Hospital for Special Surgery Perspectives

Advances in Translational Research in Arthroplasty

Anya Romanowski, MS, RD

Disclosures

April 19, 2017

Editorial Collaboration

Medscape &

Background

Medscape had the privilege to interview Mathias P. Bostrom, MD, vice-chair of education and academic affairs and director of the residency program at the Hospital for Special Surgery (HSS) in New York City.

Mathias P. Bostrom, MD

In addition, Dr Bostrom is an attending arthroplasty surgeon and is heavily involved in bone health and musculoskeletal research that includes National Institutes of Health grant work. His colleagues often refer to him as the "trifecta" for his professional involvement in the clinical, academic, and research departments.

Pain and Instability in Total Knee Replacements

Medscape: You presented an instructional course on the personalized approach to painful aseptic total knee arthroplasty. Can you tell us more about this course?

Dr Bostrom: The nature of that instructional course was very clinically oriented in terms of having group discussions about problems with mechanical loosening, instability, and soft-tissue envelope issues in total knee replacements. Once you cross off the infection part, loosening, instability, and soft-tissue envelope stiffness are all real problems.

If you think about total knee replacements, 85%-90% of patients do great, but the remaining 10%-15% are not as satisfied with their knees. As a result, I think there's still a lot of work to be done on all fronts.

Medscape: Are you seeing any patterns in what is causing the dissatisfaction and the pain issues?

Dr Bostrom: I think patellofemoral issues remain a big problem in total knee arthroplasty. In addition, a problem that hasn't gone away is instability. There are varying amounts of instability, and also what we call subtle, "mid-flexion" instability issues. As much as we think that we've solved the issue of mating implants to bone, in the knee I don't think we have it solved. A large percentage of those failed because of what we refer to as "osseointegration," or fixation issues—how you get the host to truly integrate a prosthetic device.

Medscape: Are the patients' bodies rejecting the materials used, or having an allergic reaction?

Dr Bostrom: The materials we use are generally relatively bioinert, and patients don't reject them. There are cases of people who have true allergies to some of the materials we use, but that's relatively rare. The metals, plastics, and cements that we use are reasonably well-tolerated biologically. However, they don't always work mechanically.

 
Where I think we are going to make fundamental strides is going to be in the biology area, and the integration of materials to the body.
 

Medscape: In the past, there have been controversies over using metal-on-metal. Are there any new materials recently introduced or being studied? Alternatively, has the emphasis remained on surgical approaches and techniques?

Dr Bostrom: I think a lot of this goes in cycles—and I have enough gray hair to have seen multiple cycles. Right now, there's a lot of emphasis on surgical techniques and enhancements. For a while, we were dealing with different bearing materials, and prior to that, fixation methods. And they sort of cycle on what's hot. I think we are finally on the tail end of the anterior vs posterior hip approaches. That's the new fad, if you want to call it that. I think it's a fine approach, but it's not the panacea that it was initially presented to be.

Where I think we are going to make fundamental strides is going to be in the biology area, and the integration of materials to the body. We still have a ways to go there, but I think that is what's exciting.

The problem we have in arthroplasty and orthopedics is that what we do is so darn successful. If you have something that works well (such as a total hip that works exceedingly well 95%-98% of the time), you've got to make sure that what's new is going to work equally well for as long as what we are doing now.

Medscape: With something so successful, is the purpose of considering alternative surgical methods or devices to minimize pain and infections, and maximize outcomes and recovery?

Dr Bostrom: Yes, I think [we aim for] all of those things. Obviously, we want to minimize complications, such as infections, failure of the implant, or failure of the tissues around the implant. Equally, we have a lot of procedures that we do that are, as far as the surgeon is concerned, "perfect," yet the patient isn't happy. The patient outcomes issue really is a big deal.

