Additive manufacturing (AM) is widely used in the medical device industry to produce titanium implants. While cobalt chrome (CoCr) is a biocompatible alloy known for its high strength and durability, its adoption has lagged behind that of titanium.

Yet, its resistance to wear makes CoCr an ideal material for orthopedic implants, especially in large joint and total ankle applications. Unfortunately, until recently, use of CoCr in healthcare manufacturing has generally been for large implants and, therefore, cost prohibitive for AM. However, multi-laser 3D printing technologies made metal AM faster and more cost-effective. Now, manufacturers can leverage AM’s design flexibility to integrate lattice structures and 3D print personalized implants in CoCr.

The Unique Strengths of CoCr

With recent advances in 3D printing technologies, CoCr is securing its place as an important material for additive manufacturing, allowing medical device companies to:

• Increase efficiency: The combination of CoCr and AM can yield highly durable monolithic implants in a single step. Additionally, using AM to produce implants with CoCr eliminates the need for time-consuming surface treatments like porous plasma spray.
• Reduce costs: In addition to the cost savings gained through more efficient production, additively manufacturing implants using CoCr empowers medical device manufacturers to produce parts on demand, eliminating the need to stockpile large quantities of inventory that may become obsolete. Producing only what is required when it is required allows manufacturers to expand their device portfolios without investing in and holding inventory costs.
• Positively impact outcomes: 3D printing with CoCr offers unparalleled design flexibility, allowing for customized implants that optimize joint alignment. Additionally, the capability to integrate lattice structures, similar to those found in titanium devices, has the potential to enhance bone in-growth.

To better understand how to achieve these advantages, let’s explore the mechanical properties of CoCr, the optimal combination of 3D printing technology and post-processing, and the importance of validating and dedicating 3D printer platforms to CoCr production.

Advantages of a CoCr Additive Manufacturing Workflow

With AM, it’s not just about the material, the 3D printing technology, or how you finish the part. All the components must be assembled into a comprehensive solution, designed to address the application need. We believe the material is at the heart of each solution.

As a biocompatible alloy, CoCr is ideally suited for medical implants and instruments because of its natural material properties. Among these properties is CoCr’s strength and durability, which enables the implant to withstand the rigors of the human body. Its excellent wear resistance is crucial for implants that experience friction, such as joint replacements. This material is also compatible with various additive manufacturing techniques, allowing for complex and customized implant designs that are able to achieve a completely polished mirror finish in the final part with minimal post-processing steps.

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MORE INFO: Developing Orthopedic Implants with Direct Metal Printing—An Orthopedic Innovators Q&A

While compatible with a wide range of 3D printing technologies, one of the more common technologies used is laser powder bed fusion (LPBF). Of course, when the part is removed from the printer, it requires post-processing to bring it to its final state, which is ready to be placed in the human body. One of the most common is hot isostatic pressing, more commonly referred to as HIP—a post-processing technique that employs high temperature and uniform pressure to eliminate porosity and enhance the structural integrity of materials. In the course of working with a variety of medical device OEMs, vacuum stress relief (VSR) with furnace cool proved to be a more optimal heat treatment method for CoCr.

Not only is VSR a highly available option with a lower price point, it is often able to reduce lead times while maintaining the mechanical performance achieved by HIP. This becomes particularly critical for patient-specific applications where turnaround times are extremely tight. Additionally, VSR does not develop a green oxide layer, which is a risk with HIP. In applications that benefit from lattice structures, this layer becomes nearly impossible to remove. Finally, using CoCr in many advanced LPBF printers enables manufacturers to achieve printed part densities greater than 99.9% when using CoCr with VSR.

As with any medical device, production must be done in facilities that have received ISO certification (i.e., ISO 13485, ISO 52920), but each 3D printer and material must be validated. Dedicating a 3D printer to CoCr applications is essential for minimizing part-to-part variability to produce high-quality medical implants. The combination of consistent material handling and rigorous process control mitigates contamination risks, enhances production efficiency, and improves the reproducibility of implants. Ultimately, this also helps ensure compliance with regulatory standards and can lead to better patient outcomes.

Reshaping the Healthcare Landscape

While the orthopedic industry was at the forefront of adopting AM, particularly in spine surgery with titanium implants, the advent of additively manufactured CoCr is opening a host of large joint applications. Some that are gaining momentum are glenospheres, femoral components, and patellae, as well as partial and total taluses. These implants for shoulders, knees, and ankles, respectively, are used in areas of the body that withstand not only repeated movement but also significant force.

AM offers unprecedented design freedom and production efficiency that is rapidly advancing orthopedic care. Specifically, the use of CoCr alloys in LPBF manufacturing workflows is enabling the creation of intricate, patient-specific implants for joint replacement surgeries. This revolutionary approach holds the potential to significantly enhance surgical outcomes, reduce costs, and improve the overall quality of life for countless patients. With the continued acceleration of innovation—both in AM and orthopedics—the future of device manufacturing and patient care holds immense promise. 

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MORE FROM 3D SYSTEMS: PEEK-ing into the Future: How 3D Printing Is Redefining Cranial Implants

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Aaron Schmitz is additive process engineering manager with 3D Systems’ Application Innovation Group, specializing in metal laser powder bed fusion process development as well as validation and qualification. He is a seasoned mechanical engineer with prior experience as both a design engineer and additive manufacturing engineer at GE Aviation and GE Additive. Schmitz received a bachelor’s degree in mechanical engineering from the University of Wisconsin Madison and a master’s degree in mechanical engineering from The Ohio State University.

Colton Steiner is a senior validation engineer with 3D Systems focused on improving additive manufacturing processes, particularly in laser powder bed fusion and material extrusion. In this role, he helps healthcare customers build confidence in these technologies through the development, qualification, and validation of these additive processes using advanced materials. Prior to joining 3D Systems, Steiner leveraged his additive manufacturing expertise at Johnson & Johnson where he held roles as a materials and process engineer evaluating the technology’s applicability to applications in orthopedics and robotic surgery. He received bachelor’s degrees in mechanical engineering and mathematics from the University at Buffalo, and a doctorate in materials engineering from Purdue University.