 Welcome everyone to this yet another session of Radiology Journal Club, a new initiative by Indian radiologist. This is the fourth in series journal club which we are conducting online. The one which we started was with the neuroimaging session followed by pressed imaging by Dr. Shilpalad and then we had an excellent session by Dr. Amay Kulkarni on body imaging where he discussed the one interesting article and then two interesting cases. We are thankful to all the key organizers of these events, specifically Dr. Gauri Ahuja for all her efforts, Dr. Sandeep Mani sir, Dr. Deepak Patkar sir, Dr. Jignesh Thakkar, Dr. Shalindra Singh sir and Dr. Mamta Badkar ma'am. So the main intention behind these radiology journal clubs was that every month we meet together online and discuss some upcoming new article and kind of revised important highlights on these articles because we know that sub speciality is the way ahead and in our busy day-to-day schedule we might not get time to read these articles, these advances and to discuss about them. So we make an endeavour to call one expert who has dealt with these things in practical life and take advantage of their experience and make use of all these updates in our day-to-day practice. We are thankful to our key sponsors, Bayers and Phantom for their support for all these initiatives and events and they have shared important updates about their events upcoming as well as their products. So I would request all of you to go through them. So today's session is on musculoskeletal imaging and we are thankful to Dr. Chaitali Parik who agreed to be with us today. She is a young and dynamic radiologist with key interest in musculoskeletal imaging. She will be discussing one important article and after that two interesting cases. Dr. Chaitali is consultant reeling with musculoskeletal radiology with pulsed chain of diagnostic centers and United Diagnostic Center Kalyan, Mumbai. She has completed fellowship in musculoskeletal diagnostics and intervention radiology at InnoVision Imaging, Mumbai. She has received Dr. Aaron Gowell Gold Medal for best paper presentation on MSK interventions, was also selected as one of the best speakers at Redx speaker competition of radiology review courses and she is quite famous on YouTube channel of Indian radiologist with over 5,000 views on almost all her videos and updates and thank you Chaitali for joining us today and we're looking forward to this session from you. We welcome you and over to you Chaitali. Thank you so much Mitesha for this wonderful introduction and I'm extremely sorry if my voice is a bit weird I'm having a bit of a sore throat so please kindly bear with the harsh voice for today. Everybody please having the same issue now. And on the outset I would like to thank Indian radiology for this wonderful opportunity. I know it's an immediate post Christmas time and everybody would be in a vacation mode so I'm not going to keep it too long for today. The article that we are going to discuss is on shoulder instability. Just share my screen. I hope everyone can see my screen. Yes we can see your screen. Okay thanks a lot. So today's article is on shoulder instability predominantly the concept of on track and off track morphology. This article is not a very recent one. It's a couple of years back but this concept has actually gained a lot of importance in today's life and not everyone is aware of this concept but I'm sure in your day to day practice all the shoulder surgeons particularly would be really you know asking for the whether is there an engagement is there not an engagement because once we tell them what status it is of the shoulder joint that surgery plan changes. So now they routinely ask for this stuff because they know that as radiologists we can give them the accurate information and so it is really important on our part to understand that how we are supposed to take these measurements so that the information that you provide to your surgeons is an accurate one. So in today's session what we are going to discuss is first we look at the article which is from the AJR journal. Then we will come back and I will discuss with you about the concept of on track and off track morphology how to take these measurements accurately and then we'll go on to look at some of the cases. So let's just go for the article first. So I think all of you can have a look at this article the link was also shared with you before even if you've not gone through the article before that's absolutely fine you'll understand the entire gist of the article today and whenever you get time in the future you can go back to the article and have a look at it. People who don't do these instability MRIs often it is difficult to keep a track of it so whenever you get such a scan make sure you go back to the article look at the images on how to take the measurements and then you can go ahead reporting the MRI. So this article is on MRI evaluation the key is that it is about MRI evaluation of bipolar bone loss using the on track off track method and this article was written by a giftopolis et al and it was published in October 2015 in the AJR journal so as I told you it's a relatively older article but it's one of the very good articles on this particular topic so that's the reason why I've chosen it. The objective of this study was to determine whether the simultaneous MRI evaluation of hill sacks lesion and glenoid bone loss by the use of on track off track method can be used to predict engagement during arthroscopy. So the thing is that it is easy to evaluate the bone loss and the hill sacks on a CT scan but we don't want to radiate the patient to another CT scan so how can you accurately measure these measurements on an MRI the study is about that so they took 75 patients and who had a prior history of anterior shoulder instability and these patients they got a preoperative MRI done for the shoulder followed by arthroscopy in the same institution and they checked for the engagement that they the data about the engagement that they got on a preoperative MRI and they compared it with whether the shoulder was actually engaging during surgery or not. So as per the results they predicted 13 out of 18 engaging lesions correctly so it's a pretty decent sensitivity of 72% and 58 shoulders which did not engage which means that they were on track they correctly predicted 51 so again it's a pretty decent specificity the accuracy was 84.2% the positive predictive value was 65% but then and the negative was 91% which meant that if you can if you rule out or if you say that this person is not going to engage that is going to be that percentage is higher so to correctly predict that the shoulder is not going to engage is more than to correctly predict that the shoulder is going to engage. So what is this concept of bipolar bone loss bipolar bone loss means looking at the hill sacks lesion