All right, hello, my name is Chris Travers from the University of Pennsylvania. I'm gonna talk a little bit about UNIs and as they compare to an HTO. So, no relevant disclosures for this talk. And just a little bit of background, I think that you got a little bit of a background on the last talk, but I think the schools of thought for UNI versus an HTO are kind of similar indications but exact opposite goals. So with a UNI, you're trying to resurface a damaged compartment, but you're trying to keep the mechanical axis on that compartment that you've repaired, versus an HTO where you're basically seeking to unload that damaged compartment and shift the mechanical axis. You can see here, closing wedge HTO versus an open wedge HTO, both accomplishing the same goal of moving that mechanical axis over to the lateral compartment. So as far as indications, they tend to be the same. So unit compartmental OA without significant deformity and intact ligamentous supports. The contraindications for UNI compartmental knee are kind of, I think, in flux right now. So inflammatory and tricompartmental arthritis are obviously contraindications. However, these other ones vary a lot and they've kind of shrunk over time. So a large flexion contracture, large varus or valgus deformity. Incompetent ACL is probably controversial at this point. There's a lot of people doing UNI compartmental arthroplasty with an incompetent ACL. And the elevated BMI, very young age or activity level, traditionally were contraindications, but probably not so much anymore. And the question is, how do UNIs do? What are the long-term outcome data? So this is a good representative study. There are lots like this. But I think that the important thing is, what is the survivorship? So this was traditionally thought of as a temporizing measure. Someone who needed a total knee, but was a little bit younger or was older and with lower demand. I think now, though, we're looking at this as potentially a final solution for somebody with isolated compartmental arthritis. And this study shows that. So they looked at people under age 60, 65 UNIs, mean age being 54.7. And they found that after 12 years, they had a 94% survivorship, which is very good. They asked their patients if they had any limitations with sports activities. And 90% said that they had no or mild limitations. And then they had very good functional and knee score outcomes, which are shown there. But then the question is, how does this compare to HTL? So traditionally, these were kind of dueling operations, different schools of thought, obviously. And there's a number of meta-analyses that kind of look at this question. So this first one was done recently. It was published in 2018 in Journal of Arthroplasty and looked at a bunch of studies between 2011 and 2017, 10 studies total, and pooled 6,000 plus patients. So when reviewing this, they found that the revision rate of UNIs was much less than HTL with an odds ratio of .52, and that was relevant. Fewer complications with uni-compartmental arthroplasty. The typical complications seen in the HTL group were infection, blood clot, nerve injury, and then far cortex pathologic fracture compared with lower numbers in uni-compartmental group. Functional outcomes were equivalent in the study. And they did find that there was better range of motion with HTL. And I think this is probably self-evident. It's an extra-articular procedure. And any time you go into the joint, there's a risk of arthrofibrosis. So that was one benefit of HTL in these studies. All right, and then this is another meta-analysis. This is looking at a slightly older population of studies, 1986 to 2012. Similar numbers here, but a lot of these implants were older implants. So I think it's relevant to look at those since HTL has been around for a while. So it was uni at this point. This study actually did show better functional outcomes in the uni group. Specifically, they had a higher rate of excellent and good results. Unis had a higher, faster walking velocity. And again, HTL has slightly greater range of motion, which was shown in the most recent meta-analysis. And the question is, how has this been shaping out in America with American orthopedic surgeons? And how have the rates of HTL versus uni changed over time? This is an interesting study done between 2007 and 2011. It's a registry study. And basically showed that every year, unis increased by about 4.7%, and HTLs fell 3.9%. So it's kind of as unis rise, HTLs go down. And they postulated a couple of reasons for this. Maybe faster recovery with unis. There's no weight-bearing restrictions typically. Improved implant and instrument design are driving this, industry is driving it. And potentially smaller learning curve for uni versus a HTL at this point. And the question is, is this still continuing? And the answer is yes. So with the advent of outpatient surgery, uni-compartment arthroplasty is probably only going to grow. This shows the trend over time of outpatient surgery becoming much more common, to the point where it's as common as an inpatient uni-compartment arthroplasty. So my final thoughts and conclusions about this. I don't think that there's a very significant difference between uni and HTL. I think they're both adequate options for somebody who's younger and has isolated compartmental disease. But some of the recent data may favor unis over HTL due to lower complications of vision rate and maybe better functional outcomes. I think things that are clear though is that uni recovery rate is faster due to lack of post-op restrictions. Potentially it's less technically demanding with improved instrumentation. It's clear that American orthopedic surgeons are favoring this procedure. The question of why, I think I answered clearly. But this will only become more popular and I think HTL will continue to shrink to some extent, probably to a niche market. And then I think that going forward, improvements in material science, implant design, and instrumentation will probably favor uni going forward, more so than it'll favor HTL. This is because I think HTL is a little bit less of a materials and instrument procedure as opposed to an implant. That's it. Thank you. Chris, why don't you have a seat up here? Thank you. Thank you. Hey, Dr. Shelborn.

uni-compartmental knee arthroplasty

high tibial osteotomy

mechanical axis

compartmental arthritis

revision rates