Overview of Emerging Technology in Orthopedic Surgery: What is the Value in 3D Modeling and Printing? Kevin D. Tetsworth, MD, FRACS*wz and Tamer Mettyas, MBBCh, MSc, MRCS* Summary: Three-dimensional printing and modeling has evolved significantly since first introduced in the 1980s. In the last 5 years, this revolution in technology has become far more accessible and afford- able, and is already mainstream in many areas of medicine. Nowhere is this more apparent than in orthopedics, and many surgeons already incorporate aspects of 3D modeling and virtual procedures in their routine clinical practice. However, this technology promises to become even more prevalent as creative applications continue to be developed, and further innovations are certain to come. There are important public policy aspects to consider, both economic and regulatory. Regulatory issues are currently still under development, but will need to take into account sterilization, quality assurance, and product liability. The mechanical integrity of 3D-printed implants is influenced by the unique characteristics of the print process, including the energy density of the laser, the resolution of the print, and the orientation of the print on the build platform. Introduction of expensive new technology should only be done after careful consideration of the costs associated, the potential benefits, and the value that can be derived. The value in 3D modeling and printing can be considered relative to the initial costs, the experience of a 3D modeling unit, the complexity of a particular case, and the clinical expertise of the surgeons involved. There is significant potential value derived from modeling most displaced intra- articular fractures, once a 3D modeling unit is established and profi- cient. However, the greatest value comes from modeling the most highly complex cases. When the pathology is most abnormal, 3D modeling/printing can be a valuable clinical adjunct for even the most expert and experienced surgeons. Although currently hospital-based 3D modeling/printing units are uncommon, they will soon become far more common. For surgeons in developing nations, 3D printing may currently be prohibitively expensive, but 3D modeling is relatively inexpensive and therefore far more accessible. As 3D printer prices continue to fall, the ability to rapidly manufacture prototypes and patient-specific models will inevitably spread through these regions as well. However, the future for 3D-printed medical models, devices, and implants will be limited unless we are able to document their clinical superiority and confirm their value with respect to patient outcomes. Level of Evidence: Level V—expert opinion. Key Words: orthopedic surgery—3D modeling—3D printing— custom implants—rapid prototypes—virtual surgery—preoperative planning. (Tech Orthop 2016;31: 143–152) I n October 2014, many newspapers proclaimed the benefits of a “world’s first” surgical procedure in Melbourne, Australia, when Professor Peter Choong replaced a calcaneus destroyed by tumor. 1 A prosthetic bone substitute was custom 3D printed from titanium, and implanted successfully. This was portrayed in the media as a modern medical triumph where a talented surgeon, confronted with a difficult problem with no simple solution, boldly sought an alternative approach that capitalized on recent technological breakthroughs. Headlines have echoed this senti- ment repeatedly over the course of the past 2 years, with multiple other surgeons also creating bespoke bone substitutes and implants to reconstruct complex pathology in unique cases. 2–5 However, the media has failed to recognize how truly pervasive 3D modeling and 3D printing have become in con- temporary orthopedic surgery. There are no headlines for the hundreds of other procedures conducted around the world every day, where 3D modeling and virtual surgery have become an integral part of the actual procedure. Over the course of the past few years, 3D modeling and 3D printing have become standard practice in some operating theaters, although most often virtual surgical procedures are used for preoperative planning. 6–11 It is so prevalent that these tech- nologies now play an important role in perhaps the majority of complex orthopedic cases currently treated around the world. This is most apparent in the realm of adult reconstructive surgery and total joint replacement, but it is rapidly permeating every aspect of orthopedic surgery, including trauma, 7,9,12–17 spine, 17–20 hand, 21–26 shoulder, 27,28 and sports medicine. 29 Complex revision total joint arthroplasty has used cus- tom-designed 3D-printed patient-specific components for many years. This has often been in the form of custom-made triflanged acetabular components to deal with major pelvic bone loss, 30–34 as an alternative to cages and impaction grafting techniques. This has generally been on a limited basis, and typically involved a design team that worked remotely from the surgeon. Yet, that also is changing rapidly, and many surgeons have taken the opportunity to design their own cus- tom implants with the benefit of rapid prototyping using the more affordable 3D printers available today. 35 EARLY DEVELOPMENT OF 3D PRINTING 3D modeling of medical images has evolved significantly over the past 40 years, accelerating quickly immediately after CT scanning was introduced. Interpreting complex 3D geom- etry and pathologic anatomy based on 2-dimensional slices has inherent limitations, while still providing valuable information that has been of great value clinically. As computer-processing power rapidly increased over this same period, the quality of the 3D modeling has also naturally improved dramati- cally. 7,8,36 Once 3D printing appeared in the early 1980s, medical applications soon followed. 6,37–42 3D printing is also known as Additive Manufacturing (AM), and describes any of the various processes used for making a 3D object of almost any shape from a 3D model of a From the *Department of Orthopaedic Surgery, The Royal Brisbane and Women’s Hospital; wOrthopaedic Research Center of Australia; and zDepartment of Surgery, University of Queensland, School of Medicine, Brisbane, Qld, Australia. The authors declare that they have nothing to disclose. Address correspondence and reprint requests to Kevin Tetsworth, MD, FRACS, Department of Orthopaedic Surgery, The Royal Brisbane and Women’s Hospital, Level 7 NHB, Butterfield Street, Herston, Brisbane 4029, Qld, Australia. E-mail: kevin.tetsworth@health.qld.gov.au. Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved. SYMPOSIUM Techniques in Orthopaedics$  Volume 31, Number 3, 2016 www.techortho.com | 143 Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.