Abstract
Background Over the last decade, image-guided production of three-dimensional (3D) haptic biomodels,
or rapid prototyping (RP), has transformed the way surgeons conduct preoperative planning.
In contrast to earlier RP techniques such as stereolithography, 3D printing has introduced
fast, affordable office-based manufacturing. We introduce the concept of 4D printing
for the first time by introducing time as the fourth dimension to 3D printing.
Methods The bones of the thumb ray are 3D printed during various movements to demonstrate
four-dimensional (4D) printing. Principles and validation studies are presented here.
Results 4D computed tomography was performed using “single volume acquisition” technology
to reduce the exposure to radiation. Three representative scans of each thumb movement
(i.e., abduction, opposition, and key pinch) were selected and then models were fabricated
using a 3D printer. For validation, the angle between the first and the second metacarpals
from the 4D imaging data and the 4D-printed model was recorded and compared.
Conclusion We demonstrate how 4D printing accurately depicts the transition in the position
of metacarpals during thumb movement. With a fourth dimension of time, 4D printing
delivers complex spatiotemporal anatomical details effortlessly and may substantially
improve preoperative planning.
Keywords
3D printing - reconstructive surgery - template - 4D - 3D model - dimensional
