Orthotic Manufacturing Flashcards
what position is the calcaneal bisection as the positive is made
perpendicular to the ground
when i the negative cast removed
when the plaster is hardened
what are the types of positive plaster modifications
- FF platform
- heel cup accommodation
- arch fill
- “sweet” spots
how is a FF platform created
- nail is placed on the plantar sufrace of the 1st (for FF varus) OR 5th (for FF valgus) MT head to prop up the positive in the appropriate position
- plaster is applied to build a platform at an angle dictated by the position of the nail
where is the calcaneal bisection when forming a FF platform
-perpendicular to the ground or FF may be “balanced” to RF
for a FF varus, where will the FF platform me thicker
medially
fore a FF valgus, where will the platform be thicker
laterally
how is a heel cup accommodation added
plaster is added around the periphery of the heel
what does a heel cup accommodation allow for
-soft tissue spread when the patient bears weight
where are arch fills added
to the medial arch to allow for soft tissue expansion and to provide a smooth transition into the FF platform
a minimal arch fill will provide for
greater control
a heavier arch fill will allow for
more flattening of the arch
how do you accommodate for “sweet spots”/bony prominence
add a small mound of plaster to the area of the prominence which will then lead to a pocket on the shell
what are the material requirements for the shell
heat moldable
able to hold their shape
where does a standard functional device extend to
- just proximal to the MT heads distally
- to the centre of the 1st MT medially
- to the centre of the 5th MT laterally
is the device width dependent upon foot width
no!
the wider the device the —
greater the control
the width of the device is highly dependent upon
the type of shoe in which the device will be work
a wide device extends from
the medial side of the 1st MT head to the lateral side of the 5th MT head
a normal device extends from
the centre of the 1st to the centre of the 5th
a narrow device extends from
the lateral aspect of the 1st MT head to the medial aspect of the 5th MT head
where is an extrinsic RF post applied to
the shell
is an extrinsic post the same thing as a heel lift
No!
how do functional devices work
- prevent excessive pronation
- allow the STJ to function around its neutral position
- prevent compensation
what are 3 functional device theories
- pre-positioning of the foot
- proprioceptive facilitations
- altering the extrinsic moments
pre-positioning of the foot means that
- STJ neutral position
- MTJ maximally pronated (locked) position b/c that is the ideal position of the foot in the middle of midstance as it prepares for the propulsive phase of gait
what phase of gait do most pathologies occur
propulsive phase
functional orthosis generally cannot control the motion of the foot during the propulsive phase, why?
-b/c so little of the foot (only the MT heads) is actually weight bearing
how do functional orthosis help control motion of the foot
- by placing the foot in an optimum position as it enters the propulsive phase
- theoretically, the deleterious stresses will be minimized
how can orthoses prevent excessive pronation
- providing increased proprioceptive clues
- allowing the patient to respond to the rate and amount of pronation more appropriately
- the more direct contact you have on the plantar surface, the more cues you have about where your body is in space
what is posting
- bringing the ground up to the deformity
- eliminating the need for compensation
arch support provides for
- increased proprioceptive feed back
- allows for a surface in which posting may be used
does posting bring the ground up to the MT heads
NO!
Functional orthosis does not control MT head contact to the ground
how are osseous restraining mechanisms optimized
-by placing the foot in a more stable position
which part of the orthosis help prevent excessive pronation
- distal medial shell
- anterior medial edge of the RF post
- “anti-pronatory” pressure (extrinsic supinatory moment) at the distal medial calcaneal tuberosity (as determined by the contour of the heel cup)
a deep heel cup provides for —- compared to a lesser heel cup
greater control
do functional orthosis function as an arch support
NO!
The arch area of the device is not a component to control pronation
heel cup helps control
- STJ motion
- minimize the amount of calcaneal inversion and eversion
control of the lateral column provides for
increased stability of the foot
