Periprosthetic joint infection

Listen to Andrew Duckworth, Fares Haddad and Ian Kennedy discuss the papers 'Periprosthetic joint infection: navigating the literature' and 'Periprosthetic joint infection: development of a core outcome set' published in the April 2025 issue of The Bone & Joint Journal.

Click here to read the paper 'Periprosthetic joint infection: navigating the literature'.

Click here to read the paper 'Periprosthetic joint infection: development of a core outcome set'.

Find out as soon as the next episode is live by following us on X (Twitter), Instagram, LinkedIn, Tik Tok or Facebook!

Transcript

[00:00:00] Welcome everyone to this month's BJJ podcast. I'm Andrew Duckworth and a warm welcome back to you all from your team here at The Bone & Joint Journal. As always, we would like to thank you all for your continued comment and support, as well as a big gratitude to our many authors and colleagues who take part in the series that highlights just some of the great work published by our authors each month.

So today for our podcast, I have the pleasure of being joined by two authors from an editorial published in the April edition of the BJJ entitled 'Periprosthetic joint infection: navigating the literature'. So first thing, I'm very pleased to be joined by Mr Ian Kennedy, who is an arthroplasty fellow in Vancouver at the moment.

Thank you, Ian, for joining us. It's great to have you with us. Thanks, Andrew. It's a pleasure to be here. Secondly, we have the pleasure of being joined again by our awesome editor in chief here at the Journal, Professor Fares Haddad. Prof. Great to have you back with us, Andrew. Thank you. And thanks for coordinating this.

Prof, I thought we'd maybe kick off with yourself and I was hoping maybe you'd give our listeners a brief overview of the current state of the literature in the PDI, what sort of PJI and what sort of is topical, and any recent advances that you wanted to [00:01:00] highlight. Yeah, thanks, Andrew. I mean, I, I, you know, it's a really buzz area.

It's one of those areas where there is desperate need for innovation and progress, and one of those areas we probably haven't focused our attention enough. So I think if, if we look at the last few years, I think we've generally made a little bit of headway because there's been more interest in this area.

On, on the diagnostic side, probably the key things have been things like sonification, polymerase chain reaction you know, biomarkers. They've had their ups and downs, but essentially they're becoming established as part of what we can do and aiding the diagnostics in infection centres. Probably the biggest thing for me has been the shift to patient-centered care in single-stage revision.

So the, the, the, you know, the research that has shown that single-stage revision has a real place, perhaps an equivalent or better place than multi-stage surgery has been a, a big contribution. And [00:02:00] likewise, and I think now we're seeing some literature on DAIR. Re reappearing and its role, something that was quite popular in the UK perhaps confused with incision and drainage elsewhere, and not necessarily as widely applied.

And all these places are gonna sort of find their home, but there's good literature there. Yeah, and I think there, there, there's hope in. In many areas in terms of, you know, the intraosseous antibiotic story. Mm-hmm. Yeah. That's really interesting. Yeah. You, you know, is that, what place does that have to play?

Is it a revision thing? Is it a primary thing? What are the indications? But, you know, understanding that, that's been some good research around that. I'm really excited about what happens with implant coatings. Yeah. Because I think there's been huge progress limited partly by the regulatory framework, because anything that eludes.

Becomes a real problem. Mm. In terms of the regulations, but actually the potential there is massive. That'd be a game changer across all aspects of trauma and orthopaedics and then things like hydrogels. Yeah. And potentially, you know, [00:03:00] bacteria phages has suddenly become a buzz thing. Mm-hmm. So you know, I think whilst, you know, we've written this editorial and I've spoken over the last couple of years, quite a lot on the weaknesses.

Of the infection literature and there is some positivity out there and there's been some, some good progress in these areas. Yeah, that's a, that's a really nice, Prof. And maybe if I come to you, you next, Ian, 'cause I think Prof's sort of set us up well there about the current state of literature, but as you highlight.

In your editorial, despite the, these advances, there's been some, maybe a perceived little overall improvement in success rates. And, and, and there are some issues with the literature itself, and so maybe we could go into those in a little bit more detail. You know, with regards the type of studies, whether they're single centre, multi-centre, what's been the issues with the, with, with that in the PJI literature?