and the glenoid bone loss together now for people who are complete amateurs I'll just give you a brief so whenever there is a shoulder instability we all know that usually the shoulder dislocates anterior inferiorly as a result of which the posterior posterior humeral head is going to hit against the anterior inferior glenoid and because of this impaction there is a impaction fracture and an impaction injury in the posterior superior humeral head which is called as the hill sacks lesion and anterior inferiorly because of the continuous impaction either there can be an anterior inferior fracture which is called as the bony bank cart or the osceus bank cart or because of recurrent instability or recurrent anterior dislocations there is bone loss in the anterior inferior glenoid which is called as the glenoid bone loss now till today meaning till recent times the two injuries were assessed separately but with this concept of bipolar bone loss now it is emphasized that there should be a simultaneous evaluation of both hill sacks lesion and the glenoid bone loss and relation and their relation to assess engagement and of the joint so there are two concepts for this on track off track morphology the first one is the glenoid tract so glenoid tract is that so assuming that this is my glenoid articular surface this is my glenoid width right so not the entire width is in contact with the humeral head when the shoulder is in abduction and external rotation which is somewhat like your ball throwing position so this is the common position where you know you are in the end range movement of the shoulder and the shoulder is going to dislocate so the humeral head is going to come anterior inferiorly so this is your glenoid articular surface then you should just understand that sorry just one second yeah so this is the glenoid articular surface the entire glenoid width is not coming in contact with the humeral head so the key thing is that the 83 percent of the glenoid width is what is going to come in contact with the humeral head so whenever we are calculating the glenoid tract the glenoid tract is nothing but 83 percent of the intact glenoid width which is important in the measurements of on track and off track similarly in the hill sacks lesion so besides hill sacks lesion there is another concept called as the hill sacks index which i'll come a bit later so what happens is whenever the hill sacks lesion is smaller than the glenoid tract means that if this is my glenoid tract and my hill sacks lesion is smaller than the glenoid tract it is going to fit within this glenoid and in that condition the there is decreased risk of engagement and instability so if my hill sacks is smaller than the glenoid tract it is less likely that the shoulder is going to engage but if my hill sacks is larger so if this is my glenoid tract and my hill sacks is this big then obviously there is some instability in this region and it's going to dislocate it so this is what is the concept of on track and off track now when can you get the shoulder to engage so when there is a large hill sack lesion when there is a large glenoid bone defect or when it is a mild to moderate size bone defect at both these locations this third concept is really important the third point and we'll look at its examples in some time so you'll understand it better now previously our study was done where they used CT to evaluate the hill sacks lesion and glenoid bone loss along with 3D reconstructions but this article is particularly concentrating on how we can use a 2D MRI so getting a if you take a CT scan you can because it's a 3D thing you can actually rotate and get the exact glenoid articular surface but how you can use a 2D MRI to get those accurate calculations from an MRI this article is about that now this is what we were talking about so if the hill sacks index or if the hill sacks lesion is smaller as compared to the glenoid you can see that it is stable from both ends and it's not going to engage or dislocate whereas here if you see the hill sacks is way larger as compared to the glenoid so there is so here it is not supported and at this juncture it is going to dislocate out so we've discussed this I'm not going to go in details about materials and methods and everything I'll show you how we need to take a scan once we finish this article so as to get the accurate measurements we just go down first so again what I've explained you hill sacks lesion is a region of cortical impaction along the posterior superior margin of the umbral head glenoid bone loss is the percentage and size in millimeters which is best assessed by the best fit circle method now what is this best fit circle method so let's come back to these images so you can see this is an MRI of the patient and you can see the exact glenoid articular surface the n-face view of the glenoid so this is the glenoid articular surface now the best fit circle method states that you need to draw a circle on the glenoid articular surface such that it is going along the posterior and inferior aspect of the glenoid articular surface so the uh the circumference of the circle should lie on the cortex on the posterior posterior and posterior and inferior cortex of the glenoid now when you've drawn this circle properly the idea is if there is no glenoid bone loss the anterior inferior glenoid cortex will lie along the circle so the circle will overlap on the anterior inferior glenoid cortex if there is no glenoid bone loss in this patient if you see this is your circle and if you see the glenoid cortex is over here right so you can see there is this red line which is drawn so this red line is actually the width of the glenoid defect so your cortex is actually going like this and this is actually the length of the defect which is because of the glenoid bone loss so you need to get this dimension and the second thing is the diameter of the circle so the diameter of this circle is actually the diameter of an intact glenoid which should have been in a normal patient right so this is how you use the best fit circle method we'll look at more examples for this and the second thing is the Hilsex lesion now um Hilsex lesion is very well assessed on an axial MRI image the important thing to understand is there are two concepts so when we give the length of the or the transverse dimension of the Hilsex defect that is called as the Hilsex lesion another concept is Hilsex index now Hilsex index if you'll see whenever we look at the for the on track off track method the thing that we need is the Hilsex index which is the length of the Hilsex along with a bony ridge so if you see that the Hilsex is extending till this line so the orange line is your Hilsex lesion after that there is a small intact bony bar between the Hilsex lesion and the intraspinatus insertion so the length that we need is from the intraspinatus insertion up to the medial