Orthopedic Advancements through 3D Printing

Introduction:

Three-dimensional (3D) printing, also known as additive manufacturing, has transformed the design and production processes across various industries, offering significant opportunities for rapid prototyping, small-scale production, and customization. This technology enables the creation of intricate and detailed designs, including one-off manufacturing, which would be impractical using traditional methods. Unlike traditional manufacturing, which often requires centralized production facilities and large inventories, 3D printing allows for on-demand manufacturing, eliminating the need for extensive storage space. (1)

Moreover, 3D printing has become an integral part of commercial manufacturing and has even entered personal households with the introduction of desktop 3D printers. With compatible software and suitable materials, consumers can witness the entire process from raw material to finished product, facilitating the creation of customized designs. (2)

In orthopedic surgery, 3D printing has had a significant impact on patient care and education across various subspecialties. Three-dimensional printed anatomical models are frequently used in preoperative planning and serve as valuable educational tools for both patients and trainees. (3) Additionally, the adoption of 3D-printed patient-specific instrumentation (PSI) has become commonplace in orthopedic procedures such as arthroplasty and complex reconstructions. The integration of 3D printing with biomedical science holds promise for further advancements in the field. (4)

3D printing in medicine

Research on the applications of medical 3D printing (3DP) has experienced exponential growth in recent years, encompassing various areas including the manufacture of biomodels or bioreplicas, custom-made tools, implants, drugs, and biocompatible tissues (bioprinting). These applications are at different stages of maturity, as depicted by the hype cycle of emerging technologies developed by the global consulting firm Gartner. This cycle outlines the phases of a technology's life cycle, from the trigger to the peak of inflated expectations, a trough of disillusionment, a slope of enlightenment, and finally, the plateau of productivity. (5)

Despite the promising potential of 3DP in the medical sector, there are still some disadvantages that need to be addressed. Factors such as additional manufacturing time, increased costs, requirement for technical expertise, mechanical properties, and precision of certain technologies must be carefully considered depending on the specific application. (6)

Orthopedic Applications

Anatomical Models

 Three-dimensional (3D) printed anatomical models have proven invaluable in orthopedic surgery for preoperative planning and surgical education. (7) These models provide surgeons with a detailed representation of anatomical structures in 3D space, aiding in the selection of appropriate hardware and facilitating preoperative plate bending to ensure precise anatomical fit. Notably, this approach has shown promise in the management of orthopedic conditions such as clavicle fractures.

Furthermore, 3D models are utilized in the mirror imaging technique, where models of the contralateral uninjured side are printed for comparison. This enables surgeons to simulate reduction techniques and optimize surgical approaches for various orthopedic fractures, including clavicle fractures, calcaneal fractures, pilon fractures, and ankle fractures, with excellent outcomes. (8)

In the realm of orthopedic education, 3D-printed anatomical models play a crucial role in training resident surgeons and deepening their understanding of regional anatomy and surgical techniques. (9) Additionally, these models enhance patient education, leading to improved perioperative understanding and compliance. (10)

Despite their numerous benefits, third-party payers currently do not reimburse the costs associated with 3D-printed anatomical models. However, the significant reduction in operating times facilitated by these models results in potential cost savings that may offset the expenses of maintaining a 3D printing laboratory in orthopedic settings. (11)

Prosthetics and Orthotics

While traditional braces and orthotics offer limited size options and fit, customizable prosthetics have shown effectiveness, albeit with complex and costly manufacturing processes. (12)

In contrast, 3D printing has revolutionized ankle-foot orthoses (AFOs) design and production. Traditional methods involve labor-intensive plaster casting, leading to fit and comfort issues. 3D printing simplifies this process, allowing for personalized designs based on individual biomechanical metrics, with positive outcomes observed, especially for plantar fasciitis patients.

