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Lower Limb > Biomechanics > Flashcards

Biomechanics Flashcards

1
Q

What is Nutation

A

anterior tilt of the base of the sacrum relative to the ilium

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2
Q

What is counternutation

A

Posterior tilt of the base of the sacrum relative to the ilium

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3
Q

the effect of angle of femur - good or bad?

A

can have positive or negative biomechanical effects

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4
Q

Coxa vara

A
  • smaller angle
  • distal is more medial
  • <125 degrees
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5
Q

coxa valga

A
  • larger angle
  • distal is more lateral
  • > 125 degrees
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6
Q

cause of change in femur neck angle inclination

A

may change as a result of a hip fracture or specific design of prosthetic hip

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7
Q

Describe femoral on pelvic motion

A

The movement of the femur upon a relatively fixed pelvis

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8
Q

Describe pelvic on femoral motion

A

The movement of the pelvis upon the relatively fixed femur

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9
Q

Anterior pelvic tilt will result in hip joint _

A

flexion

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10
Q

posterior pelvic tilt will result in hip joint _

A

extension

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11
Q

Hiking the contralateral iliac crest creates _

A

abduction

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12
Q

lowering the contralateral iliac crest creates_

A

adduction

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13
Q

osteokinematic movements of the hip

A

flexion/extension
Abduction/adduction
rotation

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14
Q

Degrees of hip flexion

A

120 degrees

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15
Q

Degrees of hip extension

A

20 degrees

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16
Q

Flexion of knee impact on hip flexion

A

with flexed knee - 120 degrees
with extended knee 70 degrees - due to the tension in the posterior thigh muscles

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17
Q

degrees of hip abduction

A

40 degrees

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18
Q

degrees of hip adduction

A

25 degrees

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19
Q

degrees of neutral hip internal rotation

A

35 degrees

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20
Q

degrees of neutral external hip rotation

A

45 degrees

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21
Q

osteokinematics of hip flexion/extension

A

sagittal plane, medial-lateral axis

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22
Q

osteokinematics of hip abduction/adduction

A

frontal plane, anterior-posterior axis

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23
Q

osteokinematics of rotation in neutral position

A

horizontal plane, vertical axis

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24
Q

osteokinematics of hip rotation at 90 degrees flexion

A

frontal plane, anterior-posterior axis

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25
Q

which muscles help single leg stance

A

gluteus medius, minimus and tensor fascia lata (the hip abductors)

Create pelvic on femoral abduction which offsets the adduction force of the body weight

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26
Q

Hip abductor moment arms -when the hip abductor torque can’t offset the body weight torque …

A

the pelvis will drop to the contralateral side

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27
Q

Trendelenburg’s sign

A

When the pelvis drops to the opposite side during a single-leg stance

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28
Q

The angle between lateral aspect of the femur and tibia

A

170-175 degrees

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29
Q

Genu valgum

A

Decreased angle at the lateral aspect of the knee
Approx less than 170 degrees
“knock knees”

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30
Q

Genu Varum

A

Increased angle at lateral aspect of the knee
greater than 180 degrees
“bow legged”

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31
Q

excessive genu valgum places increased load on the ___ aspect of the knee

A

lateral

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32
Q

excessive genu varus places increased load on the ___ aspect of the knee

A

medial

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33
Q

How could genu valgum and genu varus affect the patellofemoral alignment

A

as the patella sits in the middle of the longitudinal axis od rotation of the lower limb, any deviation can also affect patellofemoral mechanics

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34
Q

What is the Q angle

A

A measurement of the angle of the quadriceps pull

It is determined by the intersection of
1. a line running from the central patella to the anterior superior iliac spine (the force of the quadriceps)
2. a line intersecting the tibial tuberosity and middle patella

13-15 degrees - varies

(due to the oblique angle of the femur, when the quadriceps femoris muscle contracts, it pulls the patella superiorly and in a small degree laterally

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35
Q

Factors influencing the Q angle and patella position

A

Global factors - related to the alignment of bones and joints
- sex, excessive genu valgum, tibial torsion(rotation), foot mechanics (pronation, supination)

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36
Q

Patellofemoral joint factors

A
  • forces should be balanced to allow it to move optimally during flexion and extension
  • if not balanced, it will not track efficiently - leading to increased stress of articular surfaces and risk of dislocation
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37
Q

Osteokinematics of knee flexion/extension

A

sagittal plane, medial-lateral axis

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38
Q

osteokinematics of knee internal and external rotation

A

horizontal plane, vertical axis

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39
Q

what muscles cause internal and external rotation of the knee

A

Posterior muscles of the thigh
- plus sartorius medially

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40
Q

Tibial on femoral knee rotation - rotation is ___ as tibia motion

A

the same
(tibia moves in = internal rotation)