most margin of Hilsex lesion so that entire length is the Hilsex index in some patients you may not have this bony bar in some patients if the bony bar is present in order to calculate the Hilsex index you need to add this length of bony bar to the length of the Hilsex defect that is your Hilsex index okay again we'll look at these examples for now just understand everything what it is we will look at more examples so the concept is more clear so in this particular circle the larger or the diameter of the circle is nothing but at what I told you that is the length of the width of the intact glenoid this is labed this will label as capital D B for Delhi and the small length which is nothing but the glenoid defect because of glenoid bone loss this will label as small D small deli right so the glenoid track is 0.83 of the glenoid diameter minus the glenoid defect now why 0.83 because as I told you whenever your shoulder is an adaption an external rotation in the extreme position 83% of the glenoid width is going to be in contact with the humeral head not the entire glenoid articular surface so for calculating the glenoid track this is important that you multiply the glenoid width with 0.83 or 83% of the glenoid width so this is how you will get your glenoid track we've already discussed how to get the Hilsex interval or the Hilsex index so it is the width of the Hilsex lesion plus the width of the intact bone bridge between the infraspinators or the rotator cuff attachment and the lateral margin of Hilsex lesion just remember the bone bridge is not present in all the patients but if present it should be added to the Hilsex index so lesions were considered engaging or off track when the Hilsex interval or the index exceeded the glenoid track as I told you and if it did not exceed they were non engaging or having an on track morphology another patient um yeah so this is another patient but you can see they've drawn the circle as for the best fit circle method the diameter of the circle is 27.2 millimeters if you will see the antero inferior glenoid cortex is not overlapping with the antero inferior aspect of the circle so this length in transverse dimension or actually the ap dimension is your um the small d or the width of the glenoid defect and this is the transverse dimension of the Hilsex lesion now if you see in this patient this is your infraspinators attachment right so you can appreciate this entire thing is the infraspinators tendon footprint if you use if you use non fat saturated images the work becomes even more easy so I'll show you how to measure this on a non fat saturated image as well so this is your infraspinators footprint if you'll see the the Hilsex lesion is reaching up to the infraspinators footprint so this particular patient is not having any bony bridge so the Hilsex defect band the the Hilsex defect length is same as the Hilsex index for this particular patient we go back to the previous one here you can see that there is a small bony bridge which is intact so in this case the Hilsex index is slightly larger than the Hilsex lesion okay so now let's just come to the discussion so we've already discussed the results part before in the beginning that they had an accuracy of 84.2 percent which is a very good one they predicted 13 out of 18 patients correctly and having engagement and 51 out of 58 on track lesions were correctly predicted so why all of this is important why do you need to discuss about engagement and stuff like that as I told you engagement can happen in three scenarios when your Hilsex is larger when the glenoid bone loss is more or both of them are average size now if the shoulder is engaging repeatedly by just doing a capsular labour and repair which we usually do for an anterior instability so anterior instability you have an anterior laboural tear capsular laboural tear which is also called as soft tissue bankart lesion so the surgeon goes in and repairs the labour and along with that tightens the capsule but if there is a lot of bony defect despite this soft tissue repair the patient is going to have persistent anterior instability so the surgeon needs to take a step ahead and perform some extra more complicated surgery and if we tell them that such a surgery is needed the surgeon can accordingly plan for it so whenever there is a marked glenoid bone loss they usually go for a procedure called as the lethargic procedure or the coracoid process transfer where they take the coracoid process out and put it in the defect of the anterior glenoid and that's how they increase the width of the glenoid articular surface for a large Hilsex lesion they either do a humeral head bone grafting to fill in the defect or they do a remplissage a remplissage I have just written over here so we'll just skip on to this part so remplissage is a procedure where the infraspinate is tendon and the adjacent capsule is used to fill up the Hilsex defect so he threw this and this is a bit of a complex procedure so the surgeon needs to be well prepared for it so now what were the advantages of this study the first thing is that it has shown that even an MR even if you do the simultaneous evaluation of Hilsex lesion and glenoid bone loss on a 2D MR images you can get accurate results just like 3D CT or 3D reconstruction images so you do not need an extra CT for these patients compared with the CT MRI always helps to evaluate the soft tissue injuries as well like if obviously there is going to be a labral tear there is going to be a capsular injury which you cannot evaluate but just during the CT scan so MRI is like a one-stop shop where you can evaluate everything also and on an MRI evaluating the Hilsex interval is more accurate because you can see the infraspinate is insertion so on a CT scan you cannot really appreciate the infraspinate is insertion correctly and so if whether there is an intact bone bridge or not it's difficult to evaluate on a CT scan but that is very well assessed on an MRI so your Hilsex index is more accurate on an MRI and also it will help to evaluate if there is any bone marrow edema whether the injuries are acute or sub-acute and stuff like that and just remember even if there is a bone marrow edema it is not going to influence your measurements of glenoid tracking and Hilsex index particularly if you use non-fact saturated images because the edema won't be seen separately so this was all about the article it's a bit complex thing if you're going through it for the first time so in order to simplify it I have made a PPT slide out of it so that you understand how to measure everything so the summary of the article what are the terminologies that we've used is one is bipolar bone loss as I told you previously we used to assess Hilsex and glenoid just separately but now we need to assess both of them together what is the relation between them and that is nothing but bipolar bone loss