Zimmer Biomet used its proprietary Tivanium alloy to create an alternative for knee patients with sensitivities to certain metals.
Chris Newmarker and Carrie Pallardy
Zimmer Biomet’s Persona Revision SoluTion Femur is FDA-cleared for patients with severe knee pain and disability due to a variety of reasons including collagen disorders, post-traumatic loss of joint configuration, a range of arthritic conditions, and previously failed surgical attempts. [Image courtesy of Zimmer Biomet]
The latest addition to ZB’s family of Persona knee systems, the Persona Revision SoluTion Femur utilizes the company’s proprietary Tivanium (Ti-6Al-4V) alloy that was already used for total knee replacements. Treated with a special Ti-Nidium surface hardening process, Tivanium demonstrates a hardness comparable to implants incorporating the most common metal allergens such as nickel, cobalt, and chromium.
“There are patients out there that know they have metal sensitivities, others that might have suspected metal sensitivities,” Zimmer Biomet’s Cristina Piecuch said in a Medical Design & Outsourcing interview. “There really was a need to have both on the primary side and then also on this revision side of our portfolio a complete joint replacement offering that excluded stainless steel, which has the nickel content, and cobalt chrome.”
Piecuch led the product development team in charge of the Persona Revision SoluTion Femur and is now a senior director of quality in robotics and digital technologies at the device developer.
The engineering team — composed entirely of women — brought both expertise and passion to the project, in part due to the fact that research suggests metal sensitivity may disproportionately affect women.
“This achievement represents a meaningful step forward in inclusive, patient-centered orthopedic innovation,” Piecuch said. “By leading the development of these next-generation implants, our team not only advanced patient care but also serves as a source of inspiration for young women pursuing careers in science and engineering.”
Cutaneous metal hypersensitivity affects 10–15% of the general population, according to research from 2018 cited by Zimmer Biomet. That figure may be as high as 25% among patients with metallic implants.
“Metal sensitivity is one of the potential causes of revision procedures, and the Persona Revision SoluTion Femur is yet another innovation that delivers on our commitment to solve the most meaningful challenges in musculoskeletal health,” ZB Knees President Joe Urban said when announcing the FDA 510(k) clearance.
Here is more of what Piecuch had to say about the development of the Persona Revision SoluTion Femur. The following has been lightly edited for length and clarity.
MDO: How long was the development process for the Persona Revision SoluTion Femur?
The Persona SoluTion PPS and Persona Revision SoluTion Femur team at Zimmer Biomet included (from left) Mackenzie Schultz, Maria McCoy, Tory Leonard, Cristina Piecuch, and Yulia Yatsenko. Also on the team but not pictured was Abbey DeFranco. [Photo courtesy of Zimmer Biomet]
“Our process usually takes a few years from start to finish. Rightly so with medical devices, we have quite a bit of verification and validation we have to do. Particularly with these two products, there was manufacturing process development and then process validation work that we had to do.”
Did the process take longer because it involved some material innovations?
Piecuch: “That’s right. The Ti-Nidium process that’s used to harden the Tivanium alloy to make it wear-resistant and meet the wear properties has been around for a while for Zimmer Biomet. We’ve used it on some legacy products, but we took it a step further. We implemented some new final finishing and polishing processes, and it took a little time to get the equipment we needed to make sure the process was meeting our specifications and doing our validations on that process.”
What exactly is Tivanium?
Piecuch: “It’s our internal trademark name for Ti-6Al-4V alloy. In our portfolio, we’ve used that trademarked alloy for around 17 years. Tivanium is just excellent from a biocompatibility perspective, corrosion resistance perspective and strength perspective.”
There is still nickel in the implant, but the hardening process makes it a lot more wear-resistant, correct?
Piecuch: “It has a negligible amount of nickel in it. We don’t get it certified that it’s nickel-free. If you look up the spec related to that alloy, it’s negligible. It is truly a metal-sensitive solution for patients that do have nickel sensitivity. Again, it eliminates the cobalt chrome element.
“The Ti-Nidium surface hardening process is done underneath high temperatures in a non-oxygen environment. Nitrogen is infused into the structure of the metal, strengthening it. Then, there’s a cooldown process that leaves that hardened surface finish.”
What are the benefits of this process?
Piecuch: “It is really around the wear properties we want to have. It has — through our testing — no statistical difference between it and cobalt chrome.”
Can you talk more about how you created an implant for allergy sensitivity issues that would have the same benefits as one made with legacy materials?
