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 Hi, my name's Jo Gibson and I've worked as a shoulder specialist since 1995, and I thought I'd share with you about a young lad that I was asked to review by one of my consultant colleagues.

He was a fair amount of time down the road after his shoulder surgery. But I think he really flags up some really nice interesting things about our patient group with shoulder instability and why even with surgery, it's so important to hear the whole story so that we don't miss out any nuggets that can potentially come back and bite us in the future.

This young lad was 24. He basically had a posterior labral repair in October last year. He'd had some really good physio. He was delighted with his progress but was very keen to get back in the gym and back to rock climbing. He'd taken things very slowly at the time I met him. He had got back to football but he'd generally been pretty sensible.

Now, the things he was really struggling with was bench press and also he couldn't do one pull up, whereas previously he'd been able to do quite a few. I can't wait for the day I can do quite a few of those, I'm working hard, but I'm a way off just yet.

So his key aims if you like, were to be able to do a bench press and start building that up to be able to do a pull-up, but he still had this feeling of weakness and fatigue with certain activities. Now, this guy, essentially, when we sat down, I wanted to know about his history before surgery, which he was a bit surprised about, but I said, yes, I need to understand what happened beforehand.

And he basically had a five-year history before surgery. Now, he reports a few episodes of subluxations relating to falls onto an outstretched hand. His original injury, he was actually walking up a mountain and again fell onto an outstretched hand. He wasn't aware that it dislocated at the time. He wasn't sure whether it had gone in and out, but definitely had some clicking afterwards.

He had this buildup of pain and throbbing in the posterior part of the joint, but carried on playing football, kept falling on it and never really did anything about it until he started to get some pins and needles. And when he tried to go back to the gym and build things up, he found that essentially he was fatiguing very quickly. He didn't have any strength on doing any bodyweight exercises, so any loading in plank position, he really struggled with.

He found that if he tried to do that, the pain really built up and then he ended up getting this real burning sensation in the posterior joint line. Really, really sore, ended up getting referred to a consultant who did an MR arthrogram and found that he'd got a posterior labral tear.

 Now, what's really interesting about this guy, when I asked about subluxations and things, he said, "Well, I did have lots of falls and I had some occasional clicking," but he doesn't relate instability as being one of his primary symptoms. As well as telling you what I did with this guy and what I found because that was a useful thing because it's something I see quite a lot in patients after posterior labral repairs, this guy also highlights a very common feature with people who have a traumatic posterior subluxation or dislocation, is they often don't associate it with instability. Now, there's no doubt, posterior instability, traumatic is so much less common. It's 20 times less common than your anterior dislocators. We're all brought up to believe that the most common mechanism is epileptic fits and electric shocks, whereas actually the most common mechanism is a fall onto an outstretched arm. So, there's no great surprise when you look at sports where you are more likely to get a posterior dislocation, anything where you are diving and potentially hitting the ground with your arm, anything that you're going into contact, all those things are potentially a mechanism. Now, when you look at risk factors for redislocation in this cohort, then young age, as with our anterior dislocations, certainly if it is a result of a seizure, you're more likely to have another one.

If you have a reverse Hill-Sachs lesion that's off track or engages in kind of flexion internal rotation and also glenoid retroversion have been shown to be risk factors for somebody having a high likelihood of redislocating again. But the thing I really wanted to bring out with this guy, he doesn't really describe any feelings of apprehension or feelings of instability.

So, if you look at some of our instability tests specifically for posterior instability, then something like the posterior apprehension test, interestingly, when this has been looked at in a controlled cohort of patients with proven structural pathology in that posterior labrum, what they found was only a third of patients with confirmed structural damage actually reported a feeling of apprehension or instability.

And actually two thirds a much more common finding is pain with the positive apprehension and of course a relevant history, two-thirds, pain was the most comparable finding. So just something to be a little bit aware of even if somebody's had a traumatic injury, giving them a posterior labral tear, then posterior joint pain and reproduction of pain on loading tests is often more reliable than actually using apprehension, which is clearly very different from our anterior instability cohort.

Now that's really interesting when you consider that a Delphi study that asked lots of experts who treated shoulder pain patients all the time, Sadi et al, 2020, essentially, experts felt that this description of instability was really important, and yet we see that two-thirds of patients with proven pathology don't describe instability. What does seem really key very much like this guy, is fatigue and pain when sustaining positions that load the posterior part of the joint. So, you can imagine anything with a posteriorly directed force, anything in flexion internal rotation.

