How to model an A1 orthosis?

Create an A1 model with the FreeForma tool in 5 easy steps.

The A1 orthosis is commonly used for non-/pre-/post-surgery treatment and suitable to treat a wide range of pathologies affecting the radio-carpal and the carpometacarpal joint of the hand and wrist: scaphoid fractures, radius fractures, acute arthritis flare-ups, acute TFCC ligament injuries, arthroplasty, contractures, complex regional pain syndrome, and osseous contusions. It’s also suitable in the case of radial nerve paralysis, rheumatoid arthritis, synovitis, (sub)luxation, as well as wrist strain, tendinitis, tendinosis, and wrist sprain to name a few.

If its’ your first time using the FreeForma to create an orthosis, we recommend reading this article first, where we explain all steps of modeling an orthosis with the FreeForma in detail.

We will quickly go over the following steps, in preparation for modeling the A1 orthosis:

Select the A1 model
3D scan the limb
Rectify the scan
Model the A1 orthosis

Step 1: Select the A1 model

On either the right or left upper limb, select the metacarpal region and parts of the forearm that interact with the orthosis. The A1 orthosis will be the first suggested model. Select the model and click next.

Step 2: 3D scan the limb

To achieve a perfect scan for this particular model, put the hand and thumb of

the patient in a relaxed/resting position, meaning:

Dorsiflexion of the wrist between 12°-20°.

The IP slightly flexed.
the thumb in partial opposition and facing forward.

Afbeelding met persoon

Automatisch gegenereerde beschrijving

Tip: Ask the patient to keep their arm vertically at a 90° angle. Ideally, the patient can let it rest on the back of a chair or any other object you can easily walk around.

Step 3: rectify the 3D scan

To create perfect-fitting orthoses, it’s recommended to start by rectifying the scan. By doing so you set it up for a smooth modeling experience. Rectifying the scan consists of the following easy steps: 

Cleaning up the scan. If there are irregularities or even missing pieces to the scan, you can use our tool to enhance the scan.

Change the pose of the scan. This comes in handy when you could not scan the body part in the right immobilization position.

Locally sculpt parts of the scan to add or remove volume, creating or removing pressure points.

To have a more in-depth description of the process of rectification, we recommend reading our article: ‘How to rectify the wrist’, where we fully describe how to rectify a scan.

Step 4: 3D model your A1 orthosis

Using the FreeForma tool you can now design the A1 orthosis.

Designing the overall shape

Create the shape of the orthosis by drawing on the scan with one finger.

When creating the shape, it’s important to leave enough space at the MCP region, so your patient’s fingers (digits II-V) can move functionally and keep their full Range of Motion (ROM).
The thumb is left free to move in all possible directions, full ROM is enabled.
When creating the sides of the orthosis, try to avoid implementing the styloid in your model. Even when you sculpted extra volume on that region, just to exclude any possibility of adding pressure to the styloid.

Designing the opening

Depending on the material you will use, the opening of the orthosis (to fit your wrist and arm) can differ.

Using sturdier material, the opening should be bigger to fit the arm more easily in the orthosis. It will also be more difficult to aid the patient with putting it on by wringing the orthosis open.
Using flexible material, the sides can be closer together as it will be easier to flex the orthosis and insert the limb.

Tip: When creating a more closed opening, using flexible material, be sure to have at least an opening of approximately 20 mm.

Designing the inside structure

When creating alveoli, it’s best to stretch them vertically. Horizontally wide alveoli are harder for the printing process as printing will be done vertically (with FDM and DLP). To clear large horizontal gaps you need more support which ultimately leads to more waste, more costs, and long printing times. Those are three good reasons to use vertically stretched alveoli (see picture below).

Adapt the thickness

Decide on the local and overall thickness of the orthosis.

You can adapt the thickness in some regions, depending on your patient’s needs. For example, you can add more thickness to the wrist which leads to extra support and rigidity.

Add a closing system to your design

For a more detailed description of how to add beltloops, click here.

When creating beltloops for a wrist orthosis, try to avoid putting any straps over the joint of the wrist.

Engrave the serial number

You can now engrave a serial number on your design. Just tap on Text Engrave and tap another time on your splint to make your order number appear. You can then move this serial number on the orthosis by sliding it with your finger and repositioning it using the two rotation arrows.

Step 5: export

Congratulations, you have successfully created an A1 orthosis. You can now export and print it.