20. Walking and Gait

Question 1

What is gait?

Answer 1

• Mechanism by which the body is transported using co-ordinated movements of the major lower limb joints
• requires an energy- efficient interaction between the MSK and neurological systems

Question 2

What two phases does gait consist of?

Answer 2

1) Stance phase: 60% of cycle - time in which the foot is in contact with the ground and is bearing weight
2) Swing phase: 40% of cycle - time during which the foot is not in contact with the ground

Question 3

What is the gait cycle?

Answer 3

Describes the period of time from initial contact to next initial contact on the same side of the body

Question 4

What five important attributes are needed for normal gait?

Answer 4

1) stability in stance - must be able to transfer weight from one foot to another so must be able to stand on one leg. This requires adequate neuromuscular and proprioceptive (joint position sense) function
2) foot clearance during the swing phase - need to be able to raise the foot as we bring it forward
3) pre-positioning for initial contact - be able to prepare the position of the foot for the next stance phase
4) adequate step length - lower limb should be brought forward a suitable distance during the swing phase before making contact with the ground for the next stance phase
5) energy conservation - need to make our movements as energy-efficient as possible

Question 5

What part of the foot makes the initial contact with the ground?

Answer 5

Heel

Question 6

In diplegic gait and other pathological gaits, what part of the foot makes initial contact with the ground?

Answer 6

Toes

Question 7

What are periods of double support?

Answer 7

Where both feet are in contact with the ground

for most of the cycle when one leg is in swing phase the other is in stance phase

Question 8

What happens to the period of double support when the speed of gait increases?

Answer 8

Decreases

Question 9

when does running commence in the gait cycle?

Answer 9

as soon as there is a time in the gait cycle in which neither foot is in contact with the ground. This is called double float. The faster you run, the longer the period of double float within each gait cycle

Question 10

What happens to the length of the stance and swing phases in sprinting?

Answer 10

Reverse so that stance constitutes only

40% of the gait cycle, and swing 60%

Question 11

What is the stance phase subdivided into?

Answer 11

1) initial contact - heel strike
2) loading response - period of deceleration where the shock of the impact is absorbed by the knee and ankle joints. Person rocks forwards on their heel to prepare to bring the rest of the foot into contact with the ground
3) mid-stance - foot is flat on ground and the centre of gravity of the body is shifted from behind the foot to in front of it, ready for forward propulsion
4) terminal stance - ankle is plantarflexed and the heel of the supporting leg raises from ground
5) pre-swing - the metatarsophalangeal joints flex to give a push off by the toes

during normal walking, pre-swing occurs in one limb at the same time as the loading response in the other limb

Question 12

What is the swing phase further divided into?

Answer 12

1) initial swing - knee flexes to let foot clear the ground
2) mid-swing - hip flexes and pelvis swings forward to enable forward progression. Dorsiflexion of ankle to the neutral position
3) terminal swing - knee extends, and foot is brought close to the ground to prepare for heel strike/initial contact

Question 13

What is forward progression generated by?

Answer 13

partly by:

• push off of toes
• powerful plantarflexion of ankle
• flexion of hips and swinging movements of pelvis

Question 14

What prevents tilting of the pelvis to the unsupported side when one foot is off the ground?

Answer 14

Hip abductors (gluteus medius and minimus)

Question 15

Define stride?

Answer 15

Distance from initial contact with one leg to the next initial contact with the same leg

Question 16

Define step?

Answer 16

Distance from initial contact with one leg to initial contact with the opposite leg

two steps to every stride

Question 17

Define cadence?

Answer 17

Number of steps per minute

Question 18

How is gait analysed?

Answer 18

1) kinematic season - describes motions e.g. joint angles, displacements, velocities and accelerations
2) kinetics - describes forces and moments that cause motions

Question 19

Why do muscles produce force for gait?

Answer 19

• to provide stability and oppose gravity

- to propel body segments forward through controlled movements of joints

Question 20

How do muscles work during the stance phase of gait?

Answer 20

• during heel strike the tibialis anterior works eccentrically (contracting whilst lengthening gently) to prevent the foot slapping the ground
• during mid-stance it can relax
• during terminal stance, gastrocnemius and soleus take over to generate power needed for propulsion by powerfully plantarflexing the ankle

Question 21

What are the 3 ways in which muscles work?

Answer 21

 Concentric contraction (shortening) - acceleration and power generation
 Eccentric contraction (lengthening) - deceleration and shock absorption
 Isometric contraction (same length) - stability

Question 22

How is energy conserved during normal gait?

Answer 22

• minimising the excursion of the centre of gravity of the body
• controlling momentum e.g. by eccentric muscle contraction
• transferring energy passively between body segments by using some elasticity from tendons/ ligaments
• phasic muscle action

Question 23

What is phasic muscle action?

Answer 23

Using muscles intermittently e.g. tibialis anterior switches on for mid-swing and off for mid-stance

If a muscle contracts continuously during the gait cycle, it will fatigue much more rapidly than if it is used intermittently.

