 So that brings us to the next question. Okay, it's not rotator cuff. It's not an old patient. Younger patient has come with recurrent dislocation or maybe pain. The surgeon is suspecting instability. What are the three questions you want to answer? Is there a labral tear? Is there bone loss? And what's happening to the capsule? So this is what the surgeon wants to know. Let's start with labrum. Is there a tear? What is the extent of the tear? How big is it? And is there any associated bone fragment also? What do we see here? You can clearly see an anterior inferior labral tear. This is the intact posterior labrum. This is a bank card solution in a patient who's had anterior dislocation. Another case, you can see labral tear, periosteum bit intact here. So maybe, but it's a little torn here. If intact, you can call it perthes. If you don't call these different fancy names, that's fine. Tell the extent of the tear. So we talk of quadrants. If I imagine this is the three o'clock, this is the 12, six, these are to the one and seven. So this is superior, posterior superior, posterior inferior, inferior anterior inferior, and anterior superior. So now I can tell that the tear is involving the anterior inferior quadrant from three o'clock to six o'clock. Why this is important? Because the surgeon can then decide how many anchors he's going to put if he plans to do surgery. This is important. Every anchor, the cost will increase. So the patient obviously wants to know beforehand how much is going to be the cost of surgery. Surgeon needs to be prepared how many anchors he has ready. I may say a tear involving entire anterior labrum extending across 12 o'clock up to the posterior equator. So slap tears, for example, superior labral tears. You have a classification, 10 types, 12 types. Do I remember all of them? No. If you tell this whole extent, that is good enough. So involving entire anterior labrum going across 12 o'clock up to posterior equator. So that tells you the extent of the tear. Is there also a bony fragment? So now with the labrum, there is this bony fragment. So again, non-faxact sequences help you. This is a bony, bankardly shape. So it's not only labrum, but there's a piece of bone also which has come off with it. Give size of this particular bone. Has the labrum got displaced immediately called as alpsa, anterior labral, periosteal, sleeve, avalches? If you don't call it so, just say anterior inferior labral tear displaced immediately. That's fine. Has a part of the cartilage also adjoining come off? Glynoid labrum, particular defect. So you have a particular cartilage loss also out there. So if you describe anterior inferior labral tear with this much size cartilage defect adjoining, it means the same. Are there any associated findings? For example here, yes, there is a posterior labral tear. Very clearly seen posterior inferior quadrant labral tear. No doubt about that. All of us have picked it. But what else is happening? There is a little depression, anterior superior humeral head with marrow edema. That means there has been a posterior dislocation. This is a subtle reverse hill sack solution. This is a posterior labral tear. Anterior dislocation, the patients will tell you. I feel my shoulder, something is moving. I feel the humeral head popping up. There's something coming out. Posterior dislocation may not be like that. So when you see a labral tear, not enough to say it's a labral tear, see what is the cause, can it? Here, again, I can see normal anterior labrum, tear of the posterior labrum. I can see Osh's remodeling. Can you see this? Here you have a sharp glenoid and here you have an Osh's remodeling. Posterior inferior glenoid Osh's remodeling, posterior labral tear. Then I notice the capsule is lacks all three together. I can ask the surgeon to assess for posterior instead. So look at the pattern. I see a posterior superior labral tear. Clearly, there's a small incipient parallel labral cyst which can enlarge sometimes and cause compression of the suprascapular nerve branches. I also see a posterior supraspinatus anterior infraspinatus under surface tear. Now, I find out the history. This is a young 29-year-old guy. He is into sports. He plays cricket. So overhead abduction activity. So overhead throwing athletes, cricket, gym going, people doing bench presses, badminton, squash, so all of them. If you find this together, posterior superior labral tear, posterior supranterior infraspinatus, tendon gnosis, tendon tears, think of posterior superior impingement. So you can put in your report. Please correlate clinically for posterior superior impingement. Impingement is not a radiological diagnosis, but based on the constellation of findings, you can advise, you can suggest looking for it so that the surgeon knows that he needs to look for that. Now, the next question. Is it really a tear? Now, I start looking at this case and I feel that this labrum here is absent. Anterior superior labrum I barely see. You can see how this posterior superior labrum is seen well. Okay? I see a piece here. So is this a labral tear? Yeah, looks like. But always when you feel something is like a tear, trace it down. When I trace that structure down, I can see it is elongated and inserting onto the lesser tuberosity, deep to the subscapularis tendon. Okay? I see that on sag. It is thick structure like this when I correlate it. So this is a thick middle glenohumeral ligament and the anterior superior labrum is absent. So this is a developmental condition called Buford complex. Anterior superior labrum can have lots of variants. It can be developmentally absent, can be developmentally hypoplastic. Okay? So this is a Buford complex. I just need to mention it and not confuse it with a tear, that's all. Sometimes I may see a cleft at the base of anterior superior labrum. Is it a sublabel foramen, which is a normal variant where the anterior superior labrum is not tightly attached? Or is it a tear? How do I distinguish? One thing, you usually do not get only anterior superior labral tears. It's usually an anterior inferior labral tear or a band cuts extending superiorly or it's a slap or a superior labral tear extending in field. So if you find rest of the labrum, band normal, only anterior superior labral tear, then you are thinking, is this a sublabel foramen? How do I make out? Sublabel foramen is seen in only about two or three sections. You don't see it entire extent. Margins are smooth, sharp, not irregular and you can differentiate most of the times. What if I just cannot make out and you have a labral tear, only anterior superior small one here in two sections, they'll not do anything for those tears anyways. So it's, I think it's still okay if you have not been able to distinguish and you have, they can correlate for the labral size. And that usually doesn't happen as this. At the base of superior labrum, is there a smooth cleft going medially? Underline cartilage is nice and intact. That's a sublabel recess. If it is a superior labral tear, see how the