Using a cast for a long time after a fracture can cause joint stiffness and limited movement. There are many types of rehabilitation training methods to restore the joint's range of motion, but the training gains are easily rebounded. One method of rehabilitation is to use an elastic device to stretch the joint for a long time every day (4-8 hours/day). There is a product on the market called DynaSplint that uses this method. This document introduces a low-cost design solution that can be printed using a 3D Printer. Achieve long-term elastic stretching of joints.

This splint consists of three parts，Binding of forearm(Binding1), Binding of upper arm(Binding2), elastic connection(Connection). Attach Binding1 to forearm near the wrist, attach the Binding2 near the elbow of upper arm, then use Connection to connect the two parts.

Terms and Conditions of Use <—Read this first!!

1. Three Parts of the splint 2. Connected State 3. How to Build 4. How to Adjust 5. Download CAD files

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1. Three Parts of the splint

1.1 Binding of forearm (Binding1)

3 printed parts, mounted to one binding

1.2 Binding of upper arm (Binding2)

One printed part, top view and side view

1.3 Connection

2 printed parts, 1 spring

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2. Connected State

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3. How to Build

3.1 Measurement

Measurement of Forearm near wrist

You need to measure size of 2 dimensions, width and thickness, at position of wrist, arm is not a cylinder. Width of wrist

Thickness of wrist

Measurement of Upper arm

Upper arm near the elbow is close to a cylinder, so most of the time, you only need to measure the diameter.

3.2 Design and print the models

After measurement, you can use any 3D modeling tools to design. I use open source FreeCAD, and you can download my CAD files on my website. I use Cura as slicer, to generate what 3D printer needed gcode, just as normal.

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4. How to Adjust

The core idea of spring splint is, the splint can apply a constant elastic tension on the joint. The length of the Connection must be adjustable to conform with the joint range of motion. Here is the idea of the design how to adjust the length of the Connection.

4.1 Length of spring

It’s very easy to buy a springs assortment kit on amazon, looks like:

Then you can change the spring to adjust the tension of the splint.

4.2 Length of hook

Hook is a printed part of Connection, which attaches spring to binding. You can design hooks with different length to adjust the tension of the splint. These are two models of my design.

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5. Download CAD files

The 3D models are designed with FreeCAD version 0.20, you can download FreeCAD files to edit or STL files to print:

Free CAD files: download STL files: download

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Terms and Conditions of Use

I designed the splint for personal use, If you do not agree to all of these Terms and Conditions, do not use this design and any content in this web site! The contents in this page, such as text, graphics, images, and other materials are for informational purposes only. The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this page! The use of the design and the content on this page is at your own risk.