3D anatomic models allow the surgeon and engineer to manipulate a 3D representation of the anatomy.³ These models can be used for virtual preoperative planning, in which the effects of osteotomies and the fit of implant selection can be simulated either on a two-dimensional display or in a virtual reality environment¹,² (Figure 1). 3D surgical planning of deformity cases has demonstrated that two orthogonal radiographs do not capture a rotational component of the deformity, which is commonly recognized during the 3D modeling process by comparing the surgical side with the contralateral healthy side.⁴,⁵ Surgeons have supported the utility of these preoperative modeling techniques, with the literature demonstrating improved operating metrics (eg, length of time in the operating room, functional outcomes, reduced complications, decreased blood loss, and rates of transfusion).⁶,⁷

The 3D models can come to life as 3D prints, to be physically examined by the surgical team⁸,⁹ and the patient,⁶,¹⁰ can be sterilized and manipulated during a surgical case, and are regularly used for simulating surgery⁷ and prebending/contouring of hardware (commonly for acetabular fractures).³,¹¹ Surgeons have found that these models facilitate understanding of the anatomy and improve their surgical technique.⁸,¹² As 3D printed materials have improved to allow for more machining and instrumentation, they have become widely used to train medical students, residents, and fellows.¹⁰ In addition, these models are becoming more widely available, with the advent of FDA-approved point-of-care 3D printing pathways.⁹

Patient-specific instruments, such as drill guides and cutting guides, fit to the unique bone shape with cortical read, providing a personalized navigation template⁷
for correction of deformity. These instruments are 3D printed and sterilized preoperatively, and then used during surgery to assist with drill trajectory, osteotomies, and component positioning and orientation (Figure 2). These instruments have a proven track record and efficacy with total knee arthroplasty¹³ and have been gradually gaining acceptance in spine, upper extremity,⁴,¹⁴ deformity correction, and trauma applications.¹¹ Regarding spine surgery, 3D printed drill guides provide guidance in terms of screw trajectory, depth, and size, limiting the risk of injury to neurovascular structures.⁶,¹⁰,¹⁵ A 2021 study has shown that 3D printed drill guides demonstrated improvements in accuracy of pedicle screw placement, decreased blood loss, reduced surgical times, and reduced fluoroscopic times.¹⁶ Studies have shown that these benefits of reducing blood loss, fluoroscopy time, and surgical time have also been demonstrated in pediatric orthopaedic surgery,¹,⁷,¹⁷,¹⁸ total joint arthroplasty, and trauma surgery.⁵,⁸,¹¹,¹⁹,²⁰,²¹