Ep 266: One more shoulder press for good measure, with Dr Federico Pozzi

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[00:00:58] Hello, and welcome to JOSPT Insights, the podcast that aims to help you translate quality research to quality practice. I'm Claire Ardern, the Editor-in-Chief of the Journal of Orthopedic and Sports Physical Therapy. It's great to have you listening today. How does strength factor into patients presenting with rotator cuff-related shoulder pain, and what interventions work best? And what does the research say in terms of how we can best help these patients?

[00:01:28] Today, we're going to figure that out with the help of Dr. Federico Pazzi. Dr. Pazzi is a physical therapist and rehabilitation scientist who leads the Musculoskeletal Injury and Outcome Lab at the College of Public Health and Health Professions within the University of Florida. His work focuses on why people with the same injury recover differently and how to personalize treatment for musculoskeletal pain. My name is Dan Chapman, owner of Summit Physical Therapy and Performance in Baltimore, Maryland. I'm Marquis Santa Rice.

[00:01:56] I'm a doctor of physical therapy in Baltimore, Maryland at Summit Physical Therapy and Performance. Dr. Pazzi, welcome to JOSPT Insights. Thank you for taking the time to sit down with us. Thank you for having me. Before we start, I'd like to acknowledge a team that make this work possible, especially my two graduate students, both our Nacho, who really did the heavy lifting for this work.

[00:02:18] Before we get into specifics about this review, can you tell us a little bit about what inspired your research team to look more into addressing shoulder weakness in individuals with rotator cuff related shoulder pain? To understand the inspiration for this paper, I think you really have to take a step back and look at my own training and some of my biases as a clinician and as a researcher. During my PhD, I focused on environments following total knee replacement.

[00:02:48] And one of the biggest issues in this population is persistent weakness, even after what we consider a successful surgery and rehabilitation. So then during my postdoc, I started working more with patients who had shoulder pain and rotator cuff related disorders. And I began noticing very similar patterns. When we tested these patients objectively, many of them were quite weak.

[00:03:14] And at the same time, they were consistently reporting difficulties with activities like lifting their arm, lifting an object or participating in exercises. All these activities are inherently related and require strength. So as we looked more closely at the existing literature, what stood out was how inconsistent the findings were.

[00:03:39] Even studies that use relatively intensive strength-focused rehabilitation programs often showed only moderate or marginal improvement in strength. That disconnect between what patients struggle with clinically, what we expect strengthening to accomplish, and what the literature was actually showing really prompted us to take a deeper look. That ultimately led to this systematic review.

[00:04:08] Rotator cuff related shoulder pain is a shoulder diagnosis that's gained a lot of traction here. And a lot of the kind of previous work literature has kind of looked into really defining what rotator cuff related shoulder pain is. And I feel like now we're really getting to a point to kind of say, hey, here's some of the gaps in some of the literature. This is how we apply it with like certain populations.

[00:04:30] Were there any like gaps or inconsistent literature or something that really kind of motivated your team to really look into this a little bit more? So there's definitely a connection between a different type of patient and their outcome after treatment. So we know in lower extremity there's a big emphasis on strength, especially because of the function of the lower extremity.

[00:04:56] As you have to, again, be able to sustain your upper body weight to walk and to do different functional activity. Usually strength with the poor, pure term of strength is often, I say, overlooked in upper extremity because the focus is more on, you know, muscle control, motor control, ability of like muscle, specifically the rotator cuff to center your humeral head in your glenoid during movement.

[00:05:26] However, like what we know clinically is oftentimes these patients come in, you test their strength and they're weak. Understanding if the treatment that you're doing improves strength outcome and it might not necessarily improve strength, but it might help train muscle to function better as a whole. So that's why I think also looking at strength as a pure strength outcome is important in this population.

[00:05:56] Yeah, so strength is a word that kind of oftentimes gets brought up not only in the like lay population, but I feel like in our profession, strength gets brought up with sometimes not clear meaning or understanding of what we're actually looking at. What does strength look like to you and how is it measured within some of the studies that were included in some of this review? For our team, when we set up the study and the systematic review,

[00:06:26] what we wanted to focus on was study that provide an objective measure of strength. This is often done through strength testing, muscle strength testing using a N-DAL dynamometer, and it's often done isometrically. So for us, strength meant the ability of the muscle to produce movement against resistance. The way it's tested clinically and in research is often isometrically.

