Today, I will be talking about the Conformis iView. The Conformis iView is a customized plan for a patient’s knee replacement that is based off of the patient’s CT scan, and it’s provided to the surgeon approximately 2 weeks before the procedure.
The iView does consist of two pages with the first page dedicated exclusively to images of the tibia. The second page is dedicated to the femur and the appearance of what the final implants will look like when they are inserted in the patient’s knee.
With regards to the tibia, the first set of images that will be provided will show the surgeon how the Tibial iJig should sit on the patient’s bone. These jigs were designed to reference osteophytes on the patient’s bone to help ensure a “something to grab onto” and make it easier to find the most ideal location.
As the surgeon is doing the procedure and trying to put this jig on the bone, he will look at this image to ensure that the placement of the jig is correct. Once the correct placement has been confirmed, the surgeon will pin this jig in place and will then referenced the iView to see how much bone is supposed to be removed from the tibial cut.
After confirming this amount, the surgeon will make his cut and bring this cut bone to his back table and measure the thicknesses of the resected bone at various points to ensure that enough bone has been removed. If there is a discrepancy, the surgeon will then go back with his saw blade through this jig and cut away more bone until the proper amounts has been resected.
The next image is going to show the surgeon where the final tibial implant should be located or should be placed on the tibia. This information is important to the surgeon because they really want to try to avoid malrotating the implants or giving the patient any excessive overhang of the implant over the bone, or having any under-coverage of the implant on the bone.
Since the Conformis tibia is customized for each patient and respects the shape of the patient’s knee, this helps minimize the risk that the knee can be malrotated or that there would be any overhang or significant under-coverage.
The final bit of information on the tibial page of the iView is going to show the surgeon the difference in the thickness of the polies from the medial side to the lateral side. Since Conformis respects the natural native articular geometry, or shape of the patient’s knee, we have to ensure that the polies or the plastic that’s put in at the end is offset to fill the joint space and not leave anything. Since Conformis knees are customized to respect the patient’s articulating geometry, or in other words, to respect the natural shape of their knee, this leads to the plastic or the polies needing to be offset.
The last set of images on the iView or the last set of, last bit of information on the iView on the tibial page will show the surgeon the difference between the medial and lateral thicknesses of the poly. Each knee will come with four polies and the surgeon will choose the poly that best balances the patient’s soft tissue.
The second and final page of the iView provides information on the femoral side of the procedure. The first image will show the surgeon where the distal femoral cutting jig should be placed on the bone. The surgeon will reference this image while placing the jig onto the bone. The jig will also give the surgeon feedback as to where it should sit on the bone.
Once this proper location has been confirmed, the surgeon will pin the jig in place and will check the iView to see how much bone is supposed to be removed from this cut. Once the cut has been made, the surgeon will take the resected bone, bring it to his back table and measure the cut thicknesses to ensure that the correct amount of bone has been resected. If there are any discrepancies the surgeon at this point can go back through the jig with his saw blade and remove as much bone as needs to be removed to satisfy the requirements laid out by Conformis.
The next image the surgeon will reference will be of the F-4 jig, otherwise known as the 3-in-1 block, the will want to make sure that this jig is placed on the bone so that the medial profile of the jig matches the medial profile of the patient’s bone. Once this location has been confirmed, the surgeon will pin the jig into place and then examine the cut values provided by Conformis and then proceed to make his anterior and posterior cuts.
After the cuts have been completed, the surgeon may take his resected bone to his back table and measure the thicknesses of each piece of the resected bone to make sure it matches with the values provided by Conformis. If there is a mismatch, the surgeon can go back through the jig with the saw blade and continue to resect more bone until the proper amounts has been removed.
The final images on the iView are going to show the surgeon how the final implant will look when it is placed in the bone. The surgeon will get a view of this with the leg in extension or straight from the front and the back. And then the surgeon will also get a view of how this will look with the knee flexed in 90 degrees from the front, as well as from the side.