This is a short (15 minute) video highlighting recent philosophies for alignment in TKA and a reproducible approach using Mako 2.0 Robotic Knee Surgery to align the knee. The knee is aligned cosmetically (straight) in the coronal plane and balanced in the coronal, transverse, and sagittal planes.
My name is Michael Masse. I'm an orthopedic surgeon at Trinity Health. Ih A Ann Arbor orthopedic surgery. And I'm introducing a video today discussing a systematic tripla approach to functional positioning in robotic total knee replacement coronal alignment. Philosophies have been challenged in total ne arthroplasty. Recently, with several different proposals put forth mechanical alignment as proposed by Insol has been the gold standard for decades. An atomic alignment was a different proposal put forward by Hungerford and Krakow through the PC knee system and universal instruments which helped remove outliers. Kinematic alignment was first coined by how it all in 2008. The kinematic alignment technique aims to recreate individual native limb and joint line positions and preserve the native axes of rotation about the knee. The concept of kinematic alignment is to make symmetric an atomic cuts on the femur and tibia to account for cartilage loss through these resections, calipered kinematic alignment speaks to the fact that these cuts are measured to assure that the resections are in fact symmetric and to optimize the soft tissue sleeve. The individualized alignment strategies bias bone resection toward patients native anatomy and prioritize ligament balance over two dimensional bone alignment. Multiple different studies suggest better and easier balance with fewer soft tissue releases in short to midterm time frames. Total knee arthroplasty with functional alignment aims to place components in the positions that least compromise the soft tissue envelope and restore the plane and obliquity of the joint as dictated by the soft tissues. Functional alignment combines the principles of gap balancing and measured resection and minimizes the need for soft tissue releases. Functional alignment, harnesses the benefits of robot and computer assisted platforms with optical navigation that allows pre resection determination of knee laxity through virtual implant interaction. The Trane approach detailed here is a form of alignment approach in total ne arthroplasty that uses functional positioning, robotics and navigation. No final resections are performed on the femur until balancing has occurred virtually. It introduces a systematic approach that first addresses the coronal plane to establish a cosmetic or straight knee for all patients regardless of initial alignment and deformity. It balances the coronal plane and transverse plane to within one half to one millimeter displacements simultaneously without soft tissue releases. A mechanical distractor lends consistency to the balancing process. The sagittal plane is addressed last and optimizes motion to avoid hyperextension or flexion contractures while leading to more normal rollback. The patient demographics. The patient is a male 63 A BMI of 30 as a two and failed conservative treatment for osteoarthritis of the knee. These are the preoperative x-rays. The tripla approach is basically an approach that is more systematic for robotic knee replacement. I first approached the coronal plane by establishing a cosmetic or essentially a straight knee and modify the distal femur and proximal tibia resections appropriately to optimize alignment. Secondly, I'll address the transverse plane with a term called functional positioning and modify the thermal position with virtual thermal trial to optimize balancing in the transverse plane. I finally approach the sagittal plane and select the distal resection level to optimize knee extension and if needed add slope to optimize tibial rollback relative to the femur and avoid liftoff of the tibial insert. My approach is basically a modified mid vastus approach that I've used for over 20 years. I make my incision just medial to the mito patella do the usual release of the superficial meat of collateral. And then I do an approach that's essentially like a posterior approach where I just incise the fascia and split the muscles. This is a cement less knee. So my first resection, I just do a rough cut of the patella to allow easier retraction. During the rest of the case, I essentially establish a uh self retaining system so that as we place the trackers and do the registration verification, my assistant can be out of the wound and thus out of the array path to the robot. The arrays are placed in the usual fashion, femoral and tibial pins. I do extra incisional placement so I can keep my incision where I used to do before I did robotics. Navigation is well known in orthopedics. This particular system uses navigation but also has verification because it is CT scan base. This helps to assure the accuracy of the navigation process. The yellow here is just a reminder, it's time to remove osteophytes once removed. You can then tell the pre correction deformity in both the sagittal and the coronal planes as well as determine your goal for alignment in the coronal plane that will give you a cosmetic or straight knee. This particular software has designated pivot points on both the femur and tibia. It's very important to familiarize yourself with these points. And is it allows you to selectively position the femur and make resections and adjustments to the half a degree and half a millimeter level. This allows much improved balance. Basically, I use a modified mid resection technique. The mid resection technique has previously been described, I do a tibial resection and then a posterior femoral skin cut. The skim cut is three millimeters less than the size I effectively plan to use