Supervised versus self-managed rehabilitation for patients with an acute first-time or recurrent patellar dislocation: the PRePPeD external pilot RCT and embedded qualitative study

Listen to Andrew Duckworth, Colin Forde and David Keene discuss the paper 'Supervised versus self-managed rehabilitation for patients with an acute first-time or recurrent patellar dislocation: the Physiotherapy Rehabilitation Post Patellar Dislocation (PRePPeD) external pilot randomized controlled trial and embedded qualitative study' published in the March 2026 issue of The Bone & Joint Journal.

Click here to read the paper.

If you'd like to get involved with the main trial if it is funded, please contact prepped@ndorms.ox.ac.uk.

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Transcript

[00:00:00] Welcome everyone to our BJJ podcast series. I am Andrew Duckworth and a warm welcome back to you all from your team here at The Bone & Joint Journal. As always, we'd like to thank you for all for your continued comments 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 a paper publish- published in the March edition of the Journal, looking at supervised versus self-managed rehabilitation for patients with an acute first time or recurrent patella dislocation. The PRePPeD trial or PRePPeD feasibility trial, it's in a pilot trial.

Now, before I introduce our guests, I do have a quick message from our sponsors for this episode, the International Hip Preservation Society. I'd like to make our listeners aware of the 2026 annual scientific meeting of ISHA, the International Hip Preservation Society, which will be taking place in the beautiful mediaval city of Bruges, Belgium on the 8th to the 10th of October.

This year's programme is going to have something for everyone with basic and [00:01:00] advanced streams on a range of key topics and sessions, encompassing a mix of instructional lectures, latest research presentations, and panel discussions. If you'd like to find out more, you can access the conference website via ISHASOC.net.

So back to today, first thing I have the pleasure of being joined by Colin Forde, who is a clinical physiotherapist and researcher in orthopaedic trauma rehabilitation at the Kadoorie Institute at the University of Oxford, Colin. Great to have you with us. Thanks very much for the invites. Looking forward to discussing the PRePPeD trial with you.

Great. And joining Colin and I is the senior author on the paper, Dave Keene, who is the Kadoorie Professor of Trauma Rehabilitation at University of Oxford, and also a clinical physiotherapist. Dave, great to have you with us today. Yeah, delighted to be here. Thanks for the invitation. Colin, maybe I kick off with yourself and, for the benefit of our listeners, which we do for a lot of the studies we talk about, can you give us, a brief background of what made you look at this question?

What made you delve into this area and then develop this study as you did? Yeah, so shortly after I moved to the UK in 2017, [00:02:00] I started working clinically at the John Radcliffe Hospital in outpatient rehabilitation in a trauma and orthopaedic department. And so I saw a higher volume of these patella dislocation patients that I would have seen before and quite interested in knee rehabilitation.

And so I looked at the evidence and found that there was very little high quality evidence to guide what we should do with these patients in terms of physiotherapy rehabilitation. And there was differences in what I did versus what my colleagues did. And so not much has improved since then. So there's a systematic review done by MoEZ and colleagues in 2018, and we have updated that last year.

And what this shows is there's been only two randomized control trials that have looked at rehabilitation after that initial mobilization period. So Toby Smith, who's now based at Warwick, did a trial which involved 50 people and compared different types of quadriceps strengthening programmes. And there's been a more recent trial done in Brazil, [00:03:00] which looked at quadriceps only versus quadriceps versus hip strengthening exercises.

But both of these studies were small so in total they had 90 participants. And there were some limitations in the study's design. And so what that means is we don't really have a lot of evidence about what to do with these patients. And when I speak to clinical colleagues their opinions about the quality of rehab these patients get in the NHS is variable in terms of content, but also volume.

So for me, the question is potentially, if we give patients high quality rehabilitation, which is supervised by physio over multiple sessions, that could improve the outcomes for these patients, which is o- which are often suboptimal. Now, we do also know that these patients tend to be teenagers or young adults who are often in education or in work.