Desktop 3D printers have brought 3D printing to patients' homes, enabling amputees to create their prosthetics. Although promising for affordability and accessibility, FDA approval and regulation for these 3D-printed devices are lacking. While studies report favorable patient outcomes, there is a need for rigorous comparisons with existing prosthetics to establish clinical efficacy. (13)

New Non-custom Implants

 Three-dimensional printing technology has enabled the production of orthopedic implants that are not customized. Innovative implant types for hip and knee arthroplasty have emerged due to the efficient 3D printing process. (14) For instance, 3D-printed acetabular cups, thinner and more cost-effective than traditional cups, have shown promising results in acetabular defect revision surgeries, with improved stability, hip scores, and reduced pain. The increased porosity of these cups may enhance bone growth compared to traditional options. (15)

Similarly, 3D printing has facilitated the creation of porous metal implants for foot and ankle arthrodesis, offering structural support and improved surface for biological incorporation, serving as alternatives to conventional fixation methods.

Additive manufacturing has also led to the development of innovative cage prototypes for spine surgery, aiming to better mimic native bone properties. Preliminary studies on 3D-printed intervertebral fusion cages have shown a close resemblance to trabecular bone's compressive modulus. Moreover, the implantation of 3D-printed lamellar titanium cages has resulted in high arthrodesis rates, demonstrating the potential of these implants in spinal fusion procedures. (16)

Patient-Specific Instrumentation (PSI)

Customized surgical guides produced with 3D printing technology have been utilized in orthopedic surgeries to improve precision and efficiency. While the use of PSI in total knee arthroplasty (TKA) has shown mixed results in terms of operative time and alignment, its economic efficiency remains an important consideration for maintaining high standards of patient care amidst increasing caseloads. (17)

In a randomized controlled trial comparing conventional instrumentation, PSI, and single-use instrumentation for TKA, patient-specific/reusable instrumentation emerged as the most expensive option but demonstrated favorable outcomes, including shorter surgery times, reduced blood loss, shorter hospital stays, and higher postoperative knee scores. However, the definitive advantage of PSI in primary TKA remains unclear, with most publications not claiming a significant advantage but also not identifying a negative impact on procedure accuracy. (18)

Three-dimensional printed patient-specific cutting jigs enable precise preoperative planning in complex cases of deformity, leading to improved accuracy in procedures such as medial closing wedge distal femoral osteotomy and acetabular fracture treatment. (19) However, challenges with PSI include technical complexity and potential issues such as under-correction in corrective osteotomies and difficulties in estimating osteotomy depth, highlighting the need for careful planning and evaluation during surgery.

Patient-Specific Custom Implants

Three-dimensional (3D) printing technology has revolutionized orthopedic surgery by allowing for the creation of patient-specific custom implants tailored to individual anatomical variations and complex pathologies. While standard implants serve the general population adequately, personalized implants are indispensable in cases with unique anatomical variations or extensive bone loss due to trauma, cancer, or infection.

The process of obtaining a custom implant involves careful assessment of patient needs, prescription by a physician, and collaboration with engineering teams to create a 3D model based on preoperative imaging. The final design is then approved by the surgeon before fabrication via 3D printing begins. These custom implants are granted FDA approval on a case-by-case basis and are designed specifically for each patient's anatomy and pathology, filling a niche not addressed by commercially available implants. (20)

Studies have shown promising outcomes with 3D-printed patient-specific implants, particularly in cases of severe bone defects, deformities, and arthrodesis procedures. Success rates have been high, with improvements noted in fusion rates and functional outcomes compared to traditional treatment methods. Additionally, custom implants have demonstrated advantages over standard implants in total knee and hip arthroplasty, spine surgery, and complex spinal deformities, leading to improved rotational alignment, better fit, reduced blood loss, and fewer adverse events.

However, the use of patient-specific custom implants requires careful consideration of indications, contraindications, and potential financial costs. Surgeon involvement throughout the process is crucial, and discussions with hospitals, patients, and insurance companies regarding the financial implications are essential. Despite these challenges, 3D printing has paved the way for innovative solutions in orthopedic surgery, offering personalized care and improved outcomes for patients with complex musculoskeletal conditions. (21)

Bioprinting/Four-dimensional Printing

Three-dimensional (3D) printing technology has paved the way for innovative approaches in tissue engineering and regenerative medicine, particularly through 3D bioprinting. This process involves layer-by-layer deposition of cells, biomaterials, and biological factors to create living tissues and organ analogs. (22) Hydrogels, microcarriers, and tissue strands are among the materials used as the printing medium, offering the stability and biocompatibility necessary for cellular survival and proliferation. Bioprinting methods, such as droplet, extrusion, and laser-based techniques, enable precise control over the microarchitecture and macro-architecture of the printed constructs, holding immense potential for revolutionizing regenerative medicine. (23)

