Biomechanics of the ankle & foot complex Flashcards

1
Q

Conflicting functions of the ankle-foot

A
Stability
-Provides stable BOS
-Acts as a Rigid Lever
Mobility
-Dampens LE rotations
-Adapt to varied surfaces
-Flexible to absorb shock
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2
Q

Forefoot

A

Metatarsals and phalanges

  • Adapts to terrain
  • Heavily influenced by hindfoot
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3
Q

Midfoot

A
Navicular
Cuboid
3 Cuneiforms
-Transmits hindfoot motion to forefoot
-Promotes stability
-Heavily influenced by hindfoot
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4
Q

Hindfoot

A

Talus
Calcaneus
-Converts LE transverse plane motion into sagittal, frontal, and horizontal plane motion

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5
Q

Pronation (Composite)

A

Dorsiflexion
Eversion
Abduction

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6
Q

Supination (Composite)

A

Plantarflexion
Inversion
Adduction

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7
Q

Distal Tibiofibular Syndesmosis

A

Stabilizes mortise with crural interosseous tibiofibular ligament.
Ligament pulls fibula towards tibia

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8
Q

Distal Talocrural Joint structure Transverse Plane

A

Talus body width greater anterior than posterior

Lateral surface area greater than medial surface area

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9
Q

Talocrural Dorsiflexion

A

20-30 degrees

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10
Q

Talocrural Plantarflexion

A

30-50 degrees

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11
Q

Talocrural Medial Rotation

A

7 degrees

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12
Q

Talocrural Lateral Rotation

A

10 degrees

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13
Q

Talocrural Inversion

A

5 degrees

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14
Q

Talocrural Eversion

A

5 degrees

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15
Q

Talocrural Gait requirements

A

10 degrees dorsiflexion

20 degrees plantarflexion

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16
Q

Talocrural Ascending stairs requirements

A

20-25 degrees DF

10-15 degrees PF

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17
Q

Talocrural Running Requirements

A

25 degrees DF

25 degrees PF

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18
Q

Gait talocrural compression force

A

4.5 times body weight

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19
Q

Talocrural OKC DF Arthrokinematics

A
  • Convex talus moving on concave mortise
  • Anterior talar roll and posterior slide
  • More posterior talar excursion laterally=Abduction of talus
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20
Q

Talocrural CKC DF Arthrokinematics

A

Concave mortise on convex talus
Anterior roll and anterior slide
More anterior excursion laterally=Adduction of mortise on talus
Superior glide of Fibula as larger part of talus enteres motise

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21
Q

Frontal plan ankle axis

A

8-10 degrees from horizontal

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22
Q

Transverse plane ankle axis

A

20-30 degrees from horizontal

23
Q

Anterior Talocalcaneal articulation

A

Convex talus concave calcaneus

24
Q

Middle Talocalcaneal articulation

A

Convex talus concave calcaneus

25
Q

Posterior Talocalcaneal articulation

A

Convex calcaneus concave talus

26
Q

Subtalar joint structure

A

3 articulations separated by tarsal canal
2 separate joint cavities
Dampens LE rotary forces to maintain foot contact with ground

27
Q

Subtalar Joint ligaments

A

Interosseous talocalcaneal - limits eversion
Lateral talocalcaneal - limits inversion
Ligamentum cervicis - limits inversion
Posterior talocalcaneal ligament - limits plantarflexion

28
Q

Subtalar OKC osteokinematics

A

Supination: Calcaneal Inversion, Adduction, Plantarflexion

Pronation: Calcaneal eversion, abduction, and dorsiflexion

29
Q

Subtalar CKC Osteokinematics

A

BW prevents calcaneus from ABd/ADd or DF/PF on talus
Supination: Calcaneal inversion, talar abduction, talar DF

Pronation: Calcaneal eversion, talar adduction, talar PF

Supination is closed pack

30
Q

Subtalar CKC ROM

A

20 degrees inversion
10 degrees eversion
4-6 degrees inversion and pronation required for gait