So coming to physiotherapy can be inconvenient for them and engagement with physiotherapy has been reported to be an issue. And we know from other musculoskeletal rehabilitation trials that actually sometimes a one-off physiotherapy session is [00:04:00] as effective as multiple sessions. So if we could set patients up to manage the recovery independently, that could reduce the inconvenience to them and allow very busy physio departments to concentrate on other conditions.

So essentially, the aim of this study, and what we'd like to do in future is to compare supervised rehabilitation versus a one-off programme to see which is more clinically and cost-effective. That's brilliant, Colin. I think a fantastic background to why you did it. And I think it, it's really interesting for our listeners.

The number of times when we do present a trial such as this or a similar type of work, the number of times when people actually just delve into the literature and the lack of high quality evidence despite guidance and people's dogma and similarly the very small randomized control trials that seem to have set the standard, but, that we have very little data out there.

And again, what you say as well is the variance in practice. Everybody thinks they're doing the same thing, but actually they're really not. So that's really helpful. And before we go onto the sort of nuts and bolts of say, Dave, if I could come to you next, before we look at the actual [00:05:00] design of the study, for our listeners, this is, was a feasibility study and, not everybody's familiar with that sort of concept.

So why, what's the real purpose of these type of studies and how they build into a big trial? Yeah. Thanks, Andrew. I think the main goals of a feasibility study is when we've identified some uncertainties about the design of a potential full trial where, and it can be any aspect of that final trial, or it can be multiple areas of the trial design that there are some uncertainties about in terms of the optimal way to take things forward particularly with the mindset of going for a full definitive trial where things might need to work in multiple healthcare settings, different hospitals, different care pathways.

 And feasibility studies themselves, there, there's a lot of un- confusion about the terminology but the way I tend to think about it and there's been some helpful guidance on this is the feasibility studies as being more of an umbrella for multiple different designs of studies that help you identify and study some of the uncertainties about design.

Yeah. [00:06:00] One of the common ones we see is a small version of the trial, like this one that's presented with the PRePPeD study. So in that study, we're doing a small version of the randomized control trial, road testing, the recruitment procedures, the interventions, the follow-up procedures. There can be other types of feasibility study, but that was the main thrust for us to really focus in and to inform whether we need to redesign things.

And I was thinking, these trials are very expensive for full trials. They take years and years. And the last thing you want to do is have a really good research question, stampede towards a full definitive trial, and then realize halfway through that your follow-up procedures haven't really hit the mark and you're not getting the data that you need or you realize one of the interventions isn't getting the uptake because you haven't really road tested it in a smaller scale, refined it, and then, and rolled out the optimal version of it.

So that's, that in a nutshell is my take on the feasibility. Yeah, no, I absolutely do. And that's really helpful. And I think, like you say, it is trying to make sure that when you when and [00:07:00] if you get to a big trial, and like you say the effort, time, money that goes into those, you really want to make sure, like you say, I think I like the term road tested to make sure that what you're doing is right.

And I think for our readers and listeners, I think that one important concept is that when you report it, it's not like how you would conventionally see a trial in terms of you don't have a primary outcome that you're then powering it to. You're actually trying to figure out, can this trial be delivered?

And I think that's a really important concept as we go onto the design and what the trial actually found. So Colin, if we do move on to the design then, this was a parallel two group external pilot RCT with an embedded qualitative study, which we'll, we will come onto and I think is really important and conducted in five English NHS hospital which varied in size, research, experience and location.

And there were 88 eligible patients, but what were the inclusion, exclusion criteria for this study Colin? Yeah, so we tried to recruit a patient group that we thought would be representative of those patients who typically present to NHS fracture and knee clinic. They were aged 14 and above because the highest incidence [00:08:00] of first time dislocation is in around mid-adolescence, so about 15 to 16 years of age.