[00:06:55] And again, this is potentially not the best test to reflect the complexity of strength requirement, because oftentimes when you move, you require dynamic strength to produce movement and to stabilize your shoulder. That said, using these criterion to select and include study provided a controlled way,

[00:07:23] make sure that all the study had quantified strength objectively and would not introduce bias due to external factors. It looked like reading through the paper, there was a lot for you to wade through. And we often hear a systematic review and meta-analysis is only as strong as the study includes. So can you give us an idea of the types of studies that were included in this review? And then what were you also excluding?

[00:07:52] In terms of inclusion and exclusion criteria for the study for this systematic review, I think the biggest one that we want to point out is that we looked at studies that have an objective measure of strength and then tested an intervention that was at least six weeks in length. In terms of study design, we were interested, and because we were interested in understanding changes of strength pre-post intervention,

[00:08:19] we were able to include both randomized control trial and non-randomized prospective cohort study. Because we are not interested in understanding the superiority of the treatment, I don't think it's a huge bias for our work. We wanted to have some inclusion and exclusion criteria to limit the heterogeneity of the patient included in the systematic review. So we looked at the definition of rotator cuff related shoulder pain.

[00:08:47] And oftentimes we know that this definition includes patients with rotator cuff tears. So we decided to exclude study that would target specifically patients with rotator cuff tears, because the mechanism of strength recovery may be different in this population. We also excluded a study that focused on patients who underwent surgical intervention. And to try to maintain some focus on larger cohort study, we excluded a study,

[00:09:15] even prospective study that have less than 10 people. And I totally agree that this study included in a systematic review can affect the results. So we did a formal assessment of methodological quality for the study included. And we saw that nearly half of the study were classified as having high risk of bias. So we decided to do a sensitivity analysis.

[00:09:40] And we exclude those studies from the analysis when performing the sensitivity analysis for the paper. And what the sensitivity analysis shows is that the results were quite similar compared to the primary finding of the primary meta-analysis, when all the studies were taken into account together. So this suggests that even if you have studied with high risk of bias, they were not driving our overall conclusion.

[00:10:06] It sounds like you guys did a really good job at trying to pinpoint someone who has rotator cuff related shoulder pain, who doesn't have potentially any other potential factors that would maybe change some of the results that you would want to see for people with shoulder weakness. So let's dive into some of the specifics here. Strength was the primary outcome of interest. What did you ultimately find out about strength and its impact in addressing shoulder weakness in individuals with rotator cuff related shoulder pain?

[00:10:36] One important thing to keep in mind when we interpret our finding is methodological approach. So as I said before, we focus on within group changes before and after strengthening intervention. So these allowed us to group a study based on the intervention content. So we decided what type of intervention we're doing and we labeled that as strengthening, multimodal, education, sham placebo and natural course.

[00:11:04] So we can describe the different type of intervention that we're performing, but we cannot claim that one approach is superior to another. So this I think is important when we put our finding into, to interpret our finding. So in general, what we found is that both strength-focused programs and multimodal intervention, which included active exercise but place less emphasis on strengthening specifically,

[00:11:31] they produce small to moderate improvement in strength. Clinically, this suggests that both can be a reasonable choice when we want to address weakness in a rehabilitation program. One of the more interesting findings was that less active intervention, such as education alone, placebo intervention or natural course, had little to no effect on strength outcomes.

[00:11:58] That wasn't entirely surprising, but it's an important reminder that we need to align our expectation with our outcome of interest. So education is a critical component of a well-rounded rehabilitation program. But its efficacy are likely acting through other mechanisms, such as pain or reassurance rather than strength. So a similar point can apply to natural recovery.

[00:12:25] While many patients, you know, do improve over time in terms of symptoms, I would finally suggest that without active intervention, they're likely to remain weak. It looked quite clear from what you found that the active interventions were specifically quite helpful in creating an effect and getting these patients stronger. Was there anything that came out in terms of dosing? So between the papers that did show an effect,

[00:12:55] I assume there was a difference in the programming for each of these papers. Did you happen to find any that seemed to be more effective than others? Or was that not quite clear? In the paper during our work, we were able to retrieve information regarding treatment. So we were able to get information on what type of exercise were performed,

[00:13:21] how much frequencies of exercise were during the week, how much session during the week, repetition, sets. Some of these parameters, we were able to retrieve them from this included study in the systematic review. However, we did not look specifically at dosing. We had some discussion as a team that it could be an area for future research from the data that we collected.

