Craig J. Della Valle, MD, Chief, Section of Adult Reconstruction and Professor of Orthopaedic Surgery at Rush University Medical Center, talks about a particular type of hip replacement that may allow patients full range of motion.
Talk to me about dual hip or dual mobility hip replacements. How is it different than regular hip replacements?
DELLA VALLE: Dual mobility is a minor modification of a standard hip replacement with the main objective being to reduce the risk of dislocation. This is important as dislocation is the number one cause of failure of hip replacements done in the United States. Dual mobility bearings may also provide the patient with better range of motion to do certain activities, such as yoga and pilates that normally we wouldn’t recommend after hip replacement surgery.
You said it’s just a minor difference. What is that that minor difference?
DELLA VALLE: The operation is essentially the same. The only thing that’s different is the bearing surface. So as opposed to a ball and socket articulating with each other, in a dual mobility system you’ve got a ball, a larger ball on top of it and a metal liner which goes into the cup. So, it’s a slightly more complicated bearing system, which has pros and cons. The main advantage, again, is it’s more resistant to dislocation and potentially allows higher degrees of range of motion but there are theoretical negatives as well.
Dual mobility however, is not a new concept. It’s been around, particularly in Europe and specifically France, for 30 or 40 years and was “reintroduced” into the market here in the US about a decade ago.
The main negative would be, because there are two bearing surfaces, there are potentially two surfaces that could wear. So, the concern is that you could get a higher wear rate. That being said, with the materials we are using today, the plastics are so wear resistant that I think probably for most patients it’s not a real concern.
The second concerns relates to the metal liner that is placed inside the cup for a dual mobility bearing. There is some concern about the junction between the titanium metal shell that touches the bone and the dual mobility liner that goes into the cup. Specifically, the concern is corrosion between those two metal surfaces. I believe this is somewhat design dependent but mostly a theoretical concern but it is something we are studying and watching. There is a way to do a dual mobility hip with a one-piece cup, that avoids the risk of corrosion, that we do in our practice for some patients, but that is not widely done in the US based on the increased technical difficulty with that option.
With the possibility of corrosion and more likely to be, I guess, worn easily, does this make this implant more likely to need a replacement sooner?
DELLA VALLE: To be fair, I think it is important to consider overall failure rates. The number one cause of failure of a hip replacement in the United States is dislocation. Hence in my mind I weigh the theoretical negatives of the two bearing surfaces and corrosion and the patients individual risk of dislocation. If I am treating a patient who is at high risk for dislocation, then the theoretical risks of dual mobility are outweighed by their risk of dislocation at least in my mind. For example, one of the things we’ve recognized in the past decade is patients who’ve had a fusion of their spine are at higher risk for dislocation which may be as high as 6-7%. Hence in my mind the theoretical risks of dual mobility are much lower than that six or seven percent risk of dislocation. So again, we use it in patients who we think are at higher risk either because of their anatomy or because they want to do certain activities such as yoga, Pilates or waterskiing that put them at high risk for dislocation.
So more of those active patients. There is I guess an age range that this would be more ideal for?
DELLA VALLE: Again, I wouldn’t classify it as patients who are active or in a certain age class. I would classify it as patients who want to do specific activities that require higher degrees of range of motion or want to perform activities that put them at high risk of dislocation. I think the concerns of bearing surface wear and corrosion would be exacerbated in someone who is young and active; but someone wants to do yoga and Pilates, maybe not, because they’re not impact-loading the joint.
Is there a certain age range that this would be better for?
DELLA VALLE: In general people who are older do seem to be at higher risk for dislocation. So, for example, one of the instances where we began using dual mobility bearings is in patients who broke their hip as we know that hip replacements in patients with a fracture are at high risk for dislocation. So, in my mind that was a good population to start with; people where we know are at high risk of dislocation but their activity level and unfortunately their life span may be low.
Is the surgery the same as a typical hip replacement?
DELLA VALLE: If a modular dual mobility liner is utilized (which is most commonly used in the USA) it’s essentially the same as any other hip replacement. That being said, we have learned that it is important to seat the dual mobility linter accurately to ensure it is fully seated into the cup. If a one-piece or “monoblock” dual mobility cup is used, that does add a little bit of complexity. We have a big experience doing what we call hip resurfacing, which uses a similar acetabular component so I am very comfortable with it but most surgeons in the USA are not and hence it is not used very frequently.
What’s the recovery like?
DELLA VALLE: I would say that the recovery would be the same between a dual mobility hip and a conventional hip replacement. The only difference being that I think we’ve learned over time that there may not be a benefit to restricting patient’s mobility after surgery or so-called “hip precautions”. With dual mobility, I’m even less concerned about the patient having a problem of a dislocation afterwards and hence we don’t put any type of range of motion restrictions on our patients if they have had a hip replacement with a dual mobility bearing.
Talk to me about Angelica. What led her to you?
DELLA VALLE: She’s a flight attendant and has a very busy lifestyle. She’s a young woman, and unfortunately developed arthritis of her hip that was quite painful despite extensive non-operative treatment. She’d accommodated as much as she could to the lifestyle changes to try to make it bearable to live with but I think, like most patients, she got to the point one day where she said, “you know, I really don’t want to have surgery, but I really can’t live like this anymore”.
In our course of evaluating her, there were specific activities that she wanted to do that required higher degrees of range of motion which would put her in a higher risk category for dislocation. Based on that we discussed with her the option of doing a dual mobility bearing for her specific situation.
What impact do you think this type of implant can have for someone who wants to do those more, I guess, not really high-impact activities, but more of those activities normally would be restricted with regular hip replacements?
DELLA VALLE: Total hip replacement surgery is all about restoring quality of life. Hence for people who love yoga, pilates or water skiing, it can return them to those activities which they love and augment their quality of life. That’s what they do to make themselves feel better physically and mentally. Previously I thought there were real concerns with allowing patients to enage in these types of activities, that they would put themselves at high risk for dislocating, but with this type of a bearing, we’ve really allowed patients to do that, and as far as I know, we haven’t had any problems with it, so, again, I think it’s opened up something that people really enjoy.
How long does it usually take after surgery for them to start those activities?
DELLA VALLE: I am still on the conservative side so we ask people to really “baby” their new hip for the first six weeks after surgery. Once they get to six weeks, we tell them there’s really no limit on how they move their hip if they have had a dual mobility bearing.
Anything I didn’t ask you that you feel that people should know?
0:09:05:>>CRAIG DELLA VALLE: An additional “con” of dual mobility is that the implant is more expensive. If we look at global costs for the health care systems in the facilities where we practice, we always have to be mindful to make sure that we’re getting value for our money. Hence, we typically only use dual mobility implants in patients who we think are truly at higher risk for dislocation
Talking on the flexibility side of it, would someone who likes to do all those stretches, would it allow them to still keep that flexibility compared to a regular hip replacement surgery or would they have to change up their routine?
DELLA VALLE: I don’t think patients would have to change their exercise routines, in terms of stretching, with a dual mobility bearing.
Interview conducted by Ivanhoe Broadcast News in December 2018.
END OF INTERVIEW
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