on-track lesion is where the Hilsex lesion is going to stay on the glenoid track and it will not engage so in short your Hilsex index is smaller than the glenoid track off-track lesion is where the Hilsex index or the Hilsex lesion is going to go out of the glenoid track and hence it will be unstable and it's going to dislocate or it's going to engage so which means in practical terms that your Hilsex index is larger than the glenoid track so again just an animation for you to understand that how things happen so when can a shoulder engage so this is one patient who has a decent enough or a small to moderate size Hilsex lesion not a too large one and there is no significant glenoid bone loss you can see the articular surface is decent enough now here if you see the Hilsex lesion is larger there is no significant glenoid bone loss but the Hilsex lesion is larger and if you understand here it's stable at both the ends even in the extreme position whereas here you'll see that there is meaning there is no support on this end of the Hilsex lesion and so what will happen it is going to engage or it's going to dislocate so whenever you have a large Hilsex lesion the shoulder can engage again the same this is just a normal one a small Hilsex lesion for an example this patient if you'll see the Hilsex lesion is of the same size but now this patient has a large glenoid bone loss as a result of which again if you appreciate here there is no support for this Hilsex lesion in the extreme position and again it's going to engage or dislocate so a large glenoid bone loss will cause it to engage and the third condition which is a more important one and is more commonly seen in routine day to day life so individually if you look at this you will say this is not a very big Hilsex lesion individually if you look at the glenoid also you will say that it's not a very big glenoid defect so individually if you'll see at them separately you will feel that this shoulder will not engage but when you'll actually do the measurements and when the surgeon will try to engage the shoulder in the OT so usually in the OT they try to engage the shoulder and see whether the actually the shoulder is engaging or not he will get engagement in this patient why because you can see that despite the fact that this is a moderate size Hilsex and just a moderate size glenoid but there is still the Hilsex is getting unsupported over here and this is going to result into engagement so that is why the concept of bipolar bone loss is important that is assessing both of them together so how do you calculate the glenoid tract we've seen this so the glenoid tract is 0.83 into capital D capital D is your intact glenoid diameter and this is the the width of the glenoid defect and to note just remember that even when you calculate the percentage glenoid bone loss it is the same small D and capital D which is used for the percentage glenoid bone loss so once you get these two measurements your job for glenoid is completely done you'll get all the measurements out of it and how to get them by using the best fit circle method so now let's look at it what is the best fit circle method and how to get the exact image so because your MRI is a 2D MRI it is very important that you get the exact section you'll only get one section on the sagittal image where you can see this entire articular surface of glenoid if that section is not appropriate you will never get accurate measurements out of it then you'll have to go back get a CT done or fall back the patient and get a sagittal image again so just make sure please tell your technicians to plan the sagittal image very accurately in a patient's shoulder instability because it's that one particular image which will give you all the information and if you don't have that one image your information is not going to be accurate so here you can see we all know that the sagittal is planned along the glenoid articular surface so it should be actually along the anterior glenoid so that you get this exact glenoid and face view and if you can see my my line is going just at the level of the glenoid cortex so and if you correlate this axial image to the sagittal image so this is of the same patient you can see that there is some hyper intense structure over here so first thing both of these are proton density images uh non-fat saturated because non-fat saturated usually gives a better evaluation of the bone cortex and everything because your fat marrow is going to be brighter your cortex is going to be hypo so you can actually identify the cortex very well on a proton density non-fat saturated images so here uh at this level you can see that this is your labral tear right so you can see here the labrum is very much intact there is no fluid signal between the labrum and the glenoid here you can see there is a discrete fluid signal between the labrum and the glenoid so this is an anterior inferior labral tear along with that if you can appreciate there is this gray zone over here so this gray zone is the glenoid articular cartilage this gray so this black line is the umbral cortex the gray zone above that is the umbral articular cartilage you can clearly appreciate that there is a defect in this anterior glenoid a condor defect so this is actually nothing but a glad glad is nothing but a glenoid labral cartilage so basically the cartilage is also advanced off along with the along with the labrum so this particular condor defect over here you can appreciate it even on the sagittal image so this hyper intense signal what you see is nothing but this condor defect now coming back to the best circle method so you can appreciate this particular cortex over here and you can see this entire cortex is going like this so you can clearly appreciate the glenoid uh articular cortical margin here you can see this is your tone labrum there is a gap between the glenoid cortex and the labrum so this is an anterior tone labrum and this black thickened structure is nothing but your intact posterior labrum so once you have a decent um uh meaning a very good enphase view of the glenoid you can do the measurements easily so what you do is this is your glenoid you draw a circle now the circle should be such that it's going uh it's along the cortex along the posterior and inferior cortex of the glenoid okay now just remember while taking the measurements one thing which you have to keep in mind is this it should be a complete circle and not a oval because if it becomes an oval again your measurements are going to be wrong how to make sure that it's a circle so whenever so this is a i have used it on an osiris similar thing you can also get it on the radiant viewer as well so whenever you draw the circle you're going to get the width and the height dimensions okay so just make sure that the height and the width are same only then the structure is going to be a circle and