Three-Dimensional Printing: Building a Solid Foundation for Improving Technical Accuracy in Orthopaedic Surgery

The use of additive manufacturing (3D printing) is now firmly established within the veterinary orthopaedic community. Growth in the use of three-dimensional (3D) printing has been fuelled by the widespread availability of both open-source and commercial software for building 3D models from cross-sectional (computed tomography or magnetic resonance imaging) data, as well as by expanding options for in-house or third-party printing of solid models. The creativity of surgeons in leveraging this technology has been astounding, as exemplified by the reporting of applications ranging from the fabrication of solid plastic bone models for surgical planning, to the design of custom orthotics, to the production of replacement shells for injured tortoises. While many surgeons tend to be early adopters of cutting-edge technology, the rapid acceptance of 3D printing has been underpinned by the fact that it offers the potential to improve our technical performance in the operating room, either through the use solid bone models for preoperative practice or through the intraoperative use of custom, patient-specific guides (PSGs) and patient-specific implants (PSIs).

For surgeons new to this field, especially those in specialty practice outside of a major academic centre, the barriers to entry can appear overwhelming. While the hardware to print models is widely available and generally quite affordable, little has been published with regard to practical recommendations on best practices for achieving repeatable and accurate results. When considering limb realignment surgeries, for example, the virtual realignment procedure is performed by referencing the contralateral normal leg, if available, or, more commonly, by interpolating the knowledge and expertise developed with 2D limb alignment analysis. The translation from 2D to 3D is bound to generate approximation and it has become necessary to establish limb alignment standards in 3D, similar to what was elegantly done in 2D[1] with standard radiographic techniques.

Many of the key steps in the creation of bone models, PSGs and PSIs, such as image thresholding, segmentation and shape matching, are identical across all potential applications. Standardization and optimization of the methods used for these steps would help reduce operator error, improve the accuracy of the final result in the operating room and facilitate the reporting and analysis of results from different institutions. As surgeons, we aspire to technical excellence and while it may yet be too early to state with confidence that the use of 3D printing improves clinical outcomes for our patients, several authors have published papers demonstrating improvements in technical accuracy through the use of preoperative 3D planning and intraoperative PSGs.

This special issue of Veterinary and Comparative Orthopaedics and Traumatology (VCOT) recognizes the coming of age of this nascent technology in veterinary orthopaedics by bringing you original work on virtual surgical planning for the repair of navicular bone fractures in horses,[2] the use of PSIs in spinal surgery[3] and in the management of coxofemoral luxation,[4] and the development of PSGs and PSIs for managing antebrachial deformity in dogs.[5]

As enthusiastic as we are about the potential utility of technology in improving surgical outcomes, we are duty bound to sound a note of caution and to acknowledge the limitations and risks that are inherent to the use of PSG and PSIs. Errors in segmentation, shape matching, virtual surgical correction and tool design will lead to unsatisfactory clinical outcome. It remains the responsibility of the surgeon to identify, avoid or correct potentially harmful mistakes, ideally prior to, but at the very latest during the surgical execution of the virtually planned procedure. When used appropriately and responsibly, this technology has the potential to augment the surgeon and to improve surgical accuracy, but it is not a replacement for appropriate surgical planning and technical proficiency. The use of PSGs and PSIs is not regulated in the veterinary field, so it falls to us as a community to develop, implement and audit clinical outcomes to define best practices for the future.

Publication History

Article published online:
13 January 2021

• References

• 1 Fox DB, Tomlinson JL, Cook JL, Breshears LM. Principles of uniapical and biapical radial deformity correction using dome osteotomies and the center of rotation of angulation methodology in dogs. Vet Surg 2006; 35 (01) 67-77
• 2 Biedrzycki A, Kistler HC, Perez E, Morton A. Use of Hausdorff distance and computer modelling to evaluate virtual surgical plans with three-dimensional printed guides against freehand techniques for navicular bone repair in equine orthopaedics. Vet Comp Orthop Traumatol 2021; 34 (01) 9-16
• 3 Toni C, Oxley B, Clarke S, Behr S. Accuracy of placement of pedicle screws in the lumbosacral region of dogs using 3D-printed patient-specific drill guides. Vet Comp Orthop Traumatol 2020; 34 (01) 53-58
• 4 Darrow BG, Snowdon KA, Hespel A. Accuracy of patient-specific 3D printed drill guides in the placement of a canine coxofemoral toggle pin through a minimally invasive approach. Vet Comp Orthop Traumatol 2020; 34 (01) 1-8
• 5 Carwardine DR, Gosling MJ, Burton NJ, O'Malley FL, Parsons KJ. Three-dimensional-printed patient-specific osteotomy guides, repositioning guides and titanium plates for acute correction of antebrachial limb deformities in dogs. Vet Comp Orthop Traumatol 2021; 34 (01) 43-52