[00:13:49] We could potentially look at some of the parameters and see if we can classify some of the study as high dose or low dose and see if that has an effect on threat. But if you take the finding as a whole, like if you take the finding of the study as a whole, they suggest that like if you really want to strengthen, strength is a primary goal of your treatment, it will likely require more intent and progression

[00:14:17] than what sometimes is delivered. Yes, we do unfortunately have an underdosing reputation in our profession that we are trying to fix. But I mean, it makes sense. You know, the primary outcome of interest in this paper was, is this active intervention effective, right? And so we found that it is. And so, as you said, it could be an interesting point of future research. Okay, now can we dive into programming and what types of programming and dosage

[00:14:46] might have a larger or smaller effect? You know, I think that's a great point. Were there any patient characteristics, maybe chronicity, baseline weakness, you know, high irritability or level of irritability that your team found influenced strength gains? So if you have to think about your patient and the patient that you see every day in the clinic, I think that the patient would benefit most are those who present with clear weakness at initial evaluation.

[00:15:17] These are the individuals where strengthening is likely to be most relevant and most impactful. You don't necessarily need a purely strengthened, focused program to improve strength. We saw many full strength gains, even with multimodal rehabilitation approaches, which give clinicians flexibility to address multiple aspects of a patient presentation, like pain function or movement tolerance, while still targeting weakness.

[00:15:46] We also try to emphasize in the paper that resistant exercises can be prescribed for different reasons. So even if they don't produce large improvement in strength on their own, they might still contribute to recovery through other mechanisms, such as reducing pain, improving load tolerance, or potentially influence tissue adaptation. And then lastly, in terms of patient chronicity, baseline irritability or other modifiers, it was actually very difficult for us

[00:16:15] to tease those out. For example, they often study don't compare strength recovery across acute versus chronic symptoms or across different levels of irritability. So that's potentially a really important area for future research because those characteristics likely do matter and understanding them better help us to your strengthening intervention more precisely. Just to kind of sum some of this up,

[00:16:43] one, your team looked at shoulder weakness, people with rotator cuff relief, shoulder pain. In this population, it seems as though that active interventions seem to be better than some non-active interventions and that maybe things such as eccentric exercises, NMES, maybe it's tough to say if it's like superior, but maybe more influential towards addressing shoulder weakness and that even despite people

[00:17:11] not exactly getting stronger, we're still able to see improvements in function, quality of life, symptoms, and that, of course, just like everything, it's kind of complicated and there's more areas for the research. No, I think that sums up the paper nicely. The only thing I would like to point out is, again, refrain from stating that one intervention is superior to another because that was not our intent.

[00:17:41] in the paper, even when we looked at like the secondary analysis, when we group strengthening intervention by the content, one thing that we have to take into account that some of the intervention, they have few study arms. So the estimated effect could potentially be overestimated. So that's something that we have to take into account when we look at like specific study, especially like in some of these strengthening intervention categories.

[00:18:11] I think that will help a lot of people and kind of just speaking on that, if I was a really busy clinician, I was just listening to some of this podcast, what should I take away from this? How should it change some of my clinical practice tomorrow? So first, if you evaluate a patient with shoulder pain and you identify a clear weakness, then addressing their symptom is very unlikely to happen without some sort of active, resisted exercises.

[00:18:42] So education alone or wait-and-see approaches may improve symptom for some patient, but it's not going to meaningfully improve their strength. If weakness is one of the patient's primary impairments or complaint, that should signal the need for a more targeted, strengthened component within the rehabilitation program. That doesn't necessarily mean that the program has to be strength only, but there should be a sufficient dose

[00:19:10] of resistance training to actually drive strength changes. A practical tool clinicians can use on this paper is a stable 7. So in table 7, we reported the pool effect sizes from the meta-analysis using common clinical units like kilogram force, torque, or normalized strength values. This gives a clinician realistic evidence-based ranges for how much strength changes they might expect after a strengthening

[00:19:40] or a multimodal program. So those values can be used to benchmark patient progress and help set more grounded expectations from both the clinician and the patient. So in summary, the message of the patient is relatively simple. If weakness matters for your patient, then strengthening done with enough intent and dosage needs to be part of the plan. Federico, we want to thank you and your entire team for all the work that you put

[00:20:09] into this paper. It is no small feat to wade through all of this data and then put it together succinctly for us. And then specifically, we want to thank you for coming on to JOSPT Insights and spending your time with us here sharing your expertise with all of our listeners. So thank you. Yeah, it was a pleasure. It was not my sole effort. I am here representing a team and without the team we will not be able to pull this through. So thank you for inviting me. He is a researcher and a gentleman.

[00:20:39] Dr. Patsy, thank you so much for taking the time to share your knowledge and your expertise with us and all of our listeners. And as always, we want to thank you for listening to JOSPT Insights. Thanks for listening to this episode of JOSPT Insights. For more discussion of the issues in musculoskeletal rehabilitation that are relevant to your practice, subscribe to JOSPT Insights on Apple Podcasts, Spotify, TuneIn, Stitcher, Google

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