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Joint assessment and understanding joint sounds
Part 3 - Disk displacement
Dr. Brady continues reviewing differential diagnosis of the TMJ and discusses how to determine joint vs. muscle pain.
Next in what we describe is what we called a medial pole disc displacement with reduction. Now again we're going to have a patient who comes in and says yes my joints pop or click when I open and close. But there's an interesting piece to this one when they talk about the history. What a lot of the patient in this category will tell you is you know it's really funny my joints pop and click for a long time and then they stop for a while and then the pop came back. That's really them sharing with us the history of the progression from a lateral pole with reduction to a lateral pole without reduction and now to a medial pole with reduction. And as I say one of the things that I want you to keep in mind. It is not a foregone conclusion simply because someone has a disc displacement that it will follow that cascade or follow that progression. For years we actually thought that and we actually used to teach that. But now we know if we can get to the bottom of the factors that are causing this happen, are there mitigating factors like the patient bruxing or clinching or doing things with their teeth. If we can get rid of all the signs and symptoms, the inflammation and the discomfort and we can manage that risk, it's not a foregone conclusion that they'll ultimately lose the entire disc. So what are we going to hear or feel? So now this is a patient again we're going to palpably feel a pop or click on opening but if observe carefully that noise is occurring in rotation, so very very small opening 10-20mm, less than an quarter of an inch. And most of the time if we're listening we're going to hear that pop or click in rotation but now we'll hear crepitus in the translatory movement. So the patient is off the lateral pole and they're off the medial pole but it reduces. What about pain for this patient. So typically when we think about that the medial pole of the disc is still in place so intercuspal position they're not going to have any discomfort. When they just start that early opening movement they get that disc back. So we're going to be able to see where they're going to have pain most of the time in this situation. It could be that initial loads. So if I actually have them just bite on their back teeth they may say it's uncomfortable but as soon as they open it gets better or most of the time what I see is this patient associate still with pain on those translatory movement. So that's going to be an important piece of this. Now one of the things that we want to think about with our medial pole displacement patient is that there is no disc, no hard cartilage between the fossa and the eminence and the condyle intercuspal position. So they can often experience shifts in their occlusion so their bite will change. Next group of patients are patient we're going to say have medial pole disc displacement without reduction. So the medial pole of the disc is off and it does not get back into position during any of the movements. So what are we going to feel? We're not going to feel anything unless they have such coarse crepitus that we can feel that. What's the patient's history going to be like? Again this is a patient who if you say do your joint pop or click, they're going to say no. They don't pop or click. The next question in the history needs to be have they ever pop or click or made noise. Most of these patients then will say to you now that you mentioned it you know they did, they pop and click for a while and then it went away and then it's come back and then it went again. They may lay the whole history out for you. That's not arbitrarily true. They are people who can lose the disc from a macro trauma, a car accident or a fall or a blow to the head. But for most patients there's going to be a history of some joint sounds that seem to have come and gone. So when we think about what we hear cause we said we won't feel anything. Now for this patient with a Doppler or a stethoscope when we auscultate we're actually going to hear crepitus both on rotation and on translation. So that's an important piece of this. And as we said with the last diagnosis anytime the patient is off the medial and lateral aspect of the disc what they are occluding on from a joint perspective when they have their teeth together in intercuspal position is retrodiscal tissue. It's soft tissue. It's very very easy for that to change in shape and dimension. They've also lost the joint dimension of the thickness of that piece of cartilage in the disc. So they may report to you that they've experienced some occlusal changes that all of a sudden they're back teeth were touching heavier. They developed an open bite either unilaterally or bilaterally depending on the joint condition. And even if their bite is stable it is subject to experiencing a change. So that's why these patients, patients with medial pole disc displacement are really the patients that are going to be our higher risk patients not only from the standpoint of treating them as temporomandibular disorder patient but as a restorative dentist or as an orthodontist someone who is going to go in and treat the tops of the teeth. This is someone who can seem simple if we don't discover what's going on with their joint and then turn into a patient who has a lot of problems down the road as we start some very basic therapy for them. So when we think about that people who have a lateral pole disc displacement that's the majority of the patient in my restorative practice. These are patients that are very safe for me to treat as a restorative dentist. They're safe for me to send my orthodontist, have