Trousdale v. Engh: Ceramic Heads Should Be Used in all Patients

This week’s Orthopaedic Crossfire® debate was part of the 34th Annual Current Concepts in Joint Replacement® (CCJR®), Winter 2017 meeting, which took place in Orlando. This week’s topic is “Trousdale v. Engh: Ceramic Heads Should Be Used in all Patients” For isRobert T. Trousdale, M.D., Mayo Clinic, Rochester, MinnesotaOpposing isC. Anderson Engh Jr., M.D., Anderson Orthopaedic Research Institute, Alexandria, Virginia.Moderating is Thomas S. Thornhill, M.D., Brigham and Women’s Hospital, Boston, Massachusetts.

Dr. Trousdale: This debate is going to involve the use of ceramic vs. cobalt chrome heads in total hip replacement. I’ll say instead of all patients, I use and argue for the fact that ceramic heads should be used in the majority of our patients. As you all know we’ve got a lot of options for our bearing surface and, again, Andy and I are going to discuss the role of ceramic versus cobalt chrome and we’ll limit it to highly crosslinked polyethylene as I’m sure that’s the majority of the polyethylene used throughout the world.

In my practice today, I’ll use a different bearing option in a 12-year-old with avascular necrosis who needs bilateral total replacements compared to a 78-year-old with end stage right hip arthritis

If you look at ceramic versus cobalt chrome on highly crosslinked polyethylene you’d look at wear, durability, corrosion, cytotoxicity, and cost so there are pros and cons to each of the options.

I would argue that wear is a wash. The wear of ceramic versus highly crosslinked polyethylene compared to cobalt chrome versus crosslinked polyethylene is very close. I’m going to give durability, at least now, a slight nod to ceramic. Corrosion …the big advantage of ceramic over cobalt chrome has to do with corrosion. I give cytotoxicity a slight nod to ceramic and cost I give a slight nod to ceramic.

Here’s a bit of data to justify those statements.

So how about wear? I would argue there is no significant clinical difference in the wear of ceramic versus cobalt chrome on highly crosslinked polyethylene.

In data from our colleagues in New York City (Gaudiani et al, J Arthroplasty2018), the linear wear rates were a a little bit better with ceramics. If you look at volumetric wear, the data showed a little better wear with the ceramic versus cobalt chrome but not significantly different. I think Andy’s going to show you the data that he generated (Sychterz et al, JBJS-Br2000). He states in his article that despite differences in the wear rates and head penetration, there is no clinical relevance, no increase in osteolysis between the two groups.

How about durability, endpoint to revision?

The recent data from the Australian Joint Registry demonstrates, up to 15 years, a slight advantage with ceramic and highly crosslinked poly versus cobalt chrome on highly crosslinked poly. Same data from the Dutch Registry, the ceramic on highly crosslinked polyethylene does a little bit better than the metal on highly crosslinked poly for the cumulative incidence of revision, at 5 years and 9 years.

The real issue is corrosion. I had the recent experience with a couple of patients, titanium stem, metal head, highly crosslinked poly bearing — their cobalt levels were 10, chrome was 1. We saw, when we got into the operating room, that the whole abductor mechanism was necrotic. This is a problem I do not have a good solution for. There is the corrosion on the inside of the cobalt chrome femoral head. There it is after a little debridement; the whole abductor mechanism is gone. No good answer for that problem.

Another of my patients, also titanium stem, cobalt chrome femoral head against highly crosslinked polyethylene and when we got in to open up the hip joint, going through the facia we saw that sort of dirty dishwasher appearing fluid and the abductor mechanism is completely necrotic after 8 years of use of this cobalt chrome on highly crosslinked poly bearing.

This is a problem I’ve not seen with ceramic on a titanium taper and the common thread appears to be cobalt chrome. As you see that dirty sort of dishwasher fluid, the abductor mechanism is to your right, the foot is to the left, and the whole abductor mechanism is dead. We can get rid of the cobalt chrome, but I can’t solve the abductor muscle problem.

Some basic science data from the group in London, Ontario (Tan et al, J Arthropolasty2016) looking at tribocorrosion between ceramic zirconium and cobalt chrome femoral heads. The combined score was greater with cobalt chrome versus ceramic. So, you certainly get corrosion with ceramic, but the corrosion byproducts are ceramic and titanium versus the toxic cobalt chrome.

There are a lot of unknowns with cobalt chrome heads. We don’t know the rate of clinically significant corrosion, we don’t know the factors that lead to corrosion, but we do know that cobalt chrome is the common thread.

Cytotoxicity, I also give the advantage to ceramics. Serum metals are increased, cardiac cobalt levels appear to be increased, and we know cobalt is cytotoxic.