to accommodate a larger implant if necessary. And also to facilitate rotational alignments. I then use a mechanical distractor in conjunction with the robotic digital tensioner to analyze the gaps and finally employ functional positioning or virtual motion of the femur prior to make any resections that will position the femur. Ultimately, the blue represents the bone to be removed, the white when the bone has been removed. So these are not final cuts but do facilitate placing a distractor and cleaning out the posterior aspect of the knee. I thus am creating a soft tissue sleeve that will be experienced by the final implants. Here you see it in action where I'm removing the menis, I'll also use the curved osteotome and a curette as mentioned to basically optimize the soft tissue sleeve. Mechanical distractor to me is a powerful tool in this situation because it then simulates the final implant. I place it initially in flection but also make measurements and assessments in extension as well. This portion of the video shows the mechanical distractor being put into place and distracted while inflection. I do not do any pre resection determinations as I think that can be confusing and misleading, I simply do this technique. And here you see the digital tensioner now is ultimately measuring the gaps. What I'm distracting with the mechanical distractor for this patient, he's too tight in both flexion and extension. So I simply build in two millimeters more resection of the tibia. I then have the opportunity to make all my plan through the digital tensioner and robotic software. I thus can determine that the distal resection will be symmetric as well as the flexion space will be symmetric as well. I first however, again, determine the position in the coronal plane. So for this patient, his optimum position is about four degrees of varus and I build the permanent cuts into that, meaning that I'll put in four degrees of varus on the tibia and the femur, as you can see, there are multiple, if you will pivot points that one can select. This is very important because it determines where you remove the bone from the distal femur and proximal tibia and posterior femur. Thus allowing you to balance the knee within the soft tissue sleeve. Again, for this patient, I put two degrees of varus on the femur and two on the tibia. You have to remember that the two degrees of varus is not true varus, but you're simply removing valgus from what would normally be a zero degree mechanical cut. Again, in this patient, I externally rotate the tibia as can be seen, I even flex the femur a bit so I could get my flexion and extension gaps essentially to within a half a millimeter and a half a degree. Thus, I've balanced him both flexion and extension to that precision. The resections are then performed with the robot which are part of the key because they perform such precise cuts that the planned resections become the final one so that your balancing is obtained. I then clean out the knee, removing any debris, do a final assessment of the soft tissues. And ultimately, then I'm ready to place the trial. I start with the femur, then place the tibia as well as the chosen insert. You actually get to select the size insert, you wish as you're planning this and then you can make small adjustments. I always set my insert at 10 millimeters. Therefore, I can always go down to nine or increase even to 1011 or 12 as necessary. Depending on the compliance of each individual patient's soft tissue sleeve. It's very important there. As you see, I flexed the knee and observed what happened because I'm looking there to determine whether or not there's any lift off. And also to determine that the extension is about in the two degree range. I like to avoid hyperextension as well as flexion contracture and can actually term the exact distal resection length to achieve that. Once I'm happy with my trial, I then put the final implants in place. This is a cement knee as noted, I've determined that the nine millimeter insert was uh the correct one for this patient one millimeter less than the actual plan. As he still tended to wanna have a slightly more flexion contracture. The real implants are then fully inserted. The patella is tightened down as the final step after it's been prepared, the final assessments are then observed and again, you have a well balanced knee that's straight in the coronal plane, straight in the lateral plane to within two degrees and excellent balance throughout a range. These are the post-operative x-rays. My post-operative regimen includes an adu canal catheter for 72 hours with IPAC singles shott posterior block. Many patients are performed in the outpatient scenario. I use AC PM machine and an ice machine. Patients get home physical therapy for 1 to 2 weeks. Outpatient physical therapy generally ranges from 2 to 6 weeks and longer as needed and is followed by home exercises. My post operative outcomes are outlined below. Totally arthroplasty performed prior to the Trane approach are depicted on the slide on the left. We have over five years of outcomes based through the Michigan Arthroplasty Registry called Marques. My outcomes for the Trane approach are quite short just into the six month period and I'm not sure that I could say there's really any difference at this point though, it is optimistic. Noting there may be a slight upswing in improved outcomes between the 90 day and six month period. The tripla approach is an alignment approach that uses functional positioning and a mechanical distractor in a systematic way to provide a cosmetically straight knee that is well balanced. Hopefully, it can reduce the historically identified 20% of patients who express dissatisfaction with their total ne arthroplasty. Thank you for watching this video and your attention.