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1
Q

what is kinetics

A

the study of forces that cause motion

(forces, torques)

“the study of forces associated with motion using force plates, pressure platforms and/or inshoe sensors providing a direct description/orientation of foot posture”

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2
Q

what is kinematics

A

the study of describing movements

(velocity, acceleration)

“related to the measurement of motion irrespective of the forces involved using cameras to observe the intersegmental relationship of the trunk and limbs”

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3
Q

what is the role of the human foot

A

provides support and balance during standing

stabilises the body during gait

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4
Q

what does the foot have to do during stance phase (between heel strike and toe off)

A

to adapt to a changing patter of loading as the centre of mass of the body moves

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5
Q

what is the GRF

A

ground reaction force

equal and opposite reaction when the foot comes into contact with the ground

changes in direction and magnitude as the body propels itself forwards

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6
Q

what are the important mechanical structures of the foot

3 things

A

1 - the bony skeleton, which together with the ligaments and arches, provides relative rigidity and lever arm mechanism required to maintain balance

2 - joints which allow felxibility

3 - muscle and tendons which control foot movement

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7
Q

what does the foot need to do during the stance phase and what does failure to do so lead to

A

distribute and dissipate compressive, tensile, shearing, and rotatory forces

failure can lead to abnormal movements which produces excessive stress which can result in the breakdown of soft tissue and muscle

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8
Q

how many bones are in the foot

A

26

  • 7 tarsals
  • 5 metatarsals
  • 14 phalanges
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9
Q

how many joints are in the foot

A

6

  • ankle
  • subtalar
  • midtarsal
  • tarsometatarsal
  • MTP
  • IP
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10
Q

what are the 4 segments of the foot

A

hindfoot
midfoot
forefoot
phalanges

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11
Q

what does the hindfoot consist of

A

talus

calcaneus

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12
Q

what is the function of the talus bone

A

orientated to transmit reactive forces from the foot through the ankle joint to the leg

lies between the calcaneus and tibia

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13
Q

what is the function of the calcaneus

A

largest and most posterior bone in the foot and provides a lever arm for the insertion of the Achilles tendon

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14
Q

what muscles acts through the achilles tendon and what do they do

A

gastrocnemius and soleus

impart powerful plantarfexion forces to the foot

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15
Q

what does the height, width and structure of the calcaneus allow it to do

A

withstand high tensile, bending and compressive forces on a regular basis w/out damage

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16
Q

what makes up the midfoot

A

navicular, the cuboid and three cuneiforms

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17
Q

what is the main role of the navicular bone

A

is the keystone for the medial longitudinal arch

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18
Q

what is the function of the cuneiforms

A

articulate with the first, second and third metatarsals distally

contribute to stability of midfoot

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19
Q

what makes up the forefoot

A

5 metatarsals

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20
Q

how is the first metatarsal different from the others

A

is the shortest and widest

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21
Q

how does the second metatarsal compare to the first

A

extends beyond the first

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22
Q

what is the second metatarsal so important

A

articulates with the intermediate,medial and lateral cuneiforms in a ‘key-like’ configuration which promotes stability

makes it the stiffest and most stable portion of the foot playing a key role in stabilizing foot posture after hallux surgery.

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23
Q

why attaches to the styloid, laterally and proximally on the fifth metatarsal and what injury can happen here as a result

A

the peroneus brevis tendon inserts

Avulsion # of the styloid commonly occurs when the foot is inverted against the contracting peroneus brevis muscle

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24
Q

what do the toes (phalanges) contribute to

A

weight bearing and load distribution

propulsion during the push-of phase of gait.

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25
Q

what are the 3 planes of motion in joints

A

sagittal plane
frontal (coronal) plane
transverse

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26
Q

what joints of the foot have one degree of freedom (i.e. only move in one plane)

A

subtalar
ankle
tarsometatarsal

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27
Q

what joints of the foot have two degree of freedom (i.e. move in two plane) and what are the 2 planes

A

midtarsal
MTP
IP joints

adduction-abduction
dorsiflexion-plantarflexion

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28
Q

what does the ankle joint consist of and what motion does it allow

A

articulation between distal part of the tibia and the body of the talus

dorsiflexion and plantarflexion

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29
Q

what is the ROM need at the ankle joint for normal locomotion

A

10 degrees of dorsiflexion

20 degrees of plantarflexion

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30
Q

why is there instability in the ankle joint during plantarflexion

A

has slight movement in transverse plane during plantarflexion

causing instability of the joint in this position

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31
Q

what is included in the subtalar joint

A

the talocalcaneal joint and the talocalcaneal part of the talocalcaneonavicular joint

