Moderator Maloney: David, you have 1 minute to rebut.
Dr. Lewallen: That was pretty convincing, Aaron, in case after case. But I didn’t see very many numbers. Not much data. We need data to support our arguments.
To be honest, I don’t do all-poly tibias in every patient. It’s a mix in my practice and there is a bias towards older patients. I do tend to use metal-backed implants for complicated cases where the advantages of modularity and stems are important. But I think there is a strong case to be made for all-poly components to have a major role in the reconstruction of knees, especially in patients over 65 and some of the low demand folks.
Dr. Hofmann: I agree with you. I use all-poly tibial components for the same reason you do. So, I certainly agree with your arguments and we certainly know that even with the highly cross-linked polyethylene, we’ve seen backside wear, we’ve seen some screw lysis, even though that wasn’t supposed to happen. The problem isn’t 100% solved. There’s no question about it. We’re making better locking mechanisms, but we haven’t solved it. So, there is a place for all-poly tibias. There, I’ve said it.
Moderator Maloney: So, there seems to be some agreement that there is a role for all-poly tibias. Let’s give the scenario that the 3 of us own our own hospital. We’re doing 2,000 total knees a year. We’re going to purchase our implants. The all-poly tibia is going to be probably in the neighborhood of $600 cheaper than the modular metal-backed tibia and we’re in a bundle. Where’s the cut-off going to be for that all-poly tibia?
Dr. Hofmann: Probably going to be the 75-year old patient. I’m not going to do it based on dollars.
Moderator Maloney: Is bone stock a concern?
Dr. Hofmann: No.
Moderator Maloney: David, where would you pick?
Dr. Lewallen: I think females over 65-the data would strongly support you and that would help your bundled situation greatly. And then I think in males, depending on activity level and size, very reasonable to start using it as people are a bit older, not quite as big. Maybe 70-75. Bone quality is less. Survivorship is less.
Moderator Maloney: What about versatility? Aaron makes a point that once we get options in the operating room, we hate to take them away. Every once in a while, I’ll do a trial reduction, it looks pretty good but when I put the baseplate in I find I want one size thicker. It happens.
Dr. Lewallen: I think you trial carefully and you get used to the fact that when there’s slop in the system, motion between the femoral trial and the bone, motion at the femur and the poly, motion between the poly and the baseplate trial, a little motion between…there’s a little more slack in the system, you want to play your hook, right? Play a little towards a little thicker. If you’re between a 10 and a 12, go to 12.
Moderator Maloney: We have some consensus here. There is a role for all-polyethylene tibial components and cemented total knee arthroplasty. Probably in the elderly patient. But data from the Mayo Clinic is pretty strong that if you use good surgical technique you could get pretty good results regardless of age and gender.
Gentlemen, thank you.
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