31
Q

Subtalar CKC Arthrokinematics

A

Posterior T-C: Concave talus moves on convex calcaneus

Ant and Middle T-C: Convex talus moving on concave calcaneus

32
Q

Single Axis Triplanar Subtalar ROM

A

Sagittal inclination of 42 degrees
Trasverse inclination of 16 degrees to the medial side
Allows IN/EV and ABD/ADD to be equal
Only allows minimal DF/PF

33
Q

How to calculate Rearfoot neutral

A

Measure inversion and eversion
Add inversion and eversion then divide by 3
Subtract result from eversion degree

34
Q

Mitered Hinge Subtalar Joint

A

Lateral rotation of tibia as the hindfoot supinates

35
Q

Talocalcanealnavicular Joint Structure

A

Part of the transverse tarsal joint
Convex talar head and concave posterior navicular
Ball and socket
Ligaments deepen the navicular cavity

36
Q

Talocalcanealnavicular Joint axis

A

40 degrees anterior/superior inclination saggital

30 degrees anterior/medial inclination transverse

37
Q

Transverse Tarsal Joint Structure

A

S shaped joint line
Divides midfoot from hindfoot
Sellar surfaces of the anterior calcaneus and posterior cuboid

38
Q

Calcaneocuboid Joint

A

Sellar surface-reciprocally concave/convex

39
Q

Transverse Tarsal Ligaments

A

Lateral band of the bifurcate
Dorsal calcaneocuboid
Short plantar
Long plantar

40
Q

Longitudinal axis of transverse tarsal joint

A

Up 15 degrees from A-P axis

Medially 9 degrees from A-P axis

41
Q

Oblique axis of transverse tarsal joint

A

57 degrees medially from A-P axis

52 degrees up from A-P axis

42
Q

Transverse Tarsal Joint function

A

CKC talar ABd/ADd and DF/PF cause motion at talonavicular joint

CKC Calcaneal IV/EV cause motion at calcaneocuboid joint

With STJ supination, TTJ supination (Closed pack)
With STJ pronation, TTJ pronation (Open Pack)

43
Q

Inman & Manns mechanical model

A

Lateral rotary force imposed on leg
Acts through the oblique axis of STJ and TTJ to maintain forefoot in a fixed position.
Double mitered hinge

44
Q

Tarsometatarsal Joint mechanics

A
1st and 2nd Ray axis
-Inversion with DF
-Eversion with PF
4th and 5th Ray axis
-Eversion with DF
-Inversion with PF
45
Q

Pronation and Supination twist occur when…

A

The TTJ function is inadequate

46
Q

Transverse Plantar Arch

A

Decreases in curvature from TMT to MTP

47
Q

Longitudinal Plantar Arch

A
Continuous from calc to met heads
Stability is aided by:
Spring ligament
Long plantar ligament
Plantar aponeurosis
Short plantar ligament
48
Q

Plantar Aponeurosis

A

Stabilizes arch like a tie rod

Subjected to tension loads

49
Q

Windlass Mechanism

A
  • Plantar pads move distally during toe DF
  • Plantar fascia is pulled forward and around the met heads
  • Results in supination and reduces the distance between met heads and calcaneus
  • Arch height increases
50
Q

Distribution of body weight

A

Talus 50% in bilateral stance
25% of weight goes to rearfoot
25% of weight goes to forefoot

51
Q

Consequences of compensatory pronation

A

Tension overloads the tibialis posterior

Reduces cuboid pulley and fibular longus ability to PF and Abduct first ray. Results in 2nd met head overload

52
Q

Cuboid pulley

A

Displaces fibularis longus tendon inferiorly to improve plantarflexion moment

53
Q

Manifestations of abnormal foot mechanics

A

Abnormal magnitude of joint motion
Excessive speed of joint motion
Abnormal temporal sequence of joint motion