Dr. Kurtz: A normal knee has a medial joint line that is a little lower than the lateral joint line. The ConforMIS takes that into account and it makes that joint line what their preexisting joint was before the surgery. With an off-the-shelf implant it’s just a straight joint line across and there is no way to vary that. The ConforMIS knee replacement actually builds the implant off the dimensions and shape and the curvature of the patient’s existing knee. It does the math for me and makes sure that my joint line is to the same slope as the pre-existing joint line was.
Can the implant design affect the results?
Dr. Kurtz: Off-the-shelf knee replacements, those patients a lot of times will complain of noises that their knee make or they will feel like it’s a little bit loose or feel like it’s a little bit sloppy and it limits some of their activities. So that really boils down to usually instability. The knee is not engineered to fit their normal kinematics and their normal ligaments and how those things work together and how their muscles pull on their knee. It’s not the same as it was before the surgery, so the patient has limitations. With the custom iTotal®, those curvatures and those shapes are identical to what their knee was before their knee replacement, and so those ligaments and muscles should function better and more naturally.
In your experience, what differences have you noticed between the iTotal® and Offthe-Shelf implant procedures?
Dr. Kurtz: Well, in the operating room I’ve noticed that I’ve removed a lot less bone with the ConforMIS implant. I’ve actually tracked all that data on my old implants that I was using off-the-shelf and then with the new custom iTotals. That’s in part because the implant is patient-specific, so it is tailor made to the shape and size of their bone so I’m not having to increase my bone resection just to get an implant in that I think would fit. The other thing I’ve found is that I don’t have to put an IM rod up the femoral canal, so there is less bleeding during the surgery and less bleeding after the surgery. In addition, without driving that rod up the femoral canal, I think that really helps in diminishing their pain and diminishing a lot of the swelling that is oftentimes associated with knee replacements. And therefore, I think the patients experience less swelling, they get their motion back faster, and they have less pain, so they can get back to their activities a little faster.
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