Now, there are a couple of other tests that are described, the Kim and the jerk test, which essentially are just taking the arm from a position of abduction, loading it through the humerus, and then taking it either into cross adduction and back again, which is the jerk test. A painful jerk test is thought to correlate with poorer outcomes from conservative management. And the Kim test is very similar in terms of loading, but again, often with some of these tests, they're not terribly reliable.

Now surgery had clearly made a huge difference with this guy. So, he'd been back playing football. He was pleased with his range of movement. He'd taken a few knocks. He was confident he could fall on the shoulder, but he wants to be able to do compound movements in the gym and bench press and pull up are really important to him.

He can do a shoulder press and he can raise dumbbells above his head, but as soon as he winds up into certain positions, he just doesn't have the confidence to do it. So this kind of 90, 90 position. Now, what are the clues in this guy's history that might make you think of some other things that I need to rule in or out?

Now, that key thing that he said in the history about things fatiguing and that burning pain posteriorly, and then starting to get some pins and needles and numbness. Now, when we look at nerve injuries in dislocation, again, most of the evidence looks at patients with anterior instability. So,

 if you imagine in anterior shoulder dislocations, we know that anywhere up to 50% of patients can have transient neurological symptoms.

The two most common groups are elderly ladies, particularly if they have a fracture dislocation and young men with high energy trauma. The good news that the majority are neuropraxia or axonotmesis, which generally recover well.

 Interestingly, a recent review by Gutkowska et al showed that multiple nerve involvement was more common than mononeuropathies.

The auxiliary nerve is absolutely weighing above the most common, both singly and in combination with other nerves, and there are some key risk factors. The older the patient, the higher the energy, the longer the shoulder is out of joint before it's relocated . If they have a hematoma at the time of injury, again, that's highly associated with nerve injury and as I said before, a fracture, dislocation, again, a higher risk of nerve injury.

Now, in terms of order of involvement, if you like auxiliary nerve, absolutely number one, followed by the ulnar nerve, the median nerve, the radial nerve, and the musculocutaneous nerve. Though interestingly, in some studies, the musculocutaneous nerve comes a little bit higher in the list. So, what was I interested in this guy?

Well, the thing I really wanted to share with you with this particular guy was not only that important point that the patients often won't have apprehension or feelings of instability. It's more about pain and fatigue. It was with this guy is one of the things I'm always conscious to look at with a traumatic posterior dislocation, particularly when they describe some neural type symptoms, is whether they've had any traction or irritation of the posterior cord of the auxiliary nerve.

We've talked about quadrilateral space syndrome on the Facebook lives before. And remember that quadrilateral space is formed by teres minor, teres major, the long head of triceps and the shaft, the humerus. But this is a little bit different in just in that course around the back of the humerus, depending on where it breaks out, we can actually get involvement of just posterior deltoid or posterior deltoid, and teres minor. Clearly, if you've got significant involvement, it'll be very easy to see a change in terms of muscle bulk posteriorly. But when you looked at this guy from behind, he looked, okay.

So another little test I like to do is to, before I actually do formal strength testing, is get them to lift up to 90 degrees and then bring the arms. Both back into horizontal extension. Now, if you watch deltoid, and I'm not saying this is like some massively researched reliable test, but it's something I find useful in the clinic.

And what I'm looking at is whether deltoid is recruiting on or not. And what you'll commonly see in this particular group is essentially deltoid just doesn't get going on the affected side. It either comes in right at the end of movement or there's a funny little fasciculation or a bit a whimpering wobble at the end of the movement. It doesn't really get going.

Clearly if you've had instability going on for five years, you've had some irritation of that nerve, then it's not a huge surprise to think that we might need to target posterior deltoid specifically. Now, interestingly, when we looked at this guy in ninety-ninety, we looked at his posterior cuff function, it was actually very good, both with just manual testing and with a handheld dynamometer. So, his cuff seemed to be working really well. However, when we just looked at him in prone and just did horizontal extension, he was significantly weaker on his affected side.

Now, what have I got to decide at this point? Essentially, I don't know if perhaps there is some true weakness there because this has been going on for a long period of time, or is it just that muscle needs a little bit of a wake up because it's been inhibited by that nerve involvement?

Well, one of the things that I'm really interested with this guy, but all sorts of things I can potentially do to help him recruit it. But one of the things I asked him is, "Well, what are you doing as part of your warmup when you go back to the gym?" And fundamentally, he'd stop doing any of the kind of stuff that his physiotherapist had given him before to get everything woken up and ready for action and was kind of just going back into his general gym set.

So, I did some really simple things with him in the clinic. I did some weightbearing over the ball through range. Compression is a fantastic way of just getting the system engaged. And those of you that you know me, I can't help a bit of through range TheraBand just to get the cuff and scapular muscles doing their job with a bit of kinetic chain to make it more dynamic, more sensory rich.

