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Some weeks you have a week where you see patients, you're asked to review them, they're not doing as well as people hope either after their surgery, or perhaps they've just had longstanding shoulder pain, they've improved and improved, but then they've hit a plateau and they've just stopped getting better.

And of course, there's lots of things we can look at in terms of strength, in terms of more loading, in terms of whether perhaps people are still stuck in protective patterns, but one of the themes of some of the patients I've seen this week has very much been stiffness in the AC joint. So I thought it was a great opportunity to pop on tonight and use that as a subject .

Case study - Patient with shoulder pain

So the particular patient I saw today, had had an acute injury a few months ago. The acute pain that was very much sort of subacromial pain region had settled, but now they still had a real catchy pain at the end of range of movement when they were reaching behind them and if they reached across their chest.

Now the pain was still in the original place, not superior shoulder pain, not posterior shoulder pain, very much in that subacromial region, but it was very much that high painful arc cross adduction and reaching behind their back that was still causing the problem.

Recent research around the ACJ

Now, the reason again, I decided to bring the AC joint as our subject for this evening,

, there's been a couple of papers recently that really highlighted some of what I see in the clinic and it's just to point out some things to look out for. So there's a paper by Rabar in 2022 that essentially looks at patients with frozen shoulder with pain and stiffness. And they looked at comparing standard physiotherapy, mobilisation and exercise with physiotherapy, the same programme with the addition of AC joint mobilisation.

And interestingly, when they added AC joint mobilisation into standard care, they found that actually patients got better outcomes, decreasing pain and disability. They had an improvement in active abduction range, but not in any other ranges, and that might make sense in just a moment. Now, we have to be a little bit honest,

there was only 28 in each of the different groups. So not massive numbers in terms of the study. However, when we look at the size of effect, it was kind of two points on a visual analog scale between the two interventions. 10 points on the shoulder pain and disability index that meets the clinically significant difference.

And certainly those things were maintained when they looked at a month after the treatment. Now when they looked at the difference in range of movement it was about 15 degree difference which is just above the 10 degree minimum clinical meaningful difference. Get my teeth out this morning, .

So I guess it's interesting isn't it and why would they decide to target the AC joint? Well we certainly see a lot of evidence that stiff or symptomatic AC joint problems are not an uncommon sequelae after surgery or some key pathologies. And again, it'll become clear why that might be. So another paper by Hannah et al last year looked at patients who'd had total shoulder arthroplasty.

Now this was a bigger study. It was 230 patients with a primary total shoulder arthroplasty monitored over a nine year period and good follow up. And outta those patients, 35 or 16% developed a symptomatic AC joint. And again, their initial symptoms were end range elevation, cross adduction, hand behind back, et cetera.

Most of these patients responded to a period of rest or injection, some more physiotherapy, etc. and only a tiny percentage actually had to have anything done in the form of further surgery. Now if you look at the evidence in non traumatic shoulder pain, it's pretty clear that anywhere up to 3 in 20 patients presenting with non traumatic shoulder pain are likely to have an AC joint problem.

Now you might say, Jo, why worry? Certainly, if we look at stratification studies that separate patients according to what's seen on an ultrasound scan, so perhaps degeneration in their, AC joints, some fluid in their bursa, maybe a cuff tear, and treat them according to that pathology, or another group of patients still ultrasounded,

so we've got a kind of relative representative of those different pathologies.

But in the second group, rather than treat them according to what we see on the scan, just treat them as non traumatic shoulder pain. And guess what? No difference between the two groups. So a key message is when we look at 70 to 80 percent of our patients with non traumatic shoulder pain, generally they'll respond to the same things,

done well for long enough.

However, that leaves us 20%.

Psychosocial or biomedical factors influencing the ACJ and shoulder pain?

Now I'm also very honest that when you look at the things highly associated with whether patients do well or not are much more in that lifestyle domain, comorbidities, psychosocial factors, et cetera. But we can't completely forget the biomedical because it can be relevant sometimes.

Role of the ACJ

And the AC joint has an awful lot to do. It's a tiny little joint which has a huge role both in suspension of the upper quadrant in terms of control or transfer of force and also allowing us to gain maximum range.