Cartilage Bioprinting

In the realm of orthopedics, 3D bioprinting offers a promising avenue for cartilage regeneration. Unlike conventional surgical interventions, which may yield functional but not native-like cartilage, bioprinting holds the potential to create cartilage that closely mimics the molecular composition of healthy tissue. (24) Animal studies have shown promising results, with implanted bioprinted cartilage cells demonstrating early formation and integration within cartilage defects. While much of the research remains in vitro, systematic reviews endorse the potential of bioprinted cartilage for clinical application in humans. (25)

Bone Bioprinting

Similarly, bone bioprinting holds promise for addressing challenges in bone tissue engineering and regeneration. Scaffold materials, such as calcium phosphate, play a crucial role in providing structural support and facilitating osseous ingrowth. 3D printing enables precise control over scaffold microstructure, essential for cell viability and differentiation. Despite concerns about cell viability during the printing process, bioprinted bone scaffolds have shown favorable outcomes in animal models, with calcium phosphate scaffolds demonstrating biodegradability and bone formation. (26)

Four-dimensional Printing

Four-dimensional (4D) printing represents an evolution of 3D printing technology, incorporating smart materials that can change shape over time in response to environmental stimuli. (27) This innovative approach holds the potential for creating self-reconfigurable proteins, tissues, and organs. By harnessing factors such as temperature, pH, and magnetic fields, 4D-printed constructs can self-repair or self-assemble, offering exciting possibilities for applications in tissue engineering and beyond. For example, shape memory bone tissue engineering scaffolds have shown promise in treating bone defects by adapting to the surrounding environment post-implantation, leading to improved bone formation. (28)

Conclusion:

In summary, three-dimensional (3D) printing stands as a transformative technology across various industries, offering unprecedented flexibility in manufacturing complex structures from diverse materials, including metals, plastics, and even biological cells. Its benefits include customizable shapes, intricate designs, streamlined production processes, and reduced waste.

While cost and data limitations are common drawbacks associated with new technologies, particularly in the medical sector where custom implants are concerned, patient-specific 3D-printed implants represent a promising solution for treating diverse orthopedic pathologies. As 3D printing technology continues to evolve, it holds the potential to enhance patient care and satisfaction in orthopedic surgery and beyond.

References:

1.       M.H. Michalski, J.S. Ross The shape of things to come JAMA., 312 (2014), p. 2213, 10.1001/jama.2014.9542.

2.       N. Martelli, C. Serrano, H. van den Brink, J. Pineau, P. Prognon, I. Borget, et al. Advantages and disadvantages of 3-dimensional printing in surgery: a systematic review Surgery., 159 (2016), pp. 1485-1500, 10.1016/j.surg.2015.12.017.

3.       J.-Y. Lee, J. An, C.K. Chua Fundamentals and applications of 3D printing for novel materials Appl Mater Today., 7 (2017), pp. 120-133, 10.1016/j.apmt.2017.02.004.

4.       D. Fan, Y. Li, X. Wang, T. Zhu, Q. Wang, H. Cai, et al. Progressive 3D printing technology and its application in medical materials Front Pharmacol., 11 (2020), 10.3389/fphar.2020.00122.

5.       J.D. Prince 3D printing: an industrial revolution J Electron Resour Med Libr., 11 (2014), pp. 39-45, 10.1080/15424065.2014.877247.

6.       Mulford JS, Babazadeh S, Mackay N: Three-dimensional printing in orthopaedic surgery: Review of current and future applications. ANZ J Surg 2016;86:648-653.

7.       Kang HJ, Kim BS, Kim SM, et al.: Can preoperative 3D printing change surgeon’s operative plan for distal tibia fracture? Biomed Res Int 2019;2019:7059413.

8.       Chung KJ, Huang B, Choi CH, Park YW, Kim HN: Utility of 3D printing for complex distal tibial fractures and malleolar avulsion fractures: Technical tip. Foot Ankle Int 2015;36:1504-1510.

