This week’s Orthopaedic Crossfire® debate was part of the 17th Annual Current Concepts in Joint Replacement® (CCJR), Spring meeting, which took place in Las Vegas this past May. This week’s topic is “Optimal Glenoid Fixation Requires Cement.” For the proposition is Evan L. Flatow, M.D., Mount Sinai Health System, New York, New York. Opposing is William H. Seitz, Jr., M.D., Cleveland Clinic, Cleveland, Ohio. Moderating is Thomas S. Thornhill, M.D., Harvard Medical School, Boston, Massachusetts.
Dr. Flatow: It certainly hurts me that I have to debate my good friend Bill Seitz on this very important issue. But I will persevere.
Bill has a really hopeless task here. Cemented glenoids are clearly better. The data is overwhelming. And I can’t believe he signed up for this assignment.
In a study from Mayo Clinic that Bob Cofield published and John Sperling is referred to with a minimum 20-year follow-up for patients under age 50, the hardest possible group, the all-poly cemented glenoid had an 85% survival at 25 years. That’s a pretty good record. Also, loose glenoids are well tolerated. They don’t all require revision.
Why is that? As a glenoid loosens, it migrates and then the head hits the surrounding bone which stops the migration and the pain on the glenoid. It’s almost like an auto hemiarthroplasty. Because the glenoid is small and almost like an inlay, the bone can take up the stress after the glenoid loosens. This is much, much better than a situation with the metal-backed glenoid which when the poly wears you get metal-on-metal with a lot of noise, a lot of particles, and a lot of pain.
When there is a loose poly glenoid, I’ve been able to remove most of them arthroscopically by cutting them up into little pieces and pulling them out through the arthroscope. Didn’t even require a big open revision, because it is the minority of cases.
Dr. Gilles Walch has shown a 99.7% survival at five years, 98% at ten years and he said: “It will be difficult to improve on these results at ten years, therefore any innovation in this field”…and he meant uncemented…”will need to wait five or ten years to prove any superiority.”
Cofield carefully compared a metal-backed to an all-poly glenoid and his experience was a clear benefit to the cemented poly at 15 years survival.
Pascal Boileau and his group conducted a randomized prospective trial and found 20% loosening in an uncemented metal-backed implant. In fact, a follow-up article by Boileau showed a 37% revision rate. And Bill, the title is “Metal-backed Glenoid Implant Is Not a Viable Option” You didn’t even have to read the paper, you could just look at the title without even going beyond the abstract.
And what’s the point of cementless anyway? The early idea was to avoid cement disease, but later we found out it’s not the cement causing lysis, it’s the poly wear. And metal stiffens the poly, increasing the wear and increasing the particulate debris.
So some people tried to develop soft metal to avoid this stiffening effect. There was an attempt with tantalum and titanium mesh. But even in their studies, which did better in terms of wear, 4 of 19 of the early tantalum fractured and 3 of 22 of the titanium fractured. And we only had three and four year follow-up, respectively.
There is an ingrowth all-poly glenoid that has been tried, but we don’t know what happens. You still have to cement the other pegs. The effect of poly on bone has never been good and it’s unclear what happens long-term. And even though there is bone that grows between the flanges, it’s not really ingrowth into the poly the way it is into tantalum or titanium.
The Australian Registry showed dramatically worse survival for uncemented compared to cemented. We have the same findings in the New Zealand Registry, which is really the best way to look at it generalizable to an entire population of surgeons.
Dr. Seitz: Evan, Evan, Evan. Not much has changed in the last 31 years. You gotta think outside the box a little bit so I’m going to talk not about the metal-backed implants that Evan showed fails, which it does, but rather the tantalum anchored polyethylene implant, which is a totally different animal.
Glenoid loosening with polymethylmethacrylate cement is well known. Survival rates in extremely capable hands are very good. But if you look across the literature and look at it carefully, lucent lines have been reported in up to 96% of cases, most commonly in the 20% to 30% range.
Frank loosening has been described in 10% to 25%. It does cause pain. And Evan, auto hemiarthroplasty is painful. I suspect that most hemiarthroplasties, like those you do in your institution, show that a true total joint replacement does better than a hemi. But what happens is you can get bone loss and then it does need revision.
There have been attempts at better implant designs, changes in cement—as Evan showed you—changes in pegs, keels, posts. Metal backs have been shown not to work. And there is no significant improvement in the rate of lucent lines and/or loosening that’s been based on these changes in design.