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32
Q

at what degree does the axis of motion pass through the subtalar joint

A

42 degrees from the Transverse plane and 16 degree from the sagittal plane

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33
Q

what are the motions permitted at the subtalar joint

A

supination

pronation

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34
Q

what together forms the midtarsal joint

A

The talonavicular and the calcaneocuboid joints

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35
Q

what are the two axis of motion of the midtarsal joint and what motion does it contribute to

A

oblique axis
longitudinal axis

pronation/supination

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36
Q

what is the ROM at the MTP joint

A

up to 90 degrees extension

only few degrees flexion

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37
Q

what is ROM for IP joints

A

allow extension (related to abduction)

allow flexion (related to adduction)

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38
Q

what is the medial arch comprised of

A

the calcaneus, talus, navicular, the three cuneiforms and their three metatarsals

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39
Q

what are the pillars of the medial arch

A

tuberosity of the calcaneus posteriorly

heads of the medial three metatarsal bones anteriorly

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40
Q

what is the lateral arch comprised of

A

calcaneus, the cuboid and the lateral two metatarsals

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41
Q

how does the tension in the MA and LA change during walking

A

relatively rigid in standing but become more compliant during walking; the MA being the more flexible of the two

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42
Q

there is also a series of transverse arches - where are they centered round

A

the MTP joints

- form a convex curve in the direction of the dorsum

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43
Q

what happens to the TA’s during walking

A

disappear and flatten to varying degrees during weight bearing

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44
Q

what supports the integrity of the arches

A

ligaments (particularly in LA)
muscles (particularly in MA)
tendons

provide strength, flexibility and movement.

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45
Q

what are the two groups of muscles operating on the foot

A

extrinsic muscles - from lower leg

intrinsic muscles - within foot itself

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46
Q

what is the function of the muscles during locomotion

A

provide stability and balance during standing

and a strong lever arm effect during propulsion

47
Q

what are most of the problems associated with foot disorders related to

A

the weight bearing process at the foot-ground or foot/shoe-ground interface

48
Q

what is the reference for one full gait cycle (GC) and what is the time interval known as

A

time interval between two consecutive heel strikes of the same foot on the ground

time interval known as stride time

49
Q

stages of GC

A 
heel strike 
forefoot loading 
midstance
heel off
toe off
50
Q

what are the 2 phases of GC

A 
stance phase (60%)
swing phase (40%)
51
Q

what is double support in GC

A

when both feet are in touch with the ground

lasts 10% of GC and occurs twice in any GC

52
Q

what counteracts the GRF

A

function of the lower limb muscles in conjunction with bones, joints and tendons of the foot

53
Q

what is the function of lower limb muscles during gait

A

to stabilise and accelerate/decelerate the foot during both wt bearing and propulsion

54
Q

some muscles in lower limb have more than one function - what roles does the long extensors have

A
  • stabilise the joints of the toes during propulsion
  • serve as accelerators in ankle joint dorsiflexion following toe off
  • assist as decelerators of the foot at HS
55
Q

some muscles in lower limb have more than one function - what roles does the tibialis anterior have

A
  • decelerates the foot following HS

- accelerates to assist in ankle joint dorsiflexion following TO.

56
Q

what occurs very shortly after HS

A

transient period

  • GRF is anterior to both ankle and knee joint
  • lasts between 10 and 20ms
57
Q

how does the location of the GRF change after HS and what does this create

A

changes to a location posterior to both joints (ankle and knee)

creates an external plantarflexion moment around the ankle joint

58
Q

what happens instantaneously when this external plantarflexion moment occurs

A

the tibialis anterior and the extensor hallucis longus muscle contract eccentrically

producing an internal dorsiflexion moment which decelerates the rate of ankle joint plantarflexion

59
Q

what does the combo of the external plantarflexion moment and the internal dorsiflexion moment allow

A

synergistic action of these two muscle groups allows the foot to passively plantarflex in a smooth, regulated manner

ankle joint plantarflexion is virtually stopped synchronously with the forefoot making contact with the ground.

60
Q

how is the subtalar joint, ankle and leg positioned during HS

A

subtalar - inverted
ankle - dorsiflexed
leg - internally rotated

61
Q

what time delay was observed in the tibialis anterior in diabetic patients and what does this mean

A

180ms

late firing means normal modulating role of the muscle in lowering foot to the ground after HS is disturbed

leads to forefoot slap and high plantar pressure

62
Q

during initial movement, what is the only part of the forefoot that makes contact with the ground and what happens as weight is transferred

A

the lateral side of the forefoot

as wt transferred to the forefoot, the effect of the GRF on the lateral side tends to evert the forefoot against resistance caused by contraction of TA

63
Q

what does controlled relaxation of TA facilitate

A

smooth progressive loading of the forefoot from lateral to medial locations

GRF can evert the forefoot until full foot contact is achieved and loading is then transferred from lateral to medial side

64
Q

what happens after HS but before forefoot contact

A

the calf muscles, i.e. the tibialis posterior, soleus and gastrocnemius, begin to contract

65
Q

what do the calf muscles work to do

A

function to collectively decelerate subtalar joint pronation and internal leg rotation

continue to contract throughout MS phase

relax at HO

66
Q

what happens to GRF during forefoot loading

A

GRF maintains its posterior direction but w/ increasing magnitude until MS

it then moves anteriorly along the foot - causes GRF to become smaller and ultimately reverse in direction [i.e. still posterior to the knee joint but now anterior to ankle joint]m

67
Q

what happens at the beginning of the MS period

A

the posterior calf muscles become prime movers which initiate subtalar joint supination and external leg rotation.