9.       Bizzotto N, Sandri A, Regis D, Romani D, Tami I, Magnan B: Three-dimensional printing of bone fractures: A new tangible realistic way for preoperative planning and education. Surg Innov 2015;5:548-551.

10.     Kim JW, Lee Y, Seo J, et al.: Clinical experience with three-dimensional printing techniques in orthopedic trauma. J Orthop Sci 2018;23:383-388.

11.     Kim HN, Liu XN, Noh KC: Use of a real-size 3D-printed model as a preoperative and intraoperative tool for minimally invasive plating of comminuted midshaft clavicle fractures. J Orthop Surg Res 2015;10:91.

12.     Wojciechowski E, Chang AY, Balassone D, et al.: Feasibility of designing, manufacturing and delivering 3D printed ankle-foot orthoses: A systematic review. J Foot Ankle Res 2019;12:11.

13.     Tanaka KS, Lightdale-Miric N: Advances in 3D-printed pediatric prostheses for upper extremity differences. J Bone Joint Surg Am 2016;98:1320-1326.

14.     Hodsden S: FDA clears Zimmer Biomet’s 3D-printed foot and ankle implant. Med Device Online 2016.

15.     Diment LE, Thompson MS, Bergmann JH: Three-dimensional printed upper-limb prostheses lack randomised controlled trials: A systematic review. Prosthet Orthot Int 2018;42:7-13.

16.     Serra T, Capelli C, Toumpaniari R, et al.: Design and fabrication of 3D-printed anatomically shaped lumbar cage for intervertebral disc (IVD) degeneration treatment. Biofabrication 2016;8:035001.

17.     Stone AH, Sibia US, MacDonald JH: Functional outcomes and accuracy of patient-specific instruments for total knee arthroplasty. Surg Innov 2018;25:470-475.

18.     Chen X, Zhang G, Lin H, et al.: Accurate fixation of plates and screws for the treatment of acetabular fractures using 3D-printed guiding templates: An experimental study. Injury 2017;48:1147-1154.

19.     Rosseels W, Herteleer M, Sermon A, Nijs S, Hoekstra H: Corrective osteotomies using patient-specific 3D-printed guides: A critical appraisal. Eur J Trauma Emerg Surg 2019;45:299-307.

20.     Custom Device Exemption: Guidance for Industry and Food and Drug Administration Staff. White Oak, MD, FDA, 2014.

21.     Jeng CL, Campbell JT, Tang EY, Cerrato RA, Myerson MS: Tibiotalocalcaneal arthrodesis with bulk femoral head allograft for salvage of large defects in the ankle. Foot Ankle Int 2013;34:1256-1266.

22.     Dhawan A, Kennedy PM, Rizk EB, Ozbolat IT: Three-dimensional bioprinting for bone and cartilage restoration in orthopaedic surgery. J Am Acad Orthop Surg 2019;27:e215-e226.

23.     Burnard J, Parr WCH, Choy WJ, Walsh WR, Mobbs RJ: 3D-printed spine surgery implants: A systematic review of the efficacy and clinical safety profile of patient-specific and off-the-shelf devices. Eur Spine J 2020;29:1248-1260.

24.     Tetteh ES, Bajaj S, Ghodadra NS: Basic science and surgical treatment options for articular cartilage injuries of the knee. J Orthop Sports Phys Ther 2012;42:243-253.

25.     Miller JS: The billion cell construct: Will three-dimensional printing get us there? PLoS Biol 2014;12:e1001882.

26.     Wu Y, Kennedy P, Bonazza N, Yu Y, Dhawan A, Ozbolat I: Three-dimensional bioprinting of articular cartilage: A systematic review. Cartilage 2021;12:76-92.

27.     Javaid M, Haleem A: Significant advancements of 4D printing in the field of orthopaedics. J Clin Orthop Trauma 2020;11:485-490.

28.     Wang C, Yue H, Liu J, et al.: Advanced reconfigurable scaffolds fabricated by 4D printing for treating critical-size bone defects of irregular shapes. Biofabrication 2020;12:045025.

Read more such content on @ Hidoc Dr | Medical Learning App for Doctors