Thanks Andrew. So. Firstly, I should say that single centre studies are undoubtedly an important component of the PJI literature. They provide us with [00:04:00] in-depth insights into institutional protocols and surgeon expertise, but their narrow focus can limit generalisability. For example, the patient populations MDT involvement and surgical techniques employed at a tertiary referral centre.

May not be reproducible more widely across the whole healthcare system. Hmm. Also, the majority of studies come from a limited number of specialist centres who may publish multiple analyses from overlapping cohorts, and so this can lead to skewed perceptions on the effectiveness of certain treatments.

Carsten Perka has worked with the German registry that was published in the BJJ, highlighted that perfectly. There's also the issue of small sample sizes that are inherent to single centre work. We know that PJI is a particularly complex area with multiple variables influencing outcomes, and so adequately powered studies are required if we're able to draw reliable conclusions [00:05:00] rather than coincidental ones.

I mean, ultimately we're, we're trying to improve the quality of treatment we provide, but without high quality evidence and rigorous methodology, it can be difficult to know if you're heading in the right direction. I. Yeah, no, absolutely. And I think as part of that which again you touch upon in your editorial is how we measure success.

How are we measuring the outcome of, of PJI and you highlight some interesting issues with just looking at something like for revision rates, for example. Can you just go into those a bit more detail for us? Yeah, that's a great question. Revision rates are, are obviously important, but focusing solely on this paints an incomplete picture of treatment success in PJI.

I think it's natural for us to focus on return to the operating room as a proxy for success, but it potentially overlooks domains that are more important to the patient. For example, mortality, it's something we often don't look at very [00:06:00] much, but mid-term death rates after septic revision have been reported as up to 45% in patients who die before second stage.

Reimplantation are often excluded from success calculations, and so this not only highlights the true significance of a PJI diagnosis for patients. Also can lead us to underestimate the true failure rate of our interventions. Mm-hmm. But additionally, we need to consider patient-reported outcomes. As Prof mentioned, it's not frequently reported, but.

As we know, PJI can have a profound effect on quality of life, mental health, and being able to live independently, even in cases deemed infection free. Mm-hmm. The great work that was done by the INFORM group highlighted the importance of placing patients at the centre of defining success, and so without capturing these metrics.

We're under appreciating the broader impact of PJI and failing to [00:07:00] report on what success and failure truly means. Absolutely. And, and we'll, we'll come, maybe come full circle to that towards the end of our podcast today talking about some of the work that you and Prof have done. But maybe Prof, I could come back to yourself, you know, you know, some of these issues, some would argue you know, could surely just be addressed by either using registry data or, you know, and, or well-designed RCTs.

And obviously that's something we, we obviously advocate here at the journal. What, what are your sort of thoughts on that? So I think, you know, that's been something people have been looking to do and there's a literature out there looking at registries for infection. I think it's. Partly problematic.

It's something that's improving. The reality of registry data is that it, it is often recorded at the time that the surgery is performed, and therefore it doesn't necessarily record whether there is confirmed infection. It could be suspected infection, it could be superficial or deep infection. Doesn't record the organism.

Mm-hmm. Then there's the sort of fidelity [00:08:00] of the intervention that's performed from that point of view, and most registries haven't been linked, linked to pharmacology databases or other databases that would, you know, look at treatment. Mm-hmm. Allied to that. So I think we know, even from the Danish registry who've looked at it in a very honest and transparent way that probably at least 40% of infections.

Are not being picked up by the standard registry process. So whilst it is, I have to say the registries are quite useful at looking at trends. Yeah. Looking at the sort of demographics of infection management, that's been done quite well from our, our own sort of UK registry. They, they're not the perfect vehicle.

No. Unless they have a much deeper, detailed data set that's in infection specific. There are now attempts to do that and it, it, it's almost, I, I remember when the infection registry was being set up in the UK suggesting at the time you almost wanted infection centres to come together and have a much deeper, much more [00:09:00] detailed, granular set of data.

Because if, if you look at the registry outputs, I mean, probably the biggest danger, which I don't think we mention in our editorial, is the sort of output we had from the New Zealand registry on laminar flow theatres and infection rates. Where in reality, what the registry was capturing was, was the laminar flow in the hospital, rather in the operation.

Yeah. We didn't even know if it was on or off. Yeah. And you know, that, that's led to guideline changes, all sorts of things. I think we've gotta be careful. Yeah. From, from that point of view. But, but I think the registries, you know, and you know, the work that the Bone and Joint Infection Registry is doing in the UK are gonna be a step in the right direction.