not an oval so once you know that both of them are same and this is your circle and it is going along the posterior and inferior cortex of the glenoid uh adequately next thing the next step is to look at the anterior glenoid now here you can see that the circle is actually overlapping the anterior glenoid cortex so there is no glenoid bone loss in this patient first thing second thing for the glenoid tract you need the diameter of the circle which is nothing but 2.7 you can directly take it from these measurements so the diameter of the entire glenoid is 2.7 since there is no glenoid defect the small d in this patient is zero so the glenoid tract is nothing but 0.83 of 2.7 centimeter that is what is a glenoid tract now this is just a comparative image to show you that you actually get the exact same measurements between a CT and an MR so this this was the CT of the same patient you'll see I've drawn a circle here also my diameter is coming out to 2.7 centimeters there is no glenoid defect and the same thing I can reproduce on an MRI so this is just to show you that you do not need a CT for these measurements you can do it on an MRI accurately provided you have uh the proper enphase glenoid view on a PD sagittal or any sagittal image this is another patient here even on a just on eyeballing you can identify that my posterior labrum is good my posterior cortex is good so glenoid has a pear shape so it should have actually gone like this but you can see that it's blunted over here so there is some amount of anterior glenoid bone loss how much it is we'll calculate so this was my circle going uh along the posterior inferior cortex and here you can see that it is not going along the anterior cortex so this is my anterior cortex and this is my length of the glenoid defect or the small d which I'm talking about so this is the length of the glenoid defect my capital D is the intact glenoid diameter which you you did not measure actually you can directly get it from these measurements so it is 2.7 centimeter so this is my intact glenoid diameter again just remember it should be an exact circle and not an oval if you make it an oval uh your diameter your the length of the defect is going to be wrong so this is it and then you can just put it in the formula you've got the small d you've got the capital D and you'll get a glenoid tract out of it now um as just a third example again over here in this patient uh you can see that on the CT you can clearly appreciate that this patient has an anterior inferior oceus band cut or a bony band cut lesion but again you can also appreciate it on the MRI so you can see that this is my glenoid articular surface you can appreciate that this is a bone piece lying over here and identifying bone piece is more easy on a proton density image than on a meaning of proton density non-fat saturated image than on a fat saturated image so if you look at it closely even small uh bony band cut lesions can be identified on a MR image if you have the proper sections so this is my bony band cut over here which can be seen on the CT which is just for your for your visualization um and here you can see that this is my blunted anterior inferior glenoid margin so you can draw the circle and you can get the defect now why have I put this example whenever you are calculating um the glenoid tract for this patient please exclude this exclude the bone which is broken out okay so the surgeon needs to know that after you remove this bone or without this bone chunk whether the shoulder is going to engage or not going to engage you can put it in the report also clearly that excluding the uh anterior inferior oceus band cut lesion the glenoid bone loss is such and such percentage and the glenoid tract is this much so you can actually make it very specific and clear on the report that you have not included the oceus band cut lesion in the calculation of your glenoid tract and glenoid bone loss so we have seen how to calculate the glenoid tract which was the more difficult part now we look at how to calculate the hill sacs index so hill sacs index as I've told you it's hill sacs lesion plus bony bar between the lesion and the infraspinatus emphasis so again we just look at examples of this so this is a patient with the hill sacs index with the hill sacs lesion and obviously your hill sacs lesion the dimension that you need for the hill sacs index is the transverse dimension that's why I've only shown you ancient images and as I told you proton density non-fact saturated image will be more helpful in looking at the bone if you take fat saturated images there will be bone marrow edema it is difficult to identify because your bone cortex marrow and infraspinatus tendon everything is going to be shades of black and gray it is difficult to identify the exact bony bridge because bony bridge are not too long they are smaller ones and so a non-fat saturated image will be more helpful so here you can see this is my hill sacs lesion and so while giving the measurement of the hill sacs lesion I will say that the transverse dimension of the hill sacs defect is 1.1 centimeter but this patient if you see this is the level where my infraspinatus emphasis is right or the insertion is so there is an intact bone between the infraspinatus and the medial most margin of hill sacs sorry the lateral margin of hill sacs and this length is nothing but the bony bar or the bony bridge so my hill sacs index in this patient is going to be 1.1 plus 0.7 which is 1.8 centimeter while in this patient if you see the hill sacs defect is actually extending up to the insertion of the infraspinatus tendon so this patient does not have a added bony bar so in this particular case the hill sacs lesion transverse dimension is going to be the hill sacs index for the measurement of on track and off track so I hope you understood this concept of bony bar and how to find it so just remember one thing the meaning what does the what can you derive from this the hill sacs lesion which is more medially located meaning towards the humeral articular surface so the lesion which is more medially located will have a larger hill sacs index and is more likely to engage as compared to a same size of hill sacs lesion which is more laterally located towards the infraspinatus insertion right so the lesion which is more medial will engage more compared to the lesion which is more lateral towards the greater tuberosity so let's just look at the cases now okay so this is a patient um you can clearly see the hill sacs lesion in this patient so this is your proton density image and what we're going to do is we're just going to come from top to bottom now sorry okay so I don't want you guys to concentrate on the tendons and everything for now please just look at the the labrum the glenoid and the posterior superior humeral head so first we look at the posterior superior humeral head so here as