4D Printing Replaces the Traditional Cast in Orthopedic Care

The Singaporean startup Castomize has developed a 4D-printed cast that addresses the drawbacks of conventional casts: itching, sweating, irritation, and the inability to get wet. Their solution leverages the properties of smart thermoplastics, allowing the cast to be molded precisely to each patient’s anatomy at the time of application, with no prior scanning required and no saw needed for removal.

The device originated from research at the Singapore University of Technology and Design and became a commercial product in 2022. It is aimed at clinics and healthcare professionals seeking a lighter, breathable, and 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 concept of 4D printing is not new, but its translation into a viable commercial product remains rare. In short, it involves manufacturing structures that change when exposed to an external stimulus, in this case heat. The object is not customized during printing, but afterward: the cast comes out of the printer with a fixed geometry, softens when heated, and hardens when cooled. The clinician heats it, molds it over the patient’s wrist, forearm, or ankle, and waits for it to cool.