And if you like get that foundation woken up. Now I did that with him. And interestingly, when I then observed him and retested his strength, there was already an improvement just from doing those very simple things. But then I wanted to get maximum bang from my buck in terms of targeting that muscle. So, this is where when we look at type of muscle contraction, actually, there's some simple things that can make a big difference, and certainly it would seem that eccentric exercise sometimes has more proprioceptive value and gets the brain a bit more interested than some of our concentric, particularly if we slow things down. So, I got this guy on the pulleys in the gym just doing a really simple face pull, nothing very complicated doing the movement. I want the muscle to work, but again, I initiated it with the kinetic chain because the evidence suggests that it accentuates local recruitment of the shoulder muscles, but I also emphasise the eccentric phase. Now, we literally did a couple of sets of eight repetitions on the back of those other things that I talked about, went back into the clinic room, reassessed those things. I showed him the video before and after. And afterwards, his deltoid was symmetrical bilaterally, and importantly, on our horizontal extension test with a handheld dynamometer, he was scoring within 5% of the other side.

Clearly the great message for this guy is, he hasn't got a true weakness problem. He just needs to have a better warmup program to actually really remind his deltoid to get with the story. And if you think of what he was saying in these loading positions in ninety-ninety, his cuff could do his job, but he didn't have that balanced support from posterior deltoid, which is important in that posterior instability group.

 Now, what if that hadn't worked? What if I hadn't got such a quick r esponse. He was obviously delighted and confident if he just took these warmup drills into the gym and then monitored fatigue and did another kind of reset or re -exaggerate those foundations, if you like, in between. If he loaded and fatigued, then he'd just do another set to wake it up again. So, some really simple strategies that just help him keep reinforcing the good stuff.

Now, if it hadn't worked, what are the other things that I could have used? Well, this is a perfect example of when I would use muscle stim. Again, we did a Facebook Live just talking all about muscle stim, but I think often that sensory input can be a really nice way of just helping patients reaccess that kind of connection, if you like.

Certainly, if you look at some of the nerve surgeons, what they'll do is they'll actually do a neurolysis or they'll actually stimulate the nerve itself again, because they get like a bit of a recruitment block if they haven't had a neural supply for an extended period of time, so we're not talking about a nerve injury that stopped the muscle working. It's just not an efficient nerve supply. And so we get changes in that muscle function.

So this guy was really interesting. Six months down the line, great range of movements. Very happy with his progress, but clearly not back to where he wants to be. So what we found is just actually tweaking his warmup, doing something dynamic, something that targets resetting those foundations was very effective in getting deltoid to do its job again. And so clearly he's gone away with some exercises. He tells me things are going very well, but we won't be happy until he can do his pull up again.

So I just thought that brought up some nice interesting things about posterior instability and particularly about that posterior deltoid. There isn't a lot about in the literature, but there was some work way back, I think it was by Reiman , which actually showed very clearly that in a posterior instability group, there was consistent theme of weakness in that posterior deltoid. But what wasn't clear is did that relate to some irritation of that posterior cord of the auxiliary nerve because depending on where it's irritated, it can just take out posterior deltoid, it doesn't have to take out teres minor as well, because there's all sorts of anatomical variations.

So guys, just something to be aware of. As I say, I know it's not a validated test, but I really like looking at that horizontal extension from behind because it's often very obvious that there is a change in what's happening.

And what's really nice is you can see how it easy it is to change just by getting that system recruiting or giving a little bit more sensory input and those little tricks of exaggerating the kinetic chain or exaggerating that eccentric phase or even better, doing those two things together can be a really effective clinical strategy just to really get the muscle doing its job much better.

So Tim, in terms of scapular dyskinesis, the scapula's a funny old one. We've very much moved away from our obsession with what's happening with the scapula. One, because there's absolutely no doubt that classification systems aren't very reliable in terms of type 1, 2, 3. I was lucky to work with Ben Kibler, but I think it's fair to say, him using his classification system very useful. Anybody else trying to replicate it, not so useful. And so yes  no is as good as it gets. And the fact is, if you unload somebody's shoulder and give them a bit of sensory input, that can have as much effect on what their scapula's doing as anything that targets the scapula.

The bottom line is the scapula and cuff work together. So if I'm rehabbing, I'm always working them together. So I'm interested in the scapular being congruent under load, and I may target the scapula in terms of a scapular assistance test as part of my symptom modification, but really all it tells me is whether I'm gonna put a ball behind them on the wall or a TheraBand behind them as they do a through-range elevation just to change that recruitment strategy or just get them moving in a different way. I think we have to be honest that maybe we are not so clear what the mechanisms of change are.