you see um just remember for measuring of hill sacs lesion defect or even for identifying the hill sacs lesion the key thing is that you need to look at the defect at the level of porcupine process okay not below the level of porcupine process so if you'll measure over here this is not the level for a gleno for a hill sacs lesion even in normal or symptomatic individuals without any history of instability this kind of flattening is normally seen at the level of infraspinatus insertion below the level of porcupine process so if you have to identify a hill sacs lesion make sure to look at or above the level of porcupine process so here you can see that actually it should have been a complete um round structure like this so this is how my humeral head should have looked like but I can identify that mine that there is this much of flattening over here right so that so obviously this patient has a hill sacs lesion then we just look go and at the level of um sorry yeah so then at the level of maximum hill sacs lesion we take the diameter oh sorry we take the length of the hill sacs defect so here you can see that this defect is approximately 2.2 centimeters in length okay and if you'll identify the infraspinatus insertion so you can see that this is the level where my infraspinatus is actually coming and getting inserted right so it is at this level so surely there is no bone bar in this patient so the length of the hill sacs defect is going to be the hill sacs index for this particular patient so this is how you go inferiorly and this is your humeral head has been evaluated now we look on the glenoid side so again we are going to come down from top to bottom so here if you see this is my superior most labrum okay you can see that there is some linear signal over here superior labrum is best assessed on your coronal images so here you can see that so this is my level of superior labrum so you can see that there is some tear that is beginning in the superior labrum over here so there is a tear over here and as you go further inferiorly you can see that there is a tear over here the posterior labrum looks okay further inferiorly you can see that there is a tear over here there is a tear over here the posterior labrum looks okay okay so till inferior most sections you can appreciate the tear in the anterior labrum whereas the posterior labrum is intact so you have an entire anterior labrum tear over here and the posterior labrum looks good. So we assess the soft tissue banker injury so we know that there is an entire anterior labral tear. Now the most important thing is whether it's engaging or not and for that what you need is your glenoid tract. Now for the glenoid tract, the section that I need is the glenoid articulate. So you can see I'll just go a step back. So here you can see this is my cortex, the glenoid cortex very well seen. Above that you can appreciate the gray glenoid cartilage and then you have the gray cartilage of the humeral head. Now the green line is actually the planning that was done by the technician and if you see it it's exactly cutting on at the cortex of the glenoid articulate surface and hence I can get this wonderful enface view of the glenoid just like what I would have gotten a CT scan. Now when you come inferiorly it is difficult to appreciate over here that there is a bony bank cart or an auspicious bank cart but you can surely identify that there is some blunting of the anterior inferior glenoid. So here you can see it's nice and pointy here you can appreciate that it's blunted out and when you look at the corresponding sagittal image you can appreciate that there is bone over here. So you can see that this is the cortex and this is a bony chunk over here. So this is your, sorry, so this is nothing but a bony bank cart which is about seven millimeters in length and this is my enfase glenoid. I can, I, so as I've told you the glenoid has a pair shaped appearance but here you can see that it has been blunted out over here. So now when I take this circle method, okay, I'll just draw a circle and show you. So I'm going to draw a circle. Okay, so here if you can appreciate, so this circle is now very, it's properly passing along the posterior and inferior cortex of the glenoid. The diameters of both the width and the height is 2.7 centimeters, so which means that it's a proper circle. So my diameter of this intact glenoid should have been 2.7 centimeter but it is not and the defect length now over here is the, is about 3.3 millimeters or in short 3 millimeters. Okay, so you can just make the calculations. So you can just put it on the calculator and just say 0.83 of 2.7. So this is 2.2 centimeter right and so glenoid track is 0.83 into 2.7 which is 2.2 centimeter minus 0.3 centimeter. So it's going to be 1.9 centimeter. So my glenoid track then this patient is 1.9 centimeter and I have already, I think I did it at, so, sorry, and my hill sacs is approximately 2.2 centimeter. So in this particular patient, the hill sac index is larger than the glenoid so it is likely to exceed. So once when you give this information that the hill sacs is large and the glenoid bone loss is not too much, the surgeon knows that if the shoulder is engaging he needs to go for a remplissage procedure because the glenoid bone loss is not that much that he needs to do a lethargic procedure in it. So if there is engagement even on arthroscopically, he'll be well prepared before the surgery for remplissage procedure in this patient. So this is how, this was one case. Let's look at the, sorry, I do have a CT of this patient just to show you the bone beef, the Oceus Bankard. So this was the same patient and you can see this was the Oceus Bankard that we measured at 7 millimeters and even on a CT scan, you can appreciate that it is actually 7 millimeters. So if you have that exact image, you can identify the Oceus Bankard smaller ones even on an MRI. This is my second patient. So again, we are looking at the proton density action images. I'm going to pick up proton density images because as I told you for me, differentiating structures on a non-fat saturated image is more easier. So as we go from top to bottom, I told you at the level of the green coropoid process, if you begin to see a defect, that is what is a Hilsex lesion. Okay, now here you can see this patient has a more medial Hilsex lesion, right? So this, so this is my Hilsex lesion over here and on the length of the Hilsex defect is 1.1 centimeter transverse. And here, if you see my intraspinatus insertion is this. So this is my intraspinatus emphasis, this entire line. Okay, so this is my intraspinatus emphasis. So what I have is an intact bony bar between the intraspinatus emphasis, sorry, up to the, so between the intraspinatus emphasis up to the Hilsex lesion. So this intact bony bar, okay, is there. So now my Hilsex defect transverse dimension is 1.1 centimeter, but