- October 11, 2017
I’m a Dr. Kenneth Gustke. I’m with the Florida Orthopaedic Institute and I specialize in arthritis, surgery, the hip and the knee. And what I’m going to discuss today is a new application that we are using now for total knee replacement surgery. So what we do when we do an operation to replace a knee is we basically resurface the bone. So this is a model here of what a total knee replacement looks like and you can see the metal and the plastic parts become the articular surface of the total knee. And you can see in order for us to fit these, we have to make precise cuts on the end of the bone. And on an on the leg side, uh, we put another appliance that’s attached to the upper end of the leg bone that has a plastic bearing surface. This essentially becomes the new cartilage in the total knee replacement.
So again, when the knee is moving, you have a metal against a plastic articular surface. So what the robotic system allows us to do is multifactorial. We can actually customize the placement of the implants the size of the implants. So they will fit the patient perfectly. We can align the implants so that we know what their overall axial alignment is. We sorta anticipate what their alignment was before they became arthritic and try to reestablish that. And we can do that with high precision, which we’ve never been able to do before. The advent of use of robotics robot is not just for total knee replacements. We also use it for partial knee replacements. We also use a robot, uh, for total hip replacement surgery. It’s a different application. It doesn’t use a saw, but actually use a reamer to rema hemispherical circle in the socket, uh, for placement of the socket, part of the total hip replacement.
So what I’m going to show you now is the use of the Mako robotic arm, uh, uh, system. So that allows us to do total knee replacements with that high precision that I just discussed. So we take the CT scan and develop a 3D model that then shows up on this computer screen, which we then can plan as to where to place the parts and what size of the parts to use. So then what we do at surgery then is we start with this, this preoperative customized plan for the patient. From that point forward, uh, the, the robotic arm knows exactly where the bone is at every point in time. And if we were to move the knee around, a camera here sees, uh, trackers that we place on the bone and adjust for the change in the position of the leg during the operation.
So again, we can make the cuts extremely precise, usually within a half a millimeter and at the most a millimeter difference from what we are trying to achieve. What I have here is the actual robot that’s used to perform the total knee replacement surgery. This is not a robot that works autonomously independent of the surgeon. It requires the surgeon to control it. What the robot is doing is placing the tip of this saw in exactly the plane that we’ve determined from preoperative planning to make each of the individual bone cuts on the bone. So what happens is as we get ready to make a bone cut, we press the trigger on this and it does. It’s not going to move it currently because we’re not hooked up to a patient. What you press the trigger and what happens is the robot actually auto aligns the tip of the saw so that the cut is absolutely perfect to where that particular cut surface is going to be.
So then what we do is we then after we put our trial components in, this is what the knee essentially would look like and then we wanted to determine how balanced the knee is and the robotic system is going to help us with that too because we can apply force to the knee in one direction or another. Both when the knee is in is in a flexed position as well as when it’s an extended position. We then can see on the screen as we placed the knee through a varus valgus stress, what the gaps are on either side so that we eventually have a knee that’s perfectly balanced with the same amount of opening. When we apply those stresses, we call varus or valgus or inside, outside stresses to the knee so that we know the ligaments are balanced. If we see on the screen that the knee is in balance, then we have the opportunity to make changes on the fly.
As we’re going through the procedure, we will again press the trigger, the robot will auto align and we’ll redo that bone cut for us within whatever precise amount and direction and angle we want that bone recut to take. So what we’re also hoping with the total knee application is that it’ll see the same data that we’ve been able to prove with partial knee replacements and then total hip replacements .The patients will have less postoperative pain and potentially have a faster recovery. So what we’re looking for with robotic total knee replacements is, as I mentioned earlier, is we’re trying to improve the durability of total knee replacement surgery so that it has a potential to last longer. Currently, we think most total knee replacements can last 15 2025 years if put in perfectly and the knee is perfectly balanced and that’s a big if, and we have the technology now to improve that, if to a greater guarantee that you can put it in alignment and balance the knee or what is the most appropriate and customized to that particular patient.