I’m Marty Redish and am a non-fellowship trained general orthopedist in practice for 36 years in Chattanooga, Tennessee. I learned this Repicci technique when it was introduced in 1999 and started doing cases in March 2000 and have done around 4000 of them since. My interest in this has allowed me to be involved as a consultant with Biomet, MAKO, Zimmer-Biomet, and now Maxx orthopedics. I was part of an international development group to produce a new fixed bearing Uni based in Europe with Biomet. I was part of a four surgeon team to produce the lateral uni for MAKO. I was working with engineers to develop improved instrumentation for the Repicci unicondylar when the company decided to discontinue manufacturing the implant. I am now working as a consultant with Maxx orthopedics, a company that has aided me in finally accomplishing my goal, which is to develop instrumentation and power tools to make this technique easy and reproducible.
I am doing this work because of my firm belief that our profession is doing patients a disservice by doing total knees in great numbers on patients who do not need them. I want to share what I have learned with my colleagues. Like most of you, I love my job and enjoy operating on arthritic knees.This tool, the minimally invasive partial knee with a tibial inlayed component, has made my patients’ lives so much easier, and thus has been very rewarding to me. We have made the technique quick, easy, accurate and reproducible. And, dare I say, fun.
I will in the next section explain the rationale for using this system. We will examine the history of it and the reasons it is seldom used or even known about presently. We will look at how the indications for UKA are expanded by using this implant. Included will be pertinent studies and a video of the technique.
Why are so few Ukas done?
There are many reasons for this, and here are some:
- Many of us get very little training in UKA, even those of us that are fellowship trained in arthroplasty.
- The cumulative literature states that UKA has a higher revision rate than TKA.
- UKA can be more difficult to do than TKA, with no greater reimbursement.
- We are afraid that an unsuccessful UKA will compromise a future TKA that we could have done to begin with, that nobody would have faulted us for doing in the first place.
It is reason 4 that I feel is most responsible for the paucity of UKAs that are done. We all take the Hippocratic oath that we took seriously “DO NO HARM”
This is where I want to make the distinction between a “resection UKA” and a “resurfacing UKA”
Most every UKA on the market is a resection UKA, whether fixed or mobile bearing, with saw cuts and chamfers on the femur and a resected, onlay, usually metal backed tibial component.
The literature has shown that revision of these resection UKAs results in a knee that is closer to resembling results of total knee revision than it is a primary total knee.Usually long stems and/or augments are needed. That, of course, is because the resection UKA has removed some of the bone that we needed to support a primary TKA. So if our sojourn into the world of UKAs results in a revision TKA, as it is more likely to do in surgeons less experienced with the UKA, it scares us into just sticking with TKA. That is exactly what happened to me on my first UKA, using a resection technique!
But what if we had a UKA that could be converted to a primary TKA if needed, and the recovery for the patient was not much more involved than arthroscopy? If we knew that we weren’t compromising any future TKA in case the patient did poorly? Then the fear of doing harm is taken out of the equation for the most part, especially if the the procedure has a high rate of success and longevity, which I have proven to be true when properly done.Isn’t doing a TKA on thousands of people instead going to do more harm, even simply looking at no more than infection rates.
It is no wonder that when Biomet first introduced this technique, that of a” resurfacing” UKA with an all poly tibial inlayed component, that it was difficult to even get into a one day seminar to learn it because of the demand from joint surgeons. It seemed obvious at the time that this was the” next big thing”
Brief history of the resurfacing UKA with all poly inlay
The design that is used in the current Maxx orthopedic product is actually the third time a similar prosthesis has been introduced. The Marmor UKA from the early 1970s made use of an inlayed all poly tibial component and a thin resurfacing femoral component with one peg. It proved quite successful despite the smaller and thinner size of the tibial component and the less durable material then used for the plastic compared to today’s polyethylene. Because of some engineering errors by the manufacturer and ensuing medical-legal actions because of the femoral components being inaccurately sized, users of this prosthesis abandoned its use for fear of legal entanglements.
Then in 1999 Biomet introduced the “repicci” resurfacing UKA, which was done through a small muscle sparing incision without patellar dislocation. There are several reasons that the initial widespread enthusiasm for this technique eventually waned to the point that Zimmer Biomet stopped manufacturing it a few years ago. First, it was taught in one day seminars that did not prepare the surgeon properly.This led to procedures being improperly done, which resulted in an unacceptable percentage of failures as reflected in various registries. Secondly, attempts to improve the technique were abandoned by the manufacturer in favor of promoting the Oxford UKA. As a result, Biomet stopped promoting the Repicci just a few years after its introduction. This left a minority of its users who had individually succeeded in teaching themselves how to effectively use the prosthesis still using it, and by attrition and retirement of these surgeons, the sales went down to a point where it was no longer profitable to make the prosthesis.
It is critically important to note that the literature did not uniformly show this approach to be unsuccessful, but instead the results were variable depending on proficiency of surgical technique. I published a paper showing a 94.6 retention rate 10-13 years followup and Repicci and Kohane also had very favorable results.
The MAKO company was originally formed by engineers who saw the problem of the Repicci technique and tried to solve it with the use of robotics and haptic guidance. They developed a resurfacing UKA looking almost identical to the Repicci but that could be more accurately implanted using a robotic arm. Unfortunately their tibial component did not originally have a textured inferior surface, so some sudden loosening occurred at the poly-cement interface of some of their cases. This, along with the purchase by Stryker, led to the abandonment of the all-poly inlay for which the robotics were originally designed to make more accurate to implant as opposed to the freehand Repicci technique.
This new product we have created is very similar in design to the Repicci, the difference is that by creating a better workflow and new instrumentation, jigs and power tools, it is now easier, more accurate, and reproducible.Everything has been designed to be user friendly. A new rasp to flatten the bottom of the tibial pocket is a game-changer. A simple templating system ensures that the femoral component is centered on the tibial inlay. The use of a high speed aggressive burr and a bit especially designed to decorticate the femoral surface are new, easy to use tools. The surgical setup places the surgeon in a comfortable position and there are no extra holes made by alignment pins and no distraction devices are needed.
I hope that you will take the time to look at the technique video and other materials provided, and thanks for your interest.
Dr. Martin Redish 