Afsaneh, no, there wasn't a cyst. And that's a really good point because obviously anybody who's had a labral tear that presents with pain and weakness, you always want to be clear that there isn't an underlying cyst, particularly if they've had longstanding symptoms. So, if we see people who have longstanding superior labral tears it's not uncommon that they can then get compression or irritation of the suprascapular nerve. Similarly, if we have people that have long-term anterior inferior or posterior tears, again, as you can imagine, they can get a cyst and basically it's because of leakage of that synovial fluid because of the labral tear, they develop a cyst and again, that could cause pressure on the auxiliary nerve. But remember, this guy has had surgery. He's had extensive scanning and there's no evidence of a cyst at the time of surgery. But those are great points and things that you would definitely consider if I wasn't happy in terms of the other imaging and stuff that he'd had.

So, Doodson says, "Presumably, this wouldn't show on nerve conduction studies and EMG". You are absolutely right because often that irritation is only functional. So you might get some changes in the small diameter fibers, but as you know, nerve conduction studies will only pick up those large diameter fibers.

Nina Annina Schmidt did some lovely work on this, looking at using a coin in your pocket for 20 minutes or so, it'll be perceived as warm. At room temperature, it'll be perceived as cold, and also using a neurotip, and she's done some lovely work.

For me, I would use that over the posterior shoulder as part of assessing sensory change and ruling in, or ruling out any sort of nerve involvement. But you're absolutely right. If it's transient irritation, then our nerve conduction studies and EMGs often don't show up anything significant.

Tim, " When you have posterior instability, when recruitment of anterior deltoid and upper traps aren't doing their job". So again, I think the thing that's really interesting when we look at individual muscles, often when patients with non-traumatic shoulder get into these weird patterns of movement, often they can be protective and the problem is they get protective. And you can imagine as a patient, it can be fairly distressing when you don't know what's going on with your shoulder and muscles are doing weird things and you're trying to activate things.

But the bottom line is, if you are worried or you're protecting your shoulder with the best will in the world until somebody reassures you or you understand what's going on, the fact is your brain is set to protect you. And it's constantly sampling information, and of course the main information it's getting is from the muscles that are protecting you, so it can be really difficult to protect that cycle.

We've talked about moving away from this brain and periphery type model and this embodied pain where basically everything's interacting all the time and you can see the challenge of changing some of those things. So if I've got somebody, let's say, where their anterior deltoid is perhaps working too hard and pushing the shoulder out posteriorly, which is a strategy that you might see or they're not recruiting their upper traps at all, which clearly isn't gonna help at the onset of movements.

It's really a question of either, how much do I have to unload the shoulder or how much sensory input I have to give it to change that movement strategy. And that's why just these simple things we've talked about tonight, making it a little bit more dynamic, giving a bit more sensory input, maybe even giving a visual target.

All these things can be a nice way of changing that recruitment strategy. But what's lovely about your question, Tim, is that it really highlights the fact that

 I can do the best facilitation, the best symptom modification, the best exercise prescription, but fundamentally, if my patient doesn't have a good understanding of what's driving that problem and caused it in the first place, and importantly why perhaps it hasn't responded to usual treatment, then that's gonna be a massive barrier to them getting better. So, that journey together of helping patients understand is a massively important part of what we do.

 Guys, there's been some great comments thanks to you, those of you who highlighted the cyst, because again, we've talked about those in the past. It's definitely an important consideration. The great thing with this guy is we know that he's had surgery. There was no cyst. He's had this transient irritation. We are well placed to help him, but what's lovely about what everybody said is all these things are part of our differential diagnosis. If we don't have the benefit of knowing those things, I'd always start rehabbing him. But as you've all pointed out, if those things weren't changing, then I would have to have those considerations at the back of my mind. So thanks guys. This is great. Fantastic. I hope you took some useful things away from that.

I've really tried to highlight some key things about assessment if you'd met this guy acutely. Some key things that can be just useful clinically to build into your assessment in somebody who's had posterior instability and if they've had surgery, and just those little cues about nerve involvement. What to do, some additional things about assessment. But as ever, just some simple clinical tips that hopefully you can take away straight in your practice and consider if you have one of these patients in front of you in the future. And I'll definitely let you know how this guy gets on and if I have to do anything different in the future.

So guys, as ever, thank you so much for joining. I really appreciate you giving your time to listen to me. And as I say, thanks to those of you contributed with questions and comments and suggestions, that makes it even more fun for me. Bye for now and have a great evening.