ARM Cast

I am currently a student at The University of Alabama in Huntsville and I designed the adjustable, reusable and modular (ARM) cast, a replacement for the modern plaster/fiberglass cast. The plaster/fiberglass cast is the current solution for setting and keeping bones stationary while healing after a major accident or surgery. While being the current solution, the plaster/fiberglass cast has many serious disadvantages.

Disadvantages of the Plaster/Fiberglass cast:
- Long cast preparation/creation time
- Requires a skilled physician
- Custom made for each patient
- Cannot be adjusted or modified after initially made, this can lead to improper healing if bones are shifted after the cast is made
- Patient cannot wash or clean skin inside the cast, this can lead to skin infections or irritations under the cast
- The cast must be cut off, cast is destroyed after only one use and if done incorrectly could injure the patient


The ARM cast was designed to improve the current plaster/fiberglass cast and it solves many of the issues surrounding the plaster/fiberglass cast.

Advantages of the ARM cast:
- Short cast preparation/creation time
- Does not require a skilled physician, it is easily done by anyone - even the patient himself
- It is both adjustable and modular, so it fits many patients; even if it were to be too small/large in overall diameter for the patient's arm, the ARM cast can be scaled and printed in different size ranges such that it would fit anyone (The ARM cast in this entry has a diameter range of 7 to 3 cm; which would fit most youth)
- Can be adjusted during the bone’s healing process, in case the bone is shifted or is initially misaligned
- Patient can wash and clean skin inside the cast
- To remove the cast, it is just loosened and removed
- Once sterilized the cast can be reused for other patients


The ARM cast consists of 3 basic parts, the modular ring, the adjustable pads, and the elbow joint.
The modular ring forms the body of the cast and contains the adjustments for the pads (it is the large white ring in the pictures). The modular ring also is threaded on both ends, which allows it to be connected to other modular rings or the elbow joint in order to increase the length of the total cast. The elbow joint can connect two of the modular rings at a forty-five-degree angle around the patient’s elbow. Finally, the modular ring utilizes FDM printing’s ability to create “in-place” assembly’s as it prints the movable slides inside the r...