Both the TP and soleus have attachments which create significant lever arms relative to the axis of motion of the subtalar joint.

68
Q

what happens in relation to ankle after forefoot contact

A

the ankle is plantarflexed, and following this, the ankle joint begins to dorsiflex as the tibia moves forwards, over the foot.

tibia continues to move forward causing ankle joint dorsiflexion throughout MS period until point of HO

69
Q

what does deceleration of forward tibial momentum also do

A

extend the knee in preparation for HO

[muscles which decelerate the forward momentum of the tibia to assist in knee extension are those which have significant lever arms for ankle joint plantarflexion]

70
Q

what are the muscles that decelerate the forward momentum of the tibia/ have significant lever arms for ankle joint plantarflexion

[muscle that is also ankle joint plantarflexor]

A

tibialis posterior, soleus, and flexor digitorum longus

[gastrocnemius]

71
Q

what stabilises the lesser tarus during the MS period and how do they do this

A

in early MS
- soleus, tibialis posterior, peroneus longus, and peroneus brevis muscles

soleus
- maintains the Sp stability of the cuboid in order to serve as an effective pulley for the function of peroneus longus

peroneus longus
- pulls the first ray laterally against the lesser tarsus

TP
- pulls the lesser tarsal bones medially.

overall effect
- compresses the lesser tarsus in the Tp, thus producing medio-lateral stability

72
Q

how does the peroneus brevis complement the function of peroneus longus to help in maintaining transverse stability of the lesser tarsus during stance phase

A

the magnitude of the adduction force generated by TP exceeds that of the abduction force exerted by the peroneus longus.

peroneus brevis exerts an additional abduction force upon the lesser tarsus to thereby neutralize the otherwise existing imbalance.

73
Q

when the foot is fully pronated what facilitates further abduction

A

pronation of the subtalar joint

[in CP, entire foot may be pronated into a flat foot position, called peroneal spastic flatfoot]

74
Q

at HO, where is the GRF and what does it cause

A

anterior in relation to both ankle and knee joints creating an external dorsiflexor moment which is opposed by both the soleus and gastrocnemius muscles

75
Q

what happens following HO in regards in terms of wt bearing and what happens simultaneously

A

foot momentarily bears full body weight alone

the vertical GRF generated exceeds that of bodyweight and the ball of the foot is also subjected to torque and high shear forces.

76
Q

what is the major function of the intrinsic muscles during second half of MS phase

A

provide the tensile forces necessary to stabilise the bones of the metatarus and lesser tarus transversely and posteriorly against one another.

[when foot is abnormally pronated the IM muscles must function longer and stronger]

77
Q

what interaction allows for the action of heel rise

A

interaction between forward momentum of the body, deceleration of the tibia, and passive knee flexion

78
Q

what happens at the end of MS

A

the trunk is directed forwards relative to the foot, and the body is falling forwards over the weight-bearing foot.

Forward trunk momentum carries the thigh and leg with it

79
Q

what does the knee do immediately prior to heel rise and what does the tibia do thereafter

A

begin to flex

tibia continues to move forward while the heel rises, maintaining ankle dorsiflexion into the early propulsion period

80
Q

what muscles are responsible for tibia deceleration

A

TP, gastrocnemius and soleus with later assistance from the FDL and peroneus longus

81
Q

what halts knee extension just before heel rise

A

contraction of the gastrocnemius muscle

82
Q

what does the ankle do during propulsion phase

A

initially dorsiflexes slightly and then plantarflexes until TO

Shortly after heel rise, ankle dorsiflexion is stopped consequent to the weight no longer passing through the heel

calf muscles then plantarflex ankle

83
Q

during the early stage of propulsion, what muscles are contributing to ankle joint plantarflexion

A

gastrocnemius, soleus, peroneus longus

transverse pedis - transverse stabiliser of the forefoot.

84
Q

what happens shortly after heel rise and what muscles are involved

A

the lateral side of the foot lifts from the ground

weight is transferred to the medial side of forefoot where it concentrates on the great toe

peroneus longus and brevis

85
Q

The long and short plantarflexors of the lesser digits stabilise the toes against the ground - but they cannot do so unless what

A

toes are converted into rigid beams by extensor mechanism.

