A surgeon’s ability to understand the intricacies of a patient’s musculoskeletal system has largely been determined by that surgeon’s ability to read medical imaging. 3D printing can shift the reliance away from radiological expertise and enable more personalized solutions for patients.
This process involves converting a CT or MRI into a format recognizable by a 3D printers using programs such as Osirix and Mimics (Figure 1). These programs allow surgeons to create a printable file from their own desktop. 3D printing can improve the understanding of a patient’s precise anatomy with a physical model. This physical model can be used to improve preoperative surgical planning, thereby increasing implant placement precision and surgical outcomes. 3D printing can also allow for the creation of customized implants specific to a patient’s anatomy (Figure 2).
3D printing has only recently begun to be utilized in orthopaedic surgery. While there are some critics of its reliability for clinical usage, there is tremendous excitement about its future potential, especially in the field of regenerative medicine. 3D printing can allow for bioprinting, which combines cells, growth factors and supporting material. In orthopedics, artificial cartilage and bone scaffolds are two critical tissues that can be bioprinted. Often materials used to mimic these tissues such as hydrogels and polymers are unable to fully demonstrate these tissue’s properties. Bioprinting can be especially useful when an autologous bone graft would not suffice or additional support is required, in cases such as congenital abnormalities, bone tumors and complex fractures.
CURRENT STATE OF ORTHOPAEDIC PRACTICES
Orthopaedic surgery practices have primarily reacted to this innovation by reviewing research findings and technological capabilities. The research driving this adoption is primarily being conducted by large academic centers with strong engineering and computer science departments. These researchers have used 3D printing for preliminary planning, simulation of procedures, fracture repair, bone tumor removal and fixing congenital deformities.
Customized orthopaedic implants are now manufactured by third party vendors. Knee replacement manufacturers have already popularized patient specific cutting blocks. While outsourcing customized implants can be useful to familiarize a practice with new technologies, it does not necessarily take advantage of the complete purpose of additive manufacturing – to be able to efficiently and cost effectively create in-house prototypes.
While 3D printing has gained traction in many practices, some respected physicians do not trust the reliability of 3D printing for clinical applications. Recent studies have more robustly evaluated these models. Studies have assessed the degree of similarity between models and true anatomical parameters. In a recent systemic study, 3D model dimensions were found to be reliable and precise.
Considering the initially mixed reception within the orthopaedic community, many practices have been slow to buy 3D printers or begin learning to use the programs. The cost of 3D printers has significantly dropped in the last few years and therefore 3D printers already available at many large academic practices. Most practices are still waiting for the technology to advance further and for the development of a strong consensus in the field.
For an orthopedic practice, a short term recommendation would be to download and become more comfortable with the software programs that allow 3D visualization of CTs and MRIs. Many programs are free and can both provide an additional perspective on patient anatomy, and position a practice to become facile with visualization tools that are becoming increasingly important.
While printer and building materials are relatively inexpensive, the cost associated with hiring staff to operate these machines represents a significant impediment to implementation. This begs the question: Should orthopaedic practices or device manufacturers lead the creation and iteration of 3D printed models?
Understandably, practices without the support of a larger institution do not want to take on these additional costs. These practices could visit a practice with 3D printers to better understand the technology. A potential solution to the cost of staffing would be to initially outsource the printing to a third party. With technological advances, the 3D printers may eventually be able to automate the process from MRI or CT to creation of a prototype. This could ultimately allow even resource constrained practices to take advantage of 3D printing. With the continued advancements and the increasing popularity of 3D printing, its use for surgical planning, implant customization and tissue engineering is likely to become widespread in the near future.
[Word Count: 745]
 Wang et al. 3D printing technology used in severe hip deformity. Experimental and Therapeutic Medicine 14: 2017, 2595-2599
 Wong TM, Jin J, Lau TW, et al. The use of three-dimensional printing technology in orthopaedic surgery: a review. J Orthop Surg. 2017 Jan;25(1).
 You F, Eames BF, Chen X. Application of extrusion-based hydrogel bioprinting for cartilage tissue engineering. Int J Mol Sci. 2017 Jul 23;18(7).
 Vaibhav Bagaria et al. 3D printing- creating a blueprint for the future of orthopaedics: Current concept review and the road ahead. Journal of Clinical Orthopaedics and Trauma 9, 2018 207e212.
 Hitesh Lal et al. 3D printing and its applications in orthopaedic trauma: A technological marvel. Journal of Clinical Orthopaedics and Trauma 9 2018 260e268.
 Boonen B, Schotanus MG and Kort NP. Preliminary experience with the patient-specific templating total knee arthroplasty. Acta Orthop; 2012, 83: 387.
 Barrack RL, Ruh EL, Williams BM, et al. Patient specific cutting blocks are currently of no proven value. J Bone Joint Surg Br; 2012, 94: 95. 14.
 Zou Y, Han Q, Weng X, et al. The precision and reliability evaluation of 3- dimensional printed damaged bone and prosthesis models by stereolithography appearance. Medicine. 2018 Feb;97(6).
 Vaish A, Vaish R. 3D printing and its applications in Orthopaedics. J Clin Orthop Trauma. 2018 Mar 1;9:S74eS75.