Short report letter: Three-dimensional printed anatomical models in scaphoid surgery

When undertaking surgery for nonunion of scaphoid fractures, appreciation of the three dimensional (3D) anatomy and hence accurate restoration of the original shape of the bone is difficult. Computerised tomography (CT) is regularly used to evaluate scaphoid nonunions slice by slice before surgery. As a potential aid for surgical planning, we have developed a method for producing 3D printed anatomical models of the un-united scaphoid and the intact scaphoid based on the contralateral side. Bilateral CT scans of the wrist were obtained. Virtual 3D CT models of the proximal and distal nonunion fragments and the intact scaphoid, mirrored to the injured side, were created using custom image segmentation software (Dobbe et al., 2011) (Figure 1). Printing was performed using a Blueprinter M2 (Blueprinter , Copenhagen, Denmark) based on thermoplastic powder with 100mm resolution. We evaluated the use of the 3D models in an experimental bench study on palmar plate fixation of the scaphoid, which has been recommended for treatment of some nonunions (Dodds and Halim, 2016). Synthetic printed models were produced from eight patient cases with unilateral scaphoid nonunion with palmar bone loss. Three operators simulated corrective surgery on the synthetic bone