Today, I am going to talk about the Conformis iView. The iView is a customized plan that is provided to the surgeon by Conformis, that is based off of the patient’s CT. The surgeon will receive this plan about two weeks before the custom knee replacement is set to begin. That way, if there are any adjustments the surgeon needs to make beforehand, he will be aware and properly prepared before the patient enters the operating room.
The first page of the iView provides all of our needed tibial images. The first set of images is going to show us how the tibial cutting jig should sit on the bone. As the surgeon is placing this jig on the bone, he will reference this picture to ensure that the jig is in the proper location. Once the proper location has been confirmed, the jig will be pinned into place and the surgeon can proceed with his cut.
With every piece of bone that the surgeon cuts, Conformis will provide him the thicknesses that each cut should be. So, after the surgeon completes his tibial cut, he can take the resected bone to his back table, measure the cut thicknesses and compare that to the cut values Conformis provided. If there is any mismatch, the surgeon can go back and resect more bone. And so the proper amount of bone has been resected.
When looking at the cut values for the tibia, we will pay special attention to the LL cuts. LL stands for lowest point lateral. If the cut value here is greater than or equal to seven millimeters, the surgeon may consider doing a minus two cut, meaning take two millimeters less bone.
This will help to ensure that we have the opportunity to use the thinnest poly possible…Thereby, maintaining the patient’s native joint line or joint height. The next image shows the tibial tray placement. The surgeon will use this image to make sure that the final implant is placed at the right location.
The next image is the tibial tray placement. The surgeon will use this image to ensure that the implant is placed in the correct location with respect to the proper rotation and avoiding overhang of the implant off the bone or any under coverage. Since every Conformis knee is customized to respect the patient’s geometry, what shape of their bone, there should never be an instance where the tibia is malrotated. And there should also never be an instance where there is any overhang or under coverage of the tibial implant.
The final set of data, that is provided on the iView, will show the surgeon the thickness of the medial and lateral poly, or plastic that will be placed in the patient’s knee. The lateral side will always be slightly thicker than the medial side and Conformis calculates this by… The final piece of data that Conformis will provide on the tibia will be the medial and lateral insert offset.
Conformis will let the surgeon know what the patient’s distal femoral offset is. And will then design polys that respect this offset. So if the medial side of a poly is six millimeters and the offset is 0.5 millimeters, then the lateral thickness of the poly will be 6.5 millimeters. This allows Conformis to achieve a neutral mechanical alignment, which just means that the patient will receive a straight knee without the need for extra soft tissue releases.
The second page of the iView will provide all of the femoral images. The first image is going to show us how the distal femoral cutting block or jig will sit on the patient’s bone. As the surgeon advances to this part of the procedure, they will reference this image to ensure that this jig is in the proper location.
Once the proper location has been confirmed and the jig has been pinned in place, the surgeon will now make his distal femoral cut with his saw blade. Conformis will provide the cut values of the bone. After the surgeon makes his cut, he can now measure the amount of bone he has removed, and if he needs to remove more, he can go back through this jig and cut more bone. And so the proper amount has been removed.
The next image is going to show the three-in-one block, otherwise known as the F4. With this jig, the surgeon will make sure that the medial profile of the F4 matches with the medial profile of the patient’s bone. Once the location has been confirmed, the jig can be pinned into place. And now the surgeon will make his anterior cut and his posterior condylar cut.
After completing these cuts, the surgeon has the option of measuring the resected bone to ensure that the proper amount has been removed. And if not, the surgeon can go back through this jig and resect more bone. The final images, that Conformis will provide on the femoral page of the iView, will be that of the final implant construct as it will appear in the patient’s knee. Conformis will show this from the front and the back with the knee straight. As well as from the front and the side with the knee flexed at 90 degrees.
I am fellowship trained in joint replacement surgery, metabolic bone disorders, sports medicine and trauma. I specialize in total hip and knee replacements, and I have personally written most of the content on this page.
You can see my full CV at my profile page.
