How to treat a thumb fracture with UCAST

We owe a lot to our opposable thumbs; the ability to use tools, even our cultural history. A fractured thumb makes you realize just how much you need your thumbs to do – well, anything. Michael Lindroos, experienced cast tech and Dassiet COO, shares how you can use the UCAST splint to immobilize the thumb.

Simple fractures can be treated simply by immobilizing the thumb, but more complex injuries often need surgery. Fractures involving several bone fragments will need external or internal fixation. Not all thumb injuries are fractures. A good example is the Skier’s thumb injurwhich happens if you fall on your outstretched thumb. The ulnar collateral ligament in the metacarpophalangeal joint tears, which causes pain, swelling, and bruising.
UCAST thumb can be used either as a conservative treatment method or to support recovery from surgery. There are two versions you can choose from: a long and short splint. In this blog, we’ll cover both applications.

1. Prepare your UCAST

The UCAST packaging contains four splints. Start by removing them from the package and placing the number of splints you’ll need in either a flatbed heater or an express heater.
Heating times will vary slightly depending on which method you are using – check the user instruction for specifics. In our express heater, the splint will be warmed up in approximately 50 seconds.
After the splint has softened and warmed up, carefully lift it from the heater and place it onto the Unitex wrap. Apply light pressure to make the splint grip on the fabric.

2. How to apply UCAST thumb or short thumb

The application process for both splints is very similar. Start by positioning UCAST to the fracture and begin by gently wrapping the splint around the thumb. Secure the splint by wrapping the bandage around the injured digit. Then, move on to wrap the splint around the patient's palm.
With the short thumb, fixate the splint without tightening the strap. Mold the splint to the patient’s palm with a light but firm touch. When the splint is rigid, tighten the straps to 50 % of their maximal stretch.
If you chose the longer thumb splint, continue gently molding UCAST around the wrist. Finally, wrap the proximal strap around the arm to fixate the device. Lightly press to mold the device from the wrist toward the elbow. The fit should be snug, but not too tight – make sure that you can insert a finger between the splint and the skin. The splint will be fully rigid after 2–3 minutes.

3. Therapy ensures the best healing result for a thumb fracture

When the injury allows, it’s important to begin therapy to restore mobility to the thumb. UCAST splints are designed for everyday life, so they are very easy to wear and keep clean. Your patient can just wipe the splint with a cloth dabbed in some antibacterial soap and water. If the injury allows, you can also instruct the patient on how to take the splint off and put it back on for the night or therapy sessions, for example. After they have healed, the splint and bandage can be recycled.


1. Handwerk, B. How Dexterous Thumbs May Have Helped Shape Evolution Two Million Years A, 2021, Smithsonian magazine, [internet] available at:
2. Fricker, R., & Hintermann, B. (1995). Skier's thumb. Treatment, prevention and recommendations. Sports medicine (Auckland, N.Z.), 19(1), 73–79.

3. Skier's thumb, British Society for Surgery of the Hand,, [internet] available at: