Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

#2 Surg > 28 - Orthotic Fabrication I > Flashcards

28 - Orthotic Fabrication I Flashcards

1
Q

Introduction

A
  • Problems develop when the foot tries to compensate for the “birth position” that has not been corrected
  • The goal of orthotics is to stop the compensatory mechanism and get the foot position back into normal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Casting techniques

A

There are many

- Neutral, rectus, partial weight bearing, partial weight bearing rectus, pronated, vacuum, computerized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Characteristics of neutral casting

A

o Non weight-bearing
o STJ neutral
o MTJ maximally pronated
o Ankle joint dorsiflexed to slight resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Techniques (2) of neutral casting

A

WE DO SUPINE IN CLINIC
o **Supine/Grasp 4th and 5th toe sulcus
o **Supine/Thumb pressure beneath 4th and 5th metaheads
o Prone/Grasp 4th and 5th toe suclus
o Prone/Thumb pressure beneath 4th and 5th metaheads

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Step-by-step process for neutral casting

A

o 30 x 5 inch splint is folded in half lengthwise
o A ½ inch fold placed on length-wise edge for reinforcement
o Place splint around heel, 1/2 of length on each side of foot, height just below malleoli
o Mold lateral side first into arch and then medial side overlapping lateral half
o Fold excess plaster on plantar of heel towards posterior aspect
o Prepare forefoot splint same as rearfoot by folding in a half-inch reinforcement
o The sides of the plaster are folded onto the plantar aspect of the foot, starting with lateral side first
o Any excess is folded under the sulcus of the toes.
o The patient’s skin is pulled away from skin on the dorsum of the foot after the plaster is set by squeezing the skin together. The cast is ready to be removed when it feels rough and grainy.
o The cast is then grasped along the medial and lateral aspects of the heel with the fingertips of one hand, still holding the foot in neutral (some don’t do this)
o After the heel is freed, pull the cast straight towards the big toe
o Rotate the heel gently to allow removal of the toes from the cast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Checking the negative cast

A
  • 5th toe impression should NOT be dorsiflexed or plantarflexed
  • Lateral border should be straight or slightly abducted (it will be adducted in a patient with metatarsus adductus)
  • Inside of heel should be concave from medial to lateral and symmetrical from side to side
  • Skin lines should be present throughout
  • ***If the patient has a forefoot valgus, the orthotic cast will sit on the table in varus
  • ***If the patient has a forefoot varus, the orthotic cast will sit on the table in valgus
  • Lateral arch should match lateral border of foot in neutral position
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the most important way to check the quality of your cast?

A
  • ***If the patient has a forefoot valgus, the orthotic cast will sit on the table in varus
  • ***If the patient has a forefoot varus, the orthotic cast will sit on the table in valgus
    o This is the MOST IMPORTANT check of your cast
    o If you set your completed cast on the table, it should follow the rule above
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q
  • With a proper neutral position cast in a patient without metatarsus adductus, the:
    o The 5th toe should be dorsiflexed
    o The cast will tilt into valgus with a FF valgus
    o The lateral border will be straight or adducted
    o Skin lines will be visible
A

4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Neutral casting use

A
  • Neutral casting technique in non weightbearing position is utilized for all functional devices and neutral shell orthoses (rarely used)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Functional orthosis

A

A functional orthosis:
o Allows foot to function around STJ position
o PREVENTS abnormal or excessive compensation***
o Provides normal gait cycle
o Improves or changes function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Neutral shell orthosis

A

o Does not have any forefoot or rearfoot posting (like functional orthoses have) –> Pretty much it is just a regular orthotic without any posting
o A neutral shell orthosis REDUCES, but does NOT eliminate compensation – this allows for gradual posting to be done as needed
o Gradual rearfoot posting can be used to gradually stretch out Achilles tendon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Characteristics of rectus casting

A
  • ***Typically utilized when you are casting for CHILDREN
  • Non weightbearing casting with STJ neutral and MTJ maximally pronated
  • Dorsiflex ankle to slight resistance
  • Plantarflex 1st ray to level of the 5th metahead by pressing down on the dorsum of the 1st metahead or metabase or by dorsiflexing the hallux
  • Recommended casting technique by Prolab Orthotics for adults [by plantarflexing the 1st metatarsal, you are everting the long axis of the MTJ (pronation) and making the forefoot stable in stance]
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Rectus casting in children

A
  • Rectus casting utilized always in children less than 6 years of age so we do not cause a forefoot varus by not giving the talus enough time to rotate into valgus from the forefoot varus they were born with (also used in patients who need increased arch support)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

