Dr. Lachiewicz: I have some questions for both of you. The first topic that I would like to discuss is infection, which is the biggest problem, I think, after total knee arthroplasty. The beauty of the modular tibia, Aaron, is that you can remove it to do a debridement and replace that part. Do you think that’s something you have going for you? Do you always take that poly out in an infection?
Dr. Hofmann: Not always. I don’t think you have to take the poly out if the patient is a couple of weeks out. I think taking the poly in and out may be more soft tissue dissection, so I’m going to try to do whatever is the minimally invasive approach for that patient. Being able to take it out has some advantage, but I don’t take it out every time.
Dr. Lachiewicz: Really? Okay, Mike, do you think you can do a debridement in an acute or hematogenous infection with a monobloc tibia?
Dr. Berend: With the design where you can remove the polyethylene, we would always remove it if you have the one-piece with the capacity to make it modular. When we were doing AGCs and we were faced with a washout, we never changed the poly as you would suspect. I don’t have any long-term data on the efficacy of that, but it is a limitation of a one-piece design. With the all-polyethylene I think it is very easy to get that out if need be and do a one-stage and glue in another all polyethylene. We’ve started to do that as well.
Dr. Hofmann: Certainly with the all-poly you don’t have an interface to wash. There’s an advantage to having a one piece and I’m supposed to be on the other side.
Dr. Lachiewicz: Can you put a stem extension on your monobloc tibia?
Dr. Berend: No, sir. Any time you think you need a stem extension—defect, high BMI patient—or you feel like the bone quality isn’t right, some screws and cement, large medial or lateral defects, if we use a stem we have to use modular designs. We have to have both designs on the shelf.
Dr. Lachiewicz: And you said 60% monobloc; 40% modular, is that right?
Dr. Berend: Yes and I would do 100% if we had the capacity to have all the articulation changes in the 1mm increments or a stem-able type design.
Dr. Lachiewicz: One last question for each of you. Aaron, what percent do you do uncemented total knees now?
Dr. Hofmann: It’s probably approaching 20-30%. I’m getting back into my cementless mode. Obviously if you’re a cementless guy, which I am for the younger patient—younger than 65—cementless is on my mind. For the older patient, cemented is on my mind. All-poly tibias are on my mind in that same patient population.
Dr. Lachiewicz: And Mike, do you feel there’s any role in the future for cementless tibias?
Dr. Berend: I have a huge experience with uncemented knees…I’ve done 4 in the last 20 years (laughter). They’ve all been great, so that’s 100%. I think, for me, if I can have an implant that had the best polyethylene, was non-modular, had all the articulation choices, and was uncemented, that would be the implant that I would choose. That currently hasn’t been available yet.
Dr. Lachiewicz: Thank you very much.
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