Interview with Biomet GM on the new ACL sparing Total Knee
Biomet Unveils Bicruciate Retaining Total Knee (OrthoPreneur)
While a critical component of knee anatomy and kinematics, the anterior cruciate ligament (ACL) is often sacrificed in total knee arthroplasty. Biomet’s latest product in its knee line, the Vanguard XP total knee system, takes a different approach and was developed to work with the patient’s anatomy to keep healthy ligaments attached. The Vanguard XP was designed in conjunction with orthopaedic surgeons to preserve the healthy ACL and posterior cruciate ligament (PCL), while incorporating geometry to enable the ligaments’ natural functions.
The plan was to create a system that provided a high level of patient satisfaction similar to that reported with Biomet’s Oxford Partial Knee with the durability of a total knee, says Todd O. Davis, Biomet’s General Manager and Vice President of Global Knees.
ORTHOPRENEUR sat down with Davis at AAOS to discuss the technology behind the bicruciate knee, the surgical technique used to implant it and future trends in the knee market.
ORTHOPRENEUR: What problem does this technology solve?
Todd O. Davis: When we started this project about four years ago, we saw a gap between the satisfaction of patients who received a partial knee versus those who received a total knee. While many patients achieved really good pain relief with a total knee, it was clear that patients weren’t nearly as satisfied with the operation as they were the partial. We have designed the Vanguard XP to address this patient satisfaction gap. The core message is that we have designed for the satisfaction of a partial and the durability of a total knee. Our hypothesis is that it is the preservation of the ACL (and the PCL) allowing for natural ligament function which will fill this gap. The stability and, therefore, the proprioception of having the ACL were important in our design.
ORTHOPRENEUR: What is the difference between the Vanguard XP and previously-developed bicruciates?
Davis: One, we have better materials today. A downfall of previous bicruciates was that the tibial trays fractured. Today, we have forged cobalt-chrome trays for added strength. Polyethylene was a weakness in the ‘80s—everything was gamma sterilized in air. Now, we have vitamin E polyethylene. The material differences are profound. Next is the surgical technique. Looking back at techniques from the ‘80s, they treated this as a total knee where you were trying to retain the ACL, but they didn’t change the technique. We’re employing a partial knee surgical technique to a total knee. That’s allowing us to retain the ACL and the island, and that hasn’t been an issue in our early clinical experience.
ORTHOPRENEUR: What else should surgeons know about this new system?
Davis: Ten years ago, the Vanguard was the first knee system to introduce finite increments in sizing. It was the first knee system that had 2.5 mm between all of the femoral sizes. We’re taking a ten-year-old system, and we’ve modified the femoral component a bit to make it more asymmetric to allow the ACL and PCL to do the work for the stability—basically, getting the articulating surfaces out of the way. Stability is inherent through the patient’s soft tissues. The other unique thing is that the condyles on the tibia are asymmetric. Not asymmetric in shape, but asymmetric in articulation. The lateral side is a bit convex and actually allows the femur to roll off the back of the knee if it requires that for flexion. The medial side is more concave. Now the medial left is not the same as the lateral right. Even though it will fit in the tray, they’re unique and independent bearings.
ORTHOPRENEUR: What other patient benefits does the Vanguard XP offer?
Davis: These are anecdotal at this time, as we have not performed the clinical studies necessary to make these claims, but from talking to patients that we brought here to AAOS, their length of stay is shorter, and I think that’s because they’re able to do things more quickly with their physical rehab. They gained their flexion back more quickly. There are about 25 patients who have a traditional Vanguard cruciate retaining knee on one side and an XP on the other and, again anecdotally, all 25 prefer the XP knee.
ORTHOPRENEUR: You mentioned a new surgical technique. How long does it take for surgeons to adapt to using the Vanguard XP?
Davis: We have decided to take the stance that attending a training course is required before surgeons are able to make use of the XP. Our training course will be about a day and a half long, and it will allow the surgeon to use the instruments on cadavers. We think that’s important because we’re actually changing the surgical philosophy. It’s not a total knee with the ACL retained; it’s an ACL retaining procedure. Having done the training with 25 surgeons who are new users, I can say that the learning curve is fewer than five procedures—maybe as short as two. Again, that’s with a rich training program and followed with team members in the OR with surgeons for the first couple of surgeries. We’ll start training courses in June.
ORTHOPRENEUR: What other trends are you seeing in the knee market?
Davis: I think bicruciate systems are going to be a growing trend. I know that most of the other companies have looked at this space or have current, active projects in this space. We’re fortunate enough to get there first with our particular design.
Obviously, personalization has been a trend. You see that with Signature guides and patient-specific guides. I think that will continue to grow, and I think there will be a good application for Vanguard XP to use personalized implementation technology.
Todd O. Davis serves as Biomet’s General Manager and Vice President of Global Knees. He can be reached firstname.lastname@example.org.