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41
Q

Femoral-on-tibial knee rotation - rotation is ___ as femur motion

A

opposite
(femur moves in = external rotation)

42
Q

femoral on tibial flexion arthokinematics

A

The convex femur roll posteriorly and slide anteriorly on concave tibia

43
Q

femoral on tibial extension arthrokinematics

A

convex femur rolls anteriorly and slides posteriorly on concave tibia

44
Q

tibial on femur flexion arthrokinematics

A

concave tibia rolls and slides posteriorly on convex femur

45
Q

tibial on femural extension arthrokinematics

A

concave tibia rolls and aglides anteriorly on the femoral condyle

46
Q

Screw-home mechanicsm of locking knee joint

A

small smount of rotation occurs as the knee approaches full extension

results in maximum congruence of the joint surfaces(ligaments are taught, menisci tightly interposed between condyles,

47
Q

Locking of the knee is driven by

A
  1. shape of the femoral condyles
  2. passive tension in the ACL
  3. the slight lateral pull of the quadriceps femoris
48
Q

Tibial on femoral locking/unlocking

A

open chain knee extension where the tibia is free to move on the femur.
From 30 degrees of flexion into full extension, the tension is the ACL and lateral pull of the quadriceps creates EXTERNAL rotation

49
Q

Femoral of tibial locking unlocking, closed chain reaction where the femur moves upon the fixed tibia,
the shape of the femoral condyles and tension n the ACL ligament produce slight INTERNAL rotation of the femur

A
50
Q

Role of the patella

A

works as an anatomical pulley and mechanism to reduce friction between the quadriceps and femoral condyles

It increases the moment arm of the knee extensor mechanism by displacing the tendon of the quadriceps anteriorly

Therefore it enanhances the extension torque produces by quadriceps femoris

51
Q

Joint reaction force

A

The force which occurs within a joint due to the forces acting upon that joint (muscle contraction and gravity)

52
Q

patella joint force is influenced by_

A
  1. pull of the quadriceps femoris muscle and patella tendon
  2. degree of knee flexion
53
Q

Forces of the patellofemoral joint

A

lateral directed forcesforces:
iliotibial band
bowstringing force on the patella
pateral patellar retinaculr fibers

medial directed forces:
vastus medialis (oblique fibers)
raised lateral facet of the intercondylar groove
medial patellar retinacula fibers

54
Q

the ACL resists…

A

knee extension
anterior translation of the tibia on femur
posterior translation of femur on tibia

55
Q

Injury vectors of the ACL

A

hyperextension
rotation
valgus force

56
Q

the PCL resists…

A

knee flexion
posterior translation of the tibia on the femur
anterior translation of the femur on the tbia

57
Q

injurh vectors of the PCL

A

hyperflexion
posterior translation

58
Q

the MCL resists…

A

valgus
extension

59
Q

injury vectors of the MCL

A

valgus
hyperextension

60
Q

the LCL resists

A

Varus
extension

61
Q

injury vectors of the LCL

A

varus
hyperextension

62
Q

osteokinematics of talocrural dorsi/plantarflexion

A

sagittal plane, medial-lateral axis

63
Q

arthrokinematics of talocrural dorsiflexion

A

the convec talus rolls anteriorly and slides posteriorly on the concave mortice of the tibia and fibula

64
Q

arthrokinematics of talocrural plantarflexion

A

the convex talus rolls posteriorly and slides anteriorly on the concave mortice of the tibia and fibula

65
Q

combined movements of pronation

A

Dorsiflexion
abduction
eversion

66
Q

function of ankle pronation

A

the spring is storing energy
provides shock and energy absorption through the gait cycle

67
Q

when does foot pronatioon interchange to supination

A

once the 1st metatarsophalangeal joint engases with the ground

68
Q

combined movements of supination

A

plantarflexion
adduction
inversion

69
Q

function of foot supination

A

the spring is releasing energy
energy release stage of the gait cycle
energy is used to propel the limb through the next step nd set up for the next landing