I think we have to be careful that the pendulum doesn't swing too far and that's all we concentrate on, though, because it can be very short-sighted. The patient may be very happy with an implant that lasts only 2 years and looks great initially, but in the long term may not have been the right way to go. A lot of the new promising approaches can be rather short-sighted, and we have to be a little bit careful about that.

Healthcare Economics and Driving Forces

Medscape: Are there any patterns in terms of the types of patients receiving treatments who tend to have poorer outcomes (ie, patients with comorbidities)?

Dr Bostrom: There's no question that patients with diabetes, obesity, cardiac issues, or renal disease have poorer outcomes. The sicker the patient, the worse the outcome. Any way you slice it, that's going to be the case.

My research tends to be translational, if you want to call it that, from animal models to human applications. But patient outcome-type studies are incredibly important as well. What we're finding (and have heard a lot about) is the medical economics situation and care bundles. Ultimately, that's just going to lead to cherry-picking. If you're tied up in a bundle, the last thing you want to do is take care of patients with a huge amount of comorbidity, because you can get penalized. Either you or, indirectly, your group or your hospital will be penalized for taking care of those high-risk patients.

If you're tied up in a bundle, the last thing you want to do is take care of patients with a huge amount of comorbidity, because you can get penalized.

Right now, I don't think we know enough about how to triage these sick patients appropriately from a medical economics standpoint. We can take care of them, and we can minimize many of those modifiable patient risk factors.

Medscape: It seems that the care bundles don't consider the patients' comorbidities or risk factors, and whether they're high- or low-risk, which seems to be a big problem. What fascinates me is that patient life insurance premiums are higher for smokers, but that is not the case with health insurance premiums.

Dr Bostrom: No, it's all-comers. You should get a potential premium if you take care of a high-risk patient, and you modify their risk factors as best you can. You and the delivering healthcare institution physician, surgeon, or hospital should be compensated according to patient risk factors. Again, you don't want to segregate people too much. But at the same time, if you're creating a compensation system, you want to prevent picking just the low-risk patients. These medical economics issues are always a little bit challenging.

Arthroplasty and Host/Implant Interactions

Medscape: You focus mostly on bone healing and joint infections in your research, correct? Is there anything that you're currently studying?

Dr Bostrom: [I focus on] bone, and I'm really interested in the "host-implant interface" and trying to optimize that. I also have a fairly large interest in prosthetic joint infections. Those are the two major issues. In addition, I look at what makes sense in terms of the bigger-picture aspects within arthroplasty.

Joint infections are still a problem in all orthopedics. Host/-implant interactions affect not just arthroplasty, but also sports medicine and spine surgery.

My area of interest is obviously not so much patient-reported outcomes and socioeconomic issues. Those big issues are important, but are not terribly innovative if you think about it (and I'm not criticizing that kind of work). I think you need both, but one of the problems with many of these databases is that they're very retrospective. They're not necessarily pushing the needle forward; they're looking at where the needle's been. Maybe that can be used to tweak care.

I'm more interested in the innovative aspect of things. What's going to happen 5, 10, maybe 20 years down the line? I say this often. When I started in orthopedics almost 30 years ago, I thought for sure that at this point in my career, I would not be putting metal and plastic into people. As much as we've improved things, we're not quite where I thought we would be at this point.

Medscape: You recently participated in a symposium on "trunnions, tapers, and corrosion." Can you talk about what you and your colleagues were presenting?

Dr Bostrom: Again, this is a very clinically oriented symposium, similar to the other one I did earlier that day. Clinically, we use a lot of modular components in our implants. Modularity gives us a lot of flexibility from an anatomical and reconstruction standpoint, but they have downsides, because any material interface has problems with corrosion/fretting interactions. We've now found that that's a problem. I think there are some solutions to those things, but it's a topic that hasn't completely gone away. As we make things more complicated, we create new problems.

Medscape: Just as items corrode in the environment owing to weather or other changes in our atmosphere, it seems that the corrosion issues are similar in humans getting an implant.