And if they had a first time or recurrent patella dislocation that was confirmed either if it had been reduced by a healthcare professional or if the patient had a history consistent with the patella dislocation and the assessing clinician thought it was a lateral patella dislocation. And these patients then, patients were then excluded if their injury was more than 21 days ago.

The rationale for that was we were really trying to test rehabilitation in the acute phase of injury, and bearing in mind, these patients will have to wait a couple of more weeks to get to physiotherapy. That was the aim of that exclusion criteria. And patients were also excluded if they've had previous patella stabilization surgery, because they would likely go down a different treatment pathway if they required acute surgery, for example, if they had a large osteochondral fracture, or if there are any contraindications to taking part in the study interventions, or if the patient was unable to adhere to the study procedures, and similarly, if they had been already randomized into the study, for example, for their other [00:09:00] kneecap.

Okay, that's great. And like you say, I think that concept that you said at the beginning though, I think in terms of, I always say to people, when you read these RCTs, it's really important that they are in the relevant patient po- population. There's no point in doing this, say, for example like this in a load of people over the age of 50, for example, and only that because it has to be representative of what we see absolutely.

And Dave, if we then move on to the interventions there were two arms of the trial, as we alluded to, and one in, it was in terms of supervised and then self-managed rehabilitation. Can you just briefly just go over those interventions for our listeners? Yeah. So when patients joined the study they were usually in a sort of fracture clinic setting typically.

And at that point, when they were allocated to the two, one of the two intervention pathways, all the participants were issued with a workbook, a paper workbook, and if they had an email address, we would also send them a link to access an online version of that information. And it had a lot of guidance on what to do in your recovery and an exercise programme that they could follow through their rehabilitation.

They were then also then referred [00:10:00] onto the physiotherapy service. When they got to physiotherapy, the two different treatments, that's where they started to vary is the self-managed rehabilitation involved a one-off detailed assessment and advice session with the physio, and they were supported to engage with a progressive rehab programme, but the onus was on the patient to take the responsibility to drive that forwards.

They did have the option of getting contact for some advice with that physio. Or even to book in an extra follow-up if they were struggling to engage with the programme. If they were in the supervised rehab programme they were offered ... We asked for them to be offered four to six physio sessions, so that effectively they followed a whole, a programme of sessions over a six month period.

And the idea was with that one is to really give them that a chance to be reviewed, to have that tailoring and individualization of advice and exercise ... to support them towards their recovery goals. So the main difference really was that added support and onus on the physio to help problem solve through the recovery journey.

That makes total sense. And I think [00:11:00] it's nice how you l- lay those out in terms of the, there's a common theme, but then actually how then they break off in the supervisor and super, that makes total sense. And then, Colin, if we look at the outcomes, and I think this is quite an important part wh- which we've alluded to, what were you actually looking at?

What were your main outcomes for this feasibility trial? Yeah, so if we look at the feasibility outcomes first, so they're the ones, the main uncertainties about the trial. So the first one was the willingness of eligible patients to be randomized. So this was a mixed sample of people who were under the age of 16 and people who are 16 years and above, and whether they'd be willing to be randomized to a self-managed intervention, which involved just one session was uncertain.

And this was important to assess if the, if the proportion was very low, that might indicate that the study sample might be not representative. Recruitment can always be an issue in trial, so we wanted to understand the recruitment rate to plan the full scale trial if it was feasible, and then adherence to the intervention.

So what proportion in the self-managed group attended at least one session, [00:12:00] and in the supervised group, what proportion attended at least four. And that was important to make sure that there was sufficient engagement with these two interventions, but also that they were sufficiently different to justify evaluating in a full scale trial.

And then the final one was retention. So this is what proportion of patients completed the planned primary outcome which was the KOOS for nine months, and that's important because if that proportion is lower, then the results become a little bit become less credible and less usable. Yeah. So they're the feasibility outcomes, and I'm happy to discuss the clinical ones if you'd like.