Pain and movement patterns indicating ACJ involvement

And as I say, when we look at the AC joint, when people present with a symptomatic AC joint, sometimes that's very easy to tease out.

Very typical distribution of pain in terms of superior place pain. It can radiate into the lateral cervical spine and into the anterior axilla. And typically they'll have that mechanical pattern where we're loading the AC joint of higher range painful arcs, that cross adduction, and, also often that, hand behind back.

But what's very interesting in some of those studies I related to you, one of the common observations was almost a block to abduction. And if you looked at their internal rotation, they didn't have very much range, but if you brought them a little bit further forward, they had better range, which suggested it wasn't a glenohumeral joint restriction.

Now, as I say, when you look at the evidence for people who may develop these end range symptoms, but still relating to their original pain rather than the AC joint itself, people who've had rotator cuff tear surgery, patients who've had long standing biceps pathology, patients who've had slap tears that have been repaired or had a biceps tenodesis or tenotomy, as I mentioned, patients with arthroplasty.

Patients who start to get their movement back after a frozen shoulder, again it's not uncommon for them to present with some stiffness in the AC joint but it's also reported as a sequelae of neck stiffness and also patients who've had a whiplash. Could AC joint be the culprit if the pattern of reproduction is the same even though the pain is in a different place?

Protective movement strategies that may affect the ACJ

Well, if you think of the common strategies patients adapt when they've had pain for any length of time or when they've not been able to move their shoulder, we know that the clavicle movement is dependent on the scapula pushing it up with obviously the help of trapezius, serratus, All the other shoulder muscles to promote that maximum upward rotation and posterior tilt to create clavicle rotation.

And clearly if people haven't been into those ranges for a long period of time, they haven't used the muscles through range, it's not a hard leap to see that actually in some people that could get stiff.

If it's just, they've not been there and potentially it's just the muscles need a bit of reminder or they need to just reeducate movement into those ranges, then we could apply some very simple principles to try and assess that, i. e. can we change it yes or no.

Symptom modification tests

So I like some simple approaches to symptom modification like changing the lever arm, adding some resistance at the back of the wrist, a sensory cue. Also we have some evidence it has an impact on what the cuff and the scapular muscles are doing.

It's another approach to see if we can make it easier for people to move. And then of course the scapular assistance test, which you can imagine a lot of patients with AC joint problems often like the scapular assistance test because it's promoting those very mechanics that actually push the clavicle round.

Now, again, those of you that say, but we're away from biomechanics these days. Interestingly, we do have a study looking at dynamic imaging that shows that the scapular assistance test does have a biomechanical effect.

For me, it's not saying the scapula is the problem. It's saying if I unload it or give some tactile feedback that makes it easy for the patient to achieve better range with less pain.

Exercises for the ACJ

And so that's just going to form the basis for my exercise. So I might put a band behind their back or get them leaning against the wall, or a ball on the wall,, going through the range with a loop of Theraband again just to get the shoulder working a little bit differently. And that's very easy but what if that hasn't changed it? What's if that scapular assistance test hasn't made the difference?

What else would I do? Well the other thing I'd do If I suspected the AC joint because I had that very clear pattern of pain reproduction or limitation, so end range cross adduction, maybe hand behind back, but that block to abduction which gets a little bit better if I come into the scapular plane, then I would add a shrug to my symptom modification.

I could do it with a scapular assistance, but I quite often just go back and do it with the posterior cuff and again get the patient to shrug through range and shrug at the end.

Now why the shrug? One because it really emphasizes the contribution of upper traps at the beginning of the movement to get everything doing its job and secondly at the end of the movement it really promotes serratus to get that last bit of movement.

Of course it could be for lots of other reasons we're getting the patient to initiate their movement in a different way. We're maybe just exaggerating one part of the system. And we know that for quite a lot of patients with shoulder pain, one of the common ways patients try and keep their shoulders safe or protected is almost to dump their shoulder because they're protecting with all the big muscles.

And of course, that just makes it harder and less efficient to get moving. So potentially doing a shrug, is going to have it do exactly the opposite to how they want to tend to move.

So there's lots of potential mechanisms, but it's a very simple thing to do in the clinic to see if it has an immediate change in their symptoms.

