METAL AFO

Question 1

The average midsagittal line for a normal limb will intersect what three points?

Answer 1

Perineum bisect, a point 15mm medial to the leg at the knee joints axis and a point 30mm medial to the medial malleolus at the ankle joint axis

Question 2

A midsagittal line falling more than 15 mm medial for the knee indicates

Answer 2

Genu varum

Question 3

A midsagittal line falling more than 30mm medial from the medial malleolus indicates

Answer 3

Genu valgum

Question 4

A shoe attached to a metal AFO must have simultaneous

Answer 4

Full heel contact and forefoot contact under the metatarsal heads

Question 5

The location of the mechanical ankle joint axis should be

Answer 5

At the distal tip of the medial malleolus

Question 6

What is the relationship between the proximal edge of the calf band and then fibular neck?

Answer 6

They should be 20mm apart

Question 7

What should be the average clearance between the apex of the lateral malleolus And the lateral mechanical ankle joint?

Answer 7

5mm

Question 8

What is the line progression?

Answer 8

The direction of forward progression

Question 9

What is toe out?

Answer 9

The angular relationship between the line off progression and the longitudinal aspect of the foot.

Question 10

What is tibial torsion?

Answer 10

The relative external rotation of the ankle joint axis with respect to the knee joint axis

Question 11

A distal perpendicular from the bisect of the ankle joint axis will allow determination of the

Answer 11

Presence of a fixed subtalar deformity

Question 12

Why is 3mm added to the amount that the medial sidebar is anteriorly deflected to accommodate external rotation of the mechanical ankle joint axis.

Answer 12

Because the mechanical ankle joint diameter is greater than that of the anatomical ankle joint diameter

Question 13

When using 5/8 inch (15mm)x 3/16 (5mm) inch sidebar stock, the best estimate for the length of a calf band is?

Answer 13

Half the maximum anatomical, calf diameter plus 37 mm (1 1/2inches)

Question 14

Stirrup size is determined by measuring?

Answer 14

The length from one mechanical axis to the other in the uncountered condition

Question 15

The midsagittal line determines alignment in?

Answer 15

The coronal plane

Question 16

The length of a solid stirrup is the algebraic sum of

Answer 16

Twice the ankle joint height, twice the sole thickness, heel width, plus 6mm

Question 17

The ideal clearance between the medial surface of the sidebars and the skin is

Answer 17

3-6 mm

Question 18

Why is it generally best not to contour the sidebars in the area of the calf band?

Answer 18

The band can be riveted without excessive stress

Question 19

Why is the calf band length greater than half the circumference of the anatomical calf?

Answer 19

To accommodate the padding plus half the sidebar width twice

Question 20

After anterior deflection of the medial sidebar/ankle joint assembly, why are the ankle joints externally rotated?

Answer 20

To make the mechanical joint surface perpendicular to the ankle joint axis.

Question 21

When anteriorly deflecting the medial sidebar/ankle joint assembly, what is the advantage of utilizing two contours vs one?

Answer 21

So that the relationship between the mechanical ankle joint and the stirrup is the same as it is laterally

Question 22

The advantage of using a single contour in the medial sidebar to approximate the anatomical ankle joint axis is

Answer 22

Improved cosmesis, less built in stress and ease of fabrication

Question 23

What is the static posture of a patients talocrural joint when wearing a standard metal AFO when the lateral sidebar is perpendicular to the ground and the shoe has a 5/8 inch heel

Answer 23

Plantarflexion

Question 24

If a patient has a fixed subtalar varus deformity, what kind of wedge would you recommend?

Answer 24

A medial heel wedge

Question 25

If a patient has a fixed subtalar valgus deformity, what kind of wedge would you recommend?

Answer 25

A lateral heel wedge

Question 26

If a patient has a flexible subtalar valgus, to what side of the shoe would you attach the correction strap?

Answer 26

Medial

Question 27

If a patient has a flexible subtalar varus, to what side of the shoe would you attach the correction strap?

Answer 27

Lateral

Question 28

What event does a cushion heel simulate?

Answer 28

Plantar flexion at loading

Question 29

What event does a rocker bar simulate?

Answer 29

Heel rise and toe off

Question 30

When might a cushioned heel be used on a AFO with restrained dorsiflexion and plantar flexion?

Answer 30

To reduce knee flexion thrust at loading

Question 31

When might a rocker bar be used?

Answer 31

When forefoot motion is undesirable

Question 32

With what type of mechanical ankle joint adjustment might you use both a cushion heel and a rocker bar?

Answer 32

Restrained dorsiflexion and plantarflexion

Question 33

What can be the eventual consequence of not accommodating tibial torsion in a free motion AFO?

Answer 33

Iatrogenic varus deformity

Question 34

Why should the tongue of a stirrup be contoured before attaching to the shoe?

Answer 34

To prevent deformation of the shoe

Question 35

Marks left by a contouring instrument should be

Answer 35

Removed to eliminate failure causing stress risers