The high stress level that occurs at the cement layer in cemented glenoid components is part of the big problem. And when you use cemented metal-backed implants, again, the poly wear is great because of the cold flow transition to the polyethylene, which results in osteolysis.
I agree with you completely, Evan. However, there is this material which has been used in the hip and the knee very successfully. Has been used in your implants around the shoulder, both on the humeral side as well as the glenoid side. And it provides early, immediate stability and it has a very strong track record in the hip and knee.
So what is the definition of insanity? Performing the same procedure over and over again and expecting a different outcome. Evan, why not think outside the box a little bit and find a solution for this problem?
Oh, wait a minute, you did. This trabecular metal-backed implant is YOUR implant. Now, the first generation albeit did show some fractures and failures, and that was partly because of the raised tantalum button which did not allow full seating unless you were extremely careful of the polyethylene on the prepared glenoid surface.
The second-generation implant allows very easily the flush seating of the polyethylene on the surface. But it does require meticulous surgical technique. If the surgical technique is off, and there’s any offset not supporting the polyethylene, there will be micro-motion and the tantalum is brittle and can fail.
So, trabecular metal-backed “anchorage” is what we’re talking about. This is not a metal-backed implant. A perfectly flushed seating of the poly on the carefully prepared glenoid surface, allows very secure fixation of the tantalum to the bone. It anchors the bone into the scapula, it does not back the implant. And the glenoid surface is what supports the poly. You need to have good bone stock.
We have been reviewing 117 of our cases; 86 with greater than two-year follow-up; 84 showed no lucent lines. It decreased our OR time compared to cementation by 22 minutes. There was one late infection at three years, and one keel fracture from the first generation. The revision for that case was easy. The key is meticulous surface preparation and making sure you have flush seating of the poly on the glenoid.
So, Evan, look forward, not back. Embrace new technology. You’re a smart guy Evan. You were even when you were a resident. This is the total shoulder arthroplasty, Evan, not the pseudo-auto hemiarthroplasty.
Moderator Thornhill: Bill, so your unique thing you were going to bring out today is just to inset the tantalum so the poly will hit the glenoid. I’m not sure that would be transforming. So, Evan, what is the best way to configure the fixation part of the cemented glenoid?
Dr. Flatow: I think in the old days we made a big hole and tried to put in a big glob of cement. In the modern systems, the peg systems, you drill a precise hole and then you dry it and then you pressurize the cement. It results in very low lucent lines with current techniques. Even with keels. If you machine the keel and compress it very well. I think we’re much better at cementing than we used to be.
Moderator Thornhill: So quickly, before I go to Bill, give us the three key tricks to cementing the glenoid.
Dr. Flatow: The key thing for us is precise machining of the hole. The second one is drying it. We usually dry it pretty carefully and eliminate all blood. I even use a little peroxide to take out the dried blood. Then sequential pressurization usually with a plunger type tool that goes into the slots.
Moderator Thornhill: I’ve tried a lot of uncemented glenoids unfortunately. The one I used was too thin; the locking mechanism was bad, and the failure rate was pretty high. They weren’t easy revisions. You talked about this being an easy revision. There’s this big hunk of tantalum in there. You do have a hole. You can impact graft into it. Talk to us a moment about revision of these glenoids. What are your key things?
Dr. Seitz: Well, the fact is that I’ve only had to do one. And it fractured right at the face of the glenoid. The tantalum keel was very well fixed in the bone. What we did was drill right into it as if it were bone prepared for the poly glenoid and then we did cement the poly glenoid. The material that is on this implant is actually very much like bone when you actually work with it and you just have to do a lot of irrigation to get rid of all the metal debris.
Moderator Thornhill: Last question and I’m going to ask both of you very quickly. In orthopedics, we do things in quantum leaps. Nobody or almost nobody cements acetabulums any more. What’s going to be the quantum leap that’s going to make us do uncemented glenoids in all cases, Bill?
Dr. Seitz: In my mind it’s actually being able to speed up the case. This saves 22 minutes. Our infection rate is low, but the reality is if you can speed it up you’re going to lower your infection rate.
Dr. Flatow: I think there will always be a role in some elderly patients for cemented glenoids.
Moderator Thornhill: Gentlemen, thank you. It’s a really good review and some good technical tips. Thank you very much.
Please visit www.CCJR.com to register for the 2017 CCJR Spring Meeting, – May 21 – 24 in Las Vegas.