Yeah, you're very, yeah, very briefly, that'd be helpful, yeah. Yeah. So they, we did a systematic review to look at all outcomes which has been published in the Bone & Joint Open journal in this area, and this shows that actually there's a wide variety used. Now, the patients that we consulted said that the most important outcomes to them were knee symptoms and physical function, and the two kind of most commonly used ones are the Kujala Score and the Lysholm Score.

Yeah. [00:13:00] But they've got issues with using terms that might not be understandable to patients like atrophy inflection, but also a ceiling effect. So we've chosen the KOOS as the planned primary outcome for the full scale trial ... because that evaluates physical function and these symptoms. Yeah.

No, absolutely. I think that's really helpful. And again, something that we mentioned quite a lot now is the importance, of course of PPI involvement in all of these trials, but also in particular that outcome, because I think it can really surprise you what we as clinicians think is important, but actually what the patient think can be very different.

And I think that's a really important point to highlight when we're picking these outcomes. And finally, David, if I just come back to yourself before we just briefly cha- chat about the results, also as part of this was an embedded qualitative study.

And this is becoming increasingly common that we see with these trials, isn't it? And, wh- why, wh- just talk a bit about that and why it is important. Yeah. I, the, these really are becoming, e- almost expected now when you're doing a quality feasibility study in this type of design because you can get to the end of the process and be in a situation where you [00:14:00] have your feasibility outcomes, you have the data, like the proportions of people who take part, engage with the rehab.

If you don't see what you're expecting- ... the first question you have is why. Yeah. And if you haven't done any kind of element of speaking to the participants you obviously then are just relying on that simple met- quantitative metric and you can't always unpack why and know how to modify the trial design to, to optimize things for the full scale trial.

So in this study, we did semi-structured interviews. They were led by Colin and a colleague, Liz Tutton who's a qualitative research expert based in the team here. And they invited participants who were joining the trial for an interview at three months later. So they had some experience of going through the early recovery and

the intervention so that when they were interviewed there was a semi-structured guide to, and topic guide to guide them through a range of inf- information and topics that would inform and unpack why we were seeing the [00:15:00] quantitative results that we were in terms of did they turn up, were they engaged?

What would, what was their experience of filling out these questionnaires that we were sending them? What could we do to improve things for the full trial design? So it really adds that depth of experience to inform the next steps. Yeah, I totally agree, David. I think, like you say, it unpacks why if you find a problem that you, particularly if you weren't expecting, it guides you why that is.

And I think maybe for our listeners as well, I'm sure many are aware, but actually as part of these quality studies, you also can interview the clinicians as well and the people who try and recruit the studies to understand if there's a problem with equipoise or why is the patients there, but we can't get them into the trial.

So it can be so helpful. And also trying to correct your course if you're struggling with recruitment, why that might be. No, I totally agree. And I'd say they're almost becoming a standard part of these, aren't they now, I think, in terms of having an effective study. So Colin, if we just briefly move back to yourself and the results, I just thought we'd briefly just touch upon these, could you be, you've either the outcomes, briefly run through for our listeners what the findings were in relation to your spe- pre-specif- progression criteria and anything else that you think our listeners should know about?

Yeah, of [00:16:00] course. So in terms of the proportion of eligible patients who are willing to be randomized, it was 5 7%, which was above what we were hoping for. But I think importantly what we found was that two-thirds of patients aged 16 years and above were willing to take part, whereas if we look at those under the age of 16, only a th- a third of those that were eligible were willing to take part.

We also exceeded our recruitment target, so we recruited 1.4 participants per month. Intervention adherence was 72%, which wasn't quite what we were hoping for. And that was mainly driven by only around half of the patients in the supervised rehabilitation arm attending at least four of the physiotherapy sessions.

And then similarly, retention, which was the proportion of patients who returned their nine month KOOS 4 questionnaire was 62%, which was again under the 80% which we were hoping for. In terms of clinical outcomes then as you've mentioned before, we don't use these feasibility studies to compare the effectiveness of interventions, but what it [00:17:00] did show is that on average, patients recovery tended to plateau around six months.