UCBL device

A
  • Preferred device with a flexible severe flat foot in children and adults
  • Rectus casting is utilized in UCBL (University of Cal at Berkeley Labs) inserts for maximum pronatory control
  • Locks rearfoot and does not allow any movement
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Characteristics of parital weightbearing casting

A
  • Semi-weightbearing sitting position (can utilize plaster or foam box)
  • Leg is 90° to the floor and the hip, knee, and ankle are at 90°
  • Patella is aligned with 2nd metatarsal
  • STJ manipulated into neutral position
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Plaster technique of partial weightbearing casting

A
  • Plaster is applied in slipper cast manner
  • Foot is placed on a foam pad with a towel underneath foot so plantar contours of foot are not destroyed and held in place until cast hardens
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Foam box/biofoam technique

A
  • Maintain STJ in neutral with one hand and grasp lower leg with other hand
  • Lift foot and place on foam
  • Apply downward pressure to dorsal aspect of knee to drive heel into foam
  • Apply downward pressure to midfoot and then forefoot
  • Foot is withdrawn from foam by doctor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Advantages of foam box technique

A
  • Easy
  • Better judge STJ neutral position
  • Locks MTJ oblique axis via gravity against body weight (disagreement in field)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Disadvantages of foam box technique

A
  • Long axis of MTJ is supinated
  • Decrease in FF valgus and increase in FF varus
  • First ray hypermobile due to supinated position of 1st ray
20
Q

Use of partial weightbearing technique

A

Utilized for accommodative orthosis

  • Used to accommodate, pad, or protect a foot deformity
  • Usually soft materials – get pressure off of an ulcer or callus
21
Q

Characteristics of vacuum cast technique

A
  • Patient sitting non weightbearing with both legs dangling over edge
  • Slipper cast applied with plaster
  • Plastic bag placed over foot up to knee
  • Vacuum tube inserted through top of bag to mid-ankle and top of bag secured
  • Shoe slipped over bag and foot placed in STJ neutral with knee at 90°
  • Dorsiflexory force placed under 5th metahead
22
Q

Technique for vacuum casting

A
  • Vacuum turned on

- Position maintained until cast is dried

23
Q

Advantages of vacuum casting

A
  • Fabrication of better fitting orthosis in shoe – good for sports where they wear tight-fitting shoe gear (i.e. skiers, hockey players, figure skaters etc.) or for UCBL
  • Cups heel to allow more soft tissue under heel
24
Q

Disadvantages of vacuum casting

A
  • Soft tissue distortion on lateral aspect of cast
  • Adducted cast
  • Increase in arch height
  • Orthosis can only be used in shoe for which it is made (usually)
25
Q

Computerized imaging technique

A

CAD/CAM (Computer assisted design/Computer assisted manufacturing) technology
o **Scans negative cast or the foot directly
o **A physical positive cast can be milled out of a block of wood, or the orthosis can be milled directly out of a block of polypropylene from a “virtual” positive

26
Q

Hand-held scanner

A

Hand-held scanner or Prolab© digital scanner
o Laser scanning the negative plaster mold
o Never need the positive mold – saves a step, saves money
o Reduces cost of orthosis by eliminating plaster correction process

27
Q

Milled orthosis

A
  • “Milled” orthoses are carved out of a solid block of plastic after the 3-D design has been generated on a computer following a scan of the negative cast
  • ***Milled devices are more rigid because the plastic has not been heated and they have “mill lines” which are transverse corrugations in the orthosis
28
Q

How can you tell if it is a milled orthosis or not?

A
  • REMEMBER: you can always tell if an orthosis has been “milled” out of plastic or made from a positive mold by looking at the bottom of it – if there are transverse lines on it, it was “milled”
  • Since the milled device will be MORE FIRM at every thickness, you can use a thinner piece of plastic and get the same firmness (less bulk in the shoe)
  • There will be NO rearfoot post on a milled orthotic because the rearfoot post is part of what is milled out of the initial piece of plastic – you don’t need an add on
29
Q

3D printing OLT foot care

A
  • The thing of the future – can print up to 3 pairs of 3D orthoses overnight
  • No data yet about how good these orthotics work
30
Q

STUDY – A comparison of four methods of obtaining a negative impression of the foot

A 
Compared reliability and accuracy of 4 different casting techniques:
o	NWB neutral impression
o	PWB foam
o	PWB laser scanning
o	NWB laser scanning
31
Q

