Lachiewicz v. Sculco: Dual Mobility: “Everyman’s” Choice for High Risk & Recurrent Dislocation

This week’s Orthopaedic Crossfire® debate was part of the 19th Annual Current Concepts in Joint Replacement® (CCJR®), Spring meeting, which took place in Las Vegas. This week’s topic is “Dual Mobility: “Everyman’s” Choice for High Risk & Recurrent Dislocation” For is Paul F. Lachiewicz, M.D. – Duke University Medical Center, Durham, North Carolina. Opposing is Thomas P. Sculco, M.D. – Hospital for Special Surgery, New York, New York. Moderating is William J. Maloney III, M.D. – Stanford Hospital & Clinics, Stanford, California.

Dr. Lachiewicz: I’m going to convince you that the dual mobility is now the implant of choice and certainly much better than constrained liners.

There’s a long history of these designs in Europe where they’ve been used as an alternative to both large heads and constrained liners. The first one, in France for primary total hips, is now almost over 40 years old.

We presume that there is greater range of motion because you have 2 articulations and there’s increased jump distance with the very large polyethylene “head.” Some preliminary data supports our presumption from both manufacturers and independent labs.

One criticism we hear is, “Well, perhaps there’s going to be greater wear with this large polyethylene articulation.” And there was a study (Loving, et al., J Arthroplasty, 2013) that showed as long as there is some movement of the interbearing—and it’s not quite clear how much—the polyethylene wear is going to be quite low. If you do lock it and make the polyethylene be the primary articulation, you can have larger wear volumes.

There is a wide variety of European designs and for those of you who are not aware of this, there are many designs in the U.S. as well.

What are the present indications for dual mobility? Recurrent dislocation, revision of a metal-metal resurfacing and revision of a hemiarthroplasty. We use it in the second stage of an infection reimplantation, if a constrained liner fails, and Matt Abdel won a Hip Society Award for essentially saying that perhaps this is the thing to be used for all revisions.

In terms of primary total hips, I use this in patients with spine deformities and with a prior lumbar arthrodesis.

I did one of the first retrospective reviews (Lachiewicz, et al., JAAOS, 2012) and in 2012 there were only nine papers on this subject and we still showed over 90% success rate. That same year the Swedish Registry reported a 99%, two-year success rate (Hailer, et al., Acta Orthopaedica, 2012).

The same year, the UK experience (Vaskutty, et al., Bone and Joint J, 2012) came out with a French design—again a very low rate of early dislocation. At that time there were ten studies.

Since then there have been three systematic reviews published in the last year.

One of those studies came from Tom Sculco’s place and his son was a co-author (DeMartino, et al., Bone Joint Journal, 2017). They reviewed 59 articles and came to the conclusion that a dual mobility implant is certainly preferred to anything else in terms of the rates of dislocation. In primary less than 1%, revision 3%.

There is also a second review from Rush (Darrith, et al., Bone Joint Journal, 2018) and a third one with a small number of articles (Pitukanotai, et al., Eur J Orthop Surg, 2018).

Can dual mobilities fail? Of course. Anything can fail. This can also dislocate, but there are two particular ways it can dislocate. The large polyethylene “head” can come out of the metal shell. Or you can actually have a pull out of the small either metal or ceramic ball from the polyethylene.

We’ve seen one or two cases of early acute disassociation (Klement, et al., Am J Orthop, 2017). There have been several case reports. What is this due to?

We think the patients have a skirted neck. It could also be due to a closed reduction maneuver that a lot of these patients have when they try to have a dislocation reduced in the ER.

The chronic intra-prosthetic dislocation is really a phenomenon of late wear of conventional polyethylene (Hamadouche, et al., Clin Orthop, 2012). I’ve spoken to Moussa Hamadouche…they have not seen this in France with the newer polyethylenes.

Our conclusion is that dual mobility is now the standard for recurrent dislocation and high-risk primaries. It gives you better range of motion. Will these always work when the abductors are deficient? And there may be a limit to these. We don’t know what it is. We think polyethylene wear and intra-prosthetic dislocation are very rare phenomena. We certainly need more data and longer follow-up on the newer U.S. designs.

Dr. Sculco: Hip dislocation tends to be a traumatic and difficult problem to deal with. If you look at the literature, it’s now really the most common cause of revision hip replacement in the United States (22.5%).

The treatment for recurrent dislocation has evolved. Jumbo or bipolar heads are not used very much now. We are looking at dual mobility liners. And then constrained liners.

In the paper that Paul alluded to, we looked at 59 studies, over 17,000 dual mobilities. And you see, in fact, that dislocation after dual mobility is uncommon—1% in the primaries and 3% in revisions.

There is this unique type of dislocation that does occur in dual mobilities where the head is eccentric in the socket after reduction. And the reason for that is the polyethylene liner is, in fact, outside the socket. A CT scan shows it beautifully.

So in the reduction of a dislocated dual mobility, an intra-prosthetic dislocation may occur. At our institution, we’ve had four. It’s something to think about if one has a dislocation with a dual mobility that it may convert to an intra-prosthetic dislocation with reduction.

Constrained liners…you have to realize that there are different types of constrained liners. Constrained liners have gotten a bad rep because often they’re confused with the two different types of constrained liners available.

There are the constrained tripolar and the focal constraint designs. The latter adds a ring to the polyethylene in some way to try to improve the constraint of the socket and those have not done as well. I think it’s given constrained liners a bad rep.

We looked at 149 patients at our institution who received tripolar constrained liners and followed them an average of 4.2 years, where the average number of previous surgeries was 4. The indications for use of a constrained liner were recurrent dislocation in 82 of the hips and poor stability at the time of the revision procedure in 45%.