my Hilsex index is going to be 1.1 plus 0.7, which is nothing but 1.8 centimeters. So my Hilsex index is larger. Why? Because the Hilsex lesion, though it is a smaller Hilsex lesion, it's a medially placed Hilsex lesion. And such medially placed Hilsex lesions are more likely to engage. Now let's look at the labrum. So we first get a coronal view. Okay, so here, this is my coronal view. And just to tell you, the previous image was that of a 3 Tesla, but this is that of a 1.5 Tesla. So you can see that with good quality images, with the proper planning, you can get very good quality images even on a 1.5 Tesla scanner, you don't need to do our programs and stuff like that to look at the labrum. So here is where I am in the top most section, okay, here. And you can see that this place, you can get some magic angle artifact in the posterior superior labrum, but here, surely there is a labral tear, which is beginning, okay. And here you can appreciate that there is a discrete labral tear. As you go inferiorly, here also, if you appreciate that there is a tear even in the posterior superior labrum. So there is a tear here. And in fact, there is a tear here as well. You can see this white line that's going through. And as you go further inferiorly, this is your intact posterior labrum, right? So up to the level of the equator, see here you can see the tear over here. So up to the level of the, or just above the level of the equator, even the tear is extending into the posterior superior labrum. And this is your tear in the anterior labrum. And this is again your tear in the anterior inferior labrum. And now what you can see is this is the adjacent anterior glenoid condor defect, you can appreciate the rest of the cartilage very well. And as you go further inferiorly, you can see the control flap over here, right? So even on a coronal image, you can see this control flap over here. Okay. So these are the control, this is the control flap, which is actually come out from this level. Now, you can see a torn labrum. You look at this anterior inferior glenoid, it's well rounded, just like a posterior inferior glenoid. So you don't see any obvious blunting of the glenoid, it's nice and rounded. Okay. Here also, it's nice and rounded. So from this, you can judge that there is no significant anterior inferior glenoid bone loss. By significant, I mean, at least it's going to be less than 10%. So if a bone loss is less than 10%, the surgeon is not going to operate. If the bone loss is more than 25%, then they do consider a lethargic procedure between 10 to 25% is again, it's a question of debate. Some surgeons will operate and do a lethargic after if it's more than 20%, some can do if it's more than 15%. So depending upon whether shoulder is engaging or not, and depending upon what is their routine practice going to be, the percentage can vary. So it is best that you, the ortho calls that you're working with, you get an idea from them that when is it that they actually consider a lethargic procedure between 10 to 20% cases, meaning 10 to 20% glenoid bone loss cases. So here again, I'll just draw the circle quickly. Sorry. I'll just redraw the circle. Yeah. So this is my circle. Okay. Yeah. So now if you can see, I've drawn a circle, which is that, which has a diameter of 2.8 centimeter, and it's pretty much going along the anterior inferior glenoid as well. So this person does not have a glenoid bone loss. And the glenoid practice just going to be 0.83 of 2.8, which is going to be 2.3 centimeter. And my hill, though it's a, in this particular patient, though it was a medially placed, Hilsex lesion, the Hilsex index is coming out to be 1.8 centimeter. And the glenoid practice 2.3 centimeter. So this is less likely to engage. So this is our on track or a non engaging morphology. Okay. And just I would like to show you the CT image of this N-phase glenoid just to show that it really did not have a anterior glenoid bone loss. Now the third and the last case that we're going to look, this is also a 1.5 Tesla MRI. So you can see that you can appreciate the structures very nicely. So here you have a small Hilsex lesion. Okay. And at the level of the, at and above the level of chorophoid process, you can appreciate this Hilsex lesion. This is going to be the length of the Hilsex lesion. And you can clearly see that the lateral margin of the Hilsex lesion is just adjacent to the infraspinatus insertion. So your Hilsex lesion transverse dimension is same as your Hilsex index. And so here you can see that you can appreciate that there is a tear in the superior labrum over here. Okay. This thing. So you can see that there is a tear in the superior labrum. And here on the actual images, you can see that the anterior labrum is torn, but the posterior labrum is good. And inferiorly also you can appreciate the anterior labrum is gone and the posterior labrum is good. Now you can see that here on this image, there is a blunting. Okay. So this has, this is my glenoid. In this particular image also, you can appreciate that there is this blunting. So my, it's going like this. And then there is a blunting over here. Sorry, there is a blunting in this part of the glenoid, right? So this part of the glenoid is well unpointed posterior inferior and the anterior glenoid is blunted out. And if you go inferiorly, you can actually appreciate that there is a bony piece over here. So you can appreciate the cortex in this region. So this is a bony piece. And now when you look at the corresponding sagittal image, you can appreciate that this is the bony piece over here. And this is my bony chunk. So you can clearly make out this bony piece. And when you want to make the diameter, take the diameter out for the glenoid track, this is how we will measure it. So just make sure what, what I was talking about is don't get a circle like this. Okay. So now you know that one is three and one is 3.6 centimeters. So this is a oval and not a circle. So just make sure that you get a proper circle and don't over exaggerate. Don't make a bigger circle because then you will get a larger meaning if I'll take a circle like this. Okay. So this is a circle. And if I take a circle like this, I'm going to get a glenoid defect, which is like literally eight millimeters in length. But this is not the right way. The idea is that you should draw a circle just large enough so that it covers your posterior posterior and inferior aspect of glenoid. So you need to adjust it and make it a bit small. Okay. So here this looks decent enough. Now it's actually going in my posterior and inferior glenoid. And this is my level of the glenoid defect. So here I can just measure the length. So it's four. So my glenoid tract is going to be 2. So this is 2.9 centimeter. So 0.83 of 2.9 centimeter is 2.4 centimeter. And then you're going to subtract 0.4 centimeter, which is the defect of the glenoid bone loss