bright signal is going laterally, it's more irregular and you'll also see it extending anteriorly and posterior. So that becomes a superior labral tear. Sometimes can get difficult. You may sometimes very few times but it could really be difficult and then you try to look for other findings and you see whether clinically there are any labral signs. Next coming to the labrum we have seen, patient has instability, patient has bankart's lesion, bony bankart, whatever it is. Is there a hill sacs lesion? If so, what is its size? And is there marrow edema? Is it an acute situation? So this is a hill sacs lesion. It's very shallow. This one is very deep. But now we know more than depth. So yes, you give the depth also but what is more important is this transverse dimension. So we always need to mention the transverse dimension of the hill sacs. On this agital we give the superior-inferior dimension also but this is what is more important and we do give this depth also but to the surgeon what is most important is this transverse dimension. Here I'll say mind-flattening type hill sacs. Here I'll say a deep, wet-shaped hill sacs. Give the transverse dimension superior-inferior dimension and the depth of it, okay? Is it really hill sacs or not? A recap, if you see something right at the top where the humeral head begins like coracoid process and above it, then it's hill sacs. If that part of humeral head is bad normal and only inferiorly you see something smooth and nice like this, that's a normal anatomic groove. You can't have a hill sacs which is large and is extending all the way down but you will not have normal humeral head up and this small little thing here much below the coracoid that's a normal anatomic groove. It's not hill sacs. Next, the most important question the orthopedic surgeon always wants to know what's the glenoid bone loss? What's the glenoid bone loss? Is it significant or not? You look at articles, there are so many different methods. I'll talk about the one that we use. So one quick visual look, what is happening? This is the normal glenoid pear shaped and here you can see straightening. So that straight up the bat tells me this glenoid has some bone loss. Now I need to quantify it how much. How do I do it? We do use the best fit circle method. There are many methods, whichever you use is fine. We draw a straight line along the glenoid axis. We put a circle which best fits the glenoid especially the posterior inferior quadrant. Now this circle I measure the posterior diameter and the anterior diameter, they should roughly be equal. If not, so for example, this is the total diameter and suppose the bone is ending here. So in this case, if I just draw it, okay, this is kind of the circle, it comes a little down. This should have been the total diameter but in reality this is the diameter. So this minus this divided by this into 100 will give you the percentage bone loss. This is how we do it. You draw the circle, you measure it and look at how much of bone loss is out here. Is CT better, MR better? We've been able to convince our surgeons that MR is enough most of the times. I would say 95% of the time we give them but then it should be angled properly. You should take non-fat, fat, fat PD. You should angle it to the parallel to the inferior portion of the glenoid. If sometimes it's difficult. We have an odd banana shaped glenoid or angle not taken properly or not sure. Then yes, we do advise CT because a 3D CT is supposed to be the best way to identify and quantify the bone loss. So you can see this much percentage is the bone loss. What is the magic figure? Nothing. Usually about 20%, 25% is when they operate. They do a lethargy surgeon. Why is it very important? So there's no magic figure. It's not like 19 I'll not operate, 21 I'll operate because they take into account status of the labrum, bone, size of the hill sacs lesion, as well as caps all together. It's not one single value. There will obviously be some inter-observer variability. So when there's a large defect, only repairing labrum is not enough. Surgeon will take a piece of this coracoid and attach it here to try to make it normal shape. Otherwise, if he only repairs the labrum, patient will keep having the current dislocation. This is called as a lethargy procedure and usually done open. So that's why the surgeon wants to know beforehand what is the size of the bone loss. Concept of the last part I'm on, on track versus off track. You can measure the glenoid track by taking 83% of the intact glenoid diameter. From that, you subtract this percent, this amount, which is the bone loss. Okay, that's the glenoid track. For example, just to give you an example, if that is 1.2 centimeter, whatever, just to give a random figure. Then you measure the Hilsex transverse dimension, which we spoke about, that's the Hilsex interval. If glenoid track is larger than the Hilsex interval, that means it's an on track lesion. If it's large, if it's on track lesion and there's significant bone loss, he'll do lethargy. If no significant bone loss, he'll do only soft tissue repair. If it is an engaging lesion, if the Hilsex interval is larger than the glenoid track, that means it's a large Hilsex lesion. Then, in addition to treating the inferior glenoid, whatever he may do, only soft tissue repair or lethargy, whatever it may be, he'll also do a remplissage. So he'll take the infraspinatus and attach it to this defect, trying to make it less of a defect. Okay, that's remplissage. So whether he does only soft tissue repair, whether he does bone surgery, which is lethargy or whether he also does a remplissage is what we are supposed to tell him. Anterior instability, last two questions. Is the inferior glenohumeral ligament intact? Is the coracoid process intact? Because you can have injuries. Here you can see the inferior glenohumeral ligament, which is the inferior capsule itself. There is disruption from the humeral attachment. Humeral avulgen of glenohumeral ligament, haggled lesion. Very important because the surgeon, this is a blind area for him when he goes in. So he needs to know this before the surgeon to plan that he needs to repair. So this is an important question for him. Coracoid process fracture can be associated. And if already there's a coracoid fracture, he may not be able to use it for lethargy. So he needs to know whether it's there or not. So to conclude, we need to know the anatomy, obviously the first starting step. We need to give the information which will decide the management. We as radiologists need to have an active part in the whole process. It's not enough sitting in our room reporting, signing off the report and that's the end of it. You need to have constant interaction with your orthopedicians, constant meetings, clinical meetings where unless you understand the right questions, you will never be able to give the right answers. And shoulder, there are a large number of variants. Be aware of them, use the common principles and use your ability to answer the questions.