There are different types of fixation and they were about one-third, one-third, one-third in terms of revision of the whole acetabular component versus just putting a constrained liner into a compatible shell or cementing into an existing well-fixed shell in this group of patients.

Here’s the data—16 revisions (10.6%), but if you really ferret out that data only 3.3% of them—5 patients—had recurrent instability in that tripolar constrained population.

A unique problem we see with a constrained tripolar is the metal ring which goes around the polyethylene can disengage and present a problem and need for reoperation.

It’s important to differentiate the results. When you look at the literature and you talk about constrained implants, tripolar versus focally constrained, the recurrent dislocation rate in the tripolar constrained is less than 10% (Bremmer, et al. J Arthroplasty, 2003), and much, much higher in those that are focally constrained (Della Valle, J Arthroplasty, 2005); Berend, Arthroplasty, 2005; (Andersen ISRN Orthopedics, 2013; Chalmers, J Arthroplasty, 2016).

Same terminology but entirely different biomechanics.

Significantly less, so don’t mix up the two types of constrained implants when you talk about them.

At our institution, we’ve had a 96% success rate in terms of joint stability with a constrained implant for various revisions or recurrent instability.

What are the potential problems with dual mobility cups? The intra-prosthetic dislocation both I and Paul have referenced. The wear is still unclear, but probably won’t be a major problem. But when we use modular dual mobility cups, we put cobalt chrome against titanium, and I have some concern that that interface may be a problem long term just as we’ve seen with other metal-metal interfaces.

In conclusion, I still use tripolar sockets. I think they’re best with patients with severe neuromuscular disease, an absent abductor mechanism, failure of a dual mobility or when you want to avoid dissimilar metals.

I’m going to finish with a quote from Paul Lachiewicz at the 2015 Hip Society meeting, “…a cautious approach to dual mobility components for recurrent dislocation is recommended.” And I use dual mobility. And I like it as an implant, but I do think a lot of unanswered questions are still out there.

Moderator Maloney: Paul, you have one minute to rebut.

Dr. Lachiewicz: First, I now take an “audacious approach” not a “cautious approach,” based on my experience the last couple of years. Two questions, Tom. I do not understand the large number of failures. I have heard in the grapevine that at HSS you’re having more failures with these dual mobility components. I’m not quite sure why. Are these the ones with tumor prostheses? You know my friend, Stephen Jones from Cardiff, has done a meta-analysis of all the publications on constrained liners. He’s not as optimistic as you are about that. He reserves them for very select group that have almost massive destruction of the abductors.

And the other thing is, dual mobility may have three articulations, but the tripolar, I remember a paper from HSS where they said there were six different mechanisms of failure. You could pull it out in any of the different areas. And then finally, John Callaghan used to say, “I only have 3% dislocation with the constrained liner.” But if you add up his 10% loosening of acetabular components, 10% loosening of femoral components, periprosthetic fractures, the failure rate seems to skyrocket. It’s kind of how you define it.

Dr. Sculco: First, our experience with dual mobility is really quite good. I use dual mobilities both in the revision and the primary. And I use the ADM in my primary, high risk patients. I can tell you I’ve done 700-800 of them and I’ve had two dislocations. So, the dislocation rate is small in my experience. And I think in our experience in general. But I do think if you do have dislocation then this intra-prosthetic dislocation is going to be a potential issue.

Dr. Lachiewicz: Yes, I think you have to be careful. You’ve got to position the acetabular component correctly. You have to check for impingement. You can still get bone-bone impingement with dual mobility. One of the cases that we saw was due to an impingement of a skirt. If you are going to do dual mobilities, people in the audience, I would recommend against using a skirted femoral component.

Dr. Sculco: I think, the other thing Paul, I agree with you 100%. Just for the audience, you can’t put these implants in with poor position and think they’re going to be forgiving and you’re going to get away with it.

Moderator Maloney: Especially true with a constrained liner. Let’s take a scenario. You have a 65-year-old gentleman who’s got a malposition socket and it has come out four times. You’re going to do a socket revision. You take out the socket, are you going to put in a dual mobility, a constrained liner or a big femoral head? Paul you get first shot.

Dr. Lachiewicz: Nowadays I’m doing a dual mobility in that type of patient. Seems to be better…

Moderator Maloney: Are you using dual mobility now in all socket revisions?

Dr. Lachiewicz: Not on all, but almost all now. Because I’m doing a lot of metal-metal, lot of hemis.

Dr. Sculco: Same patient. If I have patient that is recurrently dislocating, 65-year-old man I probably would do a dual mobility in this day and age. If it’s an older female patient, particularly, who is frail and has poor proprioperception and poor tissues, I’m going to do a constrained liner.

Moderator Maloney: If the system allowed you to put in a constrained liner regardless of the system, you would give it a shot with a constrained liner.

Dr. Sculco: I would definitely in an older patient.

Dr. Lachiewicz: Two years ago, I did do that, Bill, because the patient was malnourished and it was a three-time acetabular revision. I didn’t want to put this patient through a two-hour surgery so I just changed the liner to a constrained liner. But I still have a lot of fear of constrained liners, Tom.

Dr. Sculco: Paul, don’t be afraid.

Moderator Maloney: Ladies and gentlemen, there is definitely a role for dual mobilities. There is also a role for constrained liners, but it’s shrinking. Thank you, gentlemen.

Please visit www.CCJR.com to register for the 2019 CCJR Winter Meeting, – December 11 – 14 in Orlando.