We do need to study this on a population basis. One of the things that will help with this certainly in France, in the UK and I hope increasingly elsewhere, is the sort of network solution of infection management. Because if you can cohort more of these cases in big centres that record their data better, we will start to understand the bigger [00:10:00] picture.

You know, understanding polymicrobial infections, understanding fungal infections, so on and so forth. From that perspective. Absolutely. Perfect. And, and, and Ian's already mentioned it. Moving on from sort of registry work, there's obviously the INFORM trial, which is an example of an RC a trial in this area, isn't it?

I mean, I'm a huge fan. The sort of what INFORM has done and you know, this is not one paper, this is a multitude. Yeah. Of, of outputs. They focused on the patient as Ian said, and having the patient front and centre. If you may remember in the Journal we coined the expression even the winners are losers.

Mm-hmm. Because, you know, surgeons may be congratulating themselves on an ablative procedure that controls the infection, whereas we've got an unhappy patient. So whilst there is some criticism of INFORM for having, a PROM as the primary outcome. That's of course required by NHR and NIHR, and ultimately that is the correct metric.

Mm-hmm. What we're looking at is do we have [00:11:00] a happy or an unhappy patient? Do we have a functional mm-hmm. Or non-functional patient. So I think INFORM's being critical in. Supporting the message that single stage is perhaps a cheaper and more patient-friendly way of delivering the same outcome. Yeah, and, and, and, and likewise.

That's why I think my personal, this is not about the literature. My personal thesis is that infection management needs to be bespoke for that patient at that time. In that institution you know, what's the best care that can be delivered? Yeah. What are the dangers of delivering something more invasive and what will the patient be happiest with long term and what happens if the current strategy fails?

Yeah. So I think INFORM has been a, a huge contribution. And it also demonstrates that in this very, very difficult area where there are extremely loud opinions, it's possible. To actually do a good randomised study. Absolutely. No, I, I, I couldn't agree more Prof and, like you say about the patient being the centre of it.

I think there's so much justification for that, like you [00:12:00] say. And before we maybe move on to looking at some of the core outcome set work that you and Ian have done, I. You know, a big question, which I know you've, you've talked and written about a lot before, is that key question of the diagnosis, you know, diagnosing PJI and there's been quite a lot of work and quite a lot of evolution even over the past decade with regards to this, hasn't there?

Yes, no, there's been an intriguing area in, in the sense that in, in 2013 we had reasonable consensus around the MSIS definition. Mm-hmm. In fact one stage shortly thereafter. Ian Stockley, myself, Sam Oussedik, and others, came out with the idea of creating something that quantified that in a, in a numerical way.

Yeah. And. It's still a, a sound idea if we had the building blocks. Absolutely right. I think the reality of definitions is we need one unified definition and we must stop changing the definition because otherwise the literature becomes very fla flaky. Yeah. Yeah. I think we took a, a big backwards step in my opinion in [00:13:00] 2018 when a, a sort of consensus definition came out prior to the consensus you know, based on data that many of us.

Still don't completely recognise and understand, you know, D-Dimer coming out of nowhere. Huge overemphasis on alpha defensin and underplaying of culture, which is, I think still at the heart of what we should be thinking about infection wise. So that created a bit of confusion and that's why the Journal, we, we've kind of landed on landed the, the EBJIS definition, which is pragmatic, sensible, agreed by the majority and is probably the current standard.

That people should be using. Until there is universal agreement over something better. And just remember, we cannot keep chopping and changing. So I, I think we've got 2013 is still a sound background moving forward. EBJIS is a good place. Others will come out, but you know, it, it's been a tricky period With that.

There's no doubt we all [00:14:00] need. A place to land on that we can agree on, but I don't think we're there yet. No, no. I, and I think that's a really lovely overview of Prof, but actually, like you say, it's so important to get that right, isn't it? Because then that all the literature really hangs off these definitions and also the outcomes as well, which I'm getting them.

Right. And that's sort of leads me nicely back to you, Ian, if I could, you know, maybe just to, just to finish up with you and Prof is just to very briefly cover your other publication, which is in the April edition, which is a entitled 'Periprosthetic joint infection: development of a core outcome set'. Can you just sort of.

