Gait and Posture

Question 1

What is meant by “gait and posture”?

What kind of activities could be involved?

Answer 1

gait and posture refers to all activities that we do that transfer the weight of our body and move us in a certain direction

• going from sitting to standing
• standing still
• walking
• running
• jumping
• climbing steps
• rowing
• cycling

Question 2

What is bipedalism?

Answer 2

the way in which humans walk using two legs, rather than 4

Question 3

Why do toddlers tend to crawl before learning how to walk?

Answer 3

not all babies crawl before walking

muscle mass has not developed enough

toddlers are going through a rapid change in brain development and they do not have the coordination / balance yet to be able to walk on 2 legs

when babies start to stand, they tend to hold onto things and pull themselves up to stand and balance

Question 4

What is shown in this image and what does it suggest?

Answer 4

“Lucy” - a skeleton found showing a very small / short figure

but had the anatomy of a biped - broad pelvis and femurs angled towards the midline

Question 5

When did hominids start to grow taller?

Why did this happen?

Answer 5

the first hominids could walk upright but still have features of a more primitive species - short legs and long arms

1.9 million years ago hominids grew taller, with longer legs

there are many theories about why we move on 2 feet, but no definitive answer

e.g. change of environment made being bipedal more advantageous

Question 6

What is gait?

Answer 6

how we translocate the centre of body mass in the direction of locomotion

joint motion, muscle activity and load bearing of limbs is generally symmetrical

gait is a cyclic activity with each cycle lasting about 1 second

Question 7

Why do we study gait?

Answer 7

physicians need sound knowledge of normal gait so they can accurately detect and interpret deviations from normal gait pattern

it is important to note that each individual displays certain variations from the norm, which are superimposed on the normal pattern of walking

Question 8

Is everyone’s gait the same?

Answer 8

everybody has their own characterisitc pattern:

• stride length
• pelvic movement
• upper body position

Question 9

What factors affect gait in normal people?

Answer 9

• height
• weight
• build
• clothing
• shoes
• weight carriage
• age

Question 10

What is meant by “weight carriage” affecting gait?

Answer 10

someone being heavier can affect their gait in different ways

an overweight person tends to walk with wider gait

in pregnancy, the weight is not evenly distributed around the body so this will affect their gait differently

Question 11

How does alcohol affect gait?

Answer 11

alcohol affects the cerebellum, which is important for balance and posture

posture / gait becomes abnormal and unsteady when the cerebellum is affected by alcohol

the cerebellum can become atrophied if someone abuses alcohol over a long period of time

patients with an alcohol problem have an irreversible change in their gait - tend to have a wider base & difficulty with balance

Question 12

What 4 factors does normal gait rely on?

Answer 12

Joints:

• intact bones & well functioning joints

Muscles:

• adequate muscle strength to support joints / bodyweight

Nerves:

• CNS & PNS supply the muscles

Vision:

• including vestibular and auditory systems

Question 13

What is the importance of vision in ensuring normal gait?

Answer 13

provides information about the movement of the head and body relative to the surroundings

it is important for the automatic balance responses to changes in surface conditions

once visual cues are taken away, gait changes and people do not move as fluidly or quickly as they are thinking about potential danger

Question 14

What are the stages involved in learning to walk?

By what age is this usually complete?

Answer 14

• sitting without support
• standing with assistance
• hands and knees crawling
• walking with assitance
• standing alone
• walking alone

the time frame is very variable but most babies are walking by 18 months

they tend to start by pulling themselves up using furniture and using this to balance as they pull themselves along

Question 15

What are the main factors influencing gait changes in the elderly?

Answer 15

• decreased muscle bulk
• decreased strength and flexibility
• some loss of hearing and vision

Question 16

Why is it important to encourage elderly people to stay active?

Answer 16

from age 35, people start to lose muscle mass

muscle atrophy is present in the elderly, affecting their gait, even if they do not have any pathology

encouraging the elderly to stay active and maintain the muscle mass reduces the risk of falls

Question 17

What are the gait changes that can be seen in the elderly?

Answer 17

major changes:

• reduction in velocity
• reduction in step / stride length

minor changes:

• decreased arm swing
• decreased rotation of the pelvis

to increase velocity, the elderly tend to take more steps instead of increasing stride length

Question 18

What is the difference in the way drunk and elderly people fall?

Answer 18

elderly:

• elderly people tend to fall forwards and sustain facial injuries
• taking more shorter steps increases this risk

drunk people:

• drunk people tend to fall backwards
• this also affects people with cerebellar damage

Question 19

What is different in the elderly when it comes to heel strike?

Answer 19

they have a more flat-footed approach to both heel strike and push off

Question 20

Why are many muscles active during standing?

Answer 20

standing supports body weight and minimises energy expenditure

the hips and knees are stable as they are extended

this minimises the need for muscular contraction during standing

Question 21

Where is the centre of gravity of the body?

Answer 21

centre of gravity is just anterior to S2 vertebra

it is slightly posterior to the hips

it is anterior to the knee and ankle

muscles in the leg need to be active during standing to maintain the centre of gravity and keep us upright

Question 22

What is the consequence of the centre of gravity passing anterior to the ankle joint?

How is this counteracted?

Answer 22

this leads to a tendency to fall forwards - “forward sway”

this is counteracted by contraction of the plantar flexors

particularly soleus, but also gastrocnemius

the plantar flexors are the muscles which would point the toes towards the floor

Question 23

What are the 2 phases of the gait cycle?

