• Ankle plantarflexion ~20°
• Knee flexion ~40°
• Hip flexes to neutral

Question 17

Preswing GRF

Answer 17

GRF passes through metatarsals
* Posterior to the knee

Question 18

Pre swing Muscle activation

Answer 18

Rectus femoris –> Control excessive knee flexion; Hip flexion
* Iliopsoas
* Adductor longus –> Decelerate passive abduction caused by weight
transfer to other foot

Question 19

Swing phase, 40% of gait cycle

Answer 19

• Swing limb as a pendulum
• The hip, knee, and ankle must flex
  sufficiently for clearance

Question 20

Muscles provide adequate power to
propel the limb into swing & energy
transfer between body segments:

Answer 20

• Triceps surae (pre-swing)
• Hip flexors (pre- & initial swing)
• Contralateral hip extensors pull
  the body forward

Question 21

Initial Swing

Answer 21

• Knee flexion ~60°
• Hip flexion ~20°
• Ankle reduces 10° of plantarflexion

Question 22

What does initial swing need?

Answer 22

• 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

Question 23

Initial swing muscle activation

Answer 23

Iliopsoas & Rectus femoris
* Sartorius & gracilis –hip & knee flexion
* Pretibial muscles –ankle dorsiflexion

Question 24

Mid swing

Answer 24

• Transition from knee flexion to extension
• Hip flexion to ~30
• Knee flexion decreases to ~30
• Active ankle dorsiflexes to neutral

Question 25

What 2 things does midswing have

Answer 25

* 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

Question 26

mid swing muscle activation

Answer 26

Pretibial muscles –ankle dorsiflexion

Question 27

Terminal swing

Answer 27

deceleration of the swing limb

Question 28

what 2 things does terminal swing do

Answer 28

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

Question 29

terminal swing muscle activation

Answer 29

* 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

Question 30

look at all the graphs from joe

Question 31

plantar flexion extension couple

Answer 31

* Midstance * Tibia advances over stationary foot * Stance stability & conserve energy

Question 32

normally, with stable foot in line of progression:

Answer 32

* 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

Question 33

look at more joe graphs

Question 34

look at all of the atypical patterns of gait

Question 35

unintended effects of orthotic usage - Limitations is segmental mobility during ambulation

Answer 35

* Medial/Lateral heel whip * Compensatory power generation at the hip

Question 36

unintended effects of orthotic usage - Limitations in higher-level gross motor skills

Answer 36

* Getting up from floor * Stair negotiation

Question 37

unintended effects of orthotic usage- Long-term changes in soft tissue characteristics (Creep)

Answer 37

* Posterior ankle/lower leg * Results in increased motion at other, adjacent, segments

Question 38

unintended effects of orthotic usage - skin irritation/breakdown

Answer 38

typically do not prescribe an orthosis to "correct" a deformity