And the other thing that can be a really useful tip is when you do it, get them doing it against the wall. So like a wall slide with that shrug. Why? Because if you do it against the wall, it really controls their axis of movement. So it really, optimizes, again we've got some lovely work from Ann Cooles, which shows that essentially that maximizes upward rotation and excursion of the scapula if patients don't get pain.

So again, if we want to be very much the biopsychosocial model and thinking that psychosocial domain of all the things that can contribute to patient's pain, of course, that's very important and in the biomedical, of course, people's lifestyle, whether they're sleeping, if they have comorbidities, but little simple things like this, that might influence that experience of movement might make it easier for patients to move and my rationale being their pattern fits with the ACJ, then it's just a really simple thing we can do in the clinic to form one foundation exercise that the patient can do to get confident and get the joint moving.

Manual therapy for a stiff ACJ?

Now there's some times that even adding in the shrug and playing around if you like with giving more support to try and help that patient achieve better range without the discomfort or the block, then in those instances,

I'm going to say it out loud, I might mobilize the AC joint. Now again we have studies that show in patients who've had pain or stiffness for a long period of time, the axis of rotation doesn't shift laterally as it should because often of those compensations. So what am I going to do about it? Well, maybe my mobilization is just a sensory input that reinforces that.

I quite like using things where I put pressure on the joint and then do some resisted exercise because it fits my bias of getting the muscle system working. Similarly, you could just do some mobilization. There's some tentative evidence for mobilizations with movements, but again, I would argue they're a sensory input.

They give the patient confidence. They have an unloading effect potentially. Irrespective of the mechanism, if I'm unable to change that very clear pattern with my symptom modification, then my go to would be to mobilize it, and that's very much how I work through my assessments. If I'm clear that that's likely to be a contributor, I can look at the movement here, I can look at the movements that reproduce their symptoms, do my symptom modification, does it change?

Yes, no. If it doesn't, I'm going to mobilize it. Is it changed? Great. Then I'm going to use very similar principles to inform my exercises. And then essentially, once we've got that movement foundation, when I just want to exaggerate and build a bit of capacity around that AC joint in terms of really promoting optimal movement and getting patients confident,

then there might be some merit in targeting serratus and trapezius in some movements that just promote that optimal excursion.

So things like a dynamic hug with serratus, the wall slide is a great exercise for promoting serratus engagement. And remember, we have three functional parts. So doing it in different ranges, simple things like push up pluses, but I actually like them working through range.

So again, I like them weight bearing and almost pushing away. And you can do that against the wall. You can do it on a bench. There's lots of different modifications to really promote what's happening. So I think sometimes an understanding of exercises that really help us get maximum value in a particular situation can have some benefit.

I always go back to say, remember in 80 percent of our patients doing the simple things well for long enough will have an effect for a lot of our patients. But occasionally when there's a history or a pathology that might actually preempt the development of AC joint stiffness, it's just nice to have some of these things in our toolbox.

When we look at enhancing trapezius, well, that upward shrug at the beginning of movement definitely gives us that.

The pushup plus, as I've already mentioned, but also things like the bow and arrow exercise or the archery exercise is a great way of actually getting the whole of trapezius working to really optimize what's happening at the AC joint.

And the fact is, Does it improve movement? Does the patient feel more confident? Well then we can just strengthen on the basis of that.

Summary - When to look at the ACJ

So guys, I just wanted to talk about the AC joint tonight because as I say, I've seen several patients that I've been asked to review recently. They've either had stiffness for a long period of time, started getting their movement back and then started getting pain at end range.

Or they're patients that have just got into a rut where they've got this constant pattern of reproduction and this block in this position that's a little bit better when it comes forward and that's just to do with length tension relationships and pushing the clavicle round. So I hope you've just taken some useful clinical tips away from that just to reflect on if you do get somebody particularly where you can't clear that end range pain or they seem to have this weird block in this position, But when you look at their glenohumeral rotation in other positions, it seems absolutely fine.

Just some simple tips and tricks, taking a sensible approach of some things that might be useful in those specific patient examples. So I hope you enjoyed that.

Join us again soon for some more tips and tricks or challenging cases or interesting things from the literature.

Have a fabulous week and I'll see you again very soon.