Cristina Piecuch [Photo courtesy of Zimmer Biomet]
“Going back to the cobalt chrome casting piece, the team would transition over from castings to forgings. With that, we had to think about how to create the same features. It was really important to make sure that the femur geometry was the same between the cobalt chrome and our new Tivanium SoluTion Femur so there would be no difference in the surgical instrumentation that would be used, for simplicity for surgeons.
“We wanted to make sure that we could incorporate all those features for that purpose, as well as for compatibility with existing augments and cones and stem extensions that allow the surgeons to fill in any bone defects and recreate the joint. We had to make sure all those features were machinable in our femur.
“We had to go through validation processes afterward on the polishing method as well. We also were ensuring that the taper junction compatibility with those stem extensions wasn’t compromised, that we were going to get the right fatigue strength properties as well.”
What kind of fatigue strength do you need for that?
Piecuch: “There are standards that we use. We have to have it at the same level as our predicate device. That’s part of the process through the 510(k) pathway that we go through. We have to prove that we have equivalency or higher levels of performance than the product that we’re basing our 510(k) on.”
What can you say about the polishing process used to ensure equivalency to the predicate device?
Piecuch: “I can’t get into too much of the details. It’s a little bit of the secret sauce. It’s an electropolishing process that we utilize. It’s automated.”
The end goal, as far as surgeons are concerned, is to offer another Persona Revision, just made of something different?
Piecuch: “Exactly. They have a seamless experience with it. They get to use the exact same instrumentation. They have all the same compatibilities with the adjunctive fixation devices, like the augments, the cones, and the stem extensions that they might need to recreate the joint, to get the right kinematics and fixation that they would need for that patient.
“With that, you have those engineering constraints you may not have with a product you’re designing that doesn’t have all of those legacy compatibilities.”
Zimmer Biomet also has a total hip solution that addresses metal allergy sensitivity. What is that product called?
Piecuch: “For the hip side of our business, that’s a little different. We have quite a few different titanium alloy stems within our hip portfolio. Avenir Complete is one of our cementless products for primary hip replacement.
“To recreate the joint, you’ll need a ball hip head. Our portfolio [includes] ceramic ball hip heads that can be used so you don’t need the cobalt chrome or the stainless steel hip heads. The cups tend to be titanium alloy. We do have a few cobalt chrome in the portfolio. Surgeons can readily recreate a joint for hip replacement patients who have metal sensitivity with our G7 shell system pairing out with a Vivacit-E poly liner using a Biolox Delta ceramic head.”
Can you address potential materials sensitivity issues in knee replacements?
Piecuch: “From a knee replacement perspective, it’s really been a challenge on the femoral side of the joint. Now, SoluTion products resolve that. You have that unique combination of the porous plasma spray, which is titanium alloy based. Now your wear surface, your articular surface, is where the challenge was. With the hardening process, and then with the polish, and then pairing that with a Vivacit-E liner, you have a long-lasting joint replacement that meets the patient’s needs.
“There is a unique subset of patients who could have a bone cement allergy, and that PPS addresses that.
“Usually, we kick off our meetings at Zimmer Biomet with our mission and guiding principles around alleviating pain and improving the quality of life for patients around the world. We have an implemented practice with our CEO to share a personal story or a story that really helps embody our mission.
“Just when we were getting ready to release our Persona PPS Solution product, one of our team members who works on our legal team reached out because she had a friend of the family who was in a situation where they had metal sensitivity and bone cement sensitivity. They were told by their doctor that there really wasn’t a solution for them. There wasn’t a product out there that really addressed that for them. We were able with this release to help that patient out, somebody close to one of our team members. It was impactful for the team working on this project.”
Looking ahead, are there any future developments you are excited for? What’s next?
Piecuch: “We’ve been on this journey as a company of pairing the latest technologies from not just an implant material manufacturing process perspective but also digital technologies. I can only imagine what the next five to 10 years are going to look like for orthopedics. There is going to be so much innovation with respect to how the surgeons perform the surgery, the improvement in the information that they’re getting to inform their decision-making early before the cases, interoperatively to really help customize the solution for the patient and how they’re making the bone cuts and orientation of the product.
“Persona really positions us well because it has such fine increments of sizing. That product paired with all of this information that the surgeon is going to have at their fingertips, and then being able to use robotics and other technologies interoperatively to help them really dial in placement of the implant, and then even before that again the bone cuts, is just going to be tremendous.”
Chris Newmarker is editor in chief of MassDevice and Medical Design & Outsourcing. Carrie Pallardy is a freelance writer and editor based in Chicago. She has more than a decade of experience writing and reporting in the healthcare space.
