4D Printing Replaces Casts: The Future of Orthopedic Care

Singapore-based startup Castomize has developed a 4D-printed cast designed to solve common problems associated with traditional casts — itching, sweating, skin irritation, and the inability to get wet. Using smart thermoplastic materials, the cast is molded precisely to each patient’s anatomy at the time of application, with no prior scanning required and no saw needed for removal.

Developed from research at the Singapore University of Technology and Design and commercialized in 2022, the device targets clinics and healthcare professionals who want a lighter, more breathable, and fully waterproof alternative to fiberglass casts.

4D cast applied to the forearm. The open lattice structure allows for air circulation and makes the piece completely waterproof.

The principle of 4D printing — producing structures that change shape or properties when exposed to an external stimulus — is well established, but few commercial products bring it into routine clinical use. Castomize’s cast is printed with a fixed geometry and a perforated lattice. When heated, the thermoplastic softens; the clinician molds the cast around the wrist, forearm, or ankle; then it hardens as it cools, creating a custom fit without digital scanning.

The lattice of perforations serves multiple purposes: it reduces weight, improves ventilation to keep skin dry, creates a waterproof barrier, and removes the need for a saw during removal. Castomize reports that, with medical approval, patients can even swim while wearing the cast.

Rather than relying on individualized scans, the system uses standard sizes that are adjusted during the appointment. If swelling changes, alignment needs correction, or an adjustment is required during treatment, the clinician can simply reheat and remold the same cast over the limb, avoiding replacement.

Castomize currently offers casts for the wrist, forearm, arm, and ankle, and is expanding its product line to include prosthetic components and medical devices for pets while further developing pediatric sizes.