70
Q

factors influencing the stability of the ankle joint

A
  1. the shape of the tibia, fibula and talus
  2. ligaments (anterior and posterior talofibular, calcaneofibular, deltoid ligaments, inferior tibiofibular joint ligaments)
  3. leg muscles (inverters and evertors)
  4. effective proprioception
71
Q

most stable ankle joint position

A

dorsiflexion

72
Q

least stable ankle joint position

A

plantarflexion

73
Q

active insufficiency

A

occurs when a multi-joint muscle reaches a shortened length where it can no longer apply an effective force

actin and myosin filaments are overlapping - cant createconcentric force

74
Q

passive insufficiency

A

the inability of a multi-joint muscle to lengthen to a degree that allows full range of motion of motion of all the joints it crosses simultaneously

sarcomeres are stretched to their limit

75
Q

key supporting ligaments of the plantar surface

A
  1. plantar calcaneonavicular ligament -spring lig
  2. plantar calcaneocuboid ligament - short plantar lig
  3. long plantar lig - b/w calcaneus and cuboid - superficial to short lig
76
Q

plantar aponeurosis function

A

structural support
supports longitudinal foot arch
protection of sole from injury

77
Q

Weight of the lower limb is transferred to the ground posteriorly by…

A

medial process of the calcaneal tuberosity

78
Q

Weight of the lower limb is transferred to the ground anteriorly by…

A

heads of the metatarsals

79
Q

the function of foot arches?

A

Shock absorption as the foot strikes the ground
Flexibility to adapt to body weight distribution and variable ground surfaces
Propel the body during walking, running and jumping

80
Q

medial longitudinal arch

A

higher and more important

Formed by - calcaneus, talus, navicular, three cuneiforms, 1-3 metatarsals

81
Q

lateral longitudinal arch

A

flatter and typically on the ground when standing

Formed by - calcaneus, cuboid, 4-5 metatarsalsF

82
Q

transverse arch

A

runs from side to side

Helf up off the ground by the longitudinal arch

Formed by - cuboid, 3 cuneiforms, bases of the metatarsals

83
Q

The arches of the foot are passively supported by…

A
  1. shape of the bones
  2. plantar ligaments (spring lig, short plantar lig, long plantar lig)
  3. Fascia (plantar aponeurosis)
84
Q

The arches of the foot are dynamically supported by

A
  1. The bracing action of intrinsic foot muscles
  2. Tonic contraction of extrinsic foot muscles via their long tendons in the foot
85
Q

the longitudinal arch is supported by which muscles?

A

Flexor hallucis longus and flexor digitorum longus

86
Q

the transverse arch is supported by which muscles?

A

tibialis posterior and fibularis longus

87
Q

Windlass mechanism

A

When the winding up of the plantar fascia, due to extension of the MTP, causes increased tension and raising of the medial longitudinal arch to create supination and sets up the swing of the foot

88
Q

Pec cavus

A

Higher arches

may result is more rigid joints of the foot and forefoot, less flexibility and therefore affecting the ability to dissipate forces during pronation of the foot

89
Q

Pes Planus

A

flattened arches

The medial longitudinal arch is typically poorly supported and reduced extension of the MTP joints limits the ability of the windlass mechanism to occur

90
Q

conditions affecting motion of the big toe

A

Osteoarthitis, gout, affecting joints and mobility of the foot

91
Q

conditions affecting mechanics of the lower limb

A

genu valgus, varus

92
Q

The gait cycle

A

The activity that occurs between the time the foot of one lower limb touches the floor and when the same foot touches the floor again

93
Q

stance phase

A

the period of activit that occurs when the foot is in contact with the ground

94
Q

phases in the stance phase

A
  • Heel contact - heel contacts floor (pronated)
    • Flat foot - entire plantar surface contacts floor
    • Mid stance - body’s weight passes directly over
    • Heel off - heel comes off ground
    • Tow off - toe comes off (supinated)
95
Q

swing phase

A

when the foot is in the air, being advanced forward for the next contact with the ground

from toe off to heel contact of the same foot

96
Q

percentage of gait cycle in the stance phase

A

60%

97
Q

percentage of gait cycle in the swing phase

A

40%

98
Q

phases of the swing phase

A
  • Early swing - toe of to mid (plantarflexion to neutral position)
    • Mid swing
    • Late swing - mid to heel contact (relatively full dorsiflexion)
99
Q

typical type of muscle contraction when pronating?

A

eccentric contraction

100
Q

typical type of foot muscle contraction when supinating

A
101
Q

The lateral compartment of the leg is most active in what phase?

A

Stance phase - throughout mid stance and push off

(support transverse and medial longitudinal arches+ stabilise joint)

102
Q

The posterior compartment of the leg is most active in what phase?

A

Stance phase - floot flat and toe off

Foot flat to heel off - eccentrically (decelerate)
Heel off to toe off - concentrically

Lower Limb (5 decks)

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