Give our listeners a brief overview of that paper and what, and what the what it found. Certainly. So, so as we've discussed, the variability in outcome reporting makes it difficult to compare studies and conduct meta analysis. So by developing a core outcome set, which is essentially a minimum agreed upon set of outcomes that should be reported in all PJI studies, we set out to standardise reporting.

Mm-hmm to obtain consensus and what outcomes should be reported. We undertook a two [00:15:00] stage Delphi process. Stage one involved a core group of nine experienced PJI researchers, and importantly, it also included five patients to include the perspective of those with lived experience. This was performed to firstly develop the key domains and outcomes and involved online voting in a virtual meeting.

In the second stage, we expanded the Delphi process and invited over 80 international stakeholders, including surgeons, infectious diseases, clinicians, and academics to vote on the core outcome set, developed in stage one and finalise it. So this resulted in 23 outcomes divided into four key domains.

First domain was patient demographics such as age, sex, comorbidities, immune and soft-tissue compromise. Secondly, infection characteristics including chronicity of infection and infective organism. We then noted [00:16:00] surgical and treatment details. For example, operative technique and antibiotic therapy. Finally, outcomes and follow-up.

This domain addresses factors such as re-operation rates, patient-reported outcomes, mortality, and follow-up period. And ultimately our hope is that by providing a comprehensive and practical guidance for future PJI studies, we can weigh the foundation for more consistent research. Absolutely. And I think it's a, a fantastic piece of work, piece of work for that very reason actually, so needed from what the, you know, the discussion we've had.

So Prof, maybe I'll FI can finish with you yourself, you know, just sort of a two part question. I mean, the first thing, just your thoughts on the core outcomes set and what that's sort of added to the literature and the, and the, the ability to perform research in this area. And what do you feel is the next steps, where are we headed in PJI research?

So, so thanks Andrew, and, and thanks again for raising this very important topic. Yeah. The, the, the core outcome set is something I've [00:17:00] been keen on for a long time, and as ever with these things, you need people with energy and it's been great to have Ian and a few others willing to drive this forward because I think we do need to standardise.

We needed to create minimums and we need to essentially set a bar for what infection papers should look like as, as a minimum. And if we go back to our earlier discussion, the, the, you know, the paper from Carsten Perka and Resl and the team looking at the German registry linkage with the insurance database is salutary because.

Many people regard the German management, particularly certain the big centres there as the standard that's taught us. Mm-hmm. How to manage infection. And yet this manuscript brings into question a lot of the data, including some of the data that's been published in the Journal previously. Mm-hmm. It really does.

So any reporting now needs to be to a minimum standard, and I think that core outcome set should be generally adopted by all those who are interested, and that should be the minimum [00:18:00] that they input. And then, you know, moving forward, that will be one of the many pillars of improving infection research. I, I think at the heart of all of this, probably the most important thing is prevention.

Yeah. So, you know, really focusing on that area rather than just the sort of management that's interesting to surgeons will be really important for the future. So I think really, let's look there. Let's look at those surfaces. Let's look at what prophylaxis we're giving. Let's look at how we're managing and optimising our patients, et cetera, et cetera, from that point of view.

And, and then larger and larger scale studies and hopefully some more RCTs, particularly as infection services are centralised. I think the one thing that's for sure is certainly in arthroplasty surgery, which is the area I'm most focused on in my own work. We, we kind of have solved many of the other failure modes, infections, the one we've gotta really capitalise on for the next ten years in order to improve the, what we deliver to our patients.

Yeah, absolutely. Prof I Yeah, that's a very good take home, take home message. And I, I [00:19:00] would really echo your comment about, I think, not just to here, but throughout medicine, we, we spend so much time focusing on intervention and treatment that actually prevention is surely. The better, the better mode for a lot of what we deal with in medicine.

Well, both, I'm, I'm afraid that's all we have time for today, but thank you to you to both so much for taking the time to join us and congratulations on a, a really, I felt a really interesting editorial and a, and a great study, which has clearly added a really important benchmark, I think, in the PJI literature of how these things should be reported moving forward and, and carried out.

It was great to have you both with us and to our listeners. We do hope you've enjoyed. Joining us and we encourage to you to share your thoughts and comments through our social, social media platforms and, and the like. Feel free to post about anything we've discussed here today, and thanks again for joining us.

Take care, everyone.