Dr Bostrom: Yes. Basically, you are putting materials in an incredibly corrosive environment. It's like putting a bunch of metals in seawater. That's what the insides of a human being consist of.

Medscape: You also attended the Orthopaedic Research Society (ORS) meeting. Is there anything from that meeting that you want to share with us?

Dr Bostrom: Much more fundamental questions are asked at the ORS meeting. They span from what is true, basic science (trying to understand molecular pathways in orthopedic and musculoskeletal disease processes) to clinical science as well, but fairly rigorous in that regard. It's not database research, but randomized controlled trials and true clinical research. In the midst of that, there is a lot of translational work (primarily small-animal to large-animal work) as we put newer innovative materials into an orthopedic or musculoskeletal setting. I think that that's where the advances are happening.

Musculoskeletal Infections

Medscape: You also presented some papers on musculoskeletal infections—research that you're highly respected for. What types of trends are you seeing now? Is there a change of different types of infections, or different causes of these infections?

Dr Bostrom: I think we're learning more about the host and how to optimize the host. At the same time, there are some really neat things that may be going on to modify risk factors in terms of our host. My interest is in how you create models (primarily animal models) to test some of these hypotheses. You can't do it in humans, obviously, and I think animal models are incredibly important.

We develop these models, and then test what new antibiotics are working, because antibiotic resistance continues to be a big issue. We need newer antibiotics and to learn how to apply them in an orthopedic/musculoskeletal setting. I think that's what is exciting.

Various simple wound approaches (cleaning them out with Betadine or hydrogen peroxide) were things that we used to do before we had broad-spectrum antibiotics. Some of us have concentrated on how we handle the tissues, and how we prepare them to minimize infection at the time of surgery.

Medscape: It's interesting because in general surgery, infection is a topic that has been coming up a lot lately, and they've been focusing on ways to minimize infections (eg, what types of meshes to use, and use of antimicrobial sutures).

Dr Bostrom: Right. How do you deal with the biofilm issue that spans not only orthopedics and musculoskeletal diseases, but all of medicine? Industry struggles similarly with biofilm and slime in pipes, oil rigs, and all sorts of things. A fundamental issue is not throwing more powerful antibiotics at it, but treating the area locally. Whatever we can do to decrease the amount of biofilm that forms will be worthwhile.

Medscape: What other types of treatment can you do, whether it's the way that you handle the tissue itself, or the types of grafts that you might use for bone healing and regeneration to minimize infections and treat wounds?

Dr Bostrom: Surgical techniques are always difficult to model. But certainly, the kinds of materials we use; how the wounds are treated; and simple things, such as which kind of suture material we use, are all important.

Also important is how you treat the operative bed, and how you treat the host beforehand with chlorhexidine and skin-surface modulation, which we use to minimize the amount of primary staph colonization. Staphylococcus aureus is the main culprit, but a lot of other infections are also there.

There are pre-, intra-, and postoperative opportunities to reduce the risk for infections. Diagnosis of infection—there's a whole field that has lots of opportunities. Then there's the treatment end of it, once you have an established infection. Those are the big silos that have lots and lots of opportunities to improve how we do things.

Medscape: Are there any other final thoughts that you might want to share with us, as far as what's excited you from what you've seen at the two meetings?

Dr Bostrom: I find that the two meetings complement each other. I think the very clinically oriented meeting is really important, and it is equally important to answer fundamental mechanistic questions and then how you translate that [information] into a preclinical model and then to a clinical setting. That's the nice thing about what we do in orthopedics: You can span the whole gamut, from very basic molecular biology to the tissue level, the organ level, and then the whole host.

Mathias P. Bostrom, MD, has disclosed the following relevant financial relationships:
Serve(d) as a director, officer, partner, employee, advisor, consultant, or trustee for: Smith & Nephew
Received a research grant from: NIH-NIAMS
Received income in an amount equal to or greater than $250 from: Smith & Nephew

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