And lastly—cost: I give a slight advantage to the cost to ceramic. Many centers are getting their ceramic heads at the same price as their cobalt chrome heads, but even if they’re a little more expensive there is a cost to working up the painful total hip replacement. If we make some assumptions, 12% of our patients have a little bit of pain, 12% of those get a work up, and 1% get a revision. Ceramics can be much more cost effective even if it’s a few more dollars at the front end. In the long-term, ceramics are going to be a little bit cheaper.

I think ceramic wins. In the elderly, they get stainless steel on highly crosslinked poly. Majority of my patients get ceramics on highly crosslinked poly, and then in the ultra-young, I’m still using ceramic on ceramic.

Dr. Engh: So, I’m going to oppose the concept that ceramic heads should be used in all patients. Rob and I are very much alike here, I have a selection process, and I’m probably about 50/50 ceramic heads and metal heads. So here in this debate, the increased use of ceramics on polyethylene is, in my opinion, a reaction to what is a poorly understood and rare problem. That problem is mechanically assisted, crevice corrosion (MACC). Not just corrosion but corrosion that leads to an adverse local tissue reaction (ALTR) called trunnionosis.

My second point is, this is really all about cost, clearly ceramic heads cost more and the question I’m going to ask you is, “What are you most concerned about today?” You have to deal with your hospital. Are you more concerned about the cost of the hospital stay, or are you more concerned about the long-term costs predicted from a model?

According to the American Joint Replacement Registry (AJRR), 53% of primary total hips are a ceramic on polyethylene bearing. Quote from the AJRR, “Factors that have contributed to this growth include, concerns regarding trunnionosis and corrosion.” This all really started in 2012. It didn’t really start then, we knew about corrosion. Corrosion has existed for a long time, but corrosion leading to an adverse local tissue reaction had been rarely described. In this first series (Cooper et al, JBJS-Am2012) there were 10 cases, it was 1.8% of their revisions.

The same center came back in 2016 with 27 cases (Plummer et al, J Arthroplasty2016). Interestingly 70% of their cases were a chrome cobalt head on a chrome cobalt taper, something that is relatively uncommon today—21 of the 27 were from a single manufacturer, and 20 of the 21 were femoral heads smaller than 36mm and most of us are tending towards the 36mm head currently.

In another study (Hussey et al, J Arthroplasty2017), a single manufacturer the data from a titanium stem with a cobalt ball was 3.2% of 1,300 cases either had an ongoing adverse local tissue reaction or had been revised.

So, a summary article from an AAHKS [American Association of Hip and Knee Surgeons] symposium from 2016 (Jacobs, J Arthroplasty) stated “As yet the incidence, etiology, and pathogenesis of MACC-associated with an adverse local tissue reaction are not well understood.” So, my question is, “Why are we reacting to a rare and poorly understood problem?”

My personal experience, I believe cost is a local issue, it’s not a long-term issue, it’s what you see in your own experience. In terms of parts per billion for cobalt, only out to 2 years, it was less than one part per billion and it didn’t change from pre-op to post-op.

This has been supported by another study that was published in 2013, interestingly after the previous study showing corrosion. They did not see cobalt levels greater than one part per billion out to 10 years in their metal on polyethylene bearings. My clinical experience with a metal ball on crosslinked poly includes a prospective randomized study now 16 years out. I’ve only had 3 revisions in these. These patients are doing very well: no infections, no loosening.

Pertinent to this talk no revisions for mechanically assisted crevice corrosion.

We have a long-term postmortem retrieval program at our center. I sent 56 of our postmortem retrievals up to Doug Padgett at HSS [Hospital for Special Surgery]. These have been in for 11 years: 43 were a cobalt chrome ball, on a cobalt chrome stem, 13 were ceramic balls, and a mix of 12, 14, 16 tapers. Both the ball and the head were graded for corrosion. The mean score in these 56 was 1.4 out of a possible 96. According to the table the HSS revisions, where you can see the corrosion scores are substantially higher.

As far as another view, for a long time we’ve been doing ball and liner exchanges for polyethylene wear. We have traditionally used a chrome cobalt stem and always replaced these balls, with a chrome cobalt ball. We took all these balls, graded them for corrosion, divided them into low grade corrosion, high grade corrosion, and saw no difference in the survivorship. Importantly, even when we put a new metal ball on a stem that had corrosion, there were no revisions for mechanically assisted crevice corrosion (Goyal et al, J Arthroplasty2014).

Looking at our database, we looked at 3,000 contemporary, primary total hips from 2006 to 2017. We identified 2 cases; this is 2.5% of our revisions, and a tenth of our primaries done during this period. We also went back and looked at our most recent 350 revisions from 2015 to 2017 and we added one additional case so this is 1% of the revisions we’re doing.

