18/19: Orthotic Materials and Construction - Cronin

Question 1

factors that affect selection of material thickness

Answer 1

• forces to be resisted
• body weight
• age
• activity

Question 2

factors that affect selection of materials for top covers

Answer 2

• diabetic foot protection
• need for cushion
• need for support
• durability of material
• memory of material
• thin cover for dress shoes

Question 3

posting materials

Answer 3

• cork
• crepe
• EVA
• felt (diagnostic purposes)

Question 4

how was the positive cast created?

Answer 4

pouring of the negative cast

Question 5

why is the negative cast bisected?

Answer 5

• negative cast is bisected to determine the forefoot to rearfoot relationship
• bisection technique- lateral curvature method

Question 6

how do you mark the lateral expansion?

Answer 6

• begins at the proximal lateral corner of the square represent the lateral platform and ends where the distal heelcup line and the lateral heel cup height intersect
• lateral expansion is meant to accommodate for soft tissue spread

Question 7

where will the balance platform be placed for an inverted forefoot?

Answer 7

beneath the first met head

• the balance platform will be placed beneath the fifth met head to balance for everted forefoot

Question 8

why is the lateral edge straight?

Answer 8

• horizontal grind is made along the lateral edge of the orthosis enusring thta tthe lateral heelcup height is maintained
• straight lateral edge also prevents the foot from pronating off the orthosis

Question 9

what is the purpose of the rearfoot post?

Answer 9

• stabilizes the orthosis shell
• stops excessive calcaneal eversion
• allows normal pronation-shock absorption
• normal pronation is accomplished by adding motion
• post motion is provided by grinding the medial plane
• amount of post motion is determined by sagittal plane inclination angle of the STJ axis

Question 10

what determines the height of the heelcup?

Answer 10

the height and width of the heel counter in the shoe