or the length of the glenoid defect. So it's going to be two centimeters. So my glenoid tract is 2 centimeter. And my Hilsex index is 1.4 centimeter because there is no extra bony bar over here. And so obviously my Hilsex is smaller than glenoid. And so this is going to be a on-track morphology. So with this, we've discussed the cases also and almost through the session now. So today what we've discussed is what exactly is the concept of bipolar bone loss. How do we take these measurements? Just remember, CP is not needed for assessing engagement if a proper MRI planning has been performed. Hilsex index and evaluation is more accurate on an MRI because you can see the intrustinitis insertion very well on an MRI. That's it for today. Thank you. Merry Christmas. Belated Merry Christmas. And if you have any queries, you can ask me. Thank you, Jathali, for this wonderful session which you took. And you have really simplified a very new concept, which looks very complex for beginners specifically. And yes, all of us who are reporting shoulders, the surgeon want to know all these measurements. So to specifically write it down that whether it is on-track or off-track, you have to give all those measurements. So and by articles, it's difficult to understand. Like if it is your first patient and you start reading the articles, you might miss very important points. So I would just remind this to everyone listening that all of this is going to be on the YouTube channel. So every time you are doing the shoulder reports, you can revise what Jathali has just discussed on the YouTube channel and understand these important measurements. There are a few questions in the channel. So one is regarding the positioning. So is that ABER positioning required or not required? And one question is that if there is a discrete bony glenoid fragment, as you showed in one of the examples, which can be reattached to the glenoid, is it necessary to describe on-track off-track? Or should we just mention as an ABER's bony fragment size and the surgeon can reattach it? So you need to understand again, what I have told is that on-track off-track is both HILSAX and glenoid put together. Okay, there are cases where you have a large HILSAX and no glenoid bone loss, yet it is going to engage. And in that case, the surgeon will have to consider replacement. Yes, you need to give the size of the bony fragment. The first thing that the surgeon is going to consider is put the bony fragment back. But one more thing that you need to remember is these patients, they don't come immediately post-injury. These patients come, some patients will come after years. And that bony fragment has actually got remodeled and the surgeon cannot. So if you want to fix back a fracture, it's like a jigsaw puzzle. The edges should match. Once the injury is old and there is an auspicious remodeling that has happened, the edges are not going to match, the surgeon won't be able to fix it back. In that case, he will take a coracoid and put it there so that he'll freshen out the edges and he'll put a coracoid trusses there. So you need to give him this for two reasons. One is if it's an old surgery, then he has all the details because he knows that he's not going to fix back that bony, the bony piece back into the glenoid. Secondly, even after fixing back the bony piece, there is still a possibility that the patient may have engagement because the hill sacs could be very long. So it is always advisable to give it to him. Thank you for taking that in details. And one more question is there that can these all be used for reverse bank card defects? No, this concept is not used for reverse bank card defects precisely because the surgery is not performed at all. So for a reverse bank card usually the surgeon does not go for a bony bank card repair or stuff like that. So the surgery, so we just need to understand that our radiology is a kind of a dependent branch. It depends upon what the orthopods are actually practicing in day to day life. We can do as many calculations as we want, but if it's not practically useful for them, we are wasting our own time. So if maybe in the future they might come up with surgeries where they will start doing a kind of a lethargic procedure even for a posterior inferior, like mean for a reverse bank card, then yes, maybe we'll get to, we'll start doing measurements for them as well. But as of today, such surgeries are not done. So it's no point that we waste our time on. And just one more query. So there is like, what is the proper time that the scan should be done like after an event of shoulder dislocation? So ideally, if there is a Osias bank card, large one, the ideal thing is that it should be done immediately. When it just after the dislocation, when it's relocated back and the surgeon will come, the patient will come for the scan. The only disadvantage with an immediate scan is that you are going to assess the soft tissue injuries. You're going to exaggerate the soft tissue injuries because of the edema. So the capsular injury, the labral tear, you might over exaggerate a bit. But if there is no proper Osias bank card lesion, then it is ideal that we do it say after four weeks, when the soft tissue injury edema has gone down, so you can evaluate it accurately. But if there is a bony piece, then obviously you need to fix the bony piece back. So in that particular case, an immediate scan is going to be more helpful. So thanks once again, Chatali. And we have taken all the questions which were there in the Q&A box. So please do visit our YouTube channel for more of such informative videos. And this particular session is also going to be there recorded. So you can revise all these details. And please do use all these things which we discussed on track, off track and different measurements for your shoulder reports that will definitely enhance the quality of your report and help your Autobots. So with this, once again, thank you for your time. And in a very short notice, you agreed to be with us today. Looking forward to more of such sessions. And thank you, Dr. Amit for your support and the entire technical things which you do for us. I would request you to please play the Sonobas video once again. Just before that, thank you so much, Mitrusha. And thank you, Indian cardiologist team. This is a very good initiative because you are right. I myself am a very horrible person for reading articles. I just cannot read articles, but this is really a good initiative to be up to date with all the new advances that are coming. Thank you. So now all of you, please do register for Sonobas. We are coming back with the actual events and conferences. So it's time to re-breathe after all this two year long pandemic which we had with all those precautions definitely. So with this, thank you all for being with us today. And let's see and meet all of us together in the Sonobas.