So, in conclusion, cost is a local issue, clearly ceramic heads cost more. Mechanically assisted crevice corrosion is poorly understood at this time. I believe it is a rare problem—certainly in my area—and I have to work with my hospital every day. Mechanically assisted crevice corrosion that leads to an adverse local tissue reaction has absolutely no effect on my hospital cost or my 90-day cost since I was in a bundle, but ceramic heads definitely increase the cost per patient for both of these.

Moderator Thornhill: Okay so let’s just take a couple things where there’s some differences in the interview. Andy, Rob said that a ceramic head is cost effective even if it’s for $486 or less. Can you take this to your hospital and get them to agree?

Dr. Engh: I think all of us have been wanting to take 10- and 15-year data to our hospital and at this point, and for as long as I’ve been in practice, hospitals are not concerned about 10 or 15 years. Patients move they go other places. It’s orthopedists that are concerned about them, the hospital just sees their cost per patient. It’s extended from their hospital stay now that we have bundles out to 90 days, but I don’t see it going past 90 days.

Moderator Thornhill:Rob, what did we do to the trunnion or the assembly that has led to this problem or did we just not have a clue that this existed?

Dr. Trousdale:We have no idea how important the surgical factors are, the design issues, but we do know cobalt chrome is a common thread. Now the cost thing is interesting, there is no question, up front, it’s a lot cheaper to use cobalt chrome heads in most hospitals. A lot of centers are getting the ceramic and cobalt chrome for the same price but up front it is more expensive, certainly down the line.

Moderator Thornhill:Andy would you prefer a ceramic head or a cobalt chrome head? You showed it both in cobalt chrome on cobalt chrome and on titanium. Some people feel that there are certain types of implants that have a predilection for trunnionosis. I don’t want to name implants, but would you prefer or be more likely to use a ceramic head on somebody with a titanium stem than a cobalt chrome stem?

Dr. Engh:My indications for using a cobalt chrome head or a ceramic head are really age related. My younger patients are getting a ceramic head. I’ve switched to titanium stems. My center’s been using chrome cobalt stems for decades, I’ve gone over to titanium stems now, so it doesn’t make a difference to me.

Dr. Trousdale:So age to me is not that important in the sense of cobalt chrome or ceramic and certainly the trunnion problem has not been age discriminatory. So, I have an 82-year-old patient, 6 years from surgery who’s getting revised for high cobalt levels and a big pseudotumor. If you are concerned about cost, there is good data on elderly patients with type C bone and a cemented stem. Use a cemented stainless-steel stem and a stainless-steel head—that corrodes! But the byproducts of stainless-steel corrosion don’t seem to be as clinically relevant as the byproducts of a cobalt chrome head.

Moderator Thornhill:Yeah, and it occurs sort of alarmingly quickly within a few years, so I think it’s a good point. Rob, you know the early iterations of ceramic heads had issues with fractures, chipping, squeaking, stripping, we fixed all of that?

Dr. Trousdale:I’ve never seen a squeaking hip with a highly crosslinked poly. Ceramic-ceramic is a different can of worms. You’ve not solved that problem. I think most us, at least in the United States, are using Delta heads. Now whether that the right thing or not, I think it’s still unknown. They certainly seem to be stronger, the fracture rate seems to be very low with the femoral heads different with Delta liners. With the zirconia that’s in the Delta, 18-20% zirconia, is that going to be a factor long-term, maybe? We don’t know, there is still some unknown with Delta ceramic as it’s relatively new.

Dr. Engh:I am very happy with the Delta heads. I have some worries about the additional modularity, sometimes you do have to put a taper sleeve in some of these ceramic heads.

Dr. Trousdale: You do, but most of those sleeves are, of course, titanium and the byproducts of titanium-on-titanium, certainly you get corrosion in that interface, but the clinical significance seems to be lower than cobalt chrome-on-titanium. That we can agree on.

Moderator Thornhill:That was my next question about the sleeved heads. Pros and cons and the reason for those that haven’t been using them.

Dr. Trousdale:I think if you are putting a ceramic head on a used trunnion, it’s probably prudent to use that titanium sleeve. You’re going to get corrosion. Again, pick your poison, you’ve got titanium poison or cobalt chrome poison. I’ll pick titanium poison any day of the week.

Dr. Engh:I agree with that completely.

Dr. Trousdale:I agree with Andy agreeing.

Moderator Thornhill:  Thank you. You two did a great job because you actually changed the debate, that’s just brilliant. We are seeing an increase in the use of ceramic heads.

Please visit www.CCJR.comto register for the 2018 CCJR Winter Meeting, – December 12 – 15 in Orlando.