orthodontic therapy done and some of them have signs and some symptoms. So they actually have some pain or inflammation in combination with the sound we may decide it's our best interest and the patient's best interest to treat those signs and symptoms prior to initiating restorative orthodontic therapy. But once we get rid of all that inflammation these are very safe patients to work with. Medial pole patients even we've done therapy in the absence of any current signs or symptoms can have that risk of something changing very rapidly. Now I work with a lot of patients of medial pole disc displacement and the biggest key for me is that they know and they have ownership around their condition that their joints will never be fully stable. And I've had medial pole disc displacement where something as simple as head cold trigger another six months of appliance therapy to try to regain that stability that we had set up before they got sick. They need to understand that and if they do this can be great rewarding patients to threat in your practice. And so one of the things to think about is how is your practice set up to manage this and are you ready to take on this group of patients. Before we leave disc and problems with disc, I want to talk about the phenomenon called the sticky disc. And the graphic on this slide and the first person I ever heard this from was [Parker Mahan]. And you know a sticky disc is kind of an interesting phenomenon. So when a person clinches or loads the joint for an extended period of time it has a significant impact on what's happening with the synovial fluid. And so one of the ways the joint stays healthy is that we open and close it. So we're constantly perfusing that joint. We moving blood in and out, oxygen in and out, taking out all the byproducts of metabolism. And so someone who holds their joint still and under load for a long time will experience synovial fluid changes. Those synovial fluid changes can actually cause the cartilaginous disc to technically get stuck to either the head of the condyle or to the fossa. And so when they first go to open after an extended period of load static clenching, power wiggling they may experience a pop or click. And it could take up to about 30 minutes or so of them opening and closing before the noise goes away and then everything is normal. So what we'll we notice in our offices, most of the time this is a patient that when we ask do you have joint sounds. They say, ìOh yeah, my joint pops and clicks.î And when you said well tell me is it all the time, is it first thing in the morning, they'll report A it's not all the time, it's intermittent. And some will have paid enough attention to be able to say, ìOh yeah you know what every morning when I get up, when I first go to open and I hear a pop and then it will counter pop and click up until maybe after breakfast and then I don't notice it anymore. Sure enough there it is the next morning.î Other patients won't be able to place the time of day or when it happens. But if you ask them may notice that it's always after a really significant workout with free weights cause they're clinching and muscle splinting. Or, you know, it only happens after I sit and I work on my computer for a few hours, so whenever they have period of time when they put that joint under load for an extended timeframe they may experience that intermittent or transient popping and clicking. Really the best way to determine a sticky disc cause most of the time n our offices we're not going to find a palpable joint noise. We're not going to hear anything with a Doppler because at that point the fluid has been worked through the joint and everything is working normally is to try to put the pieces together of that history. Now this is a patient that I worry about over time if we don't figure out how can we change or reduce those forces that load their putting their joint under will they have permanent changes to the disc, to the cartilage, to the soft tissue, to the synovial member that might result in that pop or click becoming permanent instead of intermittent. So this is somebody I might think about playing with bite appliance to see if we can alter the load across the joint enough during sleep or workout or computer time that they don't experience that sign of the disc popping for a transient period of time after they engage in that activity. The next one is one that I called ligament laxity. And really for ligament laxity these are patients that have no history of joint sounds. So when we asked them do your joints pop or click. They're going to say nope, never hear anything. Have they ever done that in the past? Nope, never hear anything. We're going to palpate and we're going to find nothing. Feels normal. We're going to listen with Doppler or stethoscope and we're not going to hear anything. So it sounds perfectly normal and quiet. And these are the patients in my practice the way I think about them are these are the folks that come in for a hygiene appointment, perfectly healthy normal joints and then they called me on my cellphone at 10 o'clock at night and they say my joint are popping and clicking and it's been doing it ever since I left your office after having my teeth clean or sometimes it's something as simple as having a buccal pit composite or the folks that start to pop and click the first week into orthodontic therapy. So what's going on at an anatomic level? What's going on is that the ligaments that help to hold that cartilage disc in place on the head of the condyle have been permanently damaged, have been stretched and no longer have the right tension to help keep that disc in place. But yet the disc is still in place because the shape of the disc that thick other band, the thin center and the way the condyle disc assembly functions is holding it in place. But