2. The Objective
Address common problems with current cast design
Create cost-effective, eco-friendly, comfortable cast
Come up with three designs, choose best one
3. Problems with Current Design: The Upper
Extremity Orthopedic Cast
Application
Materials
Exposure to water
Breathability/Unexposure
Safe removal
Restricting and uncomfortable
4. Problems with Current Design: The Upper
Extremity Orthopedic Cast
The upper extremity orthopedic cast consists of a shell encasing, often times made
from plaster, and a soft inner padding, usually cotton, used to stabilize and hold
anatomical structures, often broken bones in the lower arm such as the radius or
ulna.
● Modern casts have many problems, however, and designs have been
similar since the Egyptians use of splints 3000 BC
● Knitted fiberglass bandages saturated with polyurethane are used.
These shells are lighter and dry much faster than plaster bandages.
However, plaster can be more easily molded to make a snug and
therefore more comfortable fit. Plaster is also much smoother and
does not snag clothing or abrade the skin.
5. Problems with Current Design: The Upper
Extremity Orthopedic Cast
It seems that one of the most efficient ways of cast preparations is using
gypsum, heated, and ground to a fine powder by refining it. When water
is added, the soluble form of calcium sulfate returns to the relatively
insoluble shape, and heat is produced as a product.
2 (CaSO4·½ H2O) + 3 H2O → 2 (CaSO4.2H2O) + Heat
This method is known as the plaster of Paris method, which has been an
outdated source of casting ever since.
Removal of the traditional cast is a hastle. Removal of the cast entails
destroying the cast, which wastes materials and is not the most cost-
efficient. The process is noisy, making use of a special oscillating saw
that can easily cut hard cast material but has difficulty cutting cast
padding.
6. Design One
Mouth Guard Inspired Design
Heat moldable
Internal resistor to aid in heating
Few generic sizes to cater to all people
Use of Ultrasound to maximize blood flow to accelerate healing
7. Design One Pros and Cons
Pros:
Reusable
Custom Fit, More Comfortable
Faster Healing
Waterproof, durable
Easy Removal
Cost Effective (reusable)
Cons:
Not as protective
Initial costs are higher
8. Design Two
Dissolvable Arm Cast Design
Made from Hydrophobic Polymer
Will be removed with an alcohol or liquid hydrocarbon
Dissolved polymer can be extracted from solvent and reused
9. Design Two Pros and Cons
Pros:
Reusable material
Cheap removal equipment
Waterproof
Con:
Having to rebuild the cast from raw materials to reuse it
Difficult application
People with sensitive skin and allergies may have trouble with it
Cannot be around certain chemical solutions
10. Design Three
Air Compression Design
Large Plastic Frame
Air bags lining the inside of the frame that are blown up to fit the patient’s
arm
Doctor will have a lock to the outside of the cast, so only the doctor can
deflate it
Similar to a blood pressure arm cuff
11. Design Three Pros and
Cons
Pros:
Easy application and removal
Reusable, can be set to fit patient perfectly
No special equipment required
Inexpensive materials
Cons:
Not as structurally supportive
Large, bulky
Breakable, easy to deflate
12. Final Design Decision
We chose the first design because:
It was the most cost efficient, after start of fees it is reusable and durable
It would be the most comfortable for the patient as well as the most
supportive
Decreased healing time
Most convenient for everyday life