Radiographic Biomechanics

Front 1

Structural angular relationship vs Positional angular relationship

Back 1

Positional
The measured angle can change with
pronatory or supinatory forces acting on the
foot
 Structural
The measured angle does not change with
pronatory or supinatory forces acting on the
foot

Front 2

Forefoot Adductus Angle
-What plane
-What line?

Back 2

- the position angle that represents the reelationsh0p between the forefoot and the rearfoot
-It is a transverse plane deformity
-Angle between longitudinal bisection of the calcaneus and bistction of the 2nd Metatarsal

Front 3

What is the ideal Forefoot adductus angle?
What causes angular changes?

Back 3

8 degrees adducted
angle increases with supination and decreases with pronation
- Due to the calcaneus

Front 4

Metatarsus Adductus Angle
What plane?
What is the line?

Back 4

Structural angle that
represents the relationship
between the forefoot and the midfoot.
Transverse plane deformity
 Angle between the
Longitudinal Bisection of the lesser tarsus and the bisection of the 2nd metatarsal

Front 5

What is the normal Metatarsus Adductus Angle?

Back 5

Normal value is 10-200
 Note the metatarsals
are adducted on the midfoot
 As an aside:An MA angle > 15 affects surgical planning

Front 6

Cuboid Abduction Angle
What plane?
What lIne?

Back 6

 Positional angle that estimates the amount of abduction the midfoot has on the rearfoot
Transverse plane deformity
 Angle between the longitudinal bisection of calcaneus and lateral aspect of the cuboid
If the calcaneal bisection can’t be determined, use the lateral aspect of calcaneus

Front 7

Cuboid Abduction Angle
Normal value
What increases/decreases angle?

Back 7

Normal 0-5
Increases with pronation and decreases with supination (due to the calcaneus)

Front 8

Talocalcaneal Angle
What is another name?
What is the plane of deformity?
What line?

Back 8

This positional angle is used as an index of relative foot pronation and supination
 Transverse (and frontal) plane deformity
 If severe, can indicate a transverse plane deformity in tibia
 Angle between the longitudinal bisection of the talus and the longitudinal bisection of the
calcaneus

Front 9

What is Normal Talocaclaneal Angle?
What increases or decreases the angle?

Back 9

Normal is 17-21
increase with pronation
Decrease with supination
Due to talus (1deg) and calcaneus

Front 10

What is talonavicular congruity?
What is normal?

Back 10

 The relationship
(amount of joint
contact) between the talus and the navicular
 Normal 75% articulation

Front 11

Talonavicular congruity
What increases or decreases congruity?
What bone?

Back 11

Decreases with pronation
increases with supination
- due to the talus

Front 12

Digital Abductus angle
-what plane?
What line?
- What is normal?

Back 12

This angle is the estimation of the deviation of the second toe from the second metatarsal
Transverse plane deformity
 The greater the forefoot
adductus angle the greater
the digital abductus
 Normal abducted about 110

Front 13

What is calcaneal inclination angle?
What deformity?

Back 13

This angle is the determinate of the relative
arch height and as such varies with foot type
Sagittal plane deformity
 Angle between the inferior surface of the
calcaneus and the weight-bearing surface

Front 14

Calcaneal inclination angle, what affects it?
What is average?

Back 14

Not affected by supination or pronation
Average 25degrees

Front 15

What is talar declination angle?
What is the deformity
What is the line?

Back 15

This positional angle represents the amount
of plantarflexion of the talus
Sagittal plane deformity
 Angle between the longitudinal bisection of
the talus and the weight-bearing surface

Front 16

Talar declination angle
What is normal
What increases/Decreases
what bone?

Back 16

Normal 210
 This angle increases with pronation
and decreases with supination
Due to talus

Front 17

Lateral Talocalcaneal Angle
What plane deformity
What line?

Back 17

This positional angle is very useful to assess
the pronatory and the supinatory status of
the STJ
Sagittal plane deformity
 Angle between the longitudinal bisection of
the talus and the pitch of the calcaneus

Front 18

Lateral talocalcaneal Angle
What is normal
What increases/decreases
what bone?

Back 18

Normal 40-50
increase w/ pronation
decrease w/ supination
due to the talus

Front 19

First metatarsal declination angle
What plane deformity?
What "classification?"
What is normal?

Back 19

This angle estimates the amount of first
metatarsal plantarflexion
Sagittal plane deformity
 This angle is both structural and positional.
With pronation the first ray dorsiflexes,
thus decreasing the angle
 Normal 210

Front 20

What is Meary's angle?
what is the deformity?

Back 20

Lateral-Talo First Metatarsal
Angle (Meary’s Angle)
 This angle represents the relationship
between the declination of the talus and
the declination of the 1st metatarsal
Sagittal plane deformity

Front 21

What does Meary's angle indicate?
What classification?

Back 21

Indicates the stability of the first ray,
Both a structural and positional angle

Front 22

What does positive or negative meary's angle represent?
What is normal?

Back 22

 Positive angle (1st ray dorsiflexed) reflects
forefoot and first ray instability
 1st met bisection is above talar bisection
 Negative angle (1st ray plantarflexed)
reflects forefoot and first ray stability
 1st met bisection is below talar bisection
 Normal +/- 40

Front 23

What is Cyma Line?

Back 23

lazy S that indicates congruity of the midtarsal joint

Front 24

What does a broken Cyma line mean?

Back 24

means that surfaces are not congruous.

Front 25

How does the cyma line look in pronation?
Supination?

Back 25

Pronated= anterior break (TN in front of CC)
Supinated = posterior break (TN behind CC)

Front 26

Sinus Tarsi indicates what?
What is its normal appearance?
Appearance in Pronation?
Supination?

Back 26

Indicates proper alignment of the talus on the calcaneus (positional only)
Normal is oval
Pronated is obliterated
supinated is bullet hole.

Front 27

Back 27

1st met declination

Front 28

Back 28

Calcaneal inclination normal

Front 29

Back 29

Calcaneal inclination angle normal

Front 30

Back 30

Calcaneal inclination angle supinated

Front 31

How to draw?

Back 31

Calcaneal inclination angle

Front 32

Back 32

Calcaneal inclination pronated

Front 33

Back 33

Cuboid Abduction

Front 34

How to draw?

Back 34

Cuboid Abduction

Front 35

Back 35

Cyma Normal

Front 36

Back 36

Cyma pronated

Front 37

Back 37

Forefood Adductus

Front 38

How to draw?

Back 38

Forefoot Adductus

Front 39

Back 39

Kites Normal

Front 40

Back 40

Kites pronated

Front 41

Back 41

Kites supinated

Front 42

How to draw?

Back 42

Lateral talo First Met
MEarys

Front 43

Back 43

lateral Talo first Met
Meary's

Front 44

Back 44

lateral Talocalcaneal Normal

Front 45

How to draw?

Back 45

lateral Talocalcaneal

Front 46

Back 46

Meary's normal

Front 47

Back 47

Meary's pronated

Front 48

Back 48

Meary's

Front 49

How to draw?

Back 49

Metatarsus Adductus

Front 50

Back 50

Sinus tarsi supinated foot
bullet hole

Front 51

Back 51

Sinus tarsi

Front 52

How to draw?

Back 52

Talonavicular congruity