Question 24

What can gait abnormalities be caused by?

Answer 24

• nerve lesions
• joint instability
• immmobility of joints
• pain

Question 25

How are gait abnormalities observed and diagnosed?

Answer 25

observe phases of walking, lower limb joint movement, stride length, arm swing and lateral movements of the shoulders and head

Question 26

What is antalgic gait?

Answer 26

• Limping due to pain e.g. OA
• shortening stance phase of painful limb to minimise time spend weight- bearing on it
• automatically must shorten the swing phase of the unaffected limb to spend more time walking on unaffected limb
• uneven gait

Question 27

What do people with antalgic gait often use?

Answer 27

often use a walking stick to reduce the load through the painful limb. The walking stick should be used in the hand opposite the painful limb. The patient can then lean
towards the walking stick, shift their centre of gravity away from the painful limb and therefore reduce the load through it during the stance phase

Question 28

What is trendelenburg gait?

Answer 28

• hip adductors fail to prevent the pelvis dropping on the unsupported side during stance phase
• patient tries to compenate for this by swinging their torso over towards the affected side - waddling
• patient demonstrates a positive trendelenburg sign whilst standing on one leg

Question 29

What can cause trendelenburg gait?

Answer 29

• superior gluteal nerve lesions (and consequent muscle paralysis) e.g. as a complication of hip surgery or injections to the buttock
• muscle pain/ inhibition of function e.g. OA
• trauma e.g. fracture of the greater trochanter where gluteus medius inserts or dislocation of hip joint
• biomechanical hip instability e.g. developmental dysplasia of the hip

Question 30

What is hemiplegic gait?

Answer 30

• spasticity (continuous contraction) of affected side - most severe in flexor muscles of upper limb and extensor muscles of lower limb
• typically have a flexed upper limb and an extended lower limb
• cannot flex their hip, knee or ankle so in order to step they must lean towards the unaffected side of the body and then circumduct the paralysed leg
• short stance phase on affected limb - cant bear much weight on the paralysed leg
• gait comprises short step with unaffected leg followed by circumduction of affected leg

Question 31

What causes hemiplegic gait?

Answer 31

due to paralysis of one side of the body e.g. stroke, cerebral palsy trauma to CNS

Question 32

With what condition does diplegic gait often occur?

Answer 32

Cerebral palsy

Question 33

What is diplegic gait?

Answer 33

• spasticity affects both lower limbs
• patients walks very narrow-based gait (feet close together), dragging both legs and scraping their toes on the ground
• scissoring - legs cross midline due to spasticity in hip adductors
• spasticity in hamstrings means knees are slightly flexed and spasticity in the gastrocnemius and soleus results in plantar flexion of the ankles
• forefoot commonly makes initial contact

Question 34

What is high-steppage gait?

Answer 34

• weakness of ankle dorsiflexion = foot drop
• when the foot is raised in the swing phase, the absence of active dorsiflexion means it plantarflexes under gravity
• patient must flex hip more to lift foot and stop toes dragging on the floor
• during initial contact, the normal eccentric contraction of the tibialis anterior muscle is absent so foot tends to slap on the ground

Question 35

What are causes of high-steppage gait?

Answer 35

• common peroneal nerve palsy e.g. trauma following fracture of fibula neck, compression against fibular neck by tightly applied plaster, peripheral neuropathy e.g. poorly controlled diabetes
• sciatica (L4 myotome dorsiflexes ankle)
• neuromuscular disease e.g. Charcot-Marie-tooth —> hereditarily motor and sensory neuropathy

Question 36

What happens in the deep peroneal nerve is damaged but the superficial peroneal nerve is intact?

Answer 36

instead of a classical high-steppage gait, Patient may compensate for lack of dorsiflexion in swing phase by everting food in a sudden motion - eversion flick

Question 37

What is parkinsonian gait?

Answer 37

• difficult to initiate movement due to reduced dopamine
• to counteract this patient flexes neck and trunk forwards to move their centre of gravity in front of lower limbs
• very short steps - shuffling gait
• festinant giant - accelerating steps
• loss of arm swing

Question 38

What is an ataxic gait?

Answer 38

• clumsy, staggering movements
• broad-base (feet wide apart)
• hold out arms for balance
• whilst standing still may sway back and forth and side to side - titubation
• cant walk heel to toe or in a straight line

Question 39

What causes ataxia?

Answer 39

• proprioceptive - loss of awareness of position of joints
• cerebellar dysfunction - inherited, acquired e.g. stroke, acute alcohol intoxication
• vestibular damage - damage to organs of balance in inner ear

Question 40

What does the cerebellum coordinate?

Answer 40

Elements of movement e.g posture, balance, co-ordination, speech , resulting in smooth and balanced muscular activity

Question 41

What could be the causes of . Cerebellar dysfunction?

Answer 41

 Inherited – some degenerative conditions specifically affect the cerebellum
 Acquired e.g. a stroke affecting the cerebellum
 Due to acute alcohol intoxication (being ‘drunk’)