And patients recovered to about 75 to 80% of the full KOOS 4 score around that stage showing that they still had ongoing problems. Yeah. So this kind of highlights that, these condition, these, this injury is one where patients don't typically recover fully and yeah, we need to find out the best rehabilitation for them.

I thought it was really interesting those, the, not only the progression criteria and the various things you talked about, but also about the plateau because I think it just shows you how much information you can get from these studies in terms of informing how you then recruit and try and

I think one of the things is, obviously here is adherence and actually trying to get them to follow up because not uncommonly they're a young mobile patient population, they're working, it's hard, isn't it, with these type of studies and how you can try and correct that is really useful. And also that recovery I thought was quite interesting because again, can that can inform you where your primary outcome should really be set at, doesn't it?

At what time scale? So again, for our listeners, I think that shows the benefits of doing this type of study. And in terms of the qualitative findings, there anything [00:18:00] in particular you wanted to highlight? Yeah, so this is the first qualitative study to our knowledge that's been done after an acute patellar dislocation.

There's been one done elsewhere in Norway, I think after for people who've got recurrent patella instability. But I think what it showed is that for these patients initially, this unsurprising is a really painful and distressing injury but once that subsides physical impaired physical mobility is their biggest issue and that relates to their disruption to their everyday lives.

So it means that as you mentioned, these are many young patients, they may not be able to go to work, they may not be able to drive, fulfill caring responsibilities if they've got children, for example. And then later on, what we see is these patients are very determined to get back to their normal life and they start to physically test their knee and they found that once they get positive feedback, that kind of reinforces a sense that, exercise and physical activity is helpful and those in, that in the [00:19:00] supervised rehabilitation group found that attending the physiotherapist and then prescribing exercises was also quite motivating.

But in the longer term, what we do see is that for some patients, they recover fully and this includes getting back to, multidirectional sports, but there are a subset of patients who, although their confidence is improved, they remain very wary that the kneecap is going to dislocate again.

Yeah. And they adopt approach of trying to be very vigilant, so they might modify the activities they do, so those that they perceive a high risk of injury, but also they try to be, keep their physical fitness quite high and keeping a healthy weight et cetera. So it can have a, an ongoing issue for some patients whereas others seem to recover quite well, which I thought was an interesting finding.

Definitely. No, I totally agree. And I think again, shows the importance of that data. So I suppose Dave, maybe I come back to yourself, initially I was gonna ask you both these sort of final few [00:20:00] questions, bringing it all together, a few, I suppose few questions come to mind, what do you feel I ask this for a lot of studies, the key strengths and limitations, but I suppose maybe would you, anything you would do differently now, something you wish you'd collected that you didn't or anything like that?

 Yeah. It's always tricky when you look in the rear view mirror- Yeah. ... after years of work and C- Colin did great work leading this study and you, and when you get to the end of the journey, y- you can start seeing things that maybe could have really helped you design that next study. For me I think although we were able to engage quite closely with collaborators at the feasibility sites, so one of the nice things about the scale of a feasibility study is you get to know a handful of sites really well. Yeah.

Get that dialogue going before you try and scale things up. But we didn't have a formal qualitative study on the, from the, with involving the staff. So you never really got quite that level of depth of data and analysis to take forward to design the full trial. And I think that's one of those elements which could have strengthened our hand in terms of [00:21:00] informing the next steps.

And I think as well one of the strengths I think about doing feasibility is even within the study itself, we were able to respond to some of the issues that were arising. So partway through, we were realizing the retention of of people in the study and completing their thought data was poor.

And we were able to start implementa- implementing some strategies to try and improve the messaging and with the participants, try and get better engagement, change the how we were approaching them, how often. And so we could start seeing that even some of those things were starting to improve the trajectory of how many people were responding.

So it gave us already a bit of data as if you're responsive, we might be able to start improving that for the full design. It although it didn't hit the feasibility criteria, it did enough to tell us if we really focus on that and design something different, hopefully can get a better recruitment rate in the full trial.