Results of study for casting

A

o Plaster casting with non-weight bearing in neutral position was the most reliable when it is important to capture forefoot to rearfoot relationship (forefoot varus or valgus)
o This is just one study – not everyone’s opinion

32
Q 
Which of the following impression techniques is the impression of choice to fabricate pediatric orthoses?
o	Neutral NWB
o	Neutral Partial WB
o	Rectus
o	Pronated
o	Vacuum assisted
A

3

33
Q

When casting in partial-weightbearing, you:
o Place the STJ in neutral
o Cause a FF varus
o Lock the MTJ
o Push down on the knee
o Center the knee over the 4th metatarsal

A

Answer: 1, 2, 4 – you will invert the forefoot while doing this (causing a forefoot varus***)

34
Q

Negative cast process

A

The negative cast is filled with liquid plaster
o This is most commonly done with the calcaneal bisection perpendicular to the ground.
o When the plaster is hardened, the negative cast is then removed
o The positive is then smoothed

35
Q

How else can you create a positive cast?

A
  • The positive can also be digitally created from a scan of the negative cast or foot and then milled from a block of wood and then polypropylene is heated and pressed over wood positive mold
  • Most common, orthosis is milled from a block of polypropylene from scan and it bypasses creating a positive mold
36
Q

Balancing the cast

A
  • MOST IMPORTANT THING TO DO WITH YOUR ORTHOTIC Need to balance the cast in order to COMPENSATE for a forefoot varus or forefoot valgus
  • Necessary in order for orthotic to support the forefoot-to-rearfoot deformity
37
Q

How do you balance a cast?

A

When set on flat surface, the heel of the negative and positive cast will invert or evert the same number of degrees as the deformity
o If a forefoot valgus, the heel will invert
o If a forefoot varus, the heel will evert

The goal is to balance the cast, so that the heel does NOT invert or evert

38
Q

Example of balancing a cast

A
  • With this example of forefoot valgus, the cast is balanced by hammering a nail into the cast’s 5th metatarsal head region
  • Nail in far enough so that the cast becomes level on a flat surface
  • Plaster is built up around the nail and smoothed out so it is continuous with the arch of the mold
39
Q

Intrinsic post

A

Forefoot is now supported (with what we call an intrinsic post), so MTJ does not have to overly compensate for the forefoot valgus and can function normally in gait
o Anything we add to the positive mold is called an intrinsic modification
o In this example we have added an intrinsic forefoot post

We have essentially brought the ground up to the 5th metatarsal, and the MTJ does not have to overly compensate

40
Q

Extrinsic forefoot posting

A
  • Can also add the post with acrylic material to the outside of the finished orthotic if we did not first balance the cast
  • Not utilized much anymore because it is uncomfortable when you come off the ball of your foot
  • It feels like you are stepping on a ledge – not as comfortable
41
Q

To add an intrinsic forefoot post for FF varus:
o Elevate the 1st metatarsal head with a nail
o Add more plaster under the 5th metahead
o Add a varus post to the forefoot of the orthosis
o Add a varus post to the rearfoot of the orthosis

A

1

42
Q

Forefoot platform

A

o A nail is placed on the plantar surface of the first (for forefoot varus) or fifth (for forefoot valgus) metatarsal head to prop up the positive in the appropriate position (usually with the calcaneal bisection perpendicular to the ground).
- Plaster is then applied to build a platform at angle dictated by the position of the nail.

43
Q

For a forefoot platform, which side will be thicker for a forefoot varus? Forefoot valgus?

A

o For a forefoot varus, the platform will be thicker medially
o For a forefoot valgus, the platform will be thicker laterally

44
Q

How do you make an orthosis shell using a forefoot platform?

A

Orthosis shell is made by vacuum-forming material on the balanced cast

Pressing
o The shell material is then pressed against the positive.
o Most shell materials require heat before they can be pressed.
o The heated softened shell material is then applied to the positive, and a vacuum press molds the shell to the positive.

45
Q

Finishing the orthotic shell

A

o The shell is then trimmed to the appropriate trim lines.
o A standard functional device extends just proximal to the metatarsal heads distally, to the center of the first metatarsal medially and the center of the fifth metatarsal laterally.

46
Q

Rigid vs semi rigid orthotic

A

o The heavier the patient, the thicker the material needs to be
o Polypropylene varies from 2 mm to 6 mm in thickness
o Anything bigger than 6 mm will not fit in the shoe well
o The thicker it is, the more rigid it is

#2 Surg (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions