Lower Limb Injuries and Gait

Question 1

Gait Cycle

Answer 1

• Repetitive, alternating, plantar flexion with balance and stability
• 1 cycle: heel strikes floor > same heel strikes floor
• Each limb has own cycle
  
  • Out of phase with each other
• Phases
  
  • Stance
    
    • Limb in contact with ground
  • Swing
    
    • Limb not in contact with ground

Question 2

Heel Strike

Answer 2

At heel strike there is a tendency for:

• Flexion at the hip which is controlled by the gluteus maximus and hamstrings
• Flexion at the knee which is controlled by the quadriceps femoris plantar
• Flexion at the ankle which is controlled by the dorsiflexors (e.g. tibialis anterior)

Question 3

Midstance

Answer 3

At midstance there is a tendency for:

• Adduction at the hip which is resisted by the gluteus medius and gluteus minimus
• Flexion at the knee which is resisted by the quadriceps femoris
• Dorsiflexion at the ankle which is resisted by the gastrocnemius and soleus

Question 4

Propulsion and Efficiency

Answer 4

Propulsion

• Plantar flexors
  
  • Gastrocnemius
  • Soleus
• Plantar flexion at ankle > pushes ground down and back = ground pushes up and forward (Newton 3^rd law)

Efficiency

• Reduce excursion of COG from direction other than intended
• Vertical
  
  • COG minimized by knee flexion
• Lateral
  
  • COG minimized by having each foot pass through stance close to median plane of body > rotate pelvis around hip of supporting limb

Question 5

Gluteus maximus “lurching gait”

Answer 5

• Innervated by inferior gluteal nerve
  
  • L5, S1-2
• Active at heel strike > prevents flexion at the hip
• Weak/paralyzed > patient fall forward
• Compensate
  
  • Displace upper torso mass posteriorly at heel strike
  • Moves line of force posterior to axis of rotation at hip
• Observe
  
  • Side of heel strike at lurch = side of weak gluteus maximus

Question 6

Gluteus Medius and Gluteus Minimus “Trendelenberg gait”

Answer 6

• Innervated by superior gluteal nerve
  
  • L4-5, S1
• Active at midstance > prevents gravitational adduction of the pelvis at hip
• Weak/paralyzed > patient fall toward unsupported side
• Compensate
  
  • Displace mass of upper torso towards supported side at midstance
  • Moves the line of gravity lateral to the axis of rotation at the hip
  • Gravity as hip adductor > gravity as hip abductor
• Observe
  
  • At midstance unsupported side of pelvis drops

Question 7

Quadriceps femoris

Answer 7

• Innervated by femoral nerve
  
  • L2-4
• Active thorugh stance phase > controls gravitational flexion of thigh at knee
• Weak/paralyzed > knee buckle and fall
• Compensate
  
  • Stance phase with knee fully extended and locked
  • Lean forward > push femur back
  • Moves axis of rotation at the knee posterior to the line of force
  • Gravity as knee flexor > gravity as a knee extensor
• Observe
  
  • Ground pushes foot and leg forward with knee extended
  • Vertical excursion of COG > less efficient

Question 8

Anterior Tibial Muscles

“Steppage gait” or “circumduction”

Answer 8

• Tibialis anterior, extensor halluces longus, extensor digitorum
• Innervated by deep fibular nerve (peroneal)
  
  • L4-5, S1
• Active during swing phase > dorsiflex foot (clear ground)
• Very active at heel strike > gradually lower foot to flat position
• Weak > dorsiflex at swing, but slap foot at heel strike “foot slap”
• Paralyzed > toe strike instead of heel strike “foot drop”
  
  • Compensate
    
    • Increase flexion and hip and knee
    • Circumduct limb

Question 9

Fibular (Peroneal) Muscles

Answer 9

Fibular (Peroneal) Muscles

• Innervated by superficial fibular nerve
  
  • L5, S1-2
• Fibularis (peroneus) longus and brevis = ankle eversion
• Common fibular nerve lesion > anterior tibila muscles AND fibular muscles paralyzed > swing phase foot will be inverted and plantar flexed
• Compensate
  
  • Circumduct so plantar surface is flat and not inverted at time of contact with ground