86
Q

what factors influence propulsion phase stability of the great toe

A

stability and plantarflexion of the first ray

normal sesamoid function

normal strength and function of the muscles responsible for hallux, and first MTP joint stability.

87
Q

what movement must the hallux be able to do during final propulsion

A

65-70 degrees of dorsiflexion on the first metatarsal

or it will sublux at the first MTP joint and become unstable

88
Q

where is GRF just prior to toe off

A

anterior to the ankle and posterior to the knee

89
Q

what happens immediately before TO and what does this create

A

tibialis anterior begins to contract (until mid swing)

creates a smaller dorsiflexor moment around the ankle joint which helps in clearing the foot off the ground

90
Q

what is an issue with gait analysis labs

A

have not proven to be cost effective

91
Q

what is problems facing analysis in gait labs

A

type of analysis dependant on type of equipment and expertise of used

up to 1 and a half hour needed per subject to record gait data

92
Q

what is GaitRite

A

portable gait analysis system,

relatively cheap, easy to use and provide an almost complete analysis instantaneously

93
Q

what conditions is GaitRite useful for

A

“shuffling gait” and those with low assessment tolerance

e.g. Parkinson’s disease

94
Q

disadvantage of GaitRite

A

incompetent in providing inter-segmental relationship

crucial in patients with CP

95
Q

devices that are add-ons to measuring gait and pressure

A

portable electromyography

goniometry

energy expenditure.

96
Q

what does measuring pressure tell you

A 
gait cycle 
pressure points
gait pattern
foot print and posture
centre of pressure
97
Q

what is foot/ankle proprioception

A

awareness of the position and motion of the foot joints in space with the ability to accurately match reference joint angles without visual feedback

98
Q

how many injuries resulting in time lost through injury in running and jumping sports involve the ankle

A

20-25%

99
Q

in ruptures of the fibular collateral ligament, what was functional instability suggested to be

A

mechanical instability

peroneal weakness

tibio-fibular strain and proprioceptive deficit

100
Q

what are pilon fractures and how does it occur

A

fracture of distal part of the tibia involving the articular surface of the ankle

result of an axial loading injury which drives the talus into the tibia

101
Q

what foot movements lead to injury

A

internal rotation
external rotation
abduction
adduction

102
Q

extrinsic risk factors for the ankle

A

training errors, type of activity (e.g. sport), exercise time, equipment and environmental conditions

103
Q

intrinsic risk factors for the ankle

A

height, weight and previous Hx of ankle sprain = lateral ankle sprain

muscle strength imbalance = eversion-to-inversion strength ratio and greater plantarflexion strength = higher incidence of inversion ankle sprain

104
Q

Ankle injuries are fewer in unshod populations - what does this suggest

A

shoes may alter the ability of the protective mechanisms around the ankle in preventing damage

may be due to increased leverage at the ankle confirmed by the unnatural high heel and reduction of foot/ground sensation

105
Q

what shoes had a 123% greater injury frequency of the lower limb compared to cheap shoes

A

expensive athletic shoes to that advertised safeguard feet through ‘cushioning impact’

106
Q

what is general rules for treating a patient

A

Avoid Trial and Error Management

Always try to find the primary cause of the problem

Never treat the secondary symptoms without
knowing the primary cause

107
Q

what can form as the results of friction with the inner shoe

A

dorsal callus formation

108
Q

what causes damage in high heel shoes

A

forward shift of the centre of mass

  • results in increased pressure under the metatarsal heads and toes
  • results in abnormal joint and muscles function within the foot and lower leg
  • results in ultimately abnormal balance, proprioception and body posture
109
Q

what are the Sx that high heels cause

A

damage to calf muscles

painful knees and strained back muscles

enlarged joints

damage to soles and arches

hard skin/corns/bunions

deformed toes

110
Q

what question can you ask the patient to find out if the shoes are causing the pain

A

do you get the same pains when you walk barefooted?

111
Q

what is a compensatory measure for push off from the forefoot seen after shortening of the first rays (case B)

A

higher pressure values under the lesser toes

112
Q

why did a dome/button insole not work with the women with shortening of the first rays (case B)

A

elevated the 2nd, 3rd and 4th metatarsal shafts which further extended the lesser toes and in turn increased the pressure under them

113
Q

what was done for the women w/ increased pressure under her lesser toes (case B)

A

1 - transverse rocker that facilitates the transfer of load from the lateral to medial aspects of the foot

2- longitudinal rocker compensates for the first ray shortening and assists at the push off stage

114
Q

what did wearing shoes smaller than the patients right foot cause (case C)

A

caused abnormal longitudinal forces along the first ray in addition to the irritation caused by the built-in arch

problem was localised around the mid-pt of the flexor hallucis longus (FHL)

BMSc SB (18 decks)

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