Yeah, I think that's really interesting. And Colin, is there anything you would add to that and I suppose following on from [00:22:00] that, do you feel a full scale trial is deliverable? And if so, is there anything, modifications you'd have with it compared to this? Yeah. In terms of things that I do differently, I think we were aware that retention could be an issue based on that trial by Toby Smith.

And in that study, the patients had to come in for face-to-face follow-up. So we thought by doing remotely electronic follow-up, that would hopefully improve retention sufficiently. And that wasn't the case. So I think in hindsight, paying a bit more attention to that and engaging with, PPI a bit better to try and optimize that would have been one change I would have made.

In terms of full-scale trial, we actually have applied for the full-scale trial, so we do think it's feasible and we've made a number of modifications these include in areas around retention. So for example we've worked with the PPI group and they've recommended paying participants an amount that is an incentive to complete the questionnaires, but it's not coercive, as well as implementing some of the strategies that Dave's alluded to there that we implemented in the [00:23:00] feasibilities in the pilot study that appeared to work.

I think another area that we would need we plan to strengthen is the number of sessions that participants attended in the supervised group was lower than we had hoped for. And I think a modification will be that when people are randomized in that fracture or knee clinic, we will provide more basic information about acute injury management and some basic initial exercises and the additional materials of that first physiotherapy session with an aim to increase attendance of that physiotherapy appointment.

So there's some changes I think we'll make alongside others and just the other one actually I think would be important to highlight. Dave's mentioned we didn't get a chance to interview the partici- the physiotherapists. Yeah. So as part of that full scale trial, we plan to conduct something called a process evaluation, which will look at both quantitative data, but also it will involve qualitative interviews with a large number of participants, but also researchers who are recruiting the patient, patients [00:24:00] and physiotherapists, and that would just give us a better understanding about the results we observe if that full scale trial is funded.

No, absolutely, Colin. And that makes sense. And again, I think really highlights how the, how useful the data you've collected from this study then goes to shape the potentially a ma- a big trial and to try and make it importantly successful. And just to finish up, Dave, anything you would add to that at all?

 I think really my main take home often the experience of PRePPeD and also a lot of the other feasibility studies that we've run particularly in the rehab space is the it's been like a really positive experience ... working with a network of surgeons, nurses, physios, and other therapists all these different hospitals who have helped us road test these things, and given us the honest feedback about what's working and what's not and try and get that dialogue going to make these full trials more successful. Yeah. And even some of the learning from one feasibility study helps us design the next trial. So although they are still [00:25:00] costly in their own right and sometimes, we do have feasibility studies that don't transfer, transition straight onto a full trial application they still require a lot of collaboration over a sustained period of time.

And so I just wanted to really flag, I suppose a thanks to the clinical and research networks that we've been working with to do this programme of studies. Yeah. It's been really positive. That's great, David. And that's a really nice, that nice point to finish on. And I think it's just the, an example across the orthopaedic and the physiotherapy communities.

I think the way the collaboration has gone is just really fantastic and obviously a big, and a big part driven by the team in Oxford who've done a fantastic job with all this. Yeah, no both, I really hope you are successful in moving to the full trial. I think it would be a really good trial and a really, obviously really important question.

And I, to our listeners, if a full trial is funded please, I'm sure Dave and Colin would love you to get in touch if you're interested in being part of that. I think that would be a really positive thing. And I hope we can do more of this on the, these podcasts to try and promote these studies and actually get the community involved as best we can.

With I know that's all we have time for today, [00:26:00] but thank you so much to both of you for joining me. Congratulations on a great study and I really wish you all the best if the if the full scale trial is funded. It's been awesome to have you both with us. And to our listeners, we do hope you enjoy joining us and we encourage you to share your thoughts and comments through our social media platforms and like.

Feel free to post about anything we've discussed here today, and thanks again for joining us. Take care, everyone.