all it's going to take is one precipitating event where the disc is out of place before all of the sudden it starts popping and clicking. How are we going to find these patients. I will tell you this is a group of patients that I want to know what's going on as a new patient before we initiate therapy. So the way to find ligament laxity is very simple. You literally will just take your pinky fingers and you actually put it inside the patient's ear canal and you push forward. And so typically what I have them is I have the open as wide as possible, push forward. Now as they close if I'm able to actually push the disc forward with finger pressure, I'll now be able to feel a pop or click that totally goes away as soon as I take my fingers out of their ear. So what do I know? What I know is that those ligaments that hold the disc in place are loose enough that with my finger in their ear I can push the lateral pole of that disc forward and now hear joint sounds. But what's holding it in place is the normal anatomy of the disc and I need to share the patient that that could change. Something could precipitate a pop or click that happens all the time. From dental visit to opening really wide to eat a sub sandwich to sometimes yawning. I'm sure you've heard the patient who say is I yawn really big and my joint started popping and it never did that before. It's safe to assume they had some ligament laxity. There had been some damage before. It was just the quiet kind that we don't know about. I told you earlier we were going to talk about part of the diagnostic exam that would help us differentiate pain on range of motion be it joint pain. So is it coming from something in the condyle disc assembly or muscle pain? And again to really see this demonstrated I would encourage that you watch sort of the companion video to this one on joint diagnosis. But we called it a stabilization test. And so when we think about a stabilization test the test itself is really simplistic but yet beautiful in the information that it gives us. And so when we do a stabilization test what I asked the patients to do is bite their teeth together and clinch. As you see in the PowerPoint slide here I actually cradle the patient's mandible and apply pretty firm upward pressure with my hands against their mandible. And I asked them. I say what I'm going to ask you to do is to try to move in the direction that cause you pain when we did your range of motion studies but I don't want you to actually move your jaw but I'm giving you some pressure to brace against. So when I think about that and I think about the stabilization test and so what is that mean for the patient. Again let's go back to our joint anatomy. If it hurt when they were moving but now they're not moving. So I know the condyle disc assembly is doing what? Staying stable. There's no actual joint movement. But what happens as soon as I ask the patient to go ahead and try to move. As soon as you try to move even if you said don't bend your arm but try to bend your arm the muscles fire. It's a feedback loop from just the attempt of it. So when they're stabilize and I say try to go to the right or try to go to the left what I know is happening is their lateral pterygoid muscle, the muscle responsible for those movements is firing. But the condyle disc assembly is not moving and nothing is changing. So if the pain was there when they actually move and is gone when they try to move in a stabilization test, what I can put together is that the pain is coming from the changes in the relationship of the condyle disc assembly during rotation or translation. So they're probably pinching retrodiscal tissue. There's some inflammation but the pain is actually at the level of the joint. If they have the discomfort during actual movement and they still have the pain during stabilization test the only thing that's actually working is the lateral pterygoid muscles. So now I can put together that their discomfort is actually muscular in origin. It's not coming from the level of the condyle disc assembly. So stabilization test and knowing how to do one, it's very very quick and easy, great way to differentiate muscle pain from joint pain cause patient can't. When you ask them where it hurt, they always say right here and they put their finger over their joint. So when we think about putting all of this together as we've gone through thinking about risk assessment and risk management, I hope this piece has given you a better sense of what's going on inside that joint. What is normal three dimensional anatomy look like, the relationship with condyle, the disc, the fossa and the eminence? What does it look like when we think about there is a disc displacement and how do I differentiate when I hear joint noise or there's been a history of joint noise where's the disc. Is it off on the lateral pole? Yeah. That's something that we may need to manage and work with but this is a stable patient. Or, is it off on the medial pole? Am I the right person to work with this patient to manage this, to treat this? And if the patient wants to move forward or needs restorative dentistry, orthodontic therapy, how can I help them understand what the risk and benefits are and the fact that there may not be absolute stability moving forward. So with that I would encourage you to move forward. Try to continue to work on that picture in your mind's eye. It is the answer to putting the puzzle together when you talk to the patient and get the history and when you gather those exam findings. Also as I've mentioned before the companion videos there's an earlier video of doing a joint and muscle exam. There's also a video just on more advance joint diagnosis are a great way now to continue this learning and be able to take it back to your office and implement. So thanks for being with me.