Answer 23

stance phase:

• makes up 60% of the gait cycle
• the foot is in contact with the ground

swing phase:

• makes up 40% of the gait cycle
• the foot is in the air

the start and end of the stance phase is marked by a short period of double support (10%) in which both feet are on the ground

Question 24

What are the 7 stages involved in the gait cycle?

Answer 24

• heel strike (initial contact)
• loading response (foot flat)
• midstance
• terminal stance (heel off)
• preswing (toe off)
• initial and midswing
• terminal swing

Question 25

Which stages of the gait cycle are part of the stance phase and swing phase?

Answer 25

**stance phase:** * heel strike * loading response * mid-stance * terminal stance * pre-swing **swing phase:** * initial swing * mid-swing * terminal swing

Question 26

What is a dynamic muscle contraction and the two types?

Answer 26

a muscle contraction in which there is a **change in length** **concentric contraction:** * muscle shortens while contracting **eccentric contraction:** * muscle lengthens while contracting

Question 27

What is an isometric muscle contraction?

Answer 27

a muscle contraction in which there is **no change in length**

Question 28

When does the heel strike phase begin? Which muscles are involved in this phase?

Answer 28

* begins when heel strikes the ground * lowering of forefoot to the ground is controlled by ***eccentric contraction*** of **tibialis anterior** * deceleration of forward momentum acheived by ***hip extension*** by **gluteus maximus** * ankle and subtalar joints accommodate terrain

Question 29

What is the loading response? Which muscles are involved in this phase?

Answer 29

* the foot comes into full contact with the ground * bodyweight is transferred to stance limb * ***knee extension*** by **quadriceps femoris** prevents the knee from buckling under the weight

Question 30

What happens during the mid-stance phase? Which muscles are involved in this phase?

Answer 30

* the opposite limb swings past the stance limb * it requires ***stabilisation of the pelvis*** to keep it level * this is acheived by ***abduction of the hip*** by **gluteus medius** and **gluteus minimus** * these muscles contract and pull the pelvis to keep it level and stop it swaying to the opposite side when the foot is taken off the ground

Question 31

What happens during the terminal stance phase? Which muscles are involved?

Answer 31

* the heel starts to lift off of the ground * this is achieved by the plantar flexors - **soleus** & **gastrocnemius** * this also ***accelerates mass forwards*** and pushes us forwards

Question 32

What is involved in the pre-swing (toe-off) phase? Which muscles are involved?

Answer 32

* final stage of the stance phase in preparation for moving into swing phase * powerful **plantarflexion of digits** to push off from the ground and accelerate mass forwards (mainly big toe) * preparation for ***hip flexion*** by eccentric contraction of **rectus femoris**

Question 33

Which digit / muscles are essential for toe-off?

Answer 33

**hallux** is essential for toe-off it is stabilised by **adductor hallucis** and **abductor hallucis brevis** misaligned or missing hallux can cause problems

Question 34

What are examples of conditions in which a missing or misaligned hallux can cause problems? How does this affect gait?

Answer 34

* hallux amputation in diabetes * hallux valgus weak push off ***(apropulsive gait)*** results in: * shorter stride length * decreased gait velocity

Question 35

What happens during the initial and mid-swing phases? Which muscles are involved?

Answer 35

* hip flexion carries the limb forwards - **iliopsoas** and **rectus femoris** * **tibialis anterior** leads to dorsiflexion of the toe and foot to allow the foot to clear the ground * knee flexion occurs to shorten the limb - **hamstrings**

Question 36

What is involved in the terminal swing phase? What muscles are involved?

Answer 36

* **quadriceps** ensures knee flexion is greater than extension to place the foot in the correct position ready for heel-strike * this is assisted by ***dorsiflexion of ankle*** ***-*** **tibialis anterior** * eccentric contraction of **hamstrings** decelerates limb in preparation for heel-strike * end of swing phase signifies 1 complete gait cycle of one lower limb

Question 37

What is the solution when limited knee flexion means that the limb can't be shortened?

Answer 37

**limb circumduction** the swinging leg moves in an arc rather than straight forwards this increases the ground clearance of the swing foot

Question 38

What is the problem associated with foot-drop? Which nerve is injured and how does the person compensate?

Answer 38

the foot cannot be dorsiflexed there is initial toe/forefoot contact with the ground rather than the heel meaning there is no push off injury to the **deep fibular nerve** this supplies the anterior compartment muscles which dorsiflex the ankle and foot so that the toes do not touch the ground

Question 39

Why is it important for the body's centre of gravity to be fairly constant?

Answer 39

it minimises energy expenditure so that walking is extremely energy efficient as you walk, the action of the muscles limits the vertical rise (up and down) of the pelvis and the lateral shift

Question 40

How does pelvic drop affect the centre of gravity? Which muscles control this and what type of gait does this lead to?

Answer 40

pelvic drop to the swing side minimises rise in centre of gravity abduction on stance side controls and limits the drop - abductor muscles maintain pelvic stability pelvic drop leads to **Trendelenberg gait**, which is seen in: * stroke * hip osteoarthritis * cerebral palsy * superior gluteal nerve damage

Question 41

What is the role of the hip adductors in maintaining centre of gravity?

Answer 41

hip adduction minimises **lateral shift** in C of G adductors pull the knees towards the midline to limit lateral shift in centre of gravity during walking this prevents broad